To see the other types of publications on this topic, follow the link: L4.
Dissertations / Theses on the topic 'L4'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'L4.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Backström, Ellenor. "Regulation of Adenoviral Gene Expression by the L4-33K and L4-22K Proteins." Doctoral thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-101324.
Full textAbstract:
The splicing pattern during an adenovirus infection is shifted at the late phase towards using weaker splice sites, splicing out larger introns. Splicing of weak 3´ splice sites usually requires recognition of the 3´AG dinucleotide before the first catalytic step of splicing. Such splicing events are said to be AG-dependent and requires an interaction of both subunits of the cellular splicing factor U2AF with the 3´ splice site. We show that splicing of transcripts that are AG-dependent in uninfected nuclear extracts (NE) becomes AG-independent in nuclear extracts prepared form adenovirus late-infected HeLa cells (Ad-NE). Further we demonstrate that the first step in splicing of a model transcript, IgM, becomes completely U2AF-independent in Ad-NE. This finding supports our working model that 3´ splice site recognition in Ad-NE is altered, and in fact might be U2AF-independent. We further show that the adenovirus late protein L4-33K acts as a virus encoded alternative splicing factor. L4-33K activates splicing of both cellular and viral transcripts containing weak 3´ splice sites. This supports the hypothesis that adenovirus alter splicing during the infection to favour usage of weak, suboptimal 3´ splice sites. However, we were unable to find an alternative U2AF-related factor that could stimulate L4-33K splicing enhancer activity. Furthermore, we demonstrate that the serine residues in the C-terminal part of L4-33K are important for the splicing enhancer activity but also for its nuclear localisation. The adenovirus major late promoter is highly activated after the onset of viral genome replication. Protein complexes binding to downstream elements of the promoter are required for full enhancement of this promoter. We show that an L4-33K-related protein, L4-22K, stimulates transcription from the major late promoter. This stimulation is mainly via the downstream elements and does not require the viral IVa2 protein, which is a transcription factor of the major late promoter.
2
Östberg, Sara. "Functional Characterization of the Evolutionarily Conserved Adenoviral Proteins L4-22K and L4-33K." Doctoral thesis, Uppsala universitet, Science for Life Laboratory, SciLifeLab, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-238487.
Full textAbstract:
Regulation of adenoviral gene expression is a complex process directed by viral proteins controlling a multitude of different activities at distinct phases of the virus life cycle. This thesis discusses adenoviral regulation of transcription and splicing by two proteins expressed at the late phase: L4-22K and L4-33K. These are closely related with a common N-terminus but unique C-terminal domains. The L4-33K protein is an alternative RNA splicing factor inducing L1-IIIa mRNA splicing, while L4-22K is stimulating transcription from the major late promoter (MLP). The L4-33K protein contains a tiny RS-repeat in its unique C-terminal end that is essential for the splicing enhancer function of the protein. Here we demonstrate that the tiny RS-repeat is required for localization of the protein to the nucleus and viral replication centers. Further, we describe an auto-regulatory loop where L4-33K enhances splicing of its own intron. The preliminary characterization of the responsive RNA-element suggests that it differs from the previously defined L4-33K-responsive element activating L1-IIIa mRNA splicing. L4-22K lacks the ability to enhance L1-IIIa splicing in vivo, and here we show that the protein is defective in L1-IIIa or other late pre-mRNA splicing reactions in vitro. Interestingly, we found a novel function for the L4-22K and L4-33K proteins as regulators of E1A alternative splicing. Both proteins selectively upregulated E1A-10S mRNA accumulation in transfection experiments, by a mechanism independent of the tiny RS-repeat. Although L4-22K is reported to be an MLP transcriptional enhancer protein, here we show that L4-22K also functions as a repressor of MLP transcription. This novel activity depends on the integrity of the major late first leader 5’ splice site. The model suggests that at low concentrations L4-22K activates MLP transcription while at high concentrations L4-22K represses transcription. So far, characterizations of the L4-22K and L4-33K proteins have been limited to human adenoviruses 2 or 5 (HAdV-2/5). We expanded our experiments to include HAdV-3, HAdV-4, HAdV-9, HAdV-11 and HAdV-41. The results demonstrated that the transcription- or splicing-enhancing properties of L4-22K and L4-33K, respectively, are evolutionarily conserved and non-overlapping. Thus, the sequence-based conservation is mirrored by the functions, as expected for functionally important proteins.
3
Backström, Ellenor. "Regulation of Adenoviral Gene Expression by the L4-33K and L4-22K Proteins." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-101324.
Full text
4
Kolarík, Tomáš. "Implementace protokolu ACP do operačního systému L4." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219477.
Full textAbstract:
This thesis deals with the implementation of ACP protocol which serves to manage the access for operation system based on L4 microkernel. The theoretical part of the thesis deals with methods of access management in computer networks. It focuses primarily on AAA systems which make access management possible. Furthermore it describes in detail the ACP protocol, the types of messages and their feedback. The next theoretical part is dedicated to operation systems and in particular to their architecture and services. Then we get a closer look at L4 microkernel family, their philosophy and properties. We continue with a detailed description of the L4 application interface and its ways of expansion. The practical section deals with the implemented concept of system for ACP protocol support in computers. General concept is then applied in real implementation of ACP protocol into the L4 operation system environment based on the L4 platform. To assist, I also included a detailed tutorial explaining the modeling and compilation of software for this platform. At this point we describe the methods used at the implementation and the description of particular modules and features. The end of the thesis concludes the information about the ways of testing and the implementation properties.
5
Trifa, Youssef. "Caractérisation de la protéine ribosomique L4 du plaste d'épinard." Grenoble 1, 1998. http://www.theses.fr/1998GRE10204.
Full textAbstract:
Le genome plastidial est transcrit par deux arn polymerases, l'une monomerique, codee dans le noyau (nep), l'autre multimerique codee par le genome plastidial (pep). La transcription de l'operon rrn plastidial est assuree, in vivo, par la nep. Le facteur cdf2 est implique dans la regulation de l'expression de cet operon, en inhibant sa transcription par pep. Dans le but de caracteriser des proteines impliquees dans la regulation de la transcription plastidiale, nous avons debute l'analyser des proteines qui co-purifient avec le facteur dcf2 et la nep. Une proteine ribosomique (cd2) a ainsi ete purifiee et sa sequence n-terminale determinee. Nous avons clone et identifie l'adn complementaire ainsi que le gene correspondant a cette proteine. Nous avons pu montrer que le gene identifie code pour la proteine l4 de grande sous unite 50s du ribosome plastidial d'epinard (spinacia oleracea). Il s'agit du premier gene nucleaire isole codant pour la proteine rpl4 d'une plante superieure. A l'image d'autres genes nucleaires codant pour des proteines ribosomiques plastidiales, nous avons montre que le gene rpl4 identifie est unique et s'exprime plus dans les tissus a capacite photosynthetique que dans les racines. La proteine rpl4 d'epinard est homologue aux proteines ribosomiques l4 de procaryotes mais s'y distingue par la presence d'une extension c-terminale acide. La proteine ribosomique l4 d'escherichia coli provoque une terminaison prematuree de la transcription de l'operon s10 au niveau d'un site de pause. Malgre la divergence avec celle d'escherichia coli, la proteine ribosomique l4 du chloroplaste d'epinard a conserve au cours de l'evolution la capacite de stimuler la pause de l'arn polymerase d'e. Coli au site d'attenuation de l'operon s10. Cette propriete laisse supposer que la proteine l4 joue un role dans la regulation de l'activite transcriptionnelle par la pep. Dans les plastes d'epinard. Rpl4 semble egalement moduler la transcription, in vitro, de l'operon rrn par la nep. Par son interaction avec les deux arn polymerases plastidiales, rpl4 semble etre une proteine-cle de la regulation transcriptionnelle plastidiale.
6
Lan, Susan. "The Multifunctional Nature of the Adenovirus L4-22K Protein." Doctoral thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-278135.
Full textAbstract:
The adenovirus major late transcription unit (MLTU) encodes for most of the mRNAs that are translated into the structural proteins of the virus capsid. Transcription from the MLTU is directed by the major late promoter (MLP), which is highly activated during the late phase of infection. This thesis discusses how the adenovirus-encoded L4-22K protein regulates the MLP at both the level of transcription and pre-mRNA splicing. The study shed new light on the complex regulation of the early to late shift of adenoviral gene expression. Here we show that the L4-22K protein has opposing effects on MLP transcription, functioning both as an activator and a repressor protein. The stimulatory effect mainly depends on the direct interaction of the L4-22K protein with the downstream element (DE element) located approximately 100 nucleotides downstream of the transcription initiation site. In addition to the DE element we also show that the promoter-proximal upstream element (UPE) acts as an L4-22K responsive enhancer element in the MLP. Preliminary data suggests that the activation of MLP transcription via DE and UPE differs mechanistically. The transactivation domain of the L4-22K protein is localized to the conserved carboxy-terminus of the protein. Our results also defined a novel low affinity L4-22K binding site, the R1 region, which functions as a repressor element in MLP transcription. At high concentrations L4-22K binds to R1 and recruits the cellular transcription factor Sp1 to a DNA segment covering the major late first leader 5´ splice site that is embedded in the R1 region. Sp1 binding to R1 results in a suppression of L4-22K-mediated activation of MLP transcription. This self-limiting effect on MLP transcription might have a function to fine-tune the MLTU gene expression. Interestingly, the L4-22K protein binds with the same sequence specificity to both the R1 double-stranded DNA and R1 single-stranded RNA (ssRNA). L4-22K binds to the R1 ssRNA with the same polarity as the MLTU nascent RNA. This binding results in the recruitment of U1 snRNA to the major late first leader 5´ splice site. This enhanced U1 snRNA recruitment leads to a suppression of MLP transcription and simultaneously an increase of major late first intron splicing.
7
Borowski, Stephan. "Vergleichende intrathekale Volumenmessungen an LWS Präparaten des Menschen mit degenerativer Spinalkanalstenose zwischen interlaminärer Dekompression L3/4, interlaminärer Dekompression L4/5 und Laminektomie L4." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=972109528.
Full text
8
Sharghi-Liebeck, Sanaz [Verfasser]. "Deutsch als L4 für Muttersprachler des Persischen / Sanaz Sharghi-Liebeck." Kassel : Universitätsbibliothek Kassel, 2016. http://d-nb.info/109387029X/34.
Full text
9
Arnelöv, Eric. "Design and Implementation of an EDF Scheduer for Fiasco.OC L4." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-301952.
Full textAbstract:
This paper describes the implementation of an EDF scheduler for the FIASCO microkernel. Benchmark test shows that the average case gain an improvement of 16-34%, in regards to schedule calls, running EDF over the existing fixed priority scheduler using Rate Monotonic (RM). A possible approach to mimic EDF scheduling with fixed priority is described using dynamic counters and worst case ready queue. The advantages and disadvantages are compared to the Fixed Priority with the Priority Promotion algorithm.
10
Ecomard, Jean-Christophe. "Approche synthétique du L4-COOH-hexanor-LTE4 : Implication dans l'Asthme." Montpellier 2, 2004. http://www.theses.fr/2004MON20182.
Full text
11
Le, Thuy D. "Duality." Thesis, Virginia Polytechnic Institute and State University, 1995. http://hdl.handle.net/10919/53402.
Full textAbstract:
Duality begins in the layers of intentions within this thesis. The thesis is approached from the primary need to address the questions of architecture by means of the intellect. Subjectivity is an inevitable intervention in the design process. Thus, there is the secondary need to address the questions of the self in which the intellect and its subjectivity are integral parts. Much of my identity is sculpted by the Buddhist philosophy. Thus it is the primary source which I draw from in the making of architecture. However, the philosophy and architecture are in diametrical opposition. Architecture is reliant on the tangibility of materiality and structure. Buddhism rejects that life in the tangibility. More acutely, its essence is an amorphism because of its inexplicable nature. Conversely, architecture's caliber resides in the clarity of form. This is an attempt in the construct of an architecture taken from outside of architecture while imbuing the quality of being architectural. In parallel, duality is in the dialectic of a thesis and an antithesis in search of a synthesis.Master of Architecture
12
Chang, Albert. "Identification and characterization of a novel kallikrein gene, KLK-L4/KLK13." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63096.pdf.
Full text
13
Formiga, Jorge Kennety Silva. "Formas normais no estudo da estabilidade para L4 no problema fotogravitacional." Instituto Nacional de Pesquisas Espaciais, 2009. http://urlib.net/sid.inpe.br/mtc-m19@80/2009/11.27.16.37.
Full textAbstract:
O estudo da estabilidade do ponto lagragiano L4 para o problema fotogravitacional é realizado. Primeiramente um método analítico-numérico para normalização de sistemas hamiltonianos com 2 e 3 graus de liberdade é apresentado. Em seguida escrevemos as equações do movimento na forma canônica generalizada que depois será colocada na forma normal usando o método de Lie-Hori. A análise da estabilidade do sistema será feita pelo teorema de Kovalev e Savechenko e aplicado ao estudo de estabilidade do ponto lagrangiano L4 no problema fotogravitacional circular restrito dos três corpos.The study of the stability of L4 point of in the photogravitational problem is accomplished. Firstly a normalization algorithm for 2 and 3 degree freedom is accomplished. The equations of motion are written in an extended canonical and then, using the Hori-Lie, method put in a normal form. The stability of the system is analyzed by the theorem of Kovalev and Savechenko be applied to the photogravitational restricted three body problem.
14
Cohen, Robert. "Traitement des instabilités lombaires dégénératives L4-L5 par ligamentoplastie inter-épineuse." Montpellier 1, 1992. http://www.theses.fr/1992MON11136.
Full text
15
Worbs, Michael. "Röntgenstrukturanalyse des Elongationsfaktors NusA und des ribosomalen Proteins L4 aus Thermotoga maritima." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962021024.
Full text
16
Döbel, Björn. "Request tracking in DROPS." Master's thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-26214.
Full textAbstract:
Runtime analysis of applications can help to gain insight into control flow of applications as well as detect performance issues. This work presents efficient means for integrating runtime monitoring facilities into the DROPS operating system and uses these to analyse performance and behavior of L4-based applications such as L4Linux.
17
Törmänen, Persson Heidi. "The Adenovirus L4-33K Protein : A Key Regulator of Virus-specific Alternative Splicing." Doctoral thesis, Uppsala universitet, Institutionen för medicinsk biokemi och mikrobiologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-159632.
Full textAbstract:
Adenoviruses have been extensively studied in the field of gene regulation, since their genes are subjected to a tightly controlled temporal expression during the virus lifetime. The early-to-late shift in adenoviral gene expression distinguishes two completely different programs in gene expression. The adenoviral L4-33K protein, which is the subject of this thesis, was previously implicated to be a key player in the transition from the early to the late phase of infection. Here we show that L4-33K activates late gene expression by functioning as a virus-encoded alternative RNA splicing factor activating splicing of transcripts containing weak 3’ splice sites; a feature common to the viral genes expressed at late times of infection. The splicing enhancer activity of L4-33K was mapped to a tiny arginine/serine (RS) repeat in the carboxyl-terminal domain of the protein. Also, the subcellular distribution to the nucleus with enrichment in the nuclear membrane and subnuclear redistribution to viral replication centers during a lytic infection was observed to depend on this motif. RS repeats are common features for the cellular splicing factors serine/arginine-rich (SR) proteins, which in turn are regulated by reversible phosphorylation. We further show that L4-33K is phosphorylated by two cellular protein kinases, the double-stranded DNA-dependent protein kinase (DNA-PK) and protein kinase A (PKA) in vitro. Interestingly, DNA-PK and PKA have opposite effects on the control of the temporally regulated L1 alternative RNA splicing. DNA-PK functions as an inhibitor of the late specific L1-IIIa pre-mRNA splicing whereas PKA functions as an activator of L1-IIIa pre-mRNA splicing. In summary, this thesis describes L4-33K as an SR protein related viral alternative splicing factor. A tiny RS repeat conveys splicing enhancer activity as well as redistribution of L4-33K to replication centers. Finally, DNA-PK and PKA that phosphorylates L4-33K are suggested to be novel regulatory factors controlling adenovirus alternative splicing.
18
Oliveira, Hudson Pina de. "O problema de Björling para superfícies máximas no espaço de Lorentz-Minkowski L4." reponame:Repositório Institucional da UnB, 2011. http://repositorio.unb.br/handle/10482/7835.
Full textAbstract:
Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Matemática, 2011.Submitted by Albânia Cézar de Melo (albania@bce.unb.br) on 2011-05-17T14:26:25Z No. of bitstreams: 1 2011_HudsonPinaOliveira.pdf: 515108 bytes, checksum: 4288511cf42f3df2bb9973a4ec166f1a (MD5)
Approved for entry into archive by Elna Araújo(elna@bce.unb.br) on 2011-05-17T20:05:49Z (GMT) No. of bitstreams: 1 2011_HudsonPinaOliveira.pdf: 515108 bytes, checksum: 4288511cf42f3df2bb9973a4ec166f1a (MD5)
Made available in DSpace on 2011-05-17T20:05:49Z (GMT). No. of bitstreams: 1 2011_HudsonPinaOliveira.pdf: 515108 bytes, checksum: 4288511cf42f3df2bb9973a4ec166f1a (MD5)
Neste trabalho apresentamos uma representação tipo Weierstrass para superfícies máximas no espaço de Lorentz -Minkowski Ln . Baseado no trabalho de Asperti e Vilhena [5], consideramos esta representação para o caso n = 4 e resolvemos o Problema de Björling em L 4. Introduzimos vários exemplos com propriedades geométricas interessantes. Baseado em [12] estudamos o problema de Calabi-Bernstein e encontramos condições para que uma superfície máxima completa em Ln, n > 4, seja uma plano. ______________________________________________________________________________ ABSTRACT
In this work we present a Weierstrass type representation for maximal surfaces in Lorentz-Minkowski space Ln. Based on work by Asperti and Vilhena [5] we consider this representation for the case n = 4 and solved the Bj orling problem in L4. We introduce several examples with interesting geometric properties. Based on [12] we studied the of Calabi-Bernstein problem and nd conditions for a maximum surfaces complete in Ln; n > 4, is a plan.
19
Colman, Bruno Fontoura da Silva. "Projeto de prótese de disco intervertebral de Ti-6Al-4V entre L4/L3." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153841.
Full textAbstract:
Submitted by BRUNO FONTOURA DA SILVA COLMAN (brunocolman@hotmail.com) on 2018-05-03T15:19:22Z
No. of bitstreams: 1
Dissertação de Mestrado - Bruno Colman Rev.36_03-05-2018.pdf: 5215084 bytes, checksum: 2152650458ee3ee274744cb5b222bb3c (MD5)Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-05-03T17:05:09Z (GMT) No. of bitstreams: 1 colman_bfs_me_ilha.pdf: 5215084 bytes, checksum: 2152650458ee3ee274744cb5b222bb3c (MD5)
Made available in DSpace on 2018-05-03T17:05:09Z (GMT). No. of bitstreams: 1 colman_bfs_me_ilha.pdf: 5215084 bytes, checksum: 2152650458ee3ee274744cb5b222bb3c (MD5) Previous issue date: 2018-03-05
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Esse trabalho tem a finalidade de projetar, com base em levantamento bibliográfico, uma prótese de disco intervertebral de Ti6Al4V pelo processo DMLS. Os sistemas de imagem de tomografias computadorizadas e ressonâncias magnéticas trabalham de maneira semelhante. Imagens em 3D de dados dos pacientes são construídas através da combinação de fatias 2D tomadas a partir de sistemas de sensores e da interpolação entre eles. A distância entre as fatias desses sistemas de imagens é grosseira comparada com a tecnologia da manufatura aditiva, portanto, esses processos combinam as imagens das fatias dentro de um software para criar um modelo 3D sobrepondo camadas, devido a essa sinergia entre os dois tipos de sistema, pesquisadores de todo o mundo tentam melhorar e inventar próteses para substituir o disco intervertebral através da ciência. Os resultados mostraram que a fabricação de uma prótese de disco com junta esférica pelo processo de manufatura aditiva é viável, porém nos segmentos menores, como na cervical ainda são difíceis de produzir devido à altura do disco intervertebral e ao limite da dimensão das camadas da manufatura aditiva, que atualmente estão por volta dos 20μm, por isso requerem tratamentos superficiais após sua fabricação. Espera-se que este trabalho possa ajudar futuros pesquisadores da área de biomecânica da coluna vertebral.
This work has the purpose of designing, based on a bibliographical survey, an intervertebral disc prosthesis of Ti6Al4V by the DMLS process. Computed tomography (CT) imaging systems and MRIs work similarly. 3D images of patients data are constructed by combining 2D slices taken from sensor systems and interpolating between them. The distance between the slices of these imaging systems is rough compared to the additive manufacturing technology, so these processes combine the slice images within a software to create a 3D model overlapping layers because of this synergy between the two system types, researchers around the world try to improve and devise prostheses to replace the intervertebral disc through science. The results showed that the manufacture of a disc prosthesis with spherical joint by the additive manufacturing process is feasible, but in the smaller segments, such as in the cervical still difficult to produce due to the height of the intervertebral disc and to the limit of the size of the layers of the manufacture additives, which are currently around 20μm, so they require surface treatments after their manufacture. It is hoped that this work may help future researchers in the area of spinal biomechanics.
CAPES - PROPG
20
Pelletier, Lucette. "Mecanismes cellulaires impliques dans l4 autoimmunite induite par hgcl : :(2) chez le rat." Paris 6, 1987. http://www.theses.fr/1987PA066573.
Full text
21
Martinez, Lozada Francisco Mauricio. "The effects of L4/5 fusion on the adjacent segments in the lumbar spine." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/the-effects-of-l45-fusion-on-the-adjacent-segments-in-the-lumbar-spine(1b88de80-7c39-4646-860d-7312ca21d947).html.
Full textAbstract:
Lumbar intervertebral disc disorder is a spinal condition that affects the normal function of the intervertebral discs mainly due to the natural aging process. This condition can manifest itself in pain and limited motion in the legs, amongst others. Posterolateral Fusion (PLF) and Posterior Lumbar Interbody Fusion (PLIF) are two of the most used surgical procedures for treating lumbar intervertebral disc disease. Although these procedures are commonly used and performed successfully the impact in terms of the stresses developed in the posterior implants employed and in the spinal components adjacent to the surgical site has not been exhaustively investigated. In addition, the consequences of the procedure on the reduction of the Range of Motion of the lumbar spine is not clearly understood. The objective of this research is to investigate the effect of one-level spinal fusion of lumbar segment L4-L5 on the stresses and the range of motion at the remaining, adjacent lumbar levels. Four 3 dimensional finite element models of a lumbosacral spine were created from Computer Tomography data (CT scan). The models were used to investigate four surgical scenarios, including the use of 0o and 4o interbody cages, in addition to the un-instrumented spine for flexion, extension, torsion and lateral bending motions. The predictions obtained from the models enabled the mechanical behaviour of the lumbar spine following fusion surgery using 0 o and 4o cages to be investigated and compared. In addition, a clinical study was performed to quantify the reduction in the range of motion for subjects who had undergone L4/5 posterior lumbar interbody fusion surgery. The clinical results were compared to those of subjects who had not undergone surgery and to the range of motion predictions from the computational model. The results from this research demonstrate that the insertion of posterior instrumentation does not have an impact on the spinal structures above the L3/4 intervertebral disc. However, the pedicle screws and the insertion of the interbody cages causes stress levels in the area adjacent to the surgical site to rise which could promote accelerated degeneration of the discs. Additionally, this study demonstrates how the pedicle screws are affected by the surgical spinal fusion techniques. Furthermore, the investigation demonstrates how posterior lumbar interbody fusion causes the range of motion of patients that had undergone this surgery to decrease. The results from the comparison of the behaviour of the use of 0º and 4º interbody cages in L4-5 posterolateral fusion demonstrates that the stress levels in the adjacent vertebrae, intervertebral discs and pedicle screw fixation system increase when 4º are used cages than when 0º cages were employed. The results from the in-vitro study show a decrease in the range of motion of the subjects who had undergone L4/5 posterior lumbar interbody fusion surgery when compared with the subjects with no low back pain history. This indicates that the PLIF surgery combined with the normal disc degeneration is subjected to higher stresses than the healthy spine.
22
Ahrens, Birgit [Verfasser], and Karl-Friedrich [Akademischer Betreuer] Fischbach. "Die Bedeutung des Kirre-Proteins für das L4-Netzwerk in der Lamina von Drosophila melanogaster." Freiburg : Universität, 2013. http://d-nb.info/1123475911/34.
Full text
23
Bellak, Christian, Reinhold Hofer, and Peter Tschmuck. "Wettbewerbs- und Strukturpolitik Österreichs." Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2001. http://epub.wu.ac.at/730/1/document.pdf.
Full textAbstract:
Dieser Beitrag gibt einen selektiven Überblick zu theoretischen Konzeptionen von Wettbewerbs- und Strukturpolitik. Anschließend wird die Wettbewerbs- und Strukturpolitik Österreichs vor und seit dem EU-Beitritt anhand eines "Ziele-Mittel-Träger" Konzeptes dargestellt. Eine Fallstudie zum Mediensektor sowie die Einbettung in den internationalen Kontext ergänzen die Ausführungen.Series: Working Papers Series "Growth and Employment in Europe: Sustainability and Competitiveness"
24
Uhlemann, Florian [Verfasser]. "Auswirkung der intrafusionalen bisegmentalen Lordose L4-S1 nach Spondylodese auf die Entwicklung einer Anschlusssegmentdegeneration / Florian Uhlemann." Ulm : Universität Ulm, 2019. http://d-nb.info/1177146983/34.
Full text
25
Lenman, James. "Realism and idealism in the theory of value." Thesis, University of St Andrews, 1995. http://hdl.handle.net/10023/14766.
Full textAbstract:
This thesis defends an account of value which emphasizes the central place occupied by experiences among the objects of evaluation, a point that is particularly stark in the case of aesthetic value, to which a chapter is devoted that adumbrates the wider understanding of value subsequently defended. More generally it is argued that values do not transcend the attitudes and institutions in which they are embodied. They nonetheless enjoy in virtue of their structuring by norms of consistency, stability and deference enough in the way of objectivity to do justice to various phenomenological considerations often thought to favour realism. It is argued however that this level of objectivity is compatible with the rejection of any form of reductive naturalism and, more generally, of cognitivism- views which should indeed, it is argued, be rejected in favour of an expressivistic understanding of value.
26
Ghezraoui, Hind. "Étude du mécanisme moléculaire de formation des translocations chromosomiques dans les cellules humaines." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA11T018.
Full textAbstract:
Les translocations chromosomiques qui consistent en l’échange de morceaux de chromosomes sont une des caractéristiques génétiques de nombreux cancers. Les séquences des jonctions des chromosomes transloqués chez les patients correspondent à une réparation par NHEJ. Nous avons étudié le rôle du complexe de ligation XRCC4/LigaseIV du C-NHEJ dans la formation de ces réarrangements chromosomiques dans les cellules humaines. Nous avons utilisé différentes nucléases artificielles (ZFN, TALEN, et CRISPR/Cas9) afin d'introduire deux CDB sur deux chromosomes et nous avons ainsi réussi à générer différentes translocations. Des lignées sauvages et mutantes pour ce complexe de ligation ont été utilisées et la fréquence formation de translocations a été quantifiée par PCR. Nous avons pu observer que celle-ci est souvent diminuée dans les différentes lignées mutantes. Les jonctions des translocations obtenues par séquençage sont modifiées dans des cellules déficientes pour ce complexe. En effet, elles présentent de longues délétions et un biais d’utilisation de microhomologies, indiquant l’utilisation d’un mécanisme alt-NHEJ. Une altération de cette voie dans les cellules humaines n’affecte d’ailleurs pas la formation de ces réarrangements chromosomiques. Ainsi, contrairement aux cellules de souris, les translocations dans les cellules humaines sont générées par le C-NHEJChromosomal translocations involve the exchange of chromosome pieces and are often associated with oncogenesis. It has been shown that breakpoint junctions of translocated chromosomes found in patients are typical of a repair by NHEJ. Here we investigated the specific role of XRCC4/LigaseIV, the ligation complex of C-NHEJ, on chromosomal translocation formation in human cells. Using different nucleases (ZFN, TALEN, et CRISPR/Cas9) targeting two chromosomes, we studied the induction of translocation in wt and KO human cells, expressing or not the XRCC4/LigaseIV complex. We found that translocation frequency was mostly reduced in XRCC4/LigaseIV deficient cells when we quantified the induction of translocation by PCR. In addition, we analyzed the breakpoint junctions by sequencing. Strikingly, we found that junctions of translocations show large deletions, and a bias towards the use of longer microhomologies only in XRCC4/LigaseIV KO cells, signature of the alt-NHEJ activity. In contrast, translocation formation was not affected in alt-NHEJ deficient cells. Thus conflicting with results obtained in rodent cells where alt-NHEJ promotes translocation formation, translocations in human cells are generated by the C-NHEJ
27
Highfield, James. "An analysis of the meroplankton assemblages of Station L4 and the development and application of molecular techniques to aid taxonomic resolution." Thesis, University of Plymouth, 2012. http://hdl.handle.net/10026.1/1171.
Full textAbstract:
Zooplankton data from the 1988-2007 Station L4 time-series were used to determine inter-and intra-annual patterns of meroplankton community change at Station L4, Plymouth, UK. Abundances were calculated for five groups: Cirripedia, Decapoda, Polychaeta, Echinodermata and Bivalvia. Analyses showed that, while there is some annual variability, seasonal variation accounts for the major changes in the meroplanktonic community composition throughout the time-series. Cirripedia were the only group to show any significant change in abundance over the time-series. Further sampling at the study site produced data at a finer taxonomic resolution allowing for the analyses of the seasonal cycles of abundance of previously unresolved families and genera from the 1988-2007 time-series. A similar pattern was shown to that seen in the earlier time-series with no evidence of major changes in the meroplanktonic community being found. Comparison with historical data taken from Lebour (1947) showed little evidence of major variation in meroplanktonic species composition. The limitations of traditional methods of taxonomic resolution were highlighted during these analyses and led to the investigation of molecular techniques as a viable aid to identification. Bivalve larval samples were identified to species in many cases using PCR and sequencing reactions focussing on the 18S rRNA gene. Larvae of Phaxas pellucidus were shown to be the most common, and further analysis revealed the presence of two groups of species within the data over the time sampled, comprising the larvae of several hard-substrata species. Development of an RFLP technique focussing on the mtCOI gene, allowed for the successful discrimination of porcellanid larvae to species that were unable to be resolved morphologically. Long-term data-sets play an important role in revealing the long-term patterns of community composition and abundance of meroplanktonic larvae and should be continued to identify those patterns not evident over the time-period studied. Molecular techniques were valuable in aiding the taxonomic resolution of meroplanktonic larvae, allowing previously unknown patterns of species diversity and richness to be ascertained.
28
Supragonaitė, Ramunė. "Stuburo stabilizavimo pratimų poveikis lėtiniam juosmeninės stuburo dalies skausmui. L4- L5 segmento dauginio bei skersinio pilvo raumenų skersmuo." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2006. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2006~D_20060509_113430-70502.
Full textAbstract:
Key words: lumbar stabilization exercise, multifidus muscle size, low back pain.
Low back pain is one of the most common conditions in mankind. Therefore, it is needed an exact diagnostic and the most effective problem solving method. There is an evidence of dysfunction in deep lower back and abdominal muscles in low back pain patients. Accordingly, the aim of this study was to define the influence of lumbar stabilization exercise for chronic low back pain, and to examine L4- L5 multifidus and transversus abdominis muscles size.
The objectives of our study: to determine and compare normal and chronic low back pain patients ranges of L4- L5 multifidus and transversus abdominis muscles size; to evaluate deep lower back and abdominal muscles function before and after lumbar stabilization exercise; to estimate chronic low back pain changes duaring stabilization exercise.
The methods of our research: ultrasound imaging, the instrument of pressure bio- feedback „Stabilizer“, Oswestry Low Back Pain Disability Index Questionnaire, the analysis of mathematical statistics. This work consists of two studies with different participants. 16 healthy individuals and 16 chronic low back pain patients were studied in ultrasound imaging measurement. 12 chronic low back pain patients (4 women and 8 men) were participated in lumbar stabilization exercise program.
Results: L4- L5 multifidus muscle size was larger (27 %) in males than in females, transversus abdominis muscle size was larger (17... [to full text]
29
FOURNEL, MICHEL. "Anatomie et radioanatomie des disques intervertebraux l4-l5 et l5-s1 normaux et pathologiques sous forme de kit d'enseignement." Nantes, 1989. http://www.theses.fr/1989NANT029M.
Full text
30
Lee, Bruce Tien-Lung. "A Meta-Evaluation of Taiwan Ministry of Education's National Technology Institutes Evaluation: A Study of Evaluation Team's and Stakeholders' Judgements on the Evaluation Practice." Diss., Virginia Tech, 1995. http://hdl.handle.net/10919/37293.
Full textAbstract:
A meta-evaluation of the Taiwan Ministry of Education's 1990 National Technology Institutes Evaluation practices was conducted. The major focus of the meta-evaluation was to compile pertinent information and to make comparisons of performance relative to the utility, feasibility, propriety, and accuracy of the Taiwan Ministry of Education's 1990 National Technology Institutes Evaluation practices as perceived by the evaluation team members (evaluators) and the stakeholders (the evaluated). The evaluation team and stakeholders were also asked to assess the importance of 30 Program Evaluation Practice Standards for the evaluation. Data were collected through mailed questionnaires and informal interviews. Information gleaned from this study were based on responses received from the 1990 Taiwan National Technology Institutes Evaluation team members and the stakeholders including institute presidents and academic program leaders. Results of the study provided the basis for improving the evaluation practices of the Taiwan National Technology Institutes Evaluation including recommendations for improving the evaluation model, policies, procedures, and practices.
Results of the study revealed that:
1. The evaluation team and stakeholders held similar beliefs regarding the importance of the 30 Program Evaluation Practice Standards for the 1990 Taiwan National Technology Institutes Evaluation. The Program Evaluation Practice Standards were perceived as important ideals for the orientation of the process and practice of evaluation in Taiwan.
2. The evaluation team and stakeholders gave similar assessments as to the utility, feasibility, propriety, and accuracy of the 1990 Taiwan National Technology Institutes Evaluation practice.
Based upon analyses of the data, the findings indicated that the evaluation system employed by the Taiwan Ministry of Education produces outcomes that are overall acceptable to both the evaluators and the evaluated. As the result, recommendations were offered and reviewed by a panel of experts in Taiwan.Ph. D.
31
Bley, Hiersemenzel Inge Anna. "L'allemand oral L4 à Hong Kong : vers l'identification des interférences phonético-phonologiques issues des langues source chez des apprenants cantophones adultes." Phd thesis, Université Rennes 2, 2012. http://tel.archives-ouvertes.fr/tel-00761211.
Full textAbstract:
Cette étude d'ordre phonético-phonologique considère la prononciation en allemand L4 chez des apprenants tardifs cantophones de la première génération postcoloniale à Hong Kong. Pour ces locuteurs dont les langues source sont le cantonais (L1) et l'anglais (L2) de Hong Kong, ainsi que le putonghua/mandarin (L3), l'allemand est la quatrième langue orale (L4). La question des transferts linguistiques issus des langues source reste mal évaluée. À travers une analyseprincipalement auditive, nous cherchons à découvrir comment l'allemand lu est prononcé sous l'effet interférentiel attendu d'une ou de plusieurs langues source. Ce travail dégage des fautes typiques et quantifiables à travers l'exploitation d'enregistrements d'apprenants cantophones adultes. Ces données élicitées aux niveaux segmental et suprasegmental ont été comparées à celles d'un groupe contrôle de locuteurs natifs, ainsi qu'à la prononciation canonique retenue. Noustentons de déterminer les causes des déviances saillantes dues aux effets interférentiels des langues source relevant du niveau phonético-phonologique. Ce travail permettra de dégager des méthodes d'apprentissage plus adaptées, une fois les différents domaines identifiés, ayant trait aux difficultés spécifiques lors de l'acquisition de l'allemand L4. Ainsi, des exercices variés et bien adaptés à ce public d'apprenants permettront d'améliorer plus rapidement l'acquisition del'allemand oral. Ce travail était dicté par le souci de fournir un ensemble d'informations potentiellement utiles aux domaines linguistique et didactique
32
Bley, Hiersemenzel Inge Anna. "L’allemand oral L4 à Hong Kong : vers l’identification des interférences phonético-phonologiques issues des langues source chez des apprenants cantophones adultes." Thesis, Rennes 2, 2012. http://www.theses.fr/2012REN20035.
Full textAbstract:
Cette étude d’ordre phonético-phonologique considère la prononciation en allemand L4 chez des apprenants tardifs cantophones de la première génération postcoloniale à Hong Kong. Pour ces locuteurs dont les langues source sont le cantonais (L1) et l’anglais (L2) de Hong Kong, ainsi que le putonghua/mandarin (L3), l’allemand est la quatrième langue orale (L4). La question des transferts linguistiques issus des langues source reste mal évaluée. À travers une analyseprincipalement auditive, nous cherchons à découvrir comment l’allemand lu est prononcé sous l’effet interférentiel attendu d’une ou de plusieurs langues source. Ce travail dégage des fautes typiques et quantifiables à travers l’exploitation d’enregistrements d’apprenants cantophones adultes. Ces données élicitées aux niveaux segmental et suprasegmental ont été comparées à celles d’un groupe contrôle de locuteurs natifs, ainsi qu’à la prononciation canonique retenue. Noustentons de déterminer les causes des déviances saillantes dues aux effets interférentiels des langues source relevant du niveau phonético-phonologique. Ce travail permettra de dégager des méthodes d’apprentissage plus adaptées, une fois les différents domaines identifiés, ayant trait aux difficultés spécifiques lors de l’acquisition de l’allemand L4. Ainsi, des exercices variés et bien adaptés à ce public d’apprenants permettront d’améliorer plus rapidement l’acquisition del’allemand oral. Ce travail était dicté par le souci de fournir un ensemble d’informations potentiellement utiles aux domaines linguistique et didactiqueThis thesis aims to investigate salient mispronunciations from Cantonese adult L4 learners of German in Hong Kong, in order to support the design of effective pedagogical and remedial instruction for pronunciation improvement. For these learners of the first post-colonial generation, the other source languages are Hong Kong English (L2) and putonghua/Mandarin (L3), both non-native/non-foreign languages. The overall aims of this study are to promote ourunderstanding of cross-linguistic interference between source languages and the target language in adult learners whose first language is genetically and typologically distant from German, as well as to identify typical linguistic features of German L4. The proposed approach involves a systematic contrastive description of phonology and phonetics primarily between German and Cantonese, followed by a shorter description of learners’ L2 and L3. To address the question of deviant features and language transfer, data gathered from students reading German were compared to native speaker data, as well as to a canonical form of pronunciation. The analysis of interlanguage data revealed segmental and suprasegmental deviations from the underlying canonical form, as well as contexts where L1 and L2 transfer effects are prominent. Thismethodology enabled us to propose an inventory of salient pronunciation errors, useful for the domain of linguistics and for pedagogical purposes. Though further studies should be conducted at both the segmental and suprasegmental level, this work contributes to our understanding of aspects of this particular L4 interlanguage
33
Le, Trang X. "Oxidation addition of H-H bonds to iridium : developing novel active water soluble catalysts for hydrogenation of unsaturates /." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09232008-144717/.
Full text
34
Le, Tru Huy. "Performance and availability analysis of Oceanic Air Traffic Control System (OATCS)." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-01242009-063216/.
Full text
35
Duso, Tomaso, Klaus Gugler, and Burcin B. Yurtoglu. "Is the event study methodology useful for merger analysis? A comparison of stock market and accounting data." Elsevier Inc, 2010. http://dx.doi.org/10.1016/j.irle.2010.02.001.
Full textAbstract:
This paper presents empirical evidence about the ability of event studies to capture mergers' ex-post profitability as measured by accounting data. We use a sample of large horizontal concentrations during the period 1990-2002 involving 482 firms either as merging firms or competitors, and contrast a measure of the mergers' profitability based on stock market event studies with one based on balance sheet profit data. We show that using a long window around the announcement date (25 or 50 days before the event) increases the ability to capture the ex-post merger effect: the pairwise correlation coefficient is positive and highly significant.
36
Leigh, Christopher. "The detection and characterisation of extrasolar planets." Thesis, University of St Andrews, 2004. http://hdl.handle.net/10023/12943.
Full textAbstract:
Since the discovery of 51 Pegasi b in 1995, continued observations have indirectly identified over 110 planetary objects. These Jupiter-mass objects cause their host star to "wobble" slightly about the common centre-of-mass of the system, which is detectable as radial motion in high-precision Doppler spectroscopy. Of the known planets, approximately 20% are found to orbit within 0.1 AU of the star, whilst the transit of HD209458 has inferred the gas-giant nature of these close-in extrasolar giant planets (CEGPs). The discovery of CEGPs has produced a wave of speculative theory as to the exact nature of these objects, and how they came to exist so close to their parent star. Our spectroscopic technique provides a method of achieving the direct detection of a CEGP atmosphere, the results of which will allow us to test emerging models that aim to predict the atmospheric nature of CEGPs and may provide additional information on the orbital inclination and mass of the planet. We start with a historical review of the field of extrasolar planets, followed by an introduction to the fundamental concepts which underpin the reflection of starlight from a planet's surface. We then investigate the prospects of detecting such a reflection, before detailing the technique we have devised and applied here to two known CEGP hosts. In the first instance, r Bootis, we combined observations at the 4.2-m William Herschel telescope in 1998, 1999 and 2000. The dataset comprised 893 high-resolution échelle spectra with a total integration time of 75hr 32min spanning 17 nights. We establish an upper limit on the planet's geometric albedo p < 0.39 (at the 99.9% significance level) at the most probable orbital inclination i ~ 36 deg, assuming a grey albedo, a Venus-like phase function and a planetary radius Rp - 1.2RJup. Although a weak candidate signal appears near to the most probable radial velocity amplitude, its statistical significance is insufficient for us to claim a detection with any confidence. In the second instance, HD75289, 4 nights of VLT(UT2)/UVES observations were secured in 2003 Jan, yielding 684 high-resolution spectra with a total integration time of 26 hours. We establish an upper limit on the planet's geometric albedo p < 0.12 (to the 99.9% significance level) at the most probable orbital inclination i ~/= 60 deg, assuming a grey albedo, a Venus-like phase function and a planetary radius Rp = 1.6RJup. In both cases, we are able to rule out some combinations of the predicted planetary radius and atmospheric albedo models with high, reflective cloud decks.
37
Lentz, Martin Christoph [Verfasser], Walter [Akademischer Betreuer] Reimers, and Karl Ulrich [Akademischer Betreuer] Kainer. "Deformation behavior of extruded magnesium alloys ME21, WE54, L4 and LA41 / Martin Christoph Lentz. Gutachter: Walter Reimers ; Karl Ulrich Kainer. Betreuer: Walter Reimers." Berlin : Technische Universität Berlin, 2015. http://d-nb.info/1070580759/34.
Full text
38
Duso, Tomaso, Klaus Gugler, and Burcin B. Yurtoglu. "How Effective is European Merger Control?" Elsevier, 2011. http://dx.doi.org/10.1016/j.euroecorev.2011.04.003.
Full textAbstract:
This paper applies an intuitive approach based on stock market data to a unique dataset of large
concentrations during the period 1990-2002 to assess the effectiveness of European merger
control. The basic idea is to relate announcement and decision abnormal returns. Under a set of
four maintained assumptions, merger control might be interpreted to be effective if rents accruing
due to the increased market power observed around the merger announcement are reversed by the
antitrust decision, i.e. if there is a negative relation between announcement and decision abnormal
returns. To clearly identify the events' competitive effects, we explicitly control for the market
expectation about the outcome of the merger control procedure and run several robustness checks
to assess the role of our maintained assumptions. We find that only outright prohibitions
completely reverse the rents measured around a merger's announcement. On average, remedies
seem to be only partially capable of reverting announcement abnormal returns. Yet they seem to be
more effective when applied during the first rather than the second investigation phase and in
subsamples where our assumptions are more likely to hold. Moreover, the European Commission
appears to learn over time. (authors' abstract)
39
Duso, Tomaso, Klaus Gugler, and Florian Szücs. "An Empirical Assessment of the 2004 EU Merger Policy Reform." Wiley, 2013. http://dx.doi.org/10.1111/ecoj.12081.
Full textAbstract:
Based on a database of 368 merger cases scrutinized by the European Commission (EC) between 1990 and 2007, we evaluate the economic impact of the change in European merger legislation in 2004. We propose a general framework to assess merger policy effectiveness, focusing on four different policy dimensions: 1) predictability, 2) decision errors, 3) reversion of anti-competitive rents, and 4)
deterrence. We compare the results before and after the reform, finding that the "more economic approach" resulted in improved ex-ante predictability of decisions and a reduction of the frequency of type I errors. Merger policy enforcement deters anti-competitive mergers without over-deterring pro-competitive transactions. Yet, the policy shift away from prohibitions, which are effective as a policy tool and as a deterrence mechanism, does not seem to be well grounded. (authors' abstract)
40
Reitt, Andrea Kim Charlotte [Verfasser], Martin [Akademischer Betreuer] Wachowski, Hans [Akademischer Betreuer] Nägerl, and Margarete [Akademischer Betreuer] Schön. "Abhängigkeit der Segmentkinematik von der Position der Vorlast im Segment L3/L4 / Andrea Kim Charlotte Reitt. Gutachter: Hans Nägerl ; Margarete Schön. Betreuer: Martin Wachowski." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://d-nb.info/1072820137/34.
Full text
41
Salazar, Francisco Javier Tipán. "Deployment and maintenance of a satellite formation flight around L4 and L5 Lagrangian points in the earth-moon system based on low cost strategies." Instituto Nacional de Pesquisas Espaciais (INPE), 2012. http://urlib.net/sid.inpe.br/mtc-m19/2012/11.22.12.22.
Full textAbstract:
Este trabalho está focado em métodos de transferência a partir de uma órbita circular ao redor da Terra até órbitas periódicas ao redor dos pontos Lagrangianos \textit{L}$_{4}$ e \textit{L}$_{5}$ no sistema Terra-Lua, com aplicações para colocar vários satélites em vôo de formação. Os pontos Lagrangianos \textit{L}$_{4}$ e \textit{L}$_{5}$ estão localizados a 60 graus acima e embaixo da linha que conecta a Terra com a Lua e formam com estes dois corpos um triângulo equilátero. Estes pontos Lagrangianos são estáveis pela relação de massa entre a Terra e a Lua. Devido à sua distância, radiações eletromagnéticas que proveem da Terra e chegam até eles são substancialmente atenuadas. Dessa maneira, estes pontos Lagrangianos representam posições extraordinárias para colocar observatórios astronômicos. Inspirados nos recentes resultados em manobras assistidas por gravidade, os métodos de transferência implementados neste trabalho usam o campo gravitacional da Lua para atingir os pontos Lagrangianos. Nós aplicamos três diferentes técnicas para intersectar a esfera de influência da Lua: Transferências de Mínima Energia, Trajetórias G e Órbitas Caóticas, e mostramos que existem novas trajetórias alternativas para chegar até nosso objetivo. Nós encontramos vantagens em relação à Transferência de Hohmann tais como gasto menor de combustível e a possibilidade de usar o mesmo lançador para enviar os satélites até os pontos \textit{L}$_{4}$ e \textit{L}$_{5}$. O trabalho também apresenta um estudo das geometrias ao redor das órbitas periódicas centradas em \textit{L}$_{4}$ com boas propriedades para vôos em formação. Nós consideramos a possibilidade da existência de regiões com aceleração radial relativa zero com respeito à trajetória nominal. As simulações numéricas mostram que para evitar grandes variações das distâncias mutuas entre os satélites, a formação tem que estar localizada não ao longo da direção de aceleração radial relativa nula senão ao longo da direção de aceleração radial relativa mínima. Este trabalho está feito utilizando o modelo Circular Restrito de Três Corpos, considerando só o movimento no plano da órbita dos sistema Terra-Lua.This thesis focuses on transfer methods from a circular parking orbit around the Earth to periodic orbits around the Lagrangian points \textit{L}$_{4}$ and \textit{L}$_{5}$ in the Earth-Moon system, with applications to place multiple satellites in formation flying. Lagrangian points \textit{L}$_{4}$ and \textit{L}$_{5}$ lie at 60 degrees ahead of and behind Moon in its orbit with respect to the Earth and form an equilateral triangle with the base of the line defined by those two bodies. These Lagrangian points are stable for the Earth-Moon mass ratio. Because of their distance, electromagnetic radiations from the Earth arrive on them substantially attenuated. As so, these Lagrangian points represent remarkable positions to host astronomical observatories. Inspired by the recent results in gravity assist maneuvers, the transfer methods implemented in this work use the gravita-tional field of the Moon to reach the Lagrangian points. We apply three different techniques to intersect the lunar sphere of influence: Minimum Energy Transfers, Trajectories G and Chaotic Orbits, and prove that there exist new alternative trajectories to reach our target. We find advantages over the Hohmann transfer such as less fuel spent and the possibility using only one rocket launcher to deliver spacecrafts to \textit{L}$_{4}$ and \textit{L}$_{5}$. The thesis also presents a study of geometries around periodic orbits centered at \textit{L}$_{4}$ with good properties for formation flying. We consider the possible existence of regions of zero relative radial acceleration with respect to the nominal trajectory. Numerical simulations show that to avoid large variations of the mutual distances between the spacecrafts, the formation flying must be arranged not along the direction of zero relative radial acceleration but along the direction of minimum relative radial acceleration. This work is done in the force model defined by the Circular Restricted Three Body Problem, considering only the motion on the plane of the orbit of the Earth-Moon system.
42
Reitt, Andrea Kim Charlotte Verfasser], Martin [Akademischer Betreuer] Wachowski, Hans [Akademischer Betreuer] [Nägerl, and Margarete [Akademischer Betreuer] Schön. "Abhängigkeit der Segmentkinematik von der Position der Vorlast im Segment L3/L4 / Andrea Kim Charlotte Reitt. Gutachter: Hans Nägerl ; Margarete Schön. Betreuer: Martin Wachowski." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://d-nb.info/1072820137/34.
Full text
43
Palmer, Becerra Romeo, and Moga Amado González. "EVOLUCIÓN CLNICA DE PACIENTES CON HERNIA DE DISCO L4-L5 POSTOPERADOS MEDIANTE NUCLEOTOMÍA PERCUTÁNEA POR LÁSER A 6 MESES EN EL CENTRO MÉDICO ISSEMYM ECATEPEC." Tesis de Licenciatura, Medicina-Quimica, 2014. http://ri.uaemex.mx/handle/123456789/14623.
Full text
44
Descours, Ghislaine. "Legionella pneumophila et macrolides : de l’antibiogramme à la caractérisation des mécanismes moléculaires impliqués dans la résistance." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10282.
Full textAbstract:
Les macrolides sont recommandés seuls ou en association dans le traitement des légionelloses. Cependant, malgré une antibiothérapie adaptée et l'absence de souches résistantes décrites, des échecs thérapeutiques sont régulièrement observés. L'isolement de souches de Legionella à partir de prélèvements respiratoires est indispensable à la réalisation d'antibiogrammes mais il n'est obtenu que dans 24% des cas en France. Au cours de ce travail, nous avons tout d'abord amélioré le rendement d'isolement des souches cliniques, notamment par des techniques de co-culture amibienne, avant de nous intéresser aux mécanismes pouvant expliquer les échecs thérapeutiques (antagonisme entre antibiotiques, sélection de résistance). Nous avons pu montrer, dans un modèle de croissance intracellulaire de Legionella pneumophila, une absence d'antagonisme entre macrolides et fluoroquinolones ou rifampicine invalidant la première hypothèse. Nous avons ensuite généré des lignées de mutants hautement résistants aux macrolides. Nous avons mis en évidence des mutations dans les gènes codant les protéines ribosomales L4 et L22 associées à un faible niveau de résistance. Des mutations dans les gènes codant l'ARN ribosomal 23S étaient associées à un niveau plus élevé de résistance, dépendant de la nature de la mutation et du nombre de copies du gène mutées. La facilité d'obtention de mutants résistants aux macrolides in vitro suggère une potentielle acquisition de résistance in vivo au décours de l'antibiothérapie et justifie une recherche systématique de cette résistance dans les prélèvements cliniquesMacrolides, alone or in combination, are recommended as first-line therapy of Legionnaires’ disease. Legionella pneumophila is characterized by a constant in vitro susceptibility to macrolides. Resistant variants have never been detected, in contrast with several therapeutic failures observed in patients receiving an adequate treatment. Legionellae isolation from respiratory secretions is needed for antibiotic susceptibility testing, but the reported culture sensitivity reaches only 24% in France. In this work, we improved Legionellae isolation rate by culture and amoebal co-culture. In a second time, we were interested in hypothetic mechanisms involved in therapeutic failures like antibiotic antagonisms and acquired resistance. We found no antagonistic effects for macrolide/fluoroquinolones and macrolide/rifampin combinations in an intracellular Legionella model, which made irrelevant our first hypothesis. In a last step, we propagated Legionella strains with increasing macrolides concentrations. This procedure provided us high-level macrolides-resistant mutants. We found that mutations in the genes encoding L4 and L22 proteins were correlated with low-level resistance. Mutations in domain V of the 23S rRNA were associated with intermediate or high-level resistance. We found a correlation between the kind of nucleotide substitution or the number of mutated ribosomal operons and the resistance level. The speed and efficiency of in vitro selection of L. pneumophila macrolide-resistant mutants suggest a potential acquisition of macrolide resistance in patients under therapy and emphasize the need to explore clinical Legionella macrolide susceptibility in order to track down resistance
45
Levy, Susan L. "Wheelchair users and housing in Dundee : the social construction and spatiality of disability." Thesis, University of St Andrews, 2002. http://hdl.handle.net/10023/2722.
Full textAbstract:
The thesis examines the experiences and perceptions of wheelchair users living in different types and tenures of housing in the City of Dundee. The interrelationships between space, society and the body are examined in the empirical context of housing, ableism and the disabled body. The voices of wheelchair users, gleaned from in-depth, semi-structured interviews, are used throughout the thesis to illustrate how the geographies of people with disabilities are delineated and constrained by socio-cultural representations of disability. Conceptually the study has been guided by the social model of disability, but insights from postmodernism and feminist literature are drawn on to add a further dimension to the interpretation of the data and the study's methodology. The social construction of difference, social exclusion and definitions of the normal and aberrant body emerge as key concepts linking analysis of the data at the spatial scales of the neighbourhood, home and the body. Spatial metaphors of 'out of place', 'marginalised' or 'socio-spatially excluded' capture the essence of the impressions people with disabilities hold of their interactions with their living spaces and service providers. The study suggests that greater reciprocal dialogue is required between service users and service providers to broaden the knowledge base from which disability related housing decisions are made.
46
Leslie, Rebekah. "A Functional Approach to Memory-Safe Operating Systems." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/499.
Full textAbstract:
Purely functional languages--with static type systems and dynamic memory management using garbage collection--are a known tool for helping programmers to reduce the number of memory errors in programs. By using such languages, we can establish correctness properties relating to memory-safety through our choice of implementation language alone. Unfortunately, the language characteristics that make purely functional languages safe also make them more difficult to apply in a low-level domain like operating systems construction. The low-level features that support the kinds of hardware manipulations required by operating systems are not typically available in memory-safe languages with garbage collection. Those that are provided may have the ability to violate memory- and type-safety, destroying the guarantees that motivate using such languages in the first place. This work demonstrates that it is possible to bridge the gap between the requirements of operating system implementations and the features of purely functional languages without sacrificing type- and memory-safety. In particular, we show that this can be achieved by isolating the potentially unsafe memory operations required by operating systems in an abstraction layer that is well integrated with a purely functional language. The salient features of this abstraction layer are that the operations it exposes are memory-safe and yet sufficiently expressive to support the implementation of realistic operating systems. The abstraction layer enables systems programmers to perform all of the low-level tasks necessary in an OS implementation, such as manipulating an MMU and executing user-level programs, without compromising the static memory-safety guarantees of programming in a purely functional language. A specific contribution of this work is an analysis of memory-safety for the abstraction layer by formalizing a meaning for memory-safety in the presence of virtual-memory using a novel application of noninterference security policies. In addition, we evaluate the expressiveness of the abstraction layer by implementing the L4 microkernel API, which has a flexible set of virtual memory management operations.
47
Cross, Jaimie. "The dynamics of suspended particles in a seasonally stratified coastal sea." Thesis, University of Plymouth, 2013. http://hdl.handle.net/10026.1/1461.
Full textAbstract:
A comprehensive investigation into the relationship between physical forcing and sus- pended particles in the shallow shelf region of the Western English Channel has been conducted, in order to evaluate the temporal dynamics of suspended particle populations. Measurements were taken across tidal cycles and seasons at station L4, part of the Western Channel Observatory (WCO), using the combination of a free-fall microstructure profiler and holographic imaging. Confirmation that L4 is weakly stratified is given, and that the formation of the seasonal thermocline is substantially altered by the spring-neap cy- cle. Stratification is variable and prone to periodic and partial erosion from atmospheric forcing during any point in any season. L4 undergoes moderate turbulent dissipation, principally as a result of tidal forcing. Typically, values of ε do not exceed 10−4 W kg−1 . L4 also exhibits tidal asymmetry, chiefly in response to stratification which, albeit weak, is frequently able to suppress turbulence when generated from the sea bed. The potential energy anomaly is small at L4, as expected for a weakly-stratified environment. Maxi- mum values in summer were shown to not exceed 50 J m−3 . Values of bed stress, τ0 , are rarely greater than around 0.18 N m−2 . Nonetheless, the critical erosion threshold falls below this, and is therefore smaller than that observed in similar locations around the UK. Seasonality in the amount of material resuspended from the seabed is important at L4. The presence of certain biological particles strongly influence particle size and may also determine if a given particle is lifted from the bed. Particles ≥ 200 μm are relatively rare, the site is dominated by particles smaller than this value in line with many other UK sites. Under certain conditions the theoretical maximum limit of particle size, the Kolmogorov length scale, does not hold and many examples of occasions when this threshold is exceeded are shown. This may generate important consequences in subsequent work undertaken at this site and other temperate shelf locations globally, particularly as these results indicate that maximum particle size appears to be governed less by the size of the local turbulent eddies and more by the presence of biological particles. This is another key seasonal component to particle dynamics in the Western English Channel. Phytoplankton populations are readily advected into and out of the L4 site, calling into question the current sampling strategy of the WCO to rely exclusively upon point measurements. Small increases in atmospheric forcing have the ability to rapidly disperse patches of phytoplankton, possibly to the point of cell mortality. Traditional sampling techniques for assessing zooplankton density have been shown to radically underestimate the number of animals present at L4, which will increase error estimates on current ecosystem models.
48
Levell, Jack William. "Material and device design for organic optoelectronics." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2066.
Full textAbstract:
This thesis describes investigations into the photophysical properties of luminescent materials and their application in optoelectronic devices such as light emitting diodes and photodetectors. The materials used were all solution processable because of the interest in low cost processing of organics. I have investigated the photophysics of 1,4,5,8,9,12-hexamethyltriphenylene, a triphenylene derivative which has its luminescence enhanced by the addition of methyl groups. These groups change the planar shape of the triphenylene molecule into a twisted one, changing the symmetry of the molecule and increasing its dipole moment in absorption and emission by ~4 fold. This increased its rate of radiative deexcitation by ~20 times. In addition, the twisted shape of the molecule prevents intermolecular interactions and concentration effects from affecting the luminescence. This results in an efficient solid-state photoluminescence quantum yield of 31%. This thesis also includes an investigation into phosphorescent polymer dendrimers, designed to have suitable viscosities in solution for inkjet printed OLED applications. A photophysical study of the intra-chain aggregation effects on the luminescence was undertaken in both homopolymers and copolymers with high energy gap spacer units. Using double dendrons to increase the steric protection of the luminescent cores, the best homopolymers achieved 12.1% external quantum efficiency (39.3 cd/A) at 100 cd/m² brightness and the best co-polymer achieved 14.7% EQE (48.3 cd/A) at 100 cd/m². This compares favourably with 11.8% EQE for the best phosphorescent polymer and 16% for the best solution processed dendrimer OLED previously reported. Finally I have applied a solution processed enhancement layer to silicon photodiodes to enhance their ultraviolet response. Using a blend of materials to give favourable absorption and emission properties, 61% external quantum efficiency was achieved at 200 nm, which is better than the 20-30% typical for vacuum deposited lumogen enhancement layers used commercially.
49
Lewis, Andrew J. "Characterisation of organic materials for photovoltaic devices." Thesis, St Andrews, 2006. http://hdl.handle.net/10023/144.
Full text
50
Lewis, Olivier Rémy Tristan David. "Explaining military, law enforcement and intelligence cooperation between Western states." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/16419.
Full textAbstract:
This thesis answers the question “Why does security cooperation occur between Western states?”. The basic answer is: “Because most state actors do not want their states to integrate”. In other words, cooperation occurs as a coping mechanism, as an imperfect substitute for integration. But the thesis does not only investigate the reasons for cooperation, what Aristotle called the final cause. The thesis also examines the material, formal and efficient causes of cooperation. Such an unorthodox causal explanation of cooperation is based on a Critical Realist philosophy of social science. The application of this philosophy to the empirical study of International Relation is rare, making this thesis original. Beyond the philosophy of social science, the thesis' research design, many of the cases, and much of the data are also rarely used. The research design is an embedded multiple-case study. The states studied are the United States of America, France and Luxembourg. Within each state, the embedded subcases are three types of state security organisations: the armed forces, law enforcement and intelligence agencies. Rarely have these three types of security organisations been compared. Similarly, Luxembourg is seldom studied. Comparing different types of states and different types of state security organisations has not only allowed the main research question to be answered. It has also allowed temporal, spatial, national, and functional variation in cooperation to be identified and theorised. The empirical evidence studied includes participant observation (at the North Atlantic Treaty Organisation) and documents (e.g. state policy documents, annual reports by organisations, reports by parliaments and non-governmental organisations, autobiographies, books by investigative journalists, articles by newspapers and magazines). The thesis is also based on a score of elite interviews (e.g. with ambassadors, diplomatic liaisons, ministerial advisors, foreign ministry officers, military commanders, etc.), and the careful study of both declassified and classified archival records.