• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 41
  • 16
  • 16
  • 12
  • 7
  • 5
  • 5
  • 3
  • 2
  • 1
  • Tagged with
  • 125
  • 21
  • 17
  • 16
  • 16
  • 14
  • 11
  • 10
  • 9
  • 8
  • 8
  • 7
  • 7
  • 7
  • 7
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Identification and Characterization of Intermediates during Folding on the β-Barrel Assembly Machine in Escherichia coli

Xue, Mingyu 04 June 2015 (has links)
β-barrel membrane proteins play important structural and functional roles in Gram negative bacteria and in mitochondria and chloroplasts of eukaryotes. A conserved machine is responsible for the folding and insertion of β-barrel membrane proteins but its mechanism remains largely unknown. In E. coli, a five protein β-barrel assembly machine (Bam) assembles β-barrel proteins into the outer membrane (OM). Among all β-barrel membrane proteins in E. coli , the β-barrel component of the OM LPS translocon is one of only two essential β-barrels, the other being the central component of the Bam machinery itself. The OM LPS translocon, which consists of OM β-barrel protein LptD (lipopolysaccharide transport) and OM lipoprotein LptE, is responsible for the final export of LPS molecules into the outer leaflet of the OM, resulting in an asymmetric bilayer that blocks the entry of toxic molecules such as antibiotics. This thesis describes the characterization of the biogenesis pathway of the OM LPS translocon and its folding and insertion into the OM by the Bam machinery. An in vivo S35-Methionine pulse-labeling assay was developed to identify intermediates along the biogenesis of the OM LPS translocon. Seven intermediates were identified along the pathway. We show that proper assembly of the OM LPS translocon involves an oxidative disulfide bond rearrangement from a nonfunctional intermediate containing non-native disulfides. We also found that the rate determining step of OM LPS translocon biogenesis is β-barrels folding process by the Bam machinery. Using in vivo chemical crosslinking, we accumulated and trapped a mutant form of LptD on BamA, the central component of the Bam machinery. We extended the S35-Methionine pulse-labeling method to allow chemical crosslinking of substrates on the Bam complex and trapped LptD while it was being folded on the Bam machine. We demonstrated that the interaction between LptD and BamA is independent of LptE, while that between LptD and BamD, the other essential component of the Bam complex beside BamA, is LptE dependent. Based on these findings, we proposed a model of Bam-assisted folding of the OM LPS translocon in which LptE templates the folding of LptD. / Chemistry and Chemical Biology
52

EFFECTS OF AUGMENTED REAL-TIME AUDITORY FEEDBACK ON TOP-LEVEL PRECISION SHOOTING PERFORMANCE

Underwood, Stacy Marie 01 January 2009 (has links)
This study examined the effects of training with real-time auditory feedback in precision shooting. Top-level shooters (N=9) were randomly assigned to the feedback or nonfeedback group. Each group performed a pre-test, a 4-week training intervention and a post-test. The feedback group was provided with augmented real-time auditory feedback based on postural and rifle barrel stability during training sessions. Increases in performance were measured through changes in postural stability, rifle barrel stability, shot outcome and shot group diameter. Real-time auditory feedback did not increase postural or rifle barrel stability in the feedback group. No meaningful differences were found related to shot outcome or shot group diameter in air rifle testing. The feedback group was able to reduce shot group diameter during smallbore testing. In summary, the augmented real-time auditory feedback did not improve postural or rifle barrel stability. Future research should focus on examining the effects of auditory feedback on smallbore performance.
53

Explorations for Efficient Reversible Barrel Shifters and Their Mappings in QCA Nanocomputing

Chen, Ke 01 January 2015 (has links)
This thesis is based on promising computing paradigm of reversible logic which generates unique outputs out of the inputs and. Reversible logic circuits maintain one-to-one mapping inside of the inputs and the outputs. Compared to the traditional irreversible computation, reversible logic circuit has the advantage that it successfully avoids the information loss during computations. Also, reversible logic is useful to design ultra-low-power nanocomputing circuits, circuits for quantum computing, and the nanocircuits that are testable in nature. Reversible computing circuits require the ancilla inputs and the garbage outputs. Ancilla input is the constant input in reversible circuits. Garbage output is the output for maintaining the reversibility of the reversible logic but is not any of the primary inputs nor a useful bit. An efficient reversible circuit will have the minimal number of garbage and ancilla bits. Barrel shifter is one of main computing systems having applications in high speed digital signal processing, oating-point arithmetic, FPGA, and Center Processing Unit (CPU). It can operate the function of shifting or rotation for multiple bits in only one clock cycle. The goal of this thesis is to design barrel shifters based on the reversible computing that are optimized in terms of the number of ancilla and garbage bits. In order to achieve this goal, a new Super Conservative Reversible Logic Gate (SCRL gate) has been used. The SCRL gate has 1 control input depending on the value of which it can swap any two n-1 data inputs. We proved that the SCRL gate is superior to the existing conservative reversible Fredkin gate. This thesis develops 5 design methodologies for reversible barrel shifters using SCRL gates that are primarily optimized with the criteria of the number of ancilla and garbage bits. The five proposed methodologies consist of reversible right rotator, reversible logical right shifter, reversible arithmetic right shifter, reversible universal right shifter and reversible universal bidirectional shifter. The proposed reversible barrel shifter design is compared with the existing works in literature and have shown improvement ranging from 8.5% to 92% by the number of garbage and ancilla bits. The SCRL gate and design methodologies of reversible barrel shifter are mapped in Quantum Dot Cellular Automata (QCA) computing. It is illustrated that the SCRL-based designs of reversible barrel shifters have less QCA cost (cost in terms of number of inverters and majority voters) compared to the Fredkin gate- based designs of reversible barrel shifters.
54

Entwicklung, Aufbau und Test eines neuen Auslesesystems für den Crystal-Barrel-Detektor zur Messung photoinduzierter Reaktionen an ELSA

Ehmanns, Andreas. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2000--Bonn.
55

Messung der Reaktionen _pn-]KSK_0 und _pn-]KSKS_

Wittmack, Karsten. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2001--Bonn.
56

Beobachtungen von Anregungen des _R(h)63(770)-Mesons im Kanal _pd-]w_0Pspectator

Pick, Burkhard. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2001--Bonn.
57

Entwicklung eines neuen Datenakquisitionssystems für das CB-ELSA-Experiment

Schmidt, Christoph. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2004--Bonn.
58

O comportamento em campo aberto como modelo para avaliar a recuperação funcional após lesão unilateral dos barris do córtex somatossensorial / Open field behavior as model to functional recovery after unilateral lesion of barrel cortex

Danielle Paes Machado de Andrade Branco 31 August 2011 (has links)
Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Em roedores, as vibrissas são detectores táteis que desempenham papel importante na exploração espacial do ambiente e na discriminação de texturas. No córtex somatosensorial, os campos receptivos de cada uma das vibrissas estão organizados no hemisfério contralateral em colunas discretas denominadas barris. A lesão unilateral dos barris produz um comportamento assimétrico caracterizado pela redução no uso da vibrissa contralateral à lesão na exploração do ambiente, assimetria esta que diminui progressivamente na medida em que os animais são repetidamente testados. Em ratos, este comportamento, normalmente medido pelo número de vezes que os animais encostam as vibrissas na parede de um campo aberto, tem se mostrado uma ferramenta importante em estudos de plasticidade e recuperação funcional após lesões corticais. Contudo, em camundongos com lesões unilaterais dos barris, o registro dos toques das vibrissas na parede tem levado a resultados contraditórios. Esse trabalho tem por objetivo principal o estabelecimento de um modelo comportamental para avaliação da recuperação funcional após lesões unilaterais dos barris do córtex somatosensorial em camundongos. Para tanto, o sentido dos deslocamentos realizados próximos às quinas do campo aberto foi registrado em camundongos Suíços machos submetidos à criolesão unilateral dos barris foi avaliado em três estudos independentes. No primeiro estudo, demonstramos que no grupo Criolesado houve um predomínio dos deslocamentos em sentido contralateral na primeira vez em que foram testados no campo aberto e este resultado foi independente do fato de na primeira sessão ter sido realizada um ou nove dias após a cirurgia. Além disso, demonstramos que o predomínio de deslocamentos em sentido contralateral foi diminuindo na medida em que os animais eram repetidamente testados no campo aberto. No segundo estudo, demonstramos que os animais do grupo Criolesado que foram previamente submetidos a cinco sessões experimentais no campo aberto não apresentaram, após a cirurgia, diferenças entre os deslocamentos realizados em sentido ipsolateral e contralateral à lesão. Já no terceiro estudo, demonstramos que os animais do grupo Criolesado que não foram previamente testados no campo aberto apresentam um predomínio de deslocamentos em sentido contralateral, mesmo quando o teste foi realizado 48 dias após a lesão unilateral dos barris. Nossos dados sugerem que o sentido dos deslocamentos próximo às quinas do campo aberto pode ser uma ferramenta importante para avaliar a recuperação das lesões unilaterais nos barris do córtex somatosensorial. Além disso, para avaliar a recuperação funcional após a lesão unilateral dos barris do córtex somatossensorial, sem o viés da habituação à situação do teste, os animais devem ser testados apenas uma vez / In rodents, the vibrissae are tactile detectors that have an important role in the spatial exploration of the environment and in texture discrimination. In the somatosensory cortex, the receptive fields of each of the vibrissae are organized into discrete columns, known as barrels, in the contralateral hemisphere. The unilateral lesions of the barrels results in an asymmetric behavior characterized by the reduction in the use of the vibrissae contralateral to the lesion during the exploration of the environment. This asymmetry progressively diminishes as the animal is repeatedly tested in the same environment. In rats, this behavior, usually assessed by the number of times the animals touch the walls of an open field arena with their vibrissae, has been considered a useful tool in studies addressing plasticity and functional recovery after cortical lesions. However, in mice with unilateral lesions of the barrels, the analysis of the number of times that the vibrissae touch the walls have lead to contradictory results. The present work aims to establish a behavioral model for the evaluation of functional recovery after unilateral lesions of the barrel field located in the somatosensory cortex of the mouse. To that end, the direction of movement near the corners of the open field of Swiss male mice subjected to unilateral cryolesion of the barrel was analyzed in three independent studies. In the first study, we demonstrated that the cryolesioned animals displayed a predominance of contralateral movements in the first time that they were tested in the open field and that this result was present whether the animals was first tested one or nine days after the lesion. Furthermore, we demonstrated that the predominance of movements toward the contralateral side of the lesion diminished as the animals were repeatedly tested in the open field. In the second study, we demonstrated that the cryolesioned animals that were, prior to barrel field lesioning, subjected to five sessions in the open field did not display, after lesioning, differences between the number of ipso and contralateral movements. In the third study, we demonstrated that the cryolesioned animals that were not previously tested in the open field displayed a predominance of contralateral movements even if the first test was carried out forty eight days after the unilateral lesion of the barrels. Our data suggest that the analysis of the direction of movement near the corners of the open field can be an important tool in the assessment of functional recovery after unilateral lesions of the barrels located in the somatosensory cortex of mice. Moreover, in order to properly assess functional recovery after unilateral lesion of the barrel field without the confounding factor of habituation, animals must be tested only once
59

Music-making in the English parish church from the 1760s to 1860s, with particular reference to Hertfordshire

Kilbey, Margaret January 2017 (has links)
This dissertation focuses on a previously unexplored aspect of music-making in the English parish church during the 1760s to 1860s, namely its local development in response to inter-related episcopal, elite, clerical and economic influences. The historiography suggests ineffectual episcopal leadership and little gentry engagement with parochial church music-making during this period. By contrast, this study presents evidence of their influence, particularly during the late eighteenth to early nineteenth centuries. Elite support for Sunday and charity schools was allied with a desire to improve congregational psalmody, and church organs and barrel-organs were given with this objective in mind. Gentry involvement with amateur military bands of music also influenced the instrumentation of choir-bands. These actions were mirrored by those further down the social scale, and formed part of a complex pattern of support for church music-making. This dissertation argues that methods adopted to improve congregational singing in one generation were reviled in the next. The suggestion that teaching charity school children to sing would result in a congregation of singing adults became a recurring theme, yet time and again it met with little success. Nineteenth-century reform of church music-making has often been presented as a clear-cut progression, with the replacement of choir-bands by a barrel-organ or harmonium, but this dissertation argues that these phases were sometimes parallel rather than sequential, with no inevitable outcome. Furthermore, new evidence reveals that nineteenth-century church rate disputes had a profound effect on church music-making, an area of research neglected in modern literature. Lack of available seating became a significant problem in parish churches owing to the often compulsory attendance of schoolchildren, which opens up another new area of research. This dissertation argues that attempts to reform music-making contributed to alterations in the church fabric long before ecclesiological reorderings, and had long-lasting repercussions.
60

O comportamento em campo aberto como modelo para avaliar a recuperação funcional após lesão unilateral dos barris do córtex somatossensorial / Open field behavior as model to functional recovery after unilateral lesion of barrel cortex

Danielle Paes Machado de Andrade Branco 31 August 2011 (has links)
Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Em roedores, as vibrissas são detectores táteis que desempenham papel importante na exploração espacial do ambiente e na discriminação de texturas. No córtex somatosensorial, os campos receptivos de cada uma das vibrissas estão organizados no hemisfério contralateral em colunas discretas denominadas barris. A lesão unilateral dos barris produz um comportamento assimétrico caracterizado pela redução no uso da vibrissa contralateral à lesão na exploração do ambiente, assimetria esta que diminui progressivamente na medida em que os animais são repetidamente testados. Em ratos, este comportamento, normalmente medido pelo número de vezes que os animais encostam as vibrissas na parede de um campo aberto, tem se mostrado uma ferramenta importante em estudos de plasticidade e recuperação funcional após lesões corticais. Contudo, em camundongos com lesões unilaterais dos barris, o registro dos toques das vibrissas na parede tem levado a resultados contraditórios. Esse trabalho tem por objetivo principal o estabelecimento de um modelo comportamental para avaliação da recuperação funcional após lesões unilaterais dos barris do córtex somatosensorial em camundongos. Para tanto, o sentido dos deslocamentos realizados próximos às quinas do campo aberto foi registrado em camundongos Suíços machos submetidos à criolesão unilateral dos barris foi avaliado em três estudos independentes. No primeiro estudo, demonstramos que no grupo Criolesado houve um predomínio dos deslocamentos em sentido contralateral na primeira vez em que foram testados no campo aberto e este resultado foi independente do fato de na primeira sessão ter sido realizada um ou nove dias após a cirurgia. Além disso, demonstramos que o predomínio de deslocamentos em sentido contralateral foi diminuindo na medida em que os animais eram repetidamente testados no campo aberto. No segundo estudo, demonstramos que os animais do grupo Criolesado que foram previamente submetidos a cinco sessões experimentais no campo aberto não apresentaram, após a cirurgia, diferenças entre os deslocamentos realizados em sentido ipsolateral e contralateral à lesão. Já no terceiro estudo, demonstramos que os animais do grupo Criolesado que não foram previamente testados no campo aberto apresentam um predomínio de deslocamentos em sentido contralateral, mesmo quando o teste foi realizado 48 dias após a lesão unilateral dos barris. Nossos dados sugerem que o sentido dos deslocamentos próximo às quinas do campo aberto pode ser uma ferramenta importante para avaliar a recuperação das lesões unilaterais nos barris do córtex somatosensorial. Além disso, para avaliar a recuperação funcional após a lesão unilateral dos barris do córtex somatossensorial, sem o viés da habituação à situação do teste, os animais devem ser testados apenas uma vez / In rodents, the vibrissae are tactile detectors that have an important role in the spatial exploration of the environment and in texture discrimination. In the somatosensory cortex, the receptive fields of each of the vibrissae are organized into discrete columns, known as barrels, in the contralateral hemisphere. The unilateral lesions of the barrels results in an asymmetric behavior characterized by the reduction in the use of the vibrissae contralateral to the lesion during the exploration of the environment. This asymmetry progressively diminishes as the animal is repeatedly tested in the same environment. In rats, this behavior, usually assessed by the number of times the animals touch the walls of an open field arena with their vibrissae, has been considered a useful tool in studies addressing plasticity and functional recovery after cortical lesions. However, in mice with unilateral lesions of the barrels, the analysis of the number of times that the vibrissae touch the walls have lead to contradictory results. The present work aims to establish a behavioral model for the evaluation of functional recovery after unilateral lesions of the barrel field located in the somatosensory cortex of the mouse. To that end, the direction of movement near the corners of the open field of Swiss male mice subjected to unilateral cryolesion of the barrel was analyzed in three independent studies. In the first study, we demonstrated that the cryolesioned animals displayed a predominance of contralateral movements in the first time that they were tested in the open field and that this result was present whether the animals was first tested one or nine days after the lesion. Furthermore, we demonstrated that the predominance of movements toward the contralateral side of the lesion diminished as the animals were repeatedly tested in the open field. In the second study, we demonstrated that the cryolesioned animals that were, prior to barrel field lesioning, subjected to five sessions in the open field did not display, after lesioning, differences between the number of ipso and contralateral movements. In the third study, we demonstrated that the cryolesioned animals that were not previously tested in the open field displayed a predominance of contralateral movements even if the first test was carried out forty eight days after the unilateral lesion of the barrels. Our data suggest that the analysis of the direction of movement near the corners of the open field can be an important tool in the assessment of functional recovery after unilateral lesions of the barrels located in the somatosensory cortex of mice. Moreover, in order to properly assess functional recovery after unilateral lesion of the barrel field without the confounding factor of habituation, animals must be tested only once

Page generated in 0.0421 seconds