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1
Grainger, Stewart L. J. "Filament structure and phosphatase activity in the Rivulariaceae." Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6498/.
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A study was carried out on phosphatase activity, phosphate uptake and its relationship to hair formation in the Rivulariaceae. The Rivulariaceae was chosen as it is a widespread taxon, where hair formation is a common occurrence, and previous studies indicated that they originate from environments where a large proportion of the phosphorus (P) is present as organic P. It seems possible that hair-forming Rivulariaceae are especially well adapted to utilize organic P. Initially 51 axenic cyanobacterial strains, from 10 genera, were screened for yields using organic P sources and for cell-bound and extracellular phosphomonoesterase (PMEase) and phosphodiesterase (PDEase) activities. All strains exhibited detectable inducible PMEase activities, and highest cell-bound PMEase activities were in hair-forming Rivulariaceae. Synechococcus had significantly low cell-bound phosphatase activities and five strains were unable to hydrolyze phytic acid. PDEase activities were lower compared to PMEase activities in all strains. Strains isolated from deepwater rice habitats had significantly higher levels of PDEase activity. In the three Calothrix strains tested, Calothrix 202, 550 and 603, inducible phosphatase activities were similar whether the P source was inorganic or organic. PMEase synthesis in these strains began when cellular P (% dry wt) values were in the range 0.60 - 1.0%. Differences in the influence of environmental variables on cell-bound and extracellular PMEase activities in hair-forming Calothrix 550 were slight, suggesting that PMEases in the two fractions had a common origin. Of the eleven ions tested Ca had the most pronounced stimulatory effect on PMEase activity. Localization of enzyme activity in Calothrix 550 suggested that the enzyme was bound to a surface. Partial purification of an extracellular PMEase fraction detected four bands of PMEase activity on a non-denaturing polyacrylamide gel. Three of the four bands were associated with carbohydrate and the bands were not extractable by mechanical means. Localization of PMEase activity in hair-forming strains by azo dye (naphthol AS-MX) and 5-bromo-4-chloro-3-indolyl phosphate (BCIP) showed that PMEase activity was associated with hair cells. Phosphate uptake experiments with Calothrix 253 and 550 suggested that uptake at high external phosphate concentrations was located in hair cells. NaCl, above 67.5 mM, inhibited hair formation and subsequently phosphatase activity in Calothrix 253 and 690. Addition of mannitol or sorbitol had no effect on hair formation, suggesting inhibition of hair formation was not an osmotic effect. Removal of P-deficient cultures from saline to freshwater media led to a marked synchronization of hair formation (in 90% of trichomes) and increase in cell-bound PMEase activity. Localization of cell-bound PMEase activity by light microscopy, using naphthol AS-MX, detected activity in the hair cells.
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Ratnayaka, Helen Sum Kay. "Effects of protein kinase inhibitors on hair bundle structure." Thesis, University of Sussex, 2010. http://sro.sussex.ac.uk/id/eprint/2335/.
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The sensory hair bundles of the cochlea are complex structures that are vital for hearing. Phosphorylation plays an important role in regulating actin in many cell types, but the role it plays in regulating the development and maintenance of the hair bundle has yet to be fully elucidated. Furthermore, the extent to which damaged hair bundles can be repaired in the mammalian cochlea remains to be determined. The aims of this study were twofold: 1) to assess the role of phosphorylation in hair bundle development and 2) to ascertain whether hair bundles could recover from any damage caused by protein kinase inhibition or the aminoglycoside neomycin. Post-natal mouse cochlear cultures were treated with a range of protein kinase inhibitors. Of those tested, the broadspectrum protein kinase inhibitor staurosporine was found to cause hair bundle collapse and detachment of the apical cell membrane from the cuticular plate without causing cell death. Further investigation suggests that staurosporine may have its effects through inhibiting the function of the Ezrin-Radixin-Moesin proteins, an important family of proteins that cross link actin to the plasma membrane. An inhibitor of c-Jun NH2-terminal kinase, JNK inhibitor I, was also found to cause the loss of hair bundles, but in contrast to staurosporine, also caused hair cell death. This was unexpected, as previous studies have shown that inhibition of c-Jun NH2-terminal kinase confers protection on hair cells from noise and aminoglycoside damage. Recovery of hair bundles was not observed following brief treatment with either staurosporine or neomycin. The current study shows that protein phosphorylation is vital for the proper maintenance of the hair bundle, and hair that bundles show little sign of recovery from limited damage in vitro.
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Baumgart, Johannes. "The Hair Bundle: Fluid-Structure Interaction in the Inner Ear." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-63810.
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A multitude of processes cooperate to produce the sensation of sound. The key initial step, the transformation from mechanical motion into an electrical signal, takes place in highly specialized mechanosensitive organelles that are called hair bundles due to their characteristic appearance. Each hair bundle comprises many apposed cylindrical stereocilia that are located in a liquid-filled compartment of the inner ear. The viscous liquid surrounding the hair bundle dissipates energy and dampens oscillations, which poses a fundamental physical challenge to the high sensitivity and sharp frequency selectivity of hearing. To understand the structure-function relationship in this complex system, a realistic physical model of the hair bundle with an appropriate representation of the fluid-structure interactions is needed to identify the relevant physical effects. In this work a novel approach is introduced to analyze the mechanics of the fluid-structure interaction problem in the inner ear. Because the motions during normal mechanotransduction are much smaller than the geometrical scales, a unified linear system of equations describes with sufficient accuracy the behavior of the liquid and solid in terms of a displacement variable. The finite-element method is employed to solve this system of partial differential equations. Based on data from the hair bundle of the bullfrog's sacculus, a detailed model is constructed that resolves simultaneously the interaction with the surrounding liquid as well as the coupling liquid in the narrow gaps between the individual stereocilia. The experimental data are from high-resolution interferometric measurements at physiologically relevant amplitudes in the range from a fraction of a nanometer to several tens of nanometers and over a broad range of frequencies from one millihertz to hundred kilohertz. Different modes of motion are analyzed and their induced viscous drag is calculated. The investigation reveals that grouping stereocilia in a bundle dramatically reduces the total drag as compared to the sum of the drags on individual stereocilia moving in isolation. The stereocilia in a hair bundle are interconnected by oblique tip links that transmit the energy in a sound to the mechanotransduction channels and by horizontal top connectors that provide elastic coupling between adjacent stereocilia. During hair-bundle deflections, the tip links induce additional drag by causing small but very dissipative relative motions between stereocilia; this effect is offset by the horizontal top connectors that restrain such relative movements, assuring that the hair bundle moves as a unit and keeping the total drag low. In the model the stiffness of the links, the stiffness of the stereocilia, and the geometry are carefully adjusted to match experimental observations. The references are stiffness and drag measurements, as well as the coherence measurements for the bundle's opposite edges, both with and without the tip links. The results are further validated by a comparison with the relative motions measured in a sinusoidally stimulated bundle for the distortion frequencies at which movements are induced by the nonlinearity imposed by channel gating. The model of the fluid-structure interactions described here provides insight into the key step in the perception of sound and the method presented provides an efficient and reliable approach to fluid-structure interaction problems at small amplitudesBei der Hörwahrnehmung eines Klangs spielen viele komplexe Prozesse zusammen. Der Schlüsselprozess, die Umwandlung mechanischer Schwingungsbewegung in elektrische Signale, findet in den Haarbündeln im Innenohr statt. Diese Haarbündel sind hoch entwickelte mechanosensitive Organellen, bestehend aus vielen nahe beieinander stehenden Stereozilien umgeben von Flüssigkeit. Die beträchtliche Viskosität dieser Flüssigkeit führt zur Energiedissipation und zur Schwingungsdämpfung, was im Gegensatz zur bekannten hohen Empfindlichkeit und der ausgezeichneten Frequenzselektivität der Hörwahrnehmung steht. Um die Komponenten des Haarbündelsystems in ihrem funktionalen Zusammenspiel besser zu verstehen, bedarf es eines wirklichkeitsgetreuen Modells unter Einbeziehung der Wechselwirkung zwischen Flüssigkeit und Struktur. Mit dieser Arbeit wird ein neuer Ansatz vorgestellt, um die Mechanik der Fluid-Struktur-Wechselwirkung im Innenohr zu analysieren. Da die Bewegungen bei der normalen Mechanotransduktion wesentlich kleiner als die geometrischen Abmessungen sind, ist es möglich, das Verhalten von Fluid und Struktur in Form der Verschiebungsvariable in einem linearen einheitlichen System von Gleichungen ausreichend genau zu beschreiben. Dieses System von partiellen Differentialgleichungen wird mit der Finite-Elemente-Methode gelöst. Basierend auf experimentell ermittelten Daten vom Haarbündel des Ochsenfrosches wird ein detailliertes Modell erstellt, welches sowohl die Interaktion mit der umgebenden Flüssigkeit als auch die koppelnde Flüssigkeit in den engen Spalten zwischen den einzelnen Stereozilien erfasst. Die experimentellen Daten sind Ergebnisse von hochauflösenden interferometrischen Messungen bei physiologisch relevanten Bewegungsamplituden im Bereich von unter einem Nanometer bis zu mehreren Dutzend Nanometern, sowie über einen breiten Frequenzbereich von einem Millihertz bis hundert Kilohertz. Das Modell erlaubt die Berechnung der auftretenden viskosen Widerstände aus der numerischen Analyse der verschiedenen beobachteten Bewegungsmoden. Es kann gezeigt werden, dass durch die Gruppierung zu einem Bündel der Gesamtwiderstand drastisch reduziert ist, im Vergleich zur Summe der Widerstände einzelner Stereozilien, die sich individuell und unabhängig voneinander bewegen. Die einzelnen Stereozilien in einem Haarbündel sind durch elastische Strukturen mechanisch miteinander verbunden: Die Energie des Schalls wird durch schräg angeordnete sogenannte Tiplinks auf die mechanotransduktiven Kanäle übertragen, wohingegen horizontale Querverbindungen die Stereozilien direkt koppeln. Während der Haarbündelauslenkung verursachen die Tiplinks zusätzlichen Widerstand durch stark dissipative Relativbewegungen zwischen den Stereozilien. Die horizontalen Querverbindungen unterdrücken diese Bewegungen und sind dafür verantwortlich, dass sich das Haarbündel als Einheit bewegt und der Gesamtwiderstand gering bleibt. Die Steifigkeit der Stereozilien und der Verbindungselemente sowie deren Geometrie sind in dem Modell sorgfältig angepasst, um eine Übereinstimmung mit den Beobachtungen aus verschiedenen Experimenten zu erzielen. Als Referenz dienen Steifigkeits- und Widerstandsmessungen, sowie Kohärenzmessungen für die gegenüberliegenden Außenkanten des Bündels, die jeweils mit und ohne Tiplinks durchgeführt wurden. Darüberhinaus sind die Ergebnisse durch den Vergleich mit experimentell beobachteten Relativbewegungen validiert, die das Haarbündel infolge von sinusförmiger Anregung bei Distorsionsfrequenzen zeigt. Diese haben ihren Ursprung in dem nichtlinearen Prozess des öffnens von Ionenkanälen. Das entwickelte Modell eines Haarbündels liefert neue Einblicke in den Schlüsselprozess der auditiven Wahrnehmung. Zur Behandlung von Problemen der Fluid-Struktur-Wechselwirkungen bei kleinen Amplituden hat sich der hier ausgearbeitete Ansatz als effizient und zuverlässig erwiesen
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Colenci, Ana Vivian Parrelli. "Efeito de uma formulação contendo o biopolímero quitosana sobre a fibra capilar caucasiana." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/82/82131/tde-14022008-090538/.
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Há um número crescente de indústrias no ramo de cosméticos atualmente, devido ao fato das pessoas se preocuparem mais com suas aparências e ansiarem por produtos de qualidade. Em decorrência desse fato as indústrias vêem investindo cada vez mais nas áreas de pesquisas e desenvolvendo tecnologia neste segmento. Este trabalho visa o estudo das fibras capilares e a interação das mesmas com uma formulação comercial contendo como ativo principal o biopolímero quitosana. Utilizou-se para tanto técnicas como microscopia eletrônica de varredura, microscopia ótica, microscopia de força atômica, análises térmicas (TG/DSC) e análise de espectroscopia de absorção na região do infravermelho. O estudo foi feito com cabelos caucasianos virgens (sem tratamento químico) e em cabelos caucasianos descoloridos. Os resultados evidenciaram melhorias na estrutura da fibra capilar. Pode-se também levantar dados como a rugosidade e a área cuticular da fibra, através desses dados verificou-se que a rugosidade na fibra capilar diminui e a área cuticular aumentou com o uso do produto. Foi observado também através da análise de infravermelho a presença da quitosana na fibra capilar.Currently exists an increasing number of companies on the cosmetic market, due to the fact that people worry more about appearance and (to) desire (for) quality products. As a result the companies are investing more in this area and developing new technologies. The purpose of this work is to study hair fibers and their interaction with a commercial product containing chitosan which is the main ingredient in the formula of Kit Bio Film® Tânagra and techniques were used, such as MEV, optic microscopy, AFM, thermal analysis (TG/DSC) and infrared absorption spectroscopy. This study was realized with caucasian virgin hair (without any chemical process) and with caucasian uncolored hair. In all analyses improvement of the hair fiber structure was observed. Also observed data such as roughness and cuticle size showed an increase in roughness and a decrease of cuticle size.The presence of chitosan in the hair fiber was also observed by infrared analysis.
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Zelenskaya, Alexandra. "Atomic force microscopic studies of inner ear structure and mechanics /." Stockholm, 2004. http://diss.kib.ki.se/2004/91-7140-021-4/.
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Duit, Rebecca Christina. "Novel insights into hair structure and the effects of chemical stressors on hair and skin using label-free advanced light microscopy." Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12101/.
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There is a need for a better method to image hair as the current methods involve embedding the hair in resin, which may produce artefacts, or using dyes which are limited in their depth of penetration into the hair. The research performed in this thesis endeavours to characterise the cellular structure of human hair with label-free imaging using autofluorescence and fluorescence lifetime imaging. Wavelengths were shown to selectively excite the hair cuticle, cortex and medulla, and subcellular compartments. Development of an optical transverse imaging method enabled discoveries including different fluorescence lifetimes across the cuticle cell layers and suggests the cuticle layers possess differing chemical environments. A new method was developed to distinguish between eumelanin and pheomelanin using 405nm and 633nm wavelengths. The newly developed methods were additionally used in the characterisation of an unidentified hair and skin disorder, which found poorly differentiated cuticle cells and showed differences in the fluorescence lifetimes of the hair compared to control hairs. The hair care industry needs more efficacious chemical depilatories and information into their action. This was elucidated using the developed methods and a new dynamic imaging method. Potassium thioglycolate was shown to cause drastic expansion of the hair which was amplified by the addition of guanidine carbonate, creating fissures through the cuticle and into the cortex. Other experimental depilatory formulations were tested and were found to have varying effects upon the structure of the hair. New chemical depilatories require development because existing depilatories can cause irritation in the skin. Potassium thioglycolate and guanidine carbonate were tested on HaCaT cells, isolated cornified envelopes, and HEKn cells in a 3D epidermal model. An investigation into the differentiation, proliferation and acute stress response of the cells showed that the treatments had no significant effect on these markers. However, the chemicals negatively affected HaCaT cell viability and damaged the cornified envelopes. Despite this, the viability and structural integrity of the living cells of the epidermal model were maintained through the protection provided by the stratum corneum.
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Nam, Jong-Hoon. "A Computational Study on the Structure, Dynamics and Mechanoelectric Transduction of Vestibular Hair cell." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28615.
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The hair cell, a specialized cell in the inner ear, is responsible for hearing and balance. The hair cell is an exquisite sensor that captures mechanical stimuli and generates neurosensory signals. A theory called gating theory has been developed and widely used to analyze the experimental data of hair cell transduction. Despite increasing knowledge about molecular structures of hair cells, the mechanical model in the gating theory remained simple. Efforts to make the most of the recent findings regarding the hair cell structures led to the development of hair cell finite element (FE) model (Cotton & Grant, 2000, 2004a, b). I have extended this approach by adding channel kinetics and structural dynamics to the FE structural model of the hair cell.
I have expanded the previous static and passive model to a dynamic and active model. It is the most detailed hair cell structural model and includes up-to-date knowledge of the hair cell structure such as the stereocilia and various extracellular links. In order to observe the dynamic response of hair bundles in the endolymph fluid, I have included fluid drag in the model. Link nonlinearity has been added to reflect recent observations (Tsuprun 2003). The lateral links stiffen as they stretch and prevent contact between stereocilia when they compress. In addition to these structural features, I added channel kinetics such as the fast adaptation. In my study, the Ca²⁺ diffusion kinetics plays a key role in the hair cell adaptations. The Ca²⁺ association rate to the fast adaptation modulator is postulated to govern the fast adaptation. I assumed that two factors--the tip link tension and the Ca²⁺ concentration at the tip of stereocilia govern the hair cell mechanoelectric transduction.
My dissertation comprises three parts--structure, dynamics and mechanotransduction of hair cells. First, the mechanical properties of hair bundle were sought by comparing my FE model with other experiments. The quantified Young's modulus of stereocilia and the stiffness of tip link agree well with other recent estimates. The stiffness of other structural elements (upper lateral and shaft links) was newly estimated through this effort. Second, I established equations of motion for the hair bundle in the fluid. Two possible loading conditions to the hair bundle were simulated. Two different hair bundles were subjected to a point load and a load induced by fluid flow. The results showed that some vestibular hair cells' transduction might be dominated by the fluid-induced force. Finally, I observed the hair cell transduction in various stimulus conditions. The results showed that the hair cell's sensitivity highly depends on the stimulus method. The fluid-jet stimulus activated fewer channels than the glass fiber and made the hair cell less sensitive. A faster stimulus opened more channels and made the hair cell more sensitive. The resting tension in the tip link, which is believed to be controlled by the Ca²⁺ concentration, also affected the hair cell sensitivity. A higher resting tension, equivalent to a lower Ca²⁺ concentration, tended to make the hair cell more sensitive.
In conclusion, I developed a new tool to study the hair cell mechanoelectric transduction. My hair cell computational model enables us (1) to study how the hair cells' morphological variations are related to their function; (2) to investigate the hair cell mechanoelectric transduction at the single channel level, in silico, as opposed to the statistical approach; (3) to test the response of hair cells under in situ force boundary conditions.Ph. D.
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Zhang, Daijiazi. "Physical, morphological and chemical structure & property relationships for alpha-keratins in bleached human hair." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/physical-morphological-and-chemical-structure--property-relationships-for-alphakeratins-in-bleached-human-hair(85eead7b-fcc3-4518-ba4c-7ca7041712c4).html.
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The surface and structural change of human hair fibre have been analysed to determine the oxidation effects for bleached hairs. Three types of bleached hairs (6% H2O2 bleach, 9% H2O2 commercial bleach and commercial persulphate bleach (contains 9% H2O2)) as well as virgin hair were evaluated with the increasing treatment time using Scanning Electron Microscopy (SEM), Reflective Spectrophotometry, Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared (FTIR) Spectroscopy. It is obvious that longer treatment times result in the greater surface and structural damage. However, commercial persulphate bleach causes less surface damage for the cuticle. 6% H202 bleach has overall moderate damage effects on both cuticle and cortex over the treatment time. 9% H2O2 commercial bleach indicates two different damage stages. The first 1.5h bleached hairs show mild oxidation to the surface, whereas the damage becomes heavy after 2h. This phenomenon results in that 9% H2O2 commercial bleach has a more intensive oxidation damage in the cortex than the commercial persulphate bleach. This is in line with DSC investigation which shows that the intermediate filament of 9% H2O2 commercial bleach is heavily damaged after the extensive oxidation time (greater than or equal to2h). Although commercial persulphate bleach contains the stronger oxidising agent, it has a less surface damage than 9% H2O2 commercial bleached hair in FTIR-ATR measurement, and a similar oxidation effect on the matrix as 6% H202 bleached hair in FTIR transmission investigation. In addition, it has been verified by colour measurements that bleached hairs have an overall lighter, yellowish and reddish colour. Consequently, commercial persulphate bleached hair is much lighter and more yellow than 9% H2O2 commercial bleached hair and 6% H202 bleached hair. DSC investigations reveal that the three bleaches have a homogenous oxidation effect on IFs and IFAPs. The deconvolution results using three Gaussian distributions confirm this observation. The stronger bleach results in a homogenous structural damage on both para- and ortho-cortex with increasing bleaching time. Commercial persulphate bleach and 9% H2O2 commercial bleach have a progressive damage effect on the ortho- and para- cortex than 6% H202 bleach. Kinetics analysis is conducted for the virgin and bleached hairs by using various heating rates according to ASTM-E698. The activation energies of 260 kJ/mol for the virgin hair and 295 kJ/mol for the commercial persulphate bleached hair (2h) are determined from the slope of the regression line of peak temperature, TD (as 1/TD) and heating rate, β (as lnβ) on the basis of the Arrhenius-equation. The predominant structural damage for various heating rates only occurs in the IF. It is shown that a linear increase in DeltaHD occurs for lower heating rates, while it is constant for higher heating rates. This can be ascribed to the hypothesis that a lower heating rate favours a crystal transformation change (alpha-β transformation), while a higher rate favours a crystalline-amorphous transformation. SEM examines the morphological changes of hair samples after DSC. The cortex has been dissolved at the lower heating rate. The commercial persulphate bleached hairs (2h) show an overall shrunk cuticle surface and fewer and smaller hydrolysed protein granules, due to the previous damage of the alpha-helix in the cortical cell.
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Cummins, Breschine. "Determining the biomechanical response of a filiform hair array a low Reynolds number fluid-structure model /." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/cummins/CumminsB0809.pdf.
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A model system that has been the subject of many anatomical, developmental, functional, and theoretical studies over the last 30 years is the cercal sensory system of the cricket. This system is composed of two antenna-like appendages covered with hundreds of filiform mechanosensory hairs, and encodes information about the direction and dynamics of low-velocity air currents. The encoding is determined by the biomechanical properties of the mechanosensory hairs. These properties are poorly understood, primarily because accurate experimental measurements of the air-current-driven movements of the hairs are difficult to obtain, and adequate mathematical tools for modeling arbitrarily complex hair-to-hair interactions within the canopy have been absent. The study presented here solves fundamental problems in both of these areas. Previous studies have characterized the biomechanics of the filiform hairs, but only one study considered the fluid-mediated interaction of closely-packed hairs. A major goal of our work was to model the motion of a dense patch of thin filaments driven by bulk fluid flow, in a context that is immediately relevant to the cercal system. To understand the function of the sensory epithelium as a whole, we developed a numerical model based on a novel mathematical tool: the method of regularized unsteady Stokeslets. This method is generally applicable to low Reynolds number fluid flow in domains that are subject to periodic forcing along the boundary. The numerical scheme associated with our mathematical model is fast, scalable, accounts for the interaction between arbitrary arrangements of hairs. We measured the biomechanical stimulus-response properties of 19 filiform hairs, and used that data to fit parameters to our mathematical model. We demonstrate for the first time that one of the mechanical parameters controlling filiform hair motion depends on the frequency of the air stimulus. Our numerical simulations demonstrate that damped and synergistic hair interactions can occur between closely-packed hairs. Low frequency signals (< 50 Hz) are damped, and higher frequency signals (50-200 Hz) are amplified. We hypothesize that the characteristic dense patch of hairs at the proximal end of the cercus acts as a noise cancellation filter that removes low frequency components of ambient environmental stimuli.
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Chidurala, Manohar. "Dynamic Characteristics of Biologically Inspired Hair Receptors for Unmanned Aerial Vehicles." ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/2040.
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The highly optimized performance of nature’s creations and biological assemblies has inspired the development of their engineered counter parts that can potentially outperform conventional systems. In particular, bat wings are populated with air flow hair receptors which feedback the information about airflow over their surfaces for enhanced stability and maneuverability during their flight. The hairs in the bat wing membrane play a role in the maneuverability tasks, especially during low-speed flight. The developments of artificial hair sensors (AHS) are inspired by biological hair cells in aerodynamic feedback control designs. Current mathematical models for hair receptors are limited by strict simplifying assumptions of creeping flow hair Reynolds number on AHS fluid-structure interaction (FSI), which may be violated for hair structures integrated on small-scaled Unmanned Aerial Vehicles (UAVs). This study motivates by an outstanding need to understand the dynamic response of hair receptors in flow regimes relevant to bat-scaled UAVs. The dynamic response of the hair receptor within the creeping flow environment is investigated at distinct freestream velocities to extend the applicability of AHS to a wider range of low Reynolds number platforms. Therefore, a threedimensional FSI model coupled with a finite element model using the computational fluid dynamics (CFD) is developed for a hair-structure and multiple hair-structures in the airflow. The Navier-Stokes equations including continuity equation are solved numerically for the CFD model. The grid independence of the FSI solution is studied from the simulations of the hairstructure mesh and flow mesh around the hair sensor. To describe the dynamic response of the hair receptors, the natural frequencies and mode shapes of the hair receptors, computed from the finite element model, are compared with the excitation frequencies in vacuum. This model is described with both the boundary layer effects and effects of inertial forces due to fluid-structure xiv interaction of the hair receptors. For supporting the FSI model, the dynamic response of the hair receptor is also validated considering the Euler-Bernoulli beam theory including the steady and unsteady airflow.
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Gomez, Salvador Gustavo. "Protein Phosphatase 1 Concentrates at the Base of Sensory Hair Cell Stereocilia, Where it May Function in Stereocilia Cytoskeletal Structure." Ohio University Art and Sciences Honors Theses / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ouashonors1556276688823712.
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Smuts, Sonia. "A Rorschach study of fifteen women with trichotillomania." Diss., Pretoria : [s.n.], 2002. http://upetd.up.ac.za/thesis/available/etd-03072005-121028.
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Davis, Julian Ly. "A Computational Study into the Effect of Structure and Orientation of the Red Ear Slider Turtle Utricle on Hair Bundle Stimulus." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/29926.
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The vestibular system consists of several organs that contribute to ones sense of balance. One set of organs, otoconial organs, have been shown to respond to linear acceleration (1949). Hair bundles (and hair cells), which are the mechano-electric transducers found within otoconial organs, respond to displacement of the overlying otoconial membrane (OM). Structure, position and orientation of the OM within the head may influence the stimulus of hair bundles by changing the deformation characteristics of the OM. Therefore, studying the deformation characteristics of the OM with finite element models presents a unique advantage: the ability to study how different variables may influence the deformation of the OM.
Previous OM models have ignored complicated OM geometry in favor of single degree of freedom (De Vries 1951)or distributed parameter models (Grant et al. 1984; Grant and Cotton 1990; Grant et al. 1994). Additionally, OMs have been modeled considering three dimensional geometry (Benser et al. 1993; Kondrachuk 2000; 2001a), however OM layer thicknesses were assumed to be constant. Further, little research has investigated the effect of position and orientation of otoconial organs on the deformation of the OM (Curthoys et al. 1999), due to natural movement of the head.
The effect of structure, position and orientation of the utricle of a red ear slider turtle on the stimulation of hair bundles in the OM is investigated here. Using confocal images, a finite element model of the utricle OM is constructed considering its full 3D geometry and varying OM layer thickness. How specific geometric variables, which are missing from other OM models, effect the deformation of the utricle OM is studied. Next, since hair bundles are part of the structure of the OM, their contribution to the deformation of the utricular OM is quantified. Then, using computed tomography of a turtle head and high speed video of turtle feeding strikes, acceleration at the utricle during natural motion is estimated. Finally, the effects of orientation of the utricle in the head on the stimulus of hair bundles within the organ is investigated.
In summary, a model and methods are developed through which deformation of the turtle utricle OM through natural movements of the head may be studied. Variables that may contribute to utricle OM deformation are investigated. Utricle OM geometry, hair bundles, position and orientation all play a role in utricle OM deflection and therefore hair bundle stimulus. Their effects are quantified and their roles are discussed in this dissertation.Ph. D.
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Syam, Diana. "Immobilizing Mutation in an Unconventional Myosin15a Affects not only the Structure of Mechanosensory Stereocilia in the Inner Ear Hair Cells but also their Ionic Conductances." UKnowledge, 2014. http://uknowledge.uky.edu/medsci_etds/2.
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In the inner and outer hair cells (OHCs) of the inner ear, an unconventional myosin 15a localizes at the tips of mechanosensory stereocilia and plays an important role in forming and maintaining their normal structure. A missense mutation makes the motor domain of myosin 15a dysfunctional and is responsible for the congenital deafness DFNB3 in humans and deafness and vestibular defects in Shaker-2 (Sh2) mouse model. All hair cells of homozygous Shaker-2 mice (Myo15sh2/sh2) have abnormally short stereocilia, but, only stereocilia of Myo15sh2/sh2OHCs start to degenerate after the first few days of postnatal development and lose filamentous tip links between stereocilia that are crucial for mechanotransduction. The exact mechanisms of this degeneration are unknown even though they may underlie DFNB3 deafness in humans. We hypothesize that structural abnormalities in Myo15sh2/sh2 OHCs may alter the mechanical forces applied to the mechano-electrical transduction (MET) channels resulting in abnormal ionic homeostasis, which may lead to eventual degeneration of Myo15sh2/sh2 OHCs. Therefore, we investigated the ionic conductances and integrity of mechanotransduction apparatus in Myo15sh2/sh2 OHCs. Surprisingly, we found that myosin 15a-deficiency is associated not only with structural abnormalities of OHC stereocilia but also with alterations of voltage-gated ion conductances.
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Gabrielaitis, Mantas Verfasser], Fred [Akademischer Betreuer] [Gutachter] Wolf, Tobias [Gutachter] [Moser, and Peter [Gutachter] Jonas. "Mathematical modeling of the structure and function of inner hair cell ribbon synapses / Mantas Gabrielaitis ; Gutachter: Fred Wolf, Tobias Moser, Peter Jonas ; Betreuer: Fred Wolf." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1125105909/34.
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Fleischer, Mario. "Mehrfeldmodellierung und Simulation der äußeren Haarsinneszelle der Cochlea." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-100717.
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Das Innenohr des Säugetieres ist ein hochspezialisiertes sensorisches System, das durch ein komplexes mechanisches Verhalten gekennzeichnet ist. Neben der komplizierten Morphometrie und Geometrie kommen auch dem richtungsabhängigen Materialverhalten eine wesentliche Bedeutung zu. Es zeigt sich, daß im Cortischen Organ mit der äußeren Haarsinneszelle ein Zelltyp vorliegt, der durch seine physikalischen Eigenschaften das Gesamtverhalten des Innenohres maßgeblich beeinflußt. Wie jede tierische Zelle weist die äußere Haarsinneszelle als biomechanisches System eine heterogene Mikrostruktur auf. Vom mechanischen Standpunkt aus gesehen, ist neben der mehrschichtigen basolateralen Zellwand jede Einzelzelle durch ein viskoses inneres Fluid (Zellplasma) und einen Zellkern (Nukleus) gekennzeichnet. Die resultierenden mechanischen Eigenschaften des Gesamtsystems ”äußere Haarsinneszelle” können durch Experimente und eine geeignete Modellierung determiniert werden.
In dieser Arbeit wird ein neuer Ansatz zur Bestimmung der viskoelastischen Materialeigenschaften der basolateralen Wand vorgestellt. Durch Anwendung einer effektiven Fluid-Struktur-Interaktion wird das Gesamtsystem geschlossen untersucht und eine umfangreiche Materialparameterstudie durchgeführt. Dabei werden im Rahmen der Kontinuumsmechanik gültige Materialgesetze angewendet. Das durch partielle Differentialgleichungen formulierte mechanische Feldproblem wird im Rahmen der Finiten-Elemente-Methode approximiert, was zu einem linearen Gleichungssystem führt. Auf dieser Grundlage wird ein Finite-Elemente-Modell der äußeren Haarsinneszelle entwickelt. Die zur Beschreibung notwendigen Systemmatrizen – insbesondere die Dämpfungsmatrix – basieren dabei vollständig auf einem viskoelastischen Materialgesetz. Die benutzte Methodik läßt weiterhin eine effiziente Berechnung im Frequenzbereich zu.
Es zeigt sich, daß eine spezielle Dämpfungsformulierung die experimentell bestimmten dynamischen Eigenschaften der Zelle adäquat widerspiegelt. Eine Analyse auf Materialgesetzebene zeigt, daß dafür reine Schubdämpfung und damit eine spezielle Anisotropie im Viskositätstensor verantwortlich ist. Diese Eigenschaft bestimmt das dynamische Verhalten der äußeren Haarsinneszelle bis mindestens 10 kHz und liegt damit im Hörbereich.
Der Modellierung der Zelle geht eine angepaßte Auswertung der experimentell ermittelten Daten voraus. Die mechanisch geeignete Auswertung der zugrundeliegenden Experimente weist dabei auf mögliche Fehlerquellen bei der Analyse der Rohdaten hin. Das hat zur Konsequenz, daß der experimentellen Umgebung die gleiche Aufmerksamkeit geschenkt werden muß wie dem Meßobjekt selbst. Nur so kann eine geeignete Extraktion der für das Meßobjekt spezifischen Eigenschaften erfolgen.
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Sabatier, Laura. "Étude des conséquences de traitements physiques sur le cheveu, de l’échelle moléculaire à celle de la fibre." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS076.
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Les traitements thermomécaniques permettent une mise en forme temporaire et aisée de la chevelure, propriétés recherchées par les utilisateurs. Cependant, les effets obtenus ne sont pas toujours à la hauteur des attentes, notamment en raison d’une mauvaise tenue de la forme dans le temps et de possibles endommagements de la chevelure. Dans le but d’améliorer les appareils de coiffage existants, nous souhaitons comprendre les effets de ces traitements sur le cheveu, pour ensuite déterminer les conditions permettant d’atteindre la meilleure rémanence de la forme tout en minimisant la dégradation du cheveu. Pour ce faire, nous nous appuyons sur des expériences de traction, microdiffraction X et spectroscopie infrarouge. Tout d’abord, nous avons étudié l’organisation structurale de cheveux naturels. Nous avons mis en évidence une distribution de structure cœur – peau avec un cœur de structure régulière d’autant plus excentré que la courbure est marquée. Ensuite, nous avons dégagé les principaux paramètres sur. lesquels jouer lors de la mise en forme: température du mandrin, contrainte et durée d’application. Les effets de ces paramètres sur le comportement mécanique et la nanostructure du cheveu ont été évalués. Il ressort de notre étude que la contrainte de mise en forme est déterminante : nous avons défini la gamme de contraintes permettant de préserver la structure et les propriétés mécaniques du cheveu et celle occasionnant la dégradation du cheveu, voire une restructuration en feuillets bêta. Nous avons également évalué l’efficacité des différentes conditions de traitement à produire une forme durable dans le temps. En complément, nous nous sommes intéressés au mécanisme structural survenant lors de l’étirement de cheveux natifs ou préalablement traités, en couplant étirement continu d’un cheveu et analyse par microdiffraction X. Ainsi nous avons réussi à suivre l’évolution sous étirement d’une structure de cheveu transformée en feuillets bêta. Les résultats originaux obtenus au cours de ce travail, qui établissent un lien entre les mécanismes moléculaires et le comportement macroscopique du cheveu, permettent d’envisager le développement de nouveaux traitements thermomécaniques à l’échelle industrielleThermomechanical hair styling is preferred by users for easy and temporary reshaping of hair. However, the result is not always up to expectations, particularly due to poor shape stability over time and possible hair damage. In this work, we aim to improve hairstyling devices. To this end, we need to understand the effects of such treatments on hair in order to determine conditions which allow the best shape holding while minimizing hair damage. To achieve this, we use tensile testing, X-ray diffraction and infrared spectroscopy experiments. First, we studied the structural organization of natural hair. We highlighted a “core-skin” distribution of structures with a regular core which is all the more off-centered as curvature is high. Subsequently, we identified the main parameters of thermomechanical reshaping: temperature, stress and application time. Then, we evaluated the effects of these parameters on mechanical behavior and hair nanostructure. Our study shows that applied stress is a key factor: we defined stresses range allowing preservation of hair structure and its mechanical properties and the one leading to degradation or even driving to beta-sheets transition. Efficiency of the different treatment conditions in producing long-lasting shape over time was then evaluated. In addition, we analyzed the structural mechanisms that occur during stretching for native and pretreated hair: we used X-ray microdiffraction coupled with continuous stretching of hair. Consequently, we were able to monitor a beta sheet structure in hair during stretching. The original results obtained during this work, bridging internal molecular mechanisms and macroscopic behavior of hair, will allow to develop new thermomechanical treatments at industrial scale
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Spoon, Corrie E. "Hair Bundle Stiffness in the Turtle Utricle: Structural and Regional Variations." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/29899.
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Vestibular hair cells are mechanotransducing sensory receptors in the vertebrate inner ear that detect movement and orientation of the head with respect to gravity. The morphologies of their ciliary bundles vary greatly for different species, endorgans, and within the same endorgan. Bundle morphology in the turtle utricle, like other species, demonstrates highly organized regional variations. These structural differences in bundles impact their mechanical behavior and the process of mechanotransduction. To further understanding of the mechanical behavior of hair bundles, this work experimentally measured the stiffness of bundles with differing morphology, the stiffness contribution of interciliary links and the mechanical properties of the kinocilium in the turtle utricle.
The stiffness of hair bundles of varying structure and location along a medial to lateral transect of the utricle was examined. Bundle stiffness was greatest in the striola and demonstrated a systematic decline with location from the line of polarity reversal. The average stiffness of bundles in the striola and extrastriola were 82 ± 46 (n=48) and 9 ± 5 (n=25) µN/m, respectively. The stiff and weak bundles demonstrated characteristic morphologies. The stiffest bundles have short kinocilium, tall stereocilia, and ratios of kinocilium to tallest stereocilia height (KS) close to 1. In contrast, the compliant bundles have tall kinocilium, short stereocilia, and KS ratios ranging from 1.6 â 8. The stiffer bundles also tend to have longer array lengths and steeper slopes. Measurements of bundle stiffness in the turtle utricle are lower than those previously reported which may be attributed to morphological differences between species.
The stiffness contributions of the interciliary links were also examined through their selective removal with exposure to the Ca2+ chelator BAPTA and the protease subtilisin. BAPTA treatment reportedly breaks tip, kinocilial and ankle links while subtilisin breaks the shaft and ankle links. Following BAPTA and subtilisin treatments, bundle stiffness reduced by 65 ± 10% and 63 ± 11%, respectively.
The mechanical properties of the kinocilium were measured with novel techniques. Flexural rigidity (EI) was measure while the kinocilium was fixed at the height of the tallest stereocilia using a glass supporting probe. Through both force deflection and a high speed video technique, measured values of EI ranged from 1460 â 6150 pN·µm2. The rotational stiffness of the kinocilium about its apical insertion was also measured. Bundles were treated with BAPTA to break the kinocilial links and separate the kinocilium from neighboring stereocilia. Using a force deflection technique, the rotational stiffness of the kinocilium was measured as 120 ± 17 pN·µm/rad.Ph. D.
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Gibson, Martin T. "The structure and function of hairs of Chaetophorales." Thesis, Durham University, 1986. http://etheses.dur.ac.uk/6753/.
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A study was carried out on the relationship between hair formation and water chemistry in three genera of Chaetophorales (especially Stigeoclonium).The relationship between environmental chemistry, algal morphology and phosphatase activity for 32 samples of natural populations in N-E. England was investigated. Two indices of hair formation were significantly correlated with aqueous P (-ve).algal N: P ratio (+ve) and phosphatase activity (+ve). Other correlations included: algal P v. aqueous P {+ve); algal P V. phosphatase activity (-ve); algal N: P ratio v. aqueous P (-ve). All algal samples with a P content of 0.96% (by weight) and above lacked hairs: all with aP content of 0.53% and below had hairs. All algal samples with N: P ratios of 5.58 and below lacked hairs: all with ratios of 6.46 and above had hairs. The influence of pH on phosphatase activity of six natural populations showed three markedly different responses, but the pH optima of three laboratory strains of Stigeoclonium were similar; pH had little influence on the phosphatase activity of two laboratory strains of Draparnaldia. Phosphatase activity was localized on hairs of Chaetophora and Draparnaldia, but the results were not clear-cut for Stigeoclonium. Elemental deficiencies gave a similar pattern of the extent of hair formation in 13 strains: - P > - N >- Fe-S >-Ca > -Mg > control. Elemental additions to five strains resulted in zoospore release; the greatest amount was released when N or P was added to N- or P-limited cultures. Five strains were grown to P-limitation in batch culture: the maximum P composition ranged from 2.4 - 6.4 % dry weight; hair formation commenced when algal P had fallen to about 1 % dry weight, long before any culture had ceased to grow or started to appear unhealthy. The strains were shown to be capable of utilizing a number of organic P sources. The possible role of hairs and similarities between hair-forming blue-green algae and Chaetophorales are discussed.
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Pichon, Eric. "Etude des propriétés mécaniques du cheveu : Essais de traction et de relaxation : modèlisation : rôle de divers facteurs expérimentaux." Besançon, 1989. http://www.theses.fr/1989BESA2014.
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Modelisation du comportement rheologique du cheveu en realisant differents tests mecaniques sous des conditions precises d'hygrometrie et de temperature. Il a ete adopte un modele non lineaire faisant intervenir une loi viscoplastique a ecrouissage additif
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Choudhary, Deepanshu. "STRUCTURAL DETERMINANTS AND BIOPHYSICAL CHARACTERIZATION OFINNER-EAR PROTEIN COMPLEXES IMPLICATED IN HEARING ANDDEAFNESS." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1565983368074763.
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Metzger, Eric L. "The relationship between total cloud lightning behavior and radar derived thunderstorm structure." Thesis, Monterey, California : Naval Postgraduate School, 2010. http://edocs.nps.edu/npspubs/scholarly/theses/2010/Mar/10Mar%5FMetzger.pdf.
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Thesis (M.S. in Meteorology)--Naval Postgraduate School, March 2010.Thesis Advisor: Nuss, Wendell. Second Reader: Pfeiffer, Karl. "March 2010." Author(s) subject terms: Total cloud lightning, thunderstorm structure, hail, severe wind(s), tornadoes, lightning jumps, lightning detection, Lightning behavior, radar derived thunderstorm structure. Includes bibliographical references (p. 83-85). Also available in print.
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Person, Vernecia. "Structure Properties of Heterophase Hairy-Nanoparticles: Organic vs. Inorganic." DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2015. http://digitalcommons.auctr.edu/cauetds/59.
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Substances that consist of nano-scale fillers dispersed in a polymer matrix are known as polymer-nanocomposites (PNCs). These materials are appealing since they have high potentials for applications, due to their mechanical, electrical, and thermo electrical properties. A common problem associated with PNCs is that the nano-fillers have a tendency to aggregate into clusters and form phase separated domains, which cause the desired properties of the system to either diminish or vanish all together. Hairy nanoparticles (HNPs) can avoid the issue of agglomeration that is commonly encountered by conventional PNCs. When polymer chains are grafted to a nanoparticle, and the coverage is high, the nanoparticles have decreased inter-particle interactions which allows for enhanced dispersion and mixing into a polymer matrix. By tailoring the architecture (functionalization of polymer chains, degree of polymerization, grafting density) of HNPs, it is possible to control the final properties of the system. An in depth study was carried out to investigate the effects of hairy-nanoparticle architecture on the resulting properties of the material itself. Atom transfer radical polymerization and living anionic polymerization were used to synthesize the polymer chains, of the HNP systems, while various instrumental methods including differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were utilized to study the physical ageing affects and self-assembly of these systems.
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Liang, Yajie. "Genome Structure of the Hairy-Root-Inducing Plasmid pRiA4b." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150895.
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Pierson, Jennifer Christy. "Genetic population structure and dispersal of two North American woodpeckers in ephemeral habitats." Diss., [Missoula, Mont.] : The University of Montana, 2009. http://etd.lib.umt.edu/theses/available/etd-03102010-112754.
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Obino, Rodrigo S. "Simulation of the Bohai Sea circulation and theromohaline structure using COHERENS model." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FObino.pdf.
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Ebna, Hai Bhuiyan Shameem Mahmood [Verfasser]. "Finite Element Approximation of Ultrasonic Wave Propagation under Fluid-Structure Interaction for Structural Health Monitoring Systems / Bhuiyan Shameem Mahmood Ebna Hai." Hamburg : Helmut-Schmidt-Universität, Bibliothek, 2017. http://d-nb.info/1148436170/34.
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Goossens, Benoît. "Système de reproduction et variabilité génétique intra- et interpopulationnelle chez la marmotte alpine (Marmota marmota L. , Sciuridé)." Université Joseph Fourier (Grenoble ; 1971-2015), 1998. http://www.theses.fr/1998GRE10034.
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La marmotte alpine (marmota marmota, sciuride), espece hautement sociale au systeme d'appariement decrit comme etant monogame, suscite un grand interet comme modele d'etude de la socialite chez les mammiferes. Elle forme des unites familiales composees d'un couple dominant et des jeunes issus de portees successives. Apres une etude de faisabilite, l'utilisation des poils comme materiel biologique et des microsatellites comme outil genetique a permis d'etudier le systeme d'appariement de la marmotte alpine en quantifiant les paternites extra-couples dans les groupes familiaux d'une population des alpes francaises (la grande sassiere, parc national de la vanoise) et en discutant les couts et les benefices pour chaque sexe d'adopter une strategie alternative a la monogamie. Le pourcentage de paternites extra-couples s'est avere eleve (plus de 30%), et nous avons identifie plus de 19% de juveniles dont le male resident n'etait pas le pere. Le polymorphisme relativement eleve des microsatellites utilises a egalement permis d'aborder la genetique des populations de marmottes alpines a deux echelles : intra- et interpopulationnelles. Avec les indices de fixation de wright, nous avons mis en evidence une forte structuration genetique intrapopulationnelle due tres vraisemblablement a la structure sociale familiale, et une tendance significative a l'evitement de la consanguinite. Selon nos resultats, cette tendance serait due plutot a un effet famille qu'a un biais sexuel de la dispersion, ou qu'a un choix par la femelle d'un partenaire non-apparente.
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Waddell, Benjamin B. "CLIC5 maintains lifelong structural integrity of sensory stereocilia by promoting Radixin phosphorylation in hair cells of the inner ear." Ohio University Honors Tutorial College / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1461332124.
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Hain, Johannes [Verfasser], and Tom [Gutachter] Fischer. "Valuation Algorithms for Structural Models of Financial Networks / Johannes Hain ; Gutachter: Tom Fischer." Würzburg : Universität Würzburg, 2016. http://d-nb.info/1126417548/34.
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Unger, Jesper. "Vilka räknesätt har företräde? : En studie om hur elever i årskurs 5 strukturerar och bokför beräkningar av numeriska uttryck." Thesis, Jönköping University, Högskolan för lärande och kommunikation, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-53770.
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För att numeriska uttryck inte ska tolkas på olika sätt finns det så kallade prioriteringsregler som bestämmer räkneoperationers ordningsföljd. Matematikdidaktisk forskning har dock visat att elever har svårigheter att följa prioriteringsregler och strukturer i matematiska uttryck. Eleverna tenderar att följa okonventionella regler som helt enkelt är egenkonstruerade. Denna studie är en re-analys av data från en tidigare studie och syftar till att undersöka hur elever i årskurs 5 strukturerar och bokför sina beräkningar av numeriska uttryck där prioriteringsregler behöver tillämpas. Data för studien är lösningar från 123 elever, vilket innehåller svar på fyra olika uppgifter presenterade på ett arbetsblad, alltså totalt 492 elevlösningar. Analysen utgår från vad tidigare forskning har visat för tendenser elever har när de beräknar numeriska uttryck. Dessa beteenden har sedan grupperats i olika aspekter för att finna likheter och skillnader i hur elever tar sig an matematiska operationer. Deltagarna utgjordes av elever från fem olika skolor. Genom analysen kunde det identifieras att elever följde prioriteringsregler på kvalitativt skilda sätt och att många gjorde detta på ett inkonsekvent vis genom de fyra uppgifterna. Flertalet av deltagarna visade brister i att strukturera beräkningar på ett konventionellt vis. Orsaken kan diskuteras i att härstamma från att eleverna saknar något som i internationell matematikdidaktisk forskning kallas för ”structure sense”, vilket innebär en förståelse av matematiska strukturer.For numerical expressions not to be interpreted in different ways, there are so-called order of operations that determine the order of arithmetic operators. In mathematics didactic research, it has been displayed that pupils have difficulty following arithmetic rules and structures in mathematical expressions. Pupils tend to follow unconventional rules that are simply self-constructed. This study is a re-analysis of data from a previous study and aims to investigate how pupils in year 5 structure and keep track of calculations of numerical expressions where rules for the order of operations needs to be applied. The data analysis is based on solutions from 123 pupils on four different tasks, thus 492 solutions in total. The participants were pupils in year 5 from five different Swedish schools. The analysis is based on what previous research has shown that tendencies pupils have when they calculate numerical expressions. These behaviors have then been grouped into different aspects to find similarities and differences in how pupils approach mathematical operators. Through the analysis, it could be identified that pupils followed arithmetic rules in qualitatively different ways and that many did so in an inconsistent manner through the four tasks. Actually, most participants could not structure their calculations in a conventional way. The reason can be discussed that it descends from the fact that the pupils lack something which in international mathematics didactic research is called “structure sense”, which means an understanding of mathematical structures.
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Nishimura, Masataka. "Structure, Chromosomal Locus, and Promoter of Mouse Hes2 Gene, a Homologue of Drosophila hairy and Enhancer of split." Kyoto University, 2000. http://hdl.handle.net/2433/180835.
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Wang, Yajie. "The Time-Course of the Effects of Growth Hormone During Zebrafish (DANIO RERIO) Auditory Hair Cell Regeneration." TopSCHOLAR®, 2012. http://digitalcommons.wku.edu/theses/1171.
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Growth hormone (GH) was upregulated in the zebrafish inner ear following sound exposure in a previous study. To identify the specific role of GH in hair cell regeneration and the possible cellular mechanisms of this regeneration, groups of zebrafish were divided into baseline (no sound exposure, no injection), buffer-injected and GH-injected groups. Buffer- and GH-injected fish were exposed to a 150 Hz tone at a source level of 179 dB re 1 μPa root mean squared (RMS) for 36 h. Phalloidin-staining was used to assess the effects of GH on hair cell bundle density; BrdU-labeling was used to assess the effects of GH on cellular proliferation; TUNEL-labeling was used to assess the effects of GH on apoptosis in the zebrafish inner ear following acoustic trauma. The time-course of hair cell bundle density, cell proliferation, and apoptosis was established by combining data for baseline fishes and sound-exposed fishes at post-sound exposure day 1 (psed1), psed2, and psed3. GH-injected fish exhibited greater densities of hair cells than bufferinjected controls. In addition, GH-injected fish had higher levels of cell proliferation and lower levels of apoptosis than buffer-injected controls. This suggests that GH may play an important role in zebrafish inner ear hair cell regeneration by stimulating cellular proliferation and inhibiting cellular apoptosis.
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Michanski, Susann [Verfasser], Tobias [Akademischer Betreuer] Moser, Tobias [Gutachter] Moser, and André [Gutachter] Fiala. "Molecular and structural investigation of assembly, maturation and heterogeneity of inner hair cell ribbon synapses / Susann Michanski ; Gutachter: Tobias Moser, André Fiala ; Betreuer: Tobias Moser." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://d-nb.info/1196873968/34.
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Wesierski, Daniel. "Visual tracking of articulated and flexible objects." Thesis, Evry, Institut national des télécommunications, 2013. http://www.theses.fr/2013TELE0007/document.
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Les humains sont capables de suivre visuellement des objets sans effort. Cependant les algorithmes de vision artificielle rencontrent des limitations pour suivre des objets en mouvement rapide, sous un éclairage variable, en présence d'occultations, dans un environnement complexe ou dont l'apparence varie à cause de déformations et de changements de point de vue. Parce que des systèmes génériques, précis, robustes et rapides sont nécessaires pour de nombreuses d’applications, le suivi d’objets reste un problème pratique important en vision par ordinateur. La première contribution de cette thèse est une approche calculatoire rapide pour le suivi d'objets de forme et de mouvement variable. Elle consiste en un système unifié et configurable pour estimer l'attitude d’un objet déformable dans un espace d'états de dimension petite ou grande. L’objet est décomposé en une suite de segments composés de parties et organisés selon une hiérarchie spatio-temporelle contrainte. L'efficacité et l’universalité de cette approche sont démontrées expérimentalement sur de nombreux exemples de suivi de divers objets flexibles et articulés. Les caractéristiques de Haar (HLF) sont abondement utilisées pour le suivi d’objets. La deuxième contribution est une méthode de décomposition des HLF permettant de les calculer de manière efficace. Ces caractéristiques sont décomposées en noyaux plus simples, éventuellement réutilisables, et reformulées comme des convolutions multi-passes. La recherche et l'alignement des noyaux dans et entre les passes permet de créer des arbres récursifs de noyaux qui nécessitent moins d’opérations en mémoire que les systèmes de calcul classiques, pour un résultat de convolution identique et une mise en œuvre plus efficace. Cette approche a été validée expérimentalement sur des exemples de HLF très utilisésHumans can visually track objects mostly effortlessly. However, it is hard for a computer to track a fast moving object under varying illumination and occlusions, in clutter, and with varying appearance in camera projective space due to its relaxed rigidity or change in viewpoint. Since a generic, precise, robust, and fast tracker could trigger many applications, object tracking has been a fundamental problem of practical importance since the beginnings of computer vision. The first contribution of the thesis is a computationally efficient approach to tracking objects of various shapes and motions. It describes a unifying tracking system that can be configured to track the pose of a deformable object in a low or high-dimensional state-space. The object is decomposed into a chained assembly of segments of multiple parts that are arranged under a hierarchy of tailored spatio-temporal constraints. The robustness and generality of the approach is widely demonstrated on tracking various flexible and articulated objects. Haar-like features are widely used in tracking. The second contribution of the thesis is a parser of ensembles of Haar-like features to compute them efficiently. The features are decomposed into simpler kernels, possibly shared by subsets of features, thus forming multi-pass convolutions. Discovering and aligning these kernels within and between passes allows forming recursive trees of kernels that require fewer memory operations than the classic computation, thereby producing the same result but more efficiently. The approach is validated experimentally on popular examples of Haar-like features
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Filén, Frida, and Sanna Sjödin. "”Revisorer har ju inga spåkulor” - En studie om svenska revisorers perspektiv på bedömningen av fortsatt drift." Thesis, Mittuniversitetet, Institutionen för ekonomi, geografi, juridik och turism, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-42370.
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Revisorer har i uppdrag att granska huruvida företagsledningens antagande om fortsatt drift stämmer eller inte. Bedömningen leder till en anmärkning i revisionsberättelsen vid tvivel om fortsatt drift, alternativt en utebliven anmärkning om tvivel inte uppstår vid granskningen. Svenska revisorer har dock problem att upptäcka de risker som indikerar konkurs. Träffsäkerheten vid anmärkningar och uteblivna anmärkningar är generellt sett låg vilket lämnar ett stort utrymme för förekomsten av s.k. typ I- och typ II-fel. Felbedömningarna och den låga träffsäkerheten medför problem för intressenter, såsom investerare och kreditgivare. Intressenterna varnas då inte om företagets fortlevnadsproblem och får därmed ingen möjlighet att vidta åtgärder för att undkomma negativa ekonomiska konsekvenser. Tidigare empiriska studier visar att revisorers bedömningar influeras av känslor såsom komfort och diskomfort. Studier visar även att erfarenhet och kompetens, struktur och bedömning samt granskningstid inverkar på fortsatt driftbedömningar samt i vilken grad revisorer upplever komfort och diskomfort i bedömningen. Revisorer uppvisar ibland en oproportionerlig tillit till företagsledningarna vilket åskådliggör en partiskhet och oberoendeproblematik i fortsatt driftbedömningarna. Tidigare studier har dock mestadels tillämpat generaliserbara tillvägagångssätt. Hur revisorer själva beskriver fortsatt driftbedömningarna och dess problematik är, så vitt vi vet, oklart. Syftet med denna studie är att beskriva och analysera de tillvägagångssätt och de förklaringar som några svenska auktoriserade revisorer anger ligger till grund för svårigheter i fortsatt driftbedömningar. Studien genomfördes hösten 2020 med en abduktiv forskningsansats och sex semistrukturerade digitala videointervjuer. Vidare användes en tematisk analysmetod för att sammanställa de transkriberade intervjuerna. Trots att de till synes är erfarna och kompetenta anger de tillfrågade revisorerna att fortsatt driftbedömningarna är svåra och medför diskomfort. Revisorerna beskriver att deras syn på och användning av standarden ISA 570 varierar med anledning av bland annat tolkningssvårigheter. De önskar ändå inte mer riktlinjer i standarden med anledning av att utrymmet för den professionella bedömningen då minskar. Revisorerna beskriver att de upplever tidsbrist i granskningen och de anger dokumentationskrav som en tidstjuv. Fortsatt driftbedömningarna influeras även av individuella känslor enligt revisorerna och en upplevd diskomfort måste reduceras genom dialog med kollegor, företagsledningen och interna experter för att övergå i komfort. Revisorerna anser inte att typ I- och typ II-fel är felaktiga bedömningar såsom teorin beskriver och vi kan därmed konstatera att skillnader mellan teori och praktik föreligger. Revisorerna beskriver att typ II-fel beror på plötsliga händelser som i princip är omöjliga att förutspå eftersom bedömningen innefattar framtiden. Argumentet om att framtiden är inte går att förutspå håller däremot inte då investerare ofta åskådliggör att detta faktiskt är möjligt. Revisorernas beskrivningar av fortsatt driftbedömningen genomsyras genomgående av ett företagsfokus framför ett intressentfokus vilket indikerar en oberoendeproblematik.Auditors are tasked with examining whether the management´s assumption of going concern is correct or not. The assessment leads to a remark in the auditor´s report in case of doubt about going concern, or alternatively a lack of remark if doubt does not arise during the audit. However, Swedish auditors have problems discovering the risk that indicate bankruptcy. The accuracy of remarks in the field of going concern is generally low, which leaves a lot of room for the occurrence of so-called type I and type II errors. The misjudgements and the low accuracy cause problems for stakeholders, such as investors and lenders. Stakeholders are then not warned about the company´s survival problems and thus were not given the opportunity to take measures to escape negative financial consequences. Previous empirical studies show that auditors´ assessments are influenced by emotions such as comfort and discomfort. Studies show that experience and competence, structure and judgement such as audit time influence going concern assessments and the extent to which auditors experience comfort and discomfort in the assessment. Auditors sometimes show a disproportionate trust in the management skills of companies, which illustrates a bias and an independence problem in going concern assessments. Previous studies, however, mostly apply generalizable approaches. How the auditors themselves describe the going concern assessments is, as far as we know, unclear. The purpose of this study is to describe and analyse the approaches and explanations given by some Swedish certified public auditors as a basis for difficulties in going concern assessments. The study was conducted in the autumn of 2020 with an abductive research approach and six semi-structured digital video interviews. Furthermore, a thematic analysis method was used to compile the transcribed interviews. Despite the fact that they seem to be experienced and competent, the auditors consulted state that going concern assessments are difficult and lead to discomfort. The auditors describe that their views on and use of the standard ISA 570 vary due to, among other things, difficulties of interpretation. However, they do not want more guidelines in the standard due to the fact that the scope for the professional judgement then decreases. The auditors describe that they experience a lack of time in the audit and they state documentation requirements as a time thief. Going concern assessments are also influenced by individual feelings according to the auditors and a perceived discomfort must be reduced through dialogue with colleagues, company management and internal experts in order to achieve comfort. The auditors do not consider that type I and type II errors are incorrect assessments as the theory describes and we can thus state that there are differences between theory and practice. The auditors describe that type II errors are due to sudden events that are impossible to predict because the assessment includes the future. The argument that the future is unpredictable can be questioned because investors often illustrate that this actually is possible. The auditors´ descriptions of the going concern assessment are permeated throughout by a company focus rather than a stakeholder focus, which indicates bias and independence issues.
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Arleskär, Staffan. "Bostadsrätt, gräsmark eller skog? : Hur har exploatering för bostadsbyggande år 2000-2015 påverkat Järvakilens funktion som spridningsväg?" Thesis, Stockholms universitet, Institutionen för naturgeografi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-132173.
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Urbanization is a key driver of habitat loss, ecosystem degradation and has a great impact on biodiversity. Exploitation of buffer zones surrounding conservation areas and green structures in urban environment can affect biodiversity through reduced total area of habitat, increased edge effects and lost connectivity on a landscape level. The previous regional development plans for the Stockholm region, had the purpose of leaving large green structures undeveloped to secure core areas of great biological value by focusing on a dense city core. However, the latest regional development strategy puts stress on the green wedges by shifting the focal areas of the development into suburban regional city centers, in many cases close to the green wedges. The purpose of this study was to map habitat loss and changes in the total area of the Järva green wedge, west of Stockholm, caused by development of housing areas in previously sparsley exploited buffer zones, during the period 2000 – 2015. The study uses theories of landscape ecology, remote sensing and GIS to map and quantify habitat loss between 2000 and 2015. Two different birds were used as surrogate species, one grassland habitat specialist – Corncrake (Crex crex) and one forest habitat generalist – Eurasian jay (Garrulus glandarius). The two different surrogate species were used to identify how loss of two nature types could influence biodiversity and connectivity for a group of species. Documents and development plans on regional and local scale were also used to map and predict further habitat loss and exploitation of the green wedge until 2030. The result of the study shows that grassland habitat lost nearly twice the area than forest habitat due to development of housing areas during the period 2000 to 2015. A total of 1.3 km² of grassland and 0.7 km² forest habitat were replaced by housing areas during the fifteen years covered in the study, and the Järva green wedge will have lost a total of 3.84 km² buffer zones by the year 2030. The Corncrake and other grassland specialist species is likely to get most affected when grassland suffered the greatest habitat loss in the area. Even though the Eurasian jay has a key ecological function for the Oak forest in the Järva green wedge and relies on forest habitat for successful breeding, the loss of forest habitat will probably not affect the habitat generalist species in the same way. On a regional scale, the study suggests that habitat loss and fragmentation may affect grassland specialist species more than forest generalist species. The overall connectivity in the Järva green wedge is likely to get affected by a shrinking total area caused by narrowing of the green wedge until 2030. The function of the Järva green wedge as a dispersal corridor for biodiversity in the Stockholm region will most certainly get affected by further loss of buffer zones caused by exploitation of land for housing areas.
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Das, Hari Sankar [Verfasser], and Biprajit [Akademischer Betreuer] Sarkar. "Ruthenium complexes with non-innocent quinonoid, quinoline-5,8-dione and iminoquinone ligands : synthesis, structure, redox properties and electron distribution / Hari Sankar Das. Betreuer: Biprajit Sarkar." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2012. http://d-nb.info/102604331X/34.
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Granemark, Elin. "Minskar införandet av skattetillägg benägenheten att begå skattebrott? : En tidsseriestudie om vilken effekt skattetillägg har på självrättelser av inkomstdeklarationer." Thesis, Uppsala universitet, Nationalekonomiska institutionen, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-449070.
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Vilken effekt har skattetillägg på självrättelser av inkomstdeklarationer för individers benägenhet att begå skattebrott? Enligt grundteorin inom 'economics of crime' bör benägenheten att begå skattebrott minska för en rationell individ av en ökad sannolikhet och kostnad att bli straffad. Studien är en tidsseriestudie som undersöker beteendeförändringar av individers självrättelser av sina inkomstdeklarationer i samband med införandet av skattetillägg som tillkom av Skatteförfarandelagens (2011:1244) reform år 2018. Studien finner statistiskt signifikanta 'structural breaks' år 2019 (med hänsyn till 'first lag') vilket indikerar på ett förändrat beteendemönster i samband med införandet av skattetillägget. Andra faktorer kan dock inte uteslutas.
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Shelley, Anthony N. "INCORPORATING MACHINE VISION IN PRECISION DAIRY FARMING TECHNOLOGIES." UKnowledge, 2016. http://uknowledge.uky.edu/ece_etds/86.
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The inclusion of precision dairy farming technologies in dairy operations is an area of increasing research and industry direction. Machine vision based systems are suitable for the dairy environment as they do not inhibit workflow, are capable of continuous operation, and can be fully automated. The research of this dissertation developed and tested 3 machine vision based precision dairy farming technologies tailored to the latest generation of RGB+D cameras. The first system focused on testing various imaging approaches for the potential use of machine vision for automated dairy cow feed intake monitoring. The second system focused on monitoring the gradual change in body condition score (BCS) for 116 cows over a nearly 7 month period. Several proposed automated BCS systems have been previously developed by researchers, but none have monitored the gradual change in BCS for a duration of this magnitude. These gradual changes infer a great deal of beneficial and immediate information on the health condition of every individual cow being monitored. The third system focused on automated dairy cow feature detection using Haar cascade classifiers to detect anatomical features. These features included the tailhead, hips, and rear regions of the cow body. The features chosen were done so in order to aid machine vision applications in determining if and where a cow is present in an image or video frame. Once the cow has been detected, it must then be automatically identified in order to keep the system fully automated, which was also studied in a machine vision based approach in this research as a complimentary aspect to incorporate along with cow detection. Such systems have the potential to catch poor health conditions developing early on, aid in balancing the diet of the individual cow, and help farm management to better facilitate resources, monetary and otherwise, in an appropriate and efficient manner. Several different applications of this research are also discussed along with future directions for research, including the potential for additional automated precision dairy farming technologies, integrating many of these technologies into a unified system, and the use of alternative, potentially more robust machine vision cameras.
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Huché, Frédéric. "Etude structurale et fonctionnelle du récepteur de membrane externe HasR de Serratia marcescens impliqué dans l'acquisition de l'hème via l'hémophore HasA = Struktur und Funktion des Aussenmembranrezeptors HasR aus Serratia marcescens im Komplex mit dem Hämophorprotein HasA /." Konstanz, 2006. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000254431.
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Keskin, Robin, and Ersad Colic. "Hur stark påverkan har aktiekursen på kapitalstrukturen? : En kvantitativ studie om sambandet mellan aktiekursen och kapitalstrukturen på Stockholmsbörsen." Thesis, Södertörns högskola, Institutionen för samhällsvetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-35512.
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Today, the capital structure is an established research area in economics. Capital structure refers to the relationship between equity and liabilities, which through history has been explored through many different aspects. Capital structure is influenced by several factors and the results is ambiguous as to which of these factors are related to capital structure and which can explain the capital structure. The purpose of this study is to investigate the relationship between the share price and capital structure as well as investigate which control variable is correlating with capital structure. The study is of quantitative form, where data was collected between 2009-2017 from the 15 largest companies, set at market value, from Large Cap and Mid Cap listings from Nasdaq Stockholm. The result of the study shows that the share price and capital structure have a positive relationship for both lists, also share price could explain variations in the capital structure. The control variables result differ significantly depending on the list and variables. Profitability is the variable that explains the capital structure best, especially on the Large Cap list. Company size has no connection with the capital structure, and the explanation rate is reasonably comparable to share price as a single independent variable. Firm age has no connection with the capital structure and only affects the explanation negatively.Idag är kapitalstruktur ett etablerat forskningsområde inom företagsekonomi. Kapitalstruktur avser förhållandet mellan eget kapital och skulder vilket har genom tiden utforskats ur mängder av aspekter. Utformningen av kapitalstrukturen påverkas av flera faktorer och idag är empirin tvetydig angående vilka av dessa faktorer som har samband med kapitalstrukturen och vilka som är kan förklara kapitalstrukturen. Syftet med denna studie är att undersöka sambandet mellan aktiekursen och kapitalstrukturen samt undersöka vilka kontrollvariabler som korrelerar kapitalstrukturen. Studien är av kvantitativ form och data samlades in mellan 2009–2017 från de 15 största företagen, sett till börsvärde, från Large Cap och Mid Cap listorna från Nasdaq Stockholm. Resultatet från studien visar att aktiekursen och kapitalstrukturen har ett positivt samband för båda listorna och att aktiekursen kan förklara variationer i kapitalstrukturen. Kontrollvariablerna skiljer sig i resultatet markant beroende på lista och variabel. Lönsamhet är den kontrollvariabeln som förklarar kapitalstrukturen bäst bland kontrollvariablerna, speciellt på Large Cap listan. Företagsstorlek har inget samband med kapitalstrukturen och ökar förklaringsgraden någorlunda jämförelsevis med aktiekurs som ensam oberoende variabel. Företagsålder har inget samband med kapitalstrukturen och påverkar förklaringsgraden endast negativt.
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Dousset, Simon. "Comportement mécanique dynamique de la glace : Contributions expérimentales et numériques pour le cas d'impacts de grêle sur structures aéronautiques." Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0023.
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L’impact de grêlons sur des aéronefs peut causer d’importants dégâts tels que des perforations de bords d’attaque. Afin de garantir la sécurité des voyageurs, tout en optimisant les structures, la simulation numérique peut être un atout majeur. Cependant, les résultats obtenus doivent être représentatifs de la réalité. Dans ce contexte, des essais expérimentaux d’impacts de grêlons de laboratoire sont réalisés. Couplés à une étude numérique d’impact, les essais expérimentaux permettent de comprendre les phénomènes mis en jeu durant l’impact d’un grêlon. Ensuite, le modèle proposé dans la littérature par Tippmann et al. (2013) est testé. Les performances obtenues sont analysées. Cette analyse permet de proposer une nouvelle démarche de modélisation afin d’améliorer les résultats des simulations actuellement proposées. Dans cette optique, une méthodologie complète de mise en oeuvre du modèle et de caractérisation du matériau est proposéeThe impactof hail on aircraft can cause significant damage such as leading edge perforations. In order to guarantee passenger safety, while optimizing structures, digital simulations can be a major advantage. However, the results obtained must be representative of reality. In this context, experimental tests of simulated hail ice (SHI) impacts are carried out. Coupled with a numerical impact study, experimental results enable to understand the phenomena involved during the impact of SHI. Then, the model proposed in the literature by Tippmann et al. (2013) is tested. Performances obtained are analysed. This analysis makes it possible to propose a new modelling approach in order to improve the results of the simulations currently proposed. In this perspective, a complete methodology for implementing the model and characterizing the material is proposed
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Derias, Bruno. "Simulation numérique pour le développement d'une nouvelle génération de structure aéronautique soumise à impacts." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0012.
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L'aéronautique recherche des matériaux à haute performance pour réduire le poids structurel et absorber l'énergie des chocs. Les matériaux composites offrent des perspectives liées au rapport de la masse et de la rigidité. Cependant, la dispersion de leurs propriétés mécaniques due aux conditions environnementales ou au comportement à l'impact entrave leur développement. Actuellement, des solutions en nid d'abeilles et des mécanismes complexes d'absorption d'énergie sont utilisées. Le dimensionnement des structures est maîtrisé pour des chargements conventionnels, mais pas pour des cas sévères comme l'impact aviaire. Dans le cadre du développement d'une structure aéronautique renforcée innovante, l'objectif de cette étude est d'identifier et de caractériser un nouveau concept de matériau composite absorbant à l'échelle du coupon. Afin d'améliorer sa fiabilité et d'optimiser ses caractéristiques d'absorption lors d'impacts à haute énergie, des travaux sont réalisés pour développer en parallèle une méthodologie d'étude expérimentale et un modèle par éléments finis. L'objectif de ce dernier est de disposer d'un outil prédictif validé par corrélation avec l'expérimental pour assurer un essai virtuel. Le manque de connaissance du comportement non linéaire du matériau composite à forte déformation, pour différentes vitesses, ainsi que des mécanismes d'endommagement et de rupture sont des freins à son développement. L'absence d'une matrice d'expérimentation dédiée présente une difficulté pour sa caractérisation et son dimensionnement. Les travaux se concentrent sur l’étude des aspects mathématique, mécanique, numérique et informatique du problème. Les trois composantes de ce problème, c’est-à-dire l’oiseau, le matériau absorbant et le concept du fond étanche sont étudiés. Pour cela, trois cas d’application sont mis en œuvre. Après le développement d'études expérimentales de caractérisation, la qualification et la justification du nouveau concept est validée par corrélation avec une méthodologie de simulation numérique dédiée. Les résultats de l'étude mettent en évidence l'analyse et le développement d'un concept intéressant. Ce projet de thèse comporte également des analyses complémentaires concernant deux autres cas d’impact aéronautique : l’impact multiple de grêlons et de débris de pneu. Ces deux cas ont été envisagés suite aux enseignements tirés des études menées précédemment. Enfin, une conclusion présente notamment des perspectives de prolongement des travaux présentésAeronautics search high performance materials for structural weight reduction and impact energy absorption. Composite offers perspectives related to mass and stiffness ratio. However, the dispersion of their mechanical properties due to environmental conditions or impact behaviour hinders their development. Currently, honeycomb solutions and complex energy absorption mechanisms are used. The sizing of structures is controlled for conventional loads, but not for severe cases such avian impact. In the context of the development of an innovative reinforced aeronautical structure, the objective of this study is to identify and characterize a new concept of absorbent composite material at the coupon scale. In order to improve reliability and optimize its absorption characteristics during high-energy impact, works are realized to develop in parallel an experimental study methodology and a finite element model. The purpose of the latter is to have a predictive tool validated by correlation with experimental to ensure virtual testing. Lack of knowledge of the nonlinear behaviour of the composite material at high deformation, for different speeds, as well as the mechanisms of damage and fracture are locks to its development. Absence of a dedicated experiment matrix presents a difficulty for its characterization and sizing. The work focuses on the study of the mathematical, mechanical, numerical and computer aspects of the problem. The three components of this problem, namely the bird, the absorbent material and the concept of the bulkhead, are studied. For this purpose, three application cases are implemented. After development of an experimental characterization study, the qualification and justification of the new concept is validated by correlation with a dedicated numerical simulation methodology. The results of the study highlight the analysis and development of an interesting concept. This thesis project also includes additional analyses of two other cases of aeronautical impact: the multiple impact of hail and tire debris. These two cases were considered following the lessons learned from previous studies. Finally, one conclusion presents, in particular, prospects for extending the work presented
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Blom, Bringlöv Agnes. "”Det handlar om att ge och ta” : En kvalitativ studie om betydelsen faktorer kopplade till schemaläggning har för upplevelse av delaktighet och inflytande." Thesis, Umeå universitet, Sociologiska institutionen, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-139948.
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Syftet med studien är att undersöka betydelsen faktorer kopplade till schemaläggning har för upplevelse av delaktighet och inflytande. De faktorer som undersökts är schemaläggningssystem, organisatoriska aspekter, samarbete, och flexibilitet. De teorier som används är Job demand-control model, Social exchange theory och Structural empowerment theory. Det är en kvalitativ intervjustudie med fem informanter som jobbar hel- eller deltid inom äldrevård eller funktionshinderomsorg i Umeå kommun. Informanterna har tre olika schemasystem med det gemensamma att samtliga informanter får ge önskemål på hur de vill att deras schema för kommande schemaperiod ska se ut. Resultatet visar att informanterna upplever olika grad av delaktighet och inflytande i sitt schemaläggningssystem. Centralt schemastöd är den funktion som minskar upplevelsen av delaktighet och inflytande för majoriteten av informanterna. Ökad utbildning, avsatt tid för schemaläggning, stöd för att öka samarbete på arbetsplatsen och kontakt med Centralt schemastöd är faktorer som sammanfattningsvis föreslås kan öka de anställdas delaktighet och inflytande i schemaläggning.
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Martin, Béatrice. "Contribution à l'étude des paysages bocagers de montagne : structure et dynamique spatiale, diversité écologique et gestion d'un patrimoine rural : l'exemple du Champsaur (Hautes-Alpes, France)." Grenoble 1, 1999. http://www.theses.fr/1999GRE10101.
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Dans cette etude, nous analysons les principales composantes de la diversite ecologique d'un bocage de montagne. Nos investigations ont porte sur la structure bocagere du champsaur dans la haute vallee du drac ou le bocage et les haies occupent desormais une place de choix dans la dynamique socio-economique locale. Une approche globale montre que les ecosystemes-haies sont etroitement lies aux elements de structure du territoire. Puis, l'analyse a deux niveaux des systemes ecologiques (reseaux et haies) met en relief les specificites de du complexe-bocager. L'etude comparative de la vegetation montre une differenciation inter-sites de la repartition des ligneux, et une inegale distribution des especes herbacees de part et d'autre des ecosystemes-haies : especes meso-xerophiles en facette adret et especes meso-hygrophiles en facette ubac et dans la haie. La variabilite des caracteristiques floristiques est correlee aux variations des regimes thermiques et pluviometriques. Ces dernieres, nuancees a l'echelle des complexes-reseaux, sont plus marquees a celle des ecosystemes-haies. Leur disparite est fonction de l'emplacement et de la porosite. Les pratiques mises en oeuvre par l'homme pour l'entretien des haies et la valorisation du territoire sont a l'origine d'une biodiversite influencee, elle-meme en interaction avec la diversite floristique liee a l'heterogeneite microclimatique. Replacee dans un contexte plus large a partir de l'analyse des perceptions de l'ensemble des acteurs, la problematique de gestion des haies est consideree comme un processus revelateur du fonctionnement de l'eco-socio-systeme. Il en ressort que le bocage et les haies sont sur le point d'acceder au rang de patrimoine. Les perspectives de gestion enoncees par certains refletent un nouvel etat d'esprit ou l'integration economie-ecologie pourrait avoir une place. Les connaissances issues de cette recherche doivent servir a alimenter ce debat en vue d'une gestion de type patrimonial.
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Rosén, Linda, and Leijon Agnes Liljekvist. "Han är som han är - En kvalitativ studie om upplevelsen av att växa upp med ett syskon som har autism." Thesis, Stockholm University, Department of Social Work, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-35173.
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The aim of this study is to examine the experienced life situations of siblings growing up with a brother or a sister diagnosed with autism. The study is qualitative and therefore suitable to the purpose of studying the informants´ own experiences. Three women and one man, aged between 18-24 years, were interviewed through chatt programs on the Internet. The constituted perspective is phenomenological and the analysis were made by identifying meaning units in the text from the interviews. The theory used to interpret the result is systems theory and more specifically the structual family therapy by Salvador Minuchin. The data was also compared to earlier research. The result showed that the siblings were affected by growing up with a brother or sister with autism. Their experiences were both of positive and negative kind. The findings further showed that the siblings had similar as well as various experiences.
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WESIERSKI, Daniel. "Visual tracking of articulated and flexible objects." Phd thesis, Institut National des Télécommunications, 2013. http://tel.archives-ouvertes.fr/tel-00939073.
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Humans can visually track objects mostly effortlessly. However, it is hard for a computer to track a fast moving object under varying illumination and occlusions, in clutter, and with varying appearance in camera projective space due to its relaxed rigidity or change in viewpoint. Since a generic, precise, robust, and fast tracker could trigger many applications, object tracking has been a fundamental problem of practical importance since the beginnings of computer vision. The first contribution of the thesis is a computationally efficient approach to tracking objects of various shapes and motions. It describes a unifying tracking system that can be configured to track the pose of a deformable object in a low or high-dimensional state-space. The object is decomposed into a chained assembly of segments of multiple parts that are arranged under a hierarchy of tailored spatio-temporal constraints. The robustness and generality of the approach is widely demonstrated on tracking various flexible and articulated objects. Haar-like features are widely used in tracking. The second contribution of the thesis is a parser of ensembles of Haar-like features to compute them efficiently. The features are decomposed into simpler kernels, possibly shared by subsets of features, thus forming multi-pass convolutions. Discovering and aligning these kernels within and between passes allows forming recursive trees of kernels that require fewer memory operations than the classic computation, thereby producing the same result but more efficiently. The approach is validated experimentally on popular examples of Haar-like features
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Kunze, Sebastian. "Untersuchungen zur Strömungs-Struktur Interaktion an dynamisch bewegten, flexiblen Oberflächen." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2011. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-71172.
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Die experimentellen Untersuchungen zur Strömungs-Struktur-Interaktion kommen zu folgenden Ergebnissen. Die als entrainment bezeichnete Verhaltensweise von Fischen kann durch den gezielten Ausgleich von Auftriebs-, Widerstands- und einer erstmals nachgewiesenen Saugkraft und der damit verbundenen Reduzierung der lokomotorischen Energie erklärt werden. Des Weiteren zeigen die Experimente an einer wellenförmig bewegten Oberfläche, dass die Strömung an einem Wellenberg zyklisch zwischen laminarem und turbulentem Regime wechselt und dass diese Oszillation zur Reduzierung des Form- und Gesamtwiderstandes der geschleppten Oberfläche führt. Dünne, flexible Häutchen hairy flaps an der Rückseite eines Zylinders führen zu einer Änderung der Struktur der Wirbelablösung an diesem. Dadurch wird sowohl die auf den Zylinder wirkende Auftriebskraft als auch die Widerstandskraft um bis zu 65% reduziert. Für die Interaktion zwischen der Strömung um zwei hintereinander positionierte elastische Zylinder und ihrer Kinematik konnte die Synchronisierung (lock-in) ihrer Bewegung mit einer verbundenen Zerstörung der Wirbelstraße hinter dem zweiten Zylinder gezeigt werdenThe experimental investigations presented herein explain the behavioural adaptation of fish called entrainment for the first time. The results confirm a balance of lift-, drag- and a suction-force, explaining the reduction of locomotive energy. Furthermore, flow measurements around an undulating membrane affirm an oscillation between laminar and turbulent flow over one period of the motion and that this oscillation decreases the pressure- and drag-force of the towed membrane. Experiments on thin and flexible flaps attached at the lee-side of a cylinder, show that the flaps alter the natural vortex separation cycle in such a way that the vortices do not shed in a staggered side-by-side arrangement but in line in a row with the cylinder wake axis. Thus, flow fluctuations are reduced by 42% in stream-wise - and 35% in transversal direction at best, compared to a reference case without hairy-flaps. Finally, investigations on the flow around and on the kinematics of two flexible cylinders in a tandem arrangement demonstrate a synchronisation of their motion (lock-in), resulting in the destruction of the vortex-street behind the second cylinder
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Prudek, Michal. "Relaxační centrum ve Velkém Meziříčí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240299.
Full textAbstract:
This thesis describes design of new relaxation centre building in town of Velké Meziříčí and creation of blueprints for building construction. Blueprints are furthermore supplemented by extensions for heating and concrete structures. The relaxation centre houses a wellness centre, a café, a hair and make-up salon with possibility of massage and an outdoor shop. The building is located in southern part of Velké Meziříčí – an urban area of both residential and industrial buildings. The centre is a three storey building with partial basement, flat single-layered roof and stairway, which serves as an access point for ventilation engine room located on top of the roof structure. This last element is distinguished from the rest of the building by different coloured façade panelling and serves as a dominant. Wellness centre covers the whole of ground floor and is interfaced with the first floor by additional wellness centre spaces and staff spaces. The first floor also includes the outdoor shop. Café and hair salon are situated on the second floor. Architectonic design is created in similarity to surrounding buildings and in relation to cardinal direction. Land lot is utilized for wellness centre purposes.