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DUTRA, José Diogo de Lisboa. "Desenvolvimento e aplicação do pacote computacional LUMPAC." Universidade Federal de Pernambuco, 2017. https://repositorio.ufpe.br/handle/123456789/20175.
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Previous issue date: 2017-01-26<br>CNPQ<br>Metodologias te´oricas s˜ao ´uteis para complementar investigac¸˜oes experimentais e guiar novos
experimentos envolvendo compostos luminescentes de lantan´ıdeos. A ausˆencia de uma ferramenta
computacional contendo tais m´etodos motivou o desenvolvimento do LUMPAC. Se por
um lado o LUMPAC difundiu o uso dessas metodologias, por outro as suas limitac¸˜oes tamb´em
foram evidenciadas. Nesse sentido, pˆode-se conhecer melhor quais m´etodos merecem uma
atenc¸˜ao especial, a saber: c´alculo dos parˆametros de intensidade (Ωλ), c´alculo da energia dos
estados excitados dos ligantes e c´alculo da taxa de emiss˜ao n˜ao-radiativa (Anrad). O objetivo
geral do presente trabalho de doutoramento consiste em corrigir algumas dessas limitac¸˜oes.
Quantoaoc´alculodosΩλ,conseguimosatenuaroproblemacomumanovaformadeajustedos
fatores de carga e das polarizabilidades atrav´es de um procedimento que foi denominado de
Modelo da UnicidadeQDC, o qual faz uso de um conjunto bastante reduzido de parˆametros
(Q,D eC). A importˆancia do ajusteQDC ´e que todas as quantidades derivadas se tornam
tamb´em ´unicas para uma dada geometria do complexo, incluindo um esquema proposto de
partic¸˜ao qu´ımico da taxa de emiss˜ao radiativa (Arad) em termos dos efeitos dos ligantes. Para
demonstrar uma das poss´ıveis aplicac¸˜oes dessa partic¸˜ao, foi considerado o caso de complexos
tern´arios de Eu3+ de ligantes n˜ao-iˆonicos repetidos e com os ligantes betadicetonatos DBM,
TTA e BTFA. A partic¸˜ao ordenou perfeitamente a combinac¸˜ao n˜ao ´obvia de pares de ligantes
n˜ao-iˆonicos que levam aos compostos misturados com os maiores valores deAexp
rad. Quanto
ao c´alculo dos estados excitados dos ligantes, ´e proposta uma parametrizac¸˜ao do m´etodo CIS
baseadonaaproximac¸˜aoNDDO,exclusivamenteparasistemaslantan´ıdicos. Al´emdisso,realizamosumestudoavaliativodemetodologiasTDDFTaplicadasaoc´alculodeestadosexcitados
de ligantes em complexos de lantan´ıdeos. Dentre os funcionais e func¸˜oes de base avaliados, a
combinac¸˜ao LC-ωPBE/6-31G(d) foi aquela que forneceu as energias tripleto mais concordantes
com os dados obtidos na literatura, sendo o erro m´edio absoluto correspondente em torno
de 1600 cm−1. Atrav´es da parametrizac¸˜ao do modelo NDDO-CIS implementado no programa
ORCA foi poss´ıvel obter um modelo semiemp´ırico para o c´alculo da energia tripleto de complexosdelantan´ıdeocom
qualidade bem superiora da melhormetodologiaTDDFT avaliada.<br>Theoretical methodologies are useful to complement experimental investigations, and to guide
new experiments involving luminescent lanthanide compounds. The lack of a software containing
these methods motivated us to the development of the user friendly software package
LUMPAC. And indeed, LUMPAC is slowly popularising the use of these theoretical methodologies
- methodologies that are being put to more frequent tests, and are, consequently, slowly
revealing their limitations. In this sense, we identified which aspects of the methods would
deserve a more special attention, namely: intensity parameters calculations (Ωλ), calculation
of the excited state energies of the ligands, and the calculation of the non-radiative decay rate
(Anrad). The overall objective of this doctoral work is to correct some of these limitations as
wellastoadvancenewdevelopments. RegardingtheΩλ calculation,wemitigatedthisproblem
with a new way to adjust the charge factors and polarizabilities through a procedure we called
theQDC Uniqueness Model, which makes use of a fairly small set of adjustaeble parameters
(Q,D, andC). The importance of theQDC adjustment is that all derived quantities become
also unique for a given complex geometry, including the chemical partition of the radiative
emission rate (Arad) in terms of the effects of the ligands, which is being advanced here. To
demonstrate one of the possible applications of this chemical partition, we address the case of
repeating non-ionic ligand ternary complexes of europium(III) with DBM, TTA, and BTFA.
The chemical partition perfectly ordered the non-obvious combination of pairs of non-ionic ligands
that led to the mixed ligand compounds with the highest values ofAexp
rad . Regarding the
calculation of the excited states of the ligands, a new parametrization of the CIS method based
on the NDDO approximation is being proposed, exclusively for lanthanide complexes. In
addition, we carried out a study to evaluate some TDDFT methodologies for the calculation of
excited states of ligands in lanthanide complexes. Among the functionals and basis sets evaluated,
the combination LC-ωPBE/6-31G(d) was the one that led to the lowest UME (unsigned
mean error), of around 1600 cm−1, for the triplet energies in comparison with data from the
literature. The parametrization of the NDDO-CIS model implemented into ORCA provided
a semiempirical method for the triplet energy calculation of lanthanide complexes with better
predictionpower thanthebestassessed TDDFT method.
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Dutra, José Diogo de Lisboa. "LUMPAC : desenvolvimento e aplicação de um pacote computacional para o estudo de estruturas luminescentes a base de Európio." Pós-Graduação em Química, 2014. https://ri.ufs.br/handle/riufs/6109.
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Lanthanide-containing systems have many applications, which extend from the biomedical field to optical images areas. Because of that, such systems have attracted the attention of several research groups around the world. It is indisputable that theoretical tools can provide useful information for the understanding of the phenomena that are not easily explained by using only experimental data. Moreover, the theoretical tools are useful for design new systems. Although several tools for the study of lanthanide complexes have been developed since the early 90 s, their use is still limited on account of these tools not being implemented into a userfriendly, free of charge computational package for the scientific community. In this context, the development of LUMPAC (LUMinescence PACkage) is inserted. With this new tool, we hope to enable experimental research groups to use theoretical tools on projects involving systems that contain lanthanide ions. In this dissertation, the methods implemented into LUMPAC are described in detail, given the user a good understanding of them. A short description on LUMPAC is introduced to provide an overview of the features that are implemented in the
package. Furthermore, a detailed manual treating all the modulus of LUMPAC is available as an appendix. The LUMPAC project started in 2008. During its development, the program was applied in many different kinds of study involving lanthanide systems, as will be shown in a chapter of this dissertation. The network of collaboration among the Pople Laboratory with some research groups of prestigious universities allowed all these applications. This way, it is then possible to have an idea about some kinds of study in which the program can be applied. So far, LUMPAC is the only software that enables the study of luminescent properties of lanthanide-containing systems, being available free of charge at the following site: http://www.lumpac.pro.br.<br>Os sistemas contendo íons lantanídeos apresentam diversas aplicações, as quais se estendem desde a área biomédica até a de imagem ótica. Em decorrência disso, a busca por tais sistemas tem atraído a atenção dos mais diversos grupos de pesquisa em todo o mundo. É incontestável que as ferramentas teóricas podem fornecer informações úteis para o entendimento de fenômenos que não são explicados simplesmente com base em dados experimentais. Além disso, as ferramentas teóricas são úteis para o planejamento de novos sistemas. Apesar de diversas ferramentas para o estudo de compostos lantanídicos terem sido desenvolvidas desde o início da década de 90, o seu uso ainda é limitado devido ao fato dessas ferramentas não estarem implementadas em um pacote computacional de fácil uso e disponível gratuitamente para a comunidade científica. É nesse contexto em que o desenvolvimento do LUMPAC (LUMinescence PACkage) está inserido. Com o LUMPAC espera-se difundir o uso de tais métodos teóricos por grupos de pesquisa, sobretudo os experimentais, que concentram seus esforços em entender e projetar novos dispositivos luminescentes a base de lantanídeos. Nesta dissertação, as metodologias que estão implementadas no LUMPAC encontram-se
apresentadas de maneira pormenorizada, conferindo ao usuário do software uma maior transparência com relação aos métodos. Uma descrição geral do LUMPAC é apresentada com a finalidade de fornecer uma ideia geral dos recursos que já estão implementados no pacote. Além do mais, um manual bastante detalhado tratando todos os módulos que compreendem o programa é disponibilizado como anexo. O projeto de desenvolvimento do LUMPAC teve início em 2008. Durante o processo de desenvolvimento do pacote, o programa encontrou uma vasta área de aplicação decorrente da rede de colaboração entre o laboratório Pople com alguns grupos de pesquisa de universidades renomadas do país. Através da apresentação dessas aplicações é possível ter uma ideia acerca dos diversos tipos de estudos em que o programa pode ser aplicado. Até o momento, o LUMPAC é o único software desenvolvido que permite o estudo de propriedades luminescentes de sistemas contendo íons lantanídeos, sendo disponibilizado gratuitamente no seguinte endereço eletrônico: http://www.lumpac.pro.br.
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Groth, Kevin M. "Nonlinear Lumped-Parameter Model of the Lumbar Intervertebral Disc: A Study on Viscoelastic Deformation and Three-Dimensional Modeling of the Spine." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/34313.
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Due to the mathematical complexity of current musculoskeletal spine models, there is a need for computationally-efficient models of the intervertebral disc (IVD). The aim of this study is to develop a mathematical model that will adequately describe the motion of the IVD under axial cyclic loading and three-dimensional quasi-static loading as well as maintain computational efficiency for use in future musculoskeletal spine models.
<p> A viscoelastic standard nonlinear solid (SNS) model is introduced within this study. It was developed to predict the axial response of the human lumbar IVD subjected to low-frequency vibration. Nonlinear axial behavior of the SNS model was simulated by a strain-dependent elastic modulus on the standard linear solid (SLS) model.
<p>
The SNS model was able to predict the dynamic modulus of the IVD for frequencies of 0.01, 0.1, and 1 Hz. Furthermore, the model was able to quantitatively predict the load relaxation at a frequency of 0.01 Hz. However, model performance was unsatisfactory when predicting load relaxation and hysteresis at higher frequencies (0.1 Hz and 1 Hz). Results suggest that the standard solid model may require strain-dependent elastic and viscous behavior to represent the dynamic response to compressive strain.
<p>
The SNS model was expanded to a three-dimensional elastic model by adding a matrix of spring elements in parallel with the SNS model. The geometry and orientation of the added elements represent the regional variations in stiffness and physiologic fiber angle. Results suggest that lordotic posture may be advantageous when modeling the intervertebral joint (IVJ) behavior.<br>Master of Science
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Malatesta, Cabrera Carlos. "Dolor lumbar." Pontificia Universidad Católica del Perú, 2008. http://repositorio.pucp.edu.pe/index//handle/123456789/21194.
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Jönsson, Bo. "Lumbar nerve root compression syndromes symptoms, signs and surgical results /." Lund : Dept. of Orthopedics, University Hospital, 1995. http://catalog.hathitrust.org/api/volumes/oclc/38155579.html.
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Wong, Wai-ning Kris. "Lumbar spinal motion analysis." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36611773.
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Wong, Wai-ning Kris, and 黃偉寧. "Lumbar spinal motion analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B36611773.
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Axelsson, Paul. "On lumbar spine stabilization." Lund : Dept. of Orthopedics, Lund University Hospital, 1996. http://catalog.hathitrust.org/api/volumes/oclc/38045390.html.
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Brzozowski, Julian Alexander. "Lumpy Gravy." reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/160766.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Literatura, Florianópolis, 2015.<br>Made available in DSpace on 2016-04-19T04:18:28Z (GMT). No. of bitstreams: 1
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Previous issue date: 2015<br>Ao estudar Lumpy Gravy de Frank Zappa, o que estamos tentando pensar é uma noção de obra de arte viva, subjetivada, que continue seu devir de pensamento enquanto deixa seu mestre caducar. Veremos que Lumpy Gravy nos auxilia, em sua montagem, na direção de tal concepção ao colocar em jogo o núcleo de negatividade que encontra-se no fazer humano. Abordaremos a obra de arte através do processo de sublimação, termo psicanalítico aqui trabalhado conforme a elaboração de Jacques Lacan no Seminário 7: a ética da psicanálise (2008). A sugestão aqui construída é de que Lumpy Gravy opere na sublimação de seu suporte material, sua condição arquívica, enquanto seu sintoma. Para isso conjugaremos a noção de sinthoma lacaniano com a sismografia de Warburg. A obra de arte encontra-se no leitor, o que quer dizer que ela encontra-se na formação de um olhar. O presente estudo é uma tentativa de elaboração sobre o olhar de Lumpy Gravy.<br><br>Abstract : While studying Frank Zappa?s Lumpy Gravy, what we?re trying to develop is a notion of living work of art, made subject, that maintains its flux while letting its master go dumb. We?ll see that Lumpy Gravy helps us, in its montage, in the direction of such a concept while putting in stake the very core of negativity that is found in human craft. We?ll take the work of art through the process of sublimation, psychoanalytic term here studied according to the elaboration of Jacques Lacan in its Seminary Book 7. The suggestion here built is that Lumpy Gravy operates in the sublimation of its material support, its archival condition, as its symptom. For that we?ll work the notion of lacanian sinthome with Warburg?s seismography. The work of art is found in the reader, which means it is found in the craft of a gaze. This study if an attempt to elaborate on the gaze of Lumpy Gravy.
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Lundin, Anders. "Corticosteroids in Lumbar Disc Surgery." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6126.
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Doyle, Simon. "Lumped element Kinetic Inductance Detectors." Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54728/.
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Kinetic Inductance Detectors (KIDs) provide a promising solution to the problem of producing large format arrays of ultra sensitive detectors for astronomy. Traditionally KIDs have been constructed from superconducting quarter-wavelength or half- wavelength resonator elements capacitively coupled to a coplanar feed line. Photons are detected by measuring the change in quasi-particle density caused by the splitting of Cooper pairs in the superconducting resonant element. This change in quasi-particle density alters the kinetic inductance, and hence the resonant frequency of the resonant element. This arrangement requires the quasi-particles generated by photon absorption to be concentrated at positions of high current density in the resonator. This is usually achieved through antenna coupling or quasi-particle trapping. For these detectors to work at wavelengths shorter than around 500 /zra where antenna coupling can introduce a significant loss of efficiency, a direct absorption method needs to be considered. One solution to this problem is the Lumped Element KID (LEKID), which shows no current variation along its length and can be arranged into a photon absorbing area coupled to free space and therefore requiring no antennas or quasi-particle trapping. The work throughout this thesis studies the properties of the LEKID device though simulation and experimental data and lays the foundation for developing an optimised detector using this direct absorption approach.
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DeBerard, M. Scott. "Predicting Lumbar Fusion Surgery Outcomes From Presurgical Patient Variables: The Utah Lumbar Fusion Outcome Study." DigitalCommons@USU, 1998. https://digitalcommons.usu.edu/etd/6142.
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Lumbar fusion surgery is a commonly used procedure to treat severe spinal pathology and associated chronic disabling low back and leg pain. Despite the common incidence of spinal fusion surgery, few studies have examined patient outcomes or predictive correlates of this procedure. The objectives of this study were to characterize Utah workers who received lumbar fusion surgery in terms of relevant presurgical and outcome variables and to identify presurgical correlates of patient outcomes. An archival prospective research design was utilized consisting of a retrospective medical chart review and a postsurgical telephone outcome survey.
Subjects were 203 workers' compensation patients from the state of Utah who have undergone spinal fusion surgery and who were at least 2 years postsurgery at time of follow-up. Outcomes were assessed for 144 of the 203 patients (71%). Presurgical measures _included demographic, work, compensation, disability, health, surgical, and physiological variables. Outcome measures included solid arthrosis, patient satisfaction, work disability status, functional disability due to back pain, and multidimensional health.
Analysis of patient outcome data revealed that solid arthrosis was achieved in 71.9% of patients. Forty-six percent of subjects felt their back/leg pain problems were worse than what they had expected following the surgery, and 42 % felt that their quality of life had not changed or worsened as a result of lumbar fusion. Twenty-eight percent of fusion patients were work disabled at follow-up. Fusion patient mean outcome scores on multidimensional health measures reflected poorer health than comparative medical patient and nonpatient norms. The most consistent presurgical correlates across outcomes were lawyer involvement, number of prior low back operations, age at injury, and household income at time of injury.
Results are compared to data from previous lumbar fusion research studies and reasons for varying findings are offered. Implications of the findings are discussed in terms of inadequate patient selection and insufficient assessment of patient outcomes in low back research studies. Limitations of the present research are discussed, including how placebo, natural history, and regression to the mean can lead to erroneous conclusions about the efficacy of lumber fusion surgery. Suggestions for improvements in low back surgery outcome research are offered.
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Abbott, Allan. "Physiotherapeutic rehabilitation and lumbar fusion surgery /." Stockholm : Department of clinical science, intevention and technology, Division of orthopaedics, Karolinska Institutet, 2010. http://diss.kib.ki.se/2010/978-91-7409-880-8/.
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Försth, Peter. "On Surgery for Lumbar Spinal Stenosis." Doctoral thesis, Uppsala universitet, Institutionen för kirurgiska vetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-262525.
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The incidence of lumbar spinal stenosis (LSS) is steadily rising, mostly because of a noticeably older age structure. In Sweden, LSS surgery has increased continuously over the years and is presently the most common argument to undergo spine surgery. The purpose of the surgery is to decompress the neural elements in the stenotic spinal canal. To avoid instability, there has been a tradition to do the decompression with a complementary fusion, especially if degenerative spondylolisthesis is present preoperatively. The overall aims of this thesis were to evaluate which method of surgery that generally can be considered to give sufficiently good clinical results with least cost to society and risk of complications and to determine whether there is a difference in outcome between smokers and non-smokers. The Swespine Register was used to collect data on clinical outcome after LSS surgery. In two of the studies, large cohorts were observed prospectively with follow-up after 2 years. Data were analysed in a multivariate model and logistic regression. In a randomised controlled trial (RCT, the Swedish Spinal Stenosis Study), 233 patients were randomised to either decompression with fusion or decompression alone and then followed for 2 years. The consequence of preoperative degenerative spondylolisthesis on the results was analysed and a health economic evaluation performed. The three-dimensional CT technique was used in a radiologic biomechanical pilot study to evaluate the stabilising role of the segmental midline structures in LSS with preoperative degenerative spondylolisthesis by comparing laminectomy with bilateral laminotomies. Smokers, in comparison with non-smokers, showed less improvement after surgery for LSS. Decompression with fusion did not lead to better results compared with decompression alone, no matter if degenerative spondylolisthesis was present preoperatively or not; nor was decompression with fusion found to be more cost-effective than decomression alone. The instability caused by a decompression proved to be minimal and removal of the midline structures by laminectomy did not result in increased instability compared with the preservation of these structures by bilateral laminotomies. In LSS surgery, decompression without fusion should generally be the treatment of choice, regardless of whether preoperative degenerative spondylolisthesis is present or not. Special efforts should be targeted towards smoking cessation prior to surgery.
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Norris, Christopher Michael. "Functional rehabilitation of the lumbar spine." Thesis, Staffordshire University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493646.
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Wong, Peter. "Biomechanical comparison of lumbar disc replacements." View the abstract Download the full-text PDF version, 2009. http://etd.utmem.edu/ABSTRACTS/2009-014-Wong-index.htm.
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Thesis (M.S.)--University of Tennessee Health Science Center, 2009.<br>Title from title page screen (viewed on October 8, 2009). Research advisor: Denis DiAngelo, Ph.D. Document formatted into pages (viii, 75 p. : ill.). Vita. Abstract. Includes bibliographical references (p. 34-38).
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Schellerich-Kaaden, Angela. "Ameisengemeinschaften südostasiatischer Baumbambusse Bestandsaufnahme der Artendiversität, Ressourcennutzung und Besiedlungsdynamik /." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963671952.
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Lynn, Jennifer. "Outcomes of early rehabilitation following lumbar microdiscectomy." University of Western Australia. School of Surgery and Pathology, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0187.
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[Truncated abstract] There have been few studies into the effects of rehabilitation following lumbar microdiscectomy and consequently little evidence of its effect, if any, on outcome. Most studies cited fall into one of two categories: research involving a spinal surgery procedure without rehabilitation, or research involving spinal surgery with a nonspecific generic 'rehabilitation' or 'physical therapy'. In an era of evidence based medicine the efficacy of specific rehabilitation protocols following defined lumbar spine surgical procedures needs to be established for surgeons, therapists and patients to have confidence that the rehabilitation is appropriate and effective. The study was proposed to investigate the outcome of a specific and novel rehabilitation protocol commenced immediately after lumbar microdiscectomy. Data collected from the research cohort were compared to data collected from a contrast group who underwent standard rehabilitation at a distant site. A retrospective study (Phase One) was carried out with a cohort of post-operative microdiscectomy patients between February 2000 and December 2002. The outcome of surgery followed by the rehabilitation protocol was assessed using validated outcome instruments. A contrast or control group was not included. After reviewing the data limitations with the design and implementation of the study were identified. A prospective study (Phase Two) was proposed and changes made in the principal outcome measure used, in the demographic data to be retrieved, the addition of pain scales, and in the exclusion of compensable patients. A contrast group was included for the prospective study. ... The study group commenced exercise and posture correction the day following surgery. There were restrictions placed on activity involving bending. The contrast group followed the advice of the surgeon in Queensland and attended rehabilitation at local physiotherapy facilities. Both groups were followed for 12 months using outcome instruments. Strict comparison between WA and QLD cohorts were limited due to sample size, however trends were observed. Data of the prospective study showed that there was greater reduction in back pain with the early rehabilitation protocol (P<.0001) compared to standard rehabilitation (P=.09), while there was no difference between groups in leg pain. There was a significant improvement in the level of functional disability between time-points for the WA cohort, and overall change from pre-operative RMQ measures to 12 months in both groups were statistically significant. The WA group was less reliant on pain medication and was more satisfied with the results of their surgery. The primary hypothesis of this study that there would be a difference in outcome following lumbar microdiscectomy in patients who receive early specific rehabilitation compared to those who receive standard rehabilitation at another centre, was supported in both primary and secondary outcome data. The key finding of this study was that commencing the early exercise protocol resulted in significantly less back pain over the 12 month time period of the study. Other major findings were that the WA cohort demonstrated significant improvement in function at all time-points and between all time-points except six to 12 months, took less pain medication and were more satisfied with the outcome of their surgery than the QLD cohort.
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Zabidi, Hareyani. "Studies of karst in Kuala Lumpur, Malaysia." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498440.
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Troke, Michael. "Three dimensional measurement of lumbar spinal motion." Thesis, University of Brighton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407676.
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Papp, Tibor. "The growth of the lumbar vertebral canal." Thesis, University of Aberdeen, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262929.
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The aim of the study was to examine the growth and the shape of the lumbar vertebral canal throughout life. A unique collection in the Natural History Museum, London provided many infant spines along with adult ones in perfect condition. Unmagnified silhouette photographs were taken of the vertebrae and the size of the canals was measured by a computer. It was found that in midsagittal diameter and cross-sectional area the vertebral canal was fully matured by 1 year of age at L1-L4 and by 6 at L5. The midsagittal dimension was larger in many infant spines that in the adult. The interpedicular diameter grew at L1 until 10 years of age, at L2-L5 until adulthood while the perimeter did not change at the cranial 3 vertebrae, however, grew at the caudal levels until 16 years of age. The shape of the vertebral canal showed changes at the cranial four levels until adulthood as regards the trefoil configuration, the circularity and the situation of the centroid. At L5 circularity increased throughout life showing degenerative changes by increasing age. Trefoil configuration appeared in adulthood at L5 and its degree as well as its incidence did not change throughout life and generally was not associated with degenerative changes. In the second study anthropometric measurements of head circumference, clavicle length and lower limb lengths were compared to vertebral canal size taken from CT scans. The midsagittal diameter of the canal did not correlate with the other bone measurements, however, the interpedicular diameter showed a relationship. This dimension has significant growth potential like the clavicles and the long bones and to a less extent the skull. This also shows that the neural contents probably exert an effect on the growth of the canal. In the third study MRI measurements of adult lumbar canals were compared to the obstetric data of the subjects to investigate whether on adverse ante-natal environment can cause a disturbance in canal growth, thus, a small canal.
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Criswell, Amy Jo. "Development of a lumbar facet joint replacement." Thesis, University of Iowa, 2013. https://ir.uiowa.edu/etd/2466.
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A majority of the American population will experience low-back pain during their lifetime. With this debilitating condition affecting more people every day, a solution is required to help the population. One of the causes of low-back pain is facet degeneration. Currently, there are no replacement devices on the market that solves this issue.
This thesis presents a design of a facet joint replacement to reduce low-back pain due to facet degeneration. A finite element model of the lumbar spine (L3-L5) was developed to evaluate the implant. Range of motion (ROM), facet contact forces and intervertebral disc stresses were compared for the instrumented and intact model. Futhermore, two additional surgical cases, a laminectomy and facetectomy, were also considered. It was found that the implant followed intact ROM and disc stresses better than a laminectomy and facetectomy. However, there was a large increase in facet contact forces at the adjacent non-operated level, which may ultimately lead to facet degeneration at the adjacent level. Further mechanical testing of the implant is required.
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Rogers, Ellen Louise. "Prolonged Lumbar Flexion Disturbs Paraspinal Reflex Behavior." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/31247.
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The neuromuscular response to prolonged lumbar flexion has recently been extensively studied in felines but has not been examined in humans. Animal studies suggest that prolonged lumbar flexion disturbs neuromuscular control of paraspinal muscles. This disturbance was linked to creep deformation of passive spinal tissues. Past research indicates that disturbance of paraspinal reflexes may limit spinal stability. The current study aimed to examine this behavior in humans. We hypothesized that prolonged lumbar flexion will disturb paraspinal reflex behavior in human subjects.
Reflex behavior was quantified following a fifteen minute period of static flexion. There was a trend suggesting an increase in reflex magnitude after flexion (p = 0.055). This trend was only significant in female subjects (p < 0.003). Increased reflex following flexion was associated with a transient period of EMG hyperexcitability similar to felines.
A second study was performed to quantify reflex behavior and creep deformation during flexion and recovery. Results indicated that creep occurred during prolonged flexion (p < 0.001). Reflexes were inhibited following flexion (p < 0.03). Both creep deformation and paraspinal reflex (p > 0.05) failed to exhibit significant recovery during the length of the test.
Inhibited paraspinal reflexes may contribute to spinal instability and risk of low back pain for workers using flexed postures, due to the inability of the neuromuscular system to coordinate an appropriate muscle response following an unexpected loading event. Future studies must examine appropriate work/rest intervals for workers using flexed postures to limit reflex disturbance from prolonged ligament strain.<br>Master of Science
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Trevett, Michael Charles. "The surgical treatment of severe lumbar spondylolisthesis." Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/26259.
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Chikka, Avanthi. "Biomechanical Evaluation of a Lumbar Interspinous Spacer." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1302258049.
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Hetherington, Jorden Hicklin. "Automated lumbar vertebral level identification using ultrasound." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62945.
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Grane, Per. "The post-operative lumbar spine : a radiological investigation of the lumbar spine after discectomy using MR imaging and CT /." Stockholm, 1998. http://diss.kib.ki.se/1998/91-628-2759-6.
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Espahbodi, Shima. "Investigation of lumbar artery haemodynamics in patients with low back pain and degenerative disc disease of the lumbar spine." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416129.
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Dubach, Roland. "Soft system stabilization of the lumbar spine as an alternative surgical modality to lumbar arthrodesis in the facet syndrome /." [S.l.] : [s.n.], 1995. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Holmes, Steve Anna Louise. "Information processing bias in chronic pain." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369878.
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Gallas, Brandon Dominic. "Signal detection in lumpy backgrounds." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/290090.
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In this dissertation we explore signal detection with model and human observers in the setting of nuclear medicine. Regarding the model observer, the main focus is on the linear observer that maximizes detectability, which we call the Hotelling observer. In particular, we outline two methods for realizing an estimate of this observer. The first uses a Fourier representation. The second uses a representation with a small number of channels chosen for optimal performance. The work employs statistically defined lumpy backgrounds to test the methods and results. These backgrounds are more complicated than correlated Gaussian noise and are meant to complicate the signal-detection task by involving random structure. Regarding the human observer, we present a literature review of psychophysical models, including results based on these models. We then examine one current front runner--a channelized-Hotelling observer with channels modeling visual-response functions---for two experiments involving the lumpy backgrounds.
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Howes, Stephen John. "Lumps, rational maps and monopoles." Thesis, Swansea University, 2001. https://cronfa.swan.ac.uk/Record/cronfa43020.
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Perrotti, Tracy Ann. "An exploration of the lumbar loads and affective responses to lumbar pain on lower limb amputees who use a prosthesis." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001327.
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Dedering, Åsa. "Lumbar muscle fatigue : analysis of electromyography, endurance time and subjective factors in patients with lumbar disc herniation and healthy subjects /." Stockholm, 2002. http://diss.kib.ki.se/2002/91-7349-302-3.
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Denoziere, Guilhem. "Numerical Modeling of a Ligamentous Lumbar Motion Segment." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4998.
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Eight out of ten people in the United States will have problems with low back pain at some point in their life. The most significant surgical treatments for low back pain can be distributed into two main groups of solutions: arthrodesis and arthroplasty. Spinal arthrodesis consists of the fusion of a degenerated functional spine unit (FSU) to alleviate pain and prevent mechanical instability. Spinal arthroplasty consists of the implantation of an artificial disc to restore the functionality of the degenerated FSU. The objective of this study is to analyze and compare the alteration of the biomechanics of the lumbar spine treated either by arthrodesis or arthroplasty.
A three-dimensional finite element model of a ligamentous lumbar motion segment, constituted of two FSUs, was built and simulated through a static analysis with the finite element software ABAQUS.
It was shown that the mobility of the segment treated by arthrodesis was reduced in all rotational degrees of freedom by an average of approximately 44%, relative to the healthy model. Conversely, the mobility of the segment treated by arthroplasty was increased in all rotational degrees of freedom by an average of approximately 52%. The FSU implanted with the artificial disc showed a high risk of instability and further degeneration. The mobility and the stresses in the healthy FSU, adjacent to the restored FSU in the segment treated by arthroplasty, were also increased.
In conclusion, the simulation of the arthroplasty model showed more risks of instability and further degeneration, on the treated level as well as on the adjacent levels, than in the arthrodesis model.
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Chiang, Kuok Vai. "Noise analysis of microwave lumped and transversal filter." Thesis, University of Macau, 2004. http://umaclib3.umac.mo/record=b1445838.
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Grenier, Sylvain. "Stabilization Strategies of the Lumbar Spine in Vivo." Thesis, University of Waterloo, 2002. http://hdl.handle.net/10012/727.
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In developing a method of quantifying stability in the lumbar spine Cholewicki and McGill (1996) have also broached the notion of sufficient stability, where too much stiffness (and stability) would hinder motion. Thus people highly skilled at maintaining stability may use different and optimal strategies, where <i>sufficient</i> stability is maintained. The purpose of this work was to explore the contributors to <i>sufficient</i> stability, how they coordinate and relate to injury mechanisms. This work represents a cascade of investigations where. 1) To explore the balance of various sources of stiffness and their effect on the critical load and post-buckling behaviour, simulations were undertaken where the buckled configuration of the spine was predicted and its stability in this new configuration was assessed. 2) The various sources of stiffness contributing to stability in the lumbar spine have been in some cases found to be deficient. The question of how these deficiencies place individuals at risk of instability, if at all, remains unresolved. A challenged breathing task was used to determine if there was a difference in stabilizing potential between healthy individuals and low back pain sufferers. Given that differences in stabilizing potential are apparent, several tasks which included a predetermined motor strategy, such as 3)pressurizing the abdomen and 4) abdominal hollowing vs. muscle bracing, were evaluated to determine if individuals can utilize motor strategies to augment stability. The stabilizing potential of abdominal pressure (IAP) and its interaction with muscle activation was evaluated. Some individuals are more skilled at stabilizing their lumbar spine than others. Some consciously controlled motor strategies are better stabilizers than others. These strategies highlight the relative contributions of various components (posture, passive tissue, muscle activation, and load) in that no single muscle dominates stability and IAP appears to augment stability beyond muscle activation alone. The margin of safety is considerable and depends on the task at hand, but it is possible to speculate on which tissues are at greatest risk of injury.
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Thompson, Rosemary Elizabeth. "Mechanical Effects of Degeneration in Lumbar Intervertebral Discs." Queensland University of Technology, 2002. http://eprints.qut.edu.au/15781/.
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Lower back injuries are an illness which plague our society. Although almost everyone will experience some form of lower back pain in his or her lifetime, it is a sickness that is poorly understood, calling for new and innovative research. Much of this back pain is attributed to mechanical factors. Hence, it is important to understand the mechanics of the spine and the mechanical effects of degenerative changes that may lead to back pain. The spine is a complex three-dimensional structure and it is therefore necessary to study its mechanics with in vitro tests that replicate physiological movements as closely as possible. Traditional spinal testing machines have been unable to simulate the kinematic behaviour of intervertebral joints as they have limited degrees of freedom and cannot produce dynamic motion. The first aim of this research was to commission a robotic testing facility to overcome the limitations of traditional testing machines. This facility incorporated a six degree-of-freedom (DOF) robot arm with a six DOF force transducer. Mechanical tests performed on this facility could simulate the dynamic three-dimensional kinematics of the lumbar spine. In addition, this research aimed to assess the existence of a region of laxity during spinal joint motion defined as the Neutral Zone, and to determine the effect of specific lesions introduced into the intervertebral disc. To investigate these aims, in vitro mechanical tests on spinal specimens were performed using the robotic testing facility. To ensure these tests produced experimental results that were indicative of the mechanics of the spine in life, the intervertebral disc height had to be representative of the disc height in life. A set of experiments was performed to determine a method for ensuring this. The post-mortem disc height change due to a period of time exposed to a moist environment, freezing, defrosting and application of a constant compressive load was documented in a group of sheep spines. Specimens that were frozen immediately upon removal from the body produced the most predictable results. These specimens required no preloading to ensure the disc height during mechanical testing was similar to that in life. In accordance with this result, specimens used in the ensuing mechanical tests were frozen immediately on removal from the body and stored frozen until required for testing. Tests performed on sheep spines with the robotic facility verified the existence of a Neutral Zone. A criterion was determined that defined the Neutral Zone as the region of spinal joint rotation where the gradient of the load/deformation curve is within +/-0.5 dNm/degree from zero. This definition was used to determine the extent of the Neutral Zone in spinal motion during different movements. A Neutral Zone of approximately four degrees was found in intact spinal motion segments during flexion/extension. Only spinal musculature can stabilise the spine in this region of rotation. The removal of the zygapophysial joints increased the Neutral Zone in flexion/extension by approximately two degrees and caused the appearance of a Neutral Zone in axial rotation of approximately one degree. This suggests that during these motions, the zygapophysial joints are the main passive stabilisers. The mechanical effects of intervertebral disc lesions were examined by experimentally introducing three types of tears (rim lesions, radial tears and concentric tears) into sheep intervertebral discs and comparing the mechanical response of the injured joint to the joint's response prior to the creation of the lesions. Radial tears and concentric tears had no effect on the maximum moments resisted by the intervertebral disc or the hysteresis of the joint's response to motion. An anterior rim lesion increased the Neutral Zone by approximately 1.5 degrees and reduced the maximum moment resisted by the intervertebral disc by approximately 20% during extension in L1/L2 specimens. Rim lesions were also found to reduce the maximum moment resisted by the intervertebral disc in lateral bending and axial rotation for all levels by approximately 15% and 25% respectively. Rim lesions did not affect the hysteresis of intervertebral disc motion. In summary, this research commissioned a robotic testing facility capable of simulating the dynamic, three-dimensional kinematics of the lumbar spine and provided a unique insight into the three-dimensional mechanics of intervertebral joints. Testing was performed on sheep joints, however the outcomes provide an insight into the mechanical response of the human spine. The Neutral Zone was shown to exist but only in flexion/extension. This implies that damage to the spinal muscles may produce an unstable structure during flexion/extension within this Neutral Zone. Rim lesions reduce the ability of the intervertebral disc to resist all modes of motion. This suggests that the presence of rim lesions will produce overloading of other spinal elements and instigate progressive degenerative changes.
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Tsantrizos, Anthony. "Biomechanical comparison of anterior lumbar interbody fusion devices." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ37173.pdf.
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Jansson, Karl-Åke. "On lumbar spinal stenosis and disc herniation surgery /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-257-8/.
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Walters, Rebecca. "Lumbar intervertebral disc infection pathology, prevention and treatment /." Click here to access, 2006. http://thesis.library.adelaide.edu.au/public/adt-SUA20061011.164644/index.html.
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Thesis (Ph.D.) -- University of Adelaide, School of Medical Sciences, Discipline of Pathology, 2006.<br>Includes author's previously published papers. "March 2006" Includes bibliographical references. Also available in a print form.
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Mejuto, Carlos. "Improved lumped parameter thermal modelling of synchronous generators." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4612.
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Within the existing available mix of numerical and analytical thermal analysis options, lumped parameter thermal modelling is selected as the operational backbone to develop an improved novel synchronous generator thermal modelling package. The objective is for the creation of a user friendly quick feedback tool, which can serve as a means to make quick machine design thermal calculations and answer customer queries quickly and reliably. Furthermore, thermally improved generator designs will allow for inevitable operational losses to be channelled away from the machine more efficiently. As a result, machine component temperatures will be reduced, allowing lower generator thermal ratings. The end result will be smaller, longer lasting, more efficient generators, with the ability to be adapted with greater ease to particular applications. With the contribution of selected numerical analysis techniques, mainly finite element analysis for the distribution of iron losses, the MySolver thermal modelling package is developed and presented in this thesis. It is this combination of numerical and analytical tools that improves synchronous generator thermal modelling accuracy, but ultimately it is the lumped parameter nature of the thermal models developed that makes MySolver succeed as a reliable quick feedback electrical machine thermal design tool, validated using experimental results for a wide range of operating conditions. The initial part of the thesis analyses the electrical machine thermal modelling techniques available today, indicating advantages and disadvantages associated with each one, and providing a rationale for the selection of lumped parameter modelling to be used by MySolver. The development of the synchronous generator lumped parameter thermal models is detailed, with examples on its construction presented. Subsequently, finite element analysis is utilised to predict the distribution of machine iron losses across the rotor and stator laminations, with the findings applied to MySolver. Furthermore, a study is performed into the lumped parameter discretisation level needed to effectively represent machine windings. MySolver is experimentally verified using experimental data from a fully instrumented synchronous generator and this data is also used to obtain further insight into the temperature distribution within the generator. In the final part results are evaluated and the use of MySolver for modelling and optimising electrical machines is discussed. Finally, appropriate conclusions on the work presented are drawn.
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Dixon, A. K. "Aspects of computed tomography of the lumbar spine." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598551.
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Kao, Yu-ping Patrick, and 高宇平. "Genetic association studies of lumbar disc degeneration (LDD)." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45154430.
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Suri, Baladitya. "Transmon qubits coupled to superconducting lumped element resonators." Thesis, University of Maryland, College Park, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3711371.
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<p> I discuss the design, fabrication and measurement at millikelvin-temperatures of Al/AlO<i><sub>x</sub></i>/Al Josephson junction-based transmon qubits coupled to superconducting thin-film lumped element microwave resonators made of aluminum on sapphire. The resonators had a center frequency of around 6GHz, and a total quality factor ranging from 15,000 to 70,000 for the various devices. The area of the transmon junctions was about 150 nm × 150 nm and with Josephson energy <i>E<sub>J</sub></i> such that 10GHz ≤ <i>E<sub>J</sub></i> ≤ 30 GHz. The charging energy of the transmons arising mostly from the large interdigital shunt capacitance, was <i>E<sub>c</sub>/h</i> ≈ 300MHz. </p><p> I present microwave spectroscopy of the devices in the strongly dispersive regime of circuit quantum electrodynamics. In this limit the ac Stark shift due to a single photon in the resonator is greater than the linewidth of the qubit transition. When the resonator is driven coherently using a coupler tone, the transmon spectrum reveals individual "photon number'' peaks, each corresponding to a single additional photon in the resonator. Using a weighted average of the peak heights in the qubit spectrum, I calculated the average number of photons <i>n¯</i> in the resonator. I also observed a nonlinear variation of <i>n¯</i> with the applied power of the coupler tone <i>P<sub>rf</sub></i>. I studied this nonlinearity using numerical simulations and found good qualitative agreement with data. </p><p> In the absence of a coherent drive on the resonator, a thermal population of 5.474 GHz photons in the resonator, at an effective temperature of 120 mK resulted in a weak <i>n</i> = 1 thermal photon peak in the qubit spectrum. In the presence of independent coupler and probe tones, the <i> n</i> = 1 thermal photon peak revealed an Autler-Townes splitting. The observed effect was explained accurately using the four lowest levels of the dispersively dressed Jaynes-Cummings transmon-resonator system, and numerical simulations of the steady-state master equation for the coupled system. </p><p> I also present time-domain measurements on transmons coupled to lumped-element resonators. From <i>T</i><sub>1</sub> and Rabi oscillation measurements, I found that my early transmon devices (called design LEv5) had lifetimes (<i>T</i><sub>1</sub> ∼ 1 μs) limited by strong coupling to the 50 Ω transmission line. This coupling was characterized by the the rate of change of the Rabi oscillation frequency with the change in the drive voltage (d<i>f<sub>Rabi</sub></i> /<i>dV</i>) – also termed the Rabi coupling to the drive. I studied the design of the transmon-resonator system using circuit analysis and microwave simulations with the aim being to reduce the Rabi coupling to the drive. By increasing the resonance frequency of the resonator ω<i><sub>r</sub></i>/2π from 5.4 GHz to 7.2 GHz, lowering the coupling of the resonator to the transmission line and thereby increasing the external quality factor <i>Q<sub>e</sub></i> from 20,000 to 70,000, and reducing the transmon-resonator coupling <i> g</i>/2π from 70 MHz to 40 MHz, I reduced the Rabi coupling to the drive by an order of magnitude (∼ factor of 20). The <i>T</i><sub> 1</sub> ∼ 4 μs of devices in the new design (LEv6) was longer than that of the early devices, but still much shorter than the lifetimes predicted from Rabi coupling, suggesting the presence of alternative sources of noise causing qubit relaxation. Microwave simulations and circuit analysis in the presence of a dielectric loss tangent tan δ ≃ 5 × 10<sup> -6</sup> agree reasonably well with the measured <i>T</i><sub> 1</sub> values, suggesting that surface dielectric loss may be causing relaxation of transmons in the new designs.</p>
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Hebron, Clair. "The biomechanical and analgesic effects of lumbar mobilisations." Thesis, University of Brighton, 2014. https://research.brighton.ac.uk/en/studentTheses/6a5baca4-2550-458f-91c0-0f0778bc73f1.
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A common treatment used by physiotherapists for patients with low back pain (LBP) is mobilisations. The aim of applying mobilisations is to increase range of movement (ROM) and reduce pain and stiffness. Therapists choose a specific dose of mobilisation for each patient, which includes a decision on the duration of applied force, commonly up to 3 minutes. Little research has been done to determine the biomechanical and analgesic effects of different durations of treatment. There is tentative evidence that increased duration beyond 3 minutes leads to an increase in range of movement and decrease in pain. This research set out to establish the biomechanical and analgesic effects of longer durations of lumbar mobilisations than commonly used in clinical practice. Only the immediate effects of a single treatment dose have been assessed to date.
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Shaw, Miranda Nicole. "A Biomechanical Evaluation of Lumbar Facet Replacement Systems." University of Toledo / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1120142792.
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Segar, Anand Hari. "The effect of obesity upon the lumbar spine." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:0db5f091-0f6f-4686-957e-22c5390232b0.
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Back pain is a massive global public health problem with multiple contributing factors including obesity. Obesity is thought to be linked to back pain through mechanical factors. However, obesity also causes a systemic low-grade inflammatory milieu. This would suggest a possible biochemical link between obesity, intervertebral disc degeneration, and back pain. Furthermore, the relationship between obesity and the clinical presentation of spine patients is unclear. This thesis aims to examine the effect of and relationship between obesity, the intervertebral discs, and back pain from biochemical, clinical, and epidemiological perspectives. In this thesis, an in vitro study assessed the effect of leptin, a fat-specific cytokine, upon the intervertebral disc. The bovine intervertebral disc was used as a model in a cell culture system. An ex vivo study examined leptin and pro-inflammatory cytokines produced by paraspinal adipose tissue taken during routine surgical procedures from spinal patients. Plasma taken from patients presenting with low back pain was analysed by mass spectrometry and multiplex immunoassay to identify possible protein biomarkers. At an epidemiological level, statistical modelling of the Genodisc patient population was conducted. This was a pan-European study of 2636 patients presenting to tertiary spinal units. Analyses were performed to examine relationships between obesity, quantified by body mass index (BMI), and pain, clinical diagnosis, and spinal degeneration identified on magnetic resonance imaging (MRI). Leptin was shown to increase the production of and expression of degradative and pain-generating molecules by disc cells. A pro-inflammatory environment, especially IL-6, potentiated this response. Leptin and pro-inflammatory cytokines produced by paraspinal fat were unrelated to clinical symptoms. However, levels of the pro-inflammatory cytokines, TNF-α and IL-6, were raised in the plasma of patients with greater pain or those with spinal stenosis. Furthermore, clusterin and complement were identified, by mass spectrometry, as potential biomarkers for spine patients. Epidemiological analyses revealed that obesity was associated with greater back pain, although the magnitude of this association was small. Similarly, obesity was associated with a diagnosis of spinal stenosis. Finally, increased BMI was found to be an independent predictor of disc degeneration, spinal stenosis, and disc herniation on MRI. In summary, this thesis has furthered the clinical understanding of lumbar spine pathology and back pain. It will provide clinicians with a better framework to assess spine patients. These results show that obesity is associated with lumbar spine degeneration and pain. Leptin could be a factor mediating this relationship. Further studies should concentrate on clarifying the mechanism of action of leptin upon the intervertebral disc and assessing the longitudinal effect of obesity upon the lumbar spine. In this thesis, an in vitro study assessed the effect of leptin, a fat-specific cytokine, upon the intervertebral disc. The bovine intervertebral disc was used as a model in a cell culture system. An ex vivo study examined leptin and pro-inflammatory cytokines produced by paraspinal adipose tissue taken during routine surgical procedures from spinal patients. Plasma taken from patients presenting with low back pain was analysed by mass spectrometry and multiplex immunoassay to identify possible protein biomarkers. At an epidemiological level, statistical modelling of the Genodisc patient population was conducted. This was a pan-European study of 2636 patients presenting to tertiary spinal units. Analyses were performed to examine relationships between obesity, quantified by body mass index (BMI), and pain, clinical diagnosis, and spinal degeneration identified on magnetic resonance imaging (MRI). Leptin was shown to increase the production of and expression of degradative and pain-generating molecules by disc cells. A pro-inflammatory environment, especially IL-6, potentiated this response. Leptin and pro-inflammatory cytokines produced by paraspinal fat were unrelated to clinical symptoms. However, levels of the pro-inflammatory cytokines, TNF-α and IL-6, were raised in the plasma of patients with greater pain or those with spinal stenosis. Furthermore, clusterin and complement were identified, by mass spectrometry, as potential biomarkers for spine patients. Epidemiological analyses revealed that obesity was associated with greater back pain, although the magnitude of this association was small. Similarly, obesity was associated with a diagnosis of spinal stenosis. Finally, increased BMI was found to be an independent predictor of disc degeneration, spinal stenosis, and disc herniation on MRI. In summary, this thesis has furthered the clinical understanding of lumbar spine pathology and back pain. It will provide clinicians with a better framework to assess spine patients. These results show that obesity is associated with lumbar spine degeneration and pain. Leptin could be a factor mediating this relationship. Further studies should concentrate on clarifying the mechanism of action of leptin upon the intervertebral disc and assessing the longitudinal effect of obesity upon the lumbar spine.
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Porter, R. W. "Spinal stenosis and disorders of the lumbar spine." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/22563.
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This is a submission of 57 publications on the subject of "Spinal stenosis and disorders of the lumbar spine". It describes work personally carried out or personally supervised, between 1978 and 1997. 30 publications describe studies of spinal stenosis. <i>The development of the vertebral canal</i> is investigated from archaeological material, foetal collections and by the studies of volunteers. Intrauterine factors are identified which influence the canal's size and shape. Epidemiological studies are presented which have measured the canal in large numbers of volunteer adults and children, and patients with low back pain. The <i>clinical significance</i> of the vertebral canal size in various back pain syndromes is identified and described. The patho-physiological mechanism of <i>neurogenic claudication</i> is investigated, demonstrating by a series of clinical and laboratory studies, that multiple level stenosis in a developmentally small canal, causes venous congestion of the cauda equina. Laser Doppler studies show that as a result of this venous congestion, there is probably a failure of arterial vasodilatation in response to exercise, responsible for leg symptoms when walking. Papers describe the natural history of stenosis syndromes, and how calcitonin was introduced and investigated as a method of conservative management of neurogenic claudication. 27 parallel publications describe investigations of <i>other lumbar spine disorders.</i> Biomechanical and ergonomic studies show that hard work can be good for the spine. In prolapse of the lumbar intervertebral disc, laboratory studies demonstrate the importance of pre-existing degeneration and the formation of a free fragment. The mechanism of the clinical signs of disc protrusion, their repeatability and new signs are described. Spondylolisthesis is investigated. Studies examine back pain epidemiology, the differential diagnosis and classification of back pain, and spinal surgery and failed surgery. There is an appendix by title only, which records many of these studies in 7 text books and 19 contributory chapters.
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Lin, Yo-Shen, and 林祐生. "Lumped-Element Uniplanar Transitions." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/35205225755032819688.
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博士<br>國立臺灣大學<br>電信工程學研究所<br>91<br>Uniplanar lines such as coplanar waveguide (CPW), coplanar stripline (CPS), and slotline (SL) have received increased attentions due to their exclusive features over the conventional microstrip lines. To fully utilize the advantages of uniplanar lines and circuit components, implementation of compact and low-loss interconnections between these uniplanar lines is of practical significance. In this study, a novel class of lumped-element uniplanar transitions is proposed and thoroughly investigated.
First, by using planar lumped-elements to replace the quarter-wavelength transformer structures in the conventional transition designs, the basic lumped-element uniplanar transitions and the lumped-element Marchand-balun type uniplanar transitions are proposed. They may achieve 1/10 the size of conventional transitions adopting quarter-wavelength transformer structures. Second, the novel lumped-element CPW-to-CPS transitions with filter characteristics are proposed, using planar lumped-elements to realize the low-pass, high-pass, and band-pass filter prototypes in the transition structures. These transitions have the combined functions of transition and filter with very compact sizes. Third, the planar lumped-elements are employed to realize the L-section matching networks in the transition structures. The resulting impedance- transforming transitions are very compact and are capable of transforming to complex impedance values.
Simple equivalent-circuit models based on close-form expressions are also established, from which the prototypes of lumped-element transitions may be easily constructed and characterized. Applications of proposed transitions in the design of miniature antenna feeding structures are also demonstrated. The proposed lumped-element uniplanar transitions have the advantages of small size, low loss, and multi-function, and may be simply designed through the proposed equivalent-circuit models. They are attractive in implementing MMIC components.