To see the other types of publications on this topic, follow the link: Peripheral.
Dissertations / Theses on the topic 'Peripheral'
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 'Peripheral.'
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
Childers, Jason C. "Peripheral Recognition." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1853.
Full textAbstract:
Perception greatly affects the way we experience and understand the world. Using self-reflective research processes and data collection, I explore how art can subjectively re-present data and what this means for research and knowledge. The artworks through which I discuss these notions are Self Checkout 2013, Bibliography of Virtual Consciousness: Uniform Resource Locator Volumes 1-12 (BOVC:URL 1-12), and Observation Box. Self Checkout 2013 is composed of all of my receipts from 2013. They not only record my transactions, but also re-present data from which one can make inferences regarding my life—my consumer identity, my needs, my desires, etc. BOVC:URL 1-12 re-presents my web history and suggests a reflection on the relationships between physical realities, virtual realities, and the consciousness that mediates experience between them. These forms of data are analyzed by me and through audience participation in Observation Box in an attempt to construct multi-perspectival knowledges from art.
2
Hausen, Doris. "Peripheral interaction." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-167337.
Full textAbstract:
In our everyday life we carry out a multitude of activities in parallel without focusing our attention explicitly on them. We drink a cup of tea while reading a book, we signal a colleague passing by with a hand gesture, that we are concentrated right now and that he should wait one moment, or we walk a few steps backwards while taking photos. Many of these interactions - like drinking, sending signals via gestures or walking - are rather complex by themselves. By means of learning and training, however, these interactions become part of our routines and habits and therefore only consume little or no attentional resources. In contrast, when interacting with digital devices, we are often asked for our full attention. To carry out - even small and marginal tasks - we are regularly forced to switch windows, do precise interactions (e.g., pointing with the mouse) and thereby these systems trigger context and focus switches, disrupting us in our main focus and task. Peripheral interaction aims at making use of human capabilities and senses like divided attention, spatial memory and proprioception to support interaction with digital devices in the periphery of the attention, consequently quasi-parallel to another primary task.
In this thesis we investigate peripheral interaction in the context of a standard desktop computer environment. We explore three interaction styles for peripheral interaction: graspable interaction, touch input and freehand gestures. StaTube investigates graspable interaction in the domain of instant messaging, while the Appointment Projection uses simple wiping gestures to access information about upcoming appointments. These two explorations focus on one interaction style each and offer first insights into the general benefits of peripheral interaction. In the following we carried out two studies comparing all three interaction styles (graspable, touch, freehand) for audio player control and for dealing with notifications. We found that all three interaction styles are generally fit for peripheral interaction but come with different advantages and disadvantages. The last set of explorative studies deals with the ability to recall spatial locations in 2D as well as 3D. The Unadorned Desk makes use of the physical space around the desktop computer and thereby offers an extended interaction space to store and retrieve virtual items such as commands, applications or tools. Finally, evaluation of peripheral interaction is not straightforward as the systems are designed to blend into the environment and not draw attention on them. We propose an additional evaluation method for the lab to complement the current evaluation practice in the field.
The main contributions of this thesis are (1) an exhaustive classification and a more detailed look at manual peripheral interaction for tangible, touch and freehand interaction. Based on these exploration with all three interaction styles, we offer (2) implications in terms of overall benefits of peripheral interaction, learnability and habituation, visual and mental attention, feedback and handedness for future peripheral interaction design. Finally, derived from a diverse set of user studies, we assess (3) evaluation strategies enriching the design process for peripheral interaction.<br>In unserem täglichen Leben führen wir eine große Anzahl an Aktivitäten parallel aus ohne uns explizit darauf zu konzentrieren. Wir trinken Tee während wir ein Buch lesen, wir signalisieren einem Kollegen durch eine Handgeste, dass wir gerade konzentriert sind und er einen Moment warten soll oder wir gehen ein paar Schritte rückwärts während wir fotografieren. Viele dieser Aktivitäten - wie beispielsweise Trinken, Gestikulieren und Laufen - sind an sich komplex. Durch Training werden diese Tätigkeiten allerdings Teil unserer Routinen und Gewohnheiten, und beanspruchen daher nur noch wenig oder sogar keine Aufmerksamkeit. Im Gegensatz dazu, verlangen digitale Geräte meist unsere volle Aufmerksamkeit während der Interaktion. Um - oftmals nur kleine - Aufgaben durchzuführen, müssen wir Fenster wechseln, präzise Aktionen durchführen (z.B. mit dem Mauszeiger zielen) und werden dabei durch die Systeme zu einem Kontext- und Fokuswechsel gezwungen. Periphere Interaktion hingegen macht sich menschliche Fähigkeiten wie geteilte Aufmerksamkeit, das räumliche Gedächtnis und Propriozeption zu Nutze um Interaktion mit digitalen Geräten am Rande der Aufmerksamkeit also der Peripherie zu ermöglichen -- quasi-parallel zu einem anderen Primärtask.
In dieser Arbeit untersuchen wir Periphere Interaktion am Computerarbeitsplatz. Dabei betrachten wir drei verschiedene Interaktionsstile: Begreifbare Interaktion (graspable), Touch Eingabe und Freiraum Gestik (freehand). StaTube untersucht Begreifbare Interaktion am Beispiel von Instant Messaging, während die Appointment Projection einfache Wischgesten nutzt, um Informationen nahender Termine verfügbar zu machen. Diese beiden Untersuchungen betrachten jeweils einen Interaktionsstil und beleuchten erste Vorteile, die durch Periphere Interaktion erzielt werden können. Aufbauend darauf führen wir zwei vergleichende Studien zwischen allen drei Interaktionsstilen durch. Als Anwendungsszenarien dienen Musiksteuerung und der Umgang mit Benachrichtigungsfenstern. Alle drei Interaktionsstile können erfolgreich für Periphere Interaktion eingesetzt werden, haben aber verschiedene Vor- und Nachteile. Die letzte Gruppe von Studien befasst sich mit dem räumlichen Gedächtnis in 2D und 3D. Das Unadorned Desk nutzt den physikalischen Raum neben dem Desktop Computer um virtuelle Objekte, beispielsweise Funktionen, Anwendungen oder Werkzeuge, zu lagern. Darüber hinaus ist die Evaluation von Peripherer Interaktion anspruchsvoll, da sich die Systeme in die Umwelt integrieren und gerade keine Aufmerksamkeit auf sich ziehen sollen. Wir schlagen eine Evaluationsmethode für das Labor vor, um die derzeitig vorherrschenden Evaluationsmethoden in diesem Forschungsfeld zu ergänzen.
Die Kernbeiträge dieser Arbeit sind eine (1) umfassende Klassifizierung und ein detaillierter Blick auf manuelle Periphere Interaktion, namentlich Begreifbare Interaktion, Touch Eingabe und Freiraum Gestik. Basierend auf unseren Untersuchungen ziehen wir (2) Schlussfolgerungen, die den generellen Nutzen von Peripherer Interaktion darlegen und Bereiche wie die Erlernbarkeit und Gewöhnung, visuelle und mentale Aufmerksamkeit, Feedback so wie Händigkeit beleuchten um zukünftige Projekte im Bereich der Peripheren Interaktion zu unterstützen. Aufbauend auf den verschiedenen Nutzerstudien, diskutieren wir Evaluationsstrategien um den Entwicklungsprozess Peripherer Interaktion zu unterstützen.
3
Burathoki, Tunna P. "China and peripheral conflicts." University of Southern Queensland, Faculty of Arts, 2004. http://eprints.usq.edu.au/archive/00002825/.
Full textAbstract:
[Abstract]: China’s enormous size and stature as a new hub of economic growth in tandem with its military modernisation make China a rising power. The strategic consequences of China’s economic growth synergised with its military muscles are multiple and profound, especially, for the neighbours in its conflict-prone periphery. The aim of this dissertation is not only to assess the importance and complexities of conflicts in the periphery of China, but also about the necessity for the neighbours to coexist with a more powerful China. At the same time, in the Chinese geopolitical context, domestic stability and hence, the CCP’s legitimacy has been perpetually paramount, and external threats or conflicts are usually perceived in the context of aggravating domestic and international stability, thereby hampering its strategic aim of achieving global economic command and power-projection military capability.With the dawn of 21st century, China is grooving to an exuberant global beat, the intensity of conflicts along China’s periphery has dimmed to such an extent that its political, economic, and social order will probably not disintegrate into chaos in the near future. Instead, China’s rapidly growing economic capacity and its soaring prestige in faraway capitals like Washington and Paris has meant an expansion of Chinese “soft power”, i.e., an assertive China with an ability to get what it wants by attracting and persuading others to adopt its goals, instead of blunt economic and military coercion. And, China could reasonably be expected to manage most, if not all, the conflicts in its periphery to its own advantage. These include: efforts to augment its military capabilities in a manner commensurate with its increased economic muscle and acquire new allies and underwrite the protection of others in its periphery. It is unlikely that the PRC will actually acquire new or reclaim old territory for China’s resources or for symbolic reasons by penalizing, if necessary, any opponents or bystanders who resist such claims. While it may wish to redress past wrongs it believes to have suffered; or attempt to rewrite the prevailing international “rules of game” to better reflect its own geostrategic interests; or in the most extreme policy choice, perhaps even ready itself for preventive war or to launch predatory attacks on its foes on the pretext of the “cult of defence,” – all of which have been seen as the bedrock of the contemporary China’s strategic culture, however, it is iiprobable that China will not pursue these at the cost of its future economic and/or social security agenda.
4
Osman, Ayman. "Autophagy in Peripheral Neuropathy." Doctoral thesis, Linköpings universitet, Avdelning för neurobiologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-142125.
Full textAbstract:
Peripheral neuropathy includes a wide range of diseases affecting millions around the world, and many of these diseases have unknown etiology. Peripheral neuropathy in diabetes represents a large proportion of peripheral neuropathies. Nerve damage can also be caused by trauma. Peripheral neuropathies are a significant clinical problem and efficient treatments are largely lacking. In the case of a transected nerve, different methods have been used to repair or reconstruct the nerve, including the use of nerve conduits, but functional recovery is usually poor. Autophagy, a cellular mechanism that recycles damaged proteins, is impaired in the brain in many neurodegenerative diseases affecting animals and humans. No research, however, has investigated the presence of autophagy in the human peripheral nervous system. In this study, I present the first structural evidence of autophagy in human peripheral nerves. I also show that the density of autophagy structures is higher in peripheral nerves of patients with chronic idiopathic axonal polyneuropathy (CIAP) and inflammatory neuropathy than in controls. The density of these structures increases with the severity of the neuropathy. In animal model, using Goto-Kakizaki (GK) rats with diabetes resembling human type 2 diabetes, activation of autophagy by local administration of rapamycin incorporated in collagen conduits that were used for reconnection of the transected sciatic nerve led to an increase in autophagy proteins LC3 and a decrease in p62 suggesting that the autophagic flux was activated. In addition, immunoreactivity of neurofilaments, which are parts of the cytoskeleton of axons, was increased indicating increased axonal regeneration. I also show that many proteins involved in axonal regeneration and cell survival were up-regulated by rapamycin in the injured sciatic nerve of GK rats four weeks after injury. Taken together, these findings provide new knowledge about the involvement of autophagy in neuropathy and after peripheral nerve injury and reconstruction using collagen conduits.
5
Mathur, Ankit. "Peripheral ocular monochromatic aberrations." Queensland University of Technology, 2009. http://eprints.qut.edu.au/30384/.
Full textAbstract:
Aberrations affect image quality of the eye away from the line of sight as well as along it. High amounts of lower order aberrations are found in the peripheral visual field and higher order aberrations change away from the centre of the visual field. Peripheral resolution is poorer than that in central vision, but peripheral vision is important for movement and detection tasks (for example driving) which are adversely affected by poor peripheral image quality. Any physiological process or intervention that affects axial image quality will affect peripheral image quality as well. The aim of this study was to investigate the effects of accommodation, myopia, age, and refractive interventions of orthokeratology, laser in situ keratomileusis and intraocular lens implantation on the peripheral aberrations of the eye. This is the first systematic investigation of peripheral aberrations in a variety of subject groups. Peripheral aberrations can be measured either by rotating a measuring instrument relative to the eye or rotating the eye relative to the instrument. I used the latter as it is much easier to do. To rule out effects of eye rotation on peripheral aberrations, I investigated the effects of eye rotation on axial and peripheral cycloplegic refraction using an open field autorefractor. For axial refraction, the subjects fixated at a target straight ahead, while their heads were rotated by ±30º with a compensatory eye rotation to view the target. For peripheral refraction, the subjects rotated their eyes to fixate on targets out to ±34° along the horizontal visual field, followed by measurements in which they rotated their heads such that the eyes stayed in the primary position relative to the head while fixating at the peripheral targets. Oblique viewing did not affect axial or peripheral refraction. Therefore it is not critical, within the range of viewing angles studied, if axial and peripheral refractions are measured with rotation of the eye relative to the instrument or rotation of the instrument relative to the eye. Peripheral aberrations were measured using a commercial Hartmann-Shack aberrometer. A number of hardware and software changes were made. The 1.4 mm range limiting aperture was replaced by a larger aperture (2.5 mm) to ensure all the light from peripheral parts of the pupil reached the instrument detector even when aberrations were high such as those occur in peripheral vision. The power of the super luminescent diode source was increased to improve detection of spots passing through the peripheral pupil. A beam splitter was placed between the subjects and the aberrometer, through which they viewed an array of targets on a wall or projected on a screen in a 6 row x 7 column matrix of points covering a visual field of 42 x 32. In peripheral vision, the pupil of the eye appears elliptical rather than circular; data were analysed off-line using custom software to determine peripheral aberrations. All analyses in the study were conducted for 5.0 mm pupils. Influence of accommodation on peripheral aberrations was investigated in young emmetropic subjects by presenting fixation targets at 25 cm and 3 m (4.0 D and 0.3 D accommodative demands, respectively). Increase in accommodation did not affect the patterns of any aberrations across the field, but there was overall negative shift in spherical aberration across the visual field of 0.10 ± 0.01m. Subsequent studies were conducted with the targets at a 1.2 m distance. Young emmetropes, young myopes and older emmetropes exhibited similar patterns of astigmatism and coma across the visual field. However, the rate of change of coma across the field was higher in young myopes than young emmetropes and was highest in older emmetropes amongst the three groups. Spherical aberration showed an overall decrease in myopes and increase in older emmetropes across the field, as compared to young emmetropes. Orthokeratology, spherical IOL implantation and LASIK altered peripheral higher order aberrations considerably, especially spherical aberration. Spherical IOL implantation resulted in an overall increase in spherical aberration across the field. Orthokeratology and LASIK reversed the direction of change in coma across the field. Orthokeratology corrected peripheral relative hypermetropia through correcting myopia in the central visual field. Theoretical ray tracing demonstrated that changes in aberrations due to orthokeratology and LASIK can be explained by the induced changes in radius of curvature and asphericity of the cornea. This investigation has shown that peripheral aberrations can be measured with reasonable accuracy with eye rotation relative to the instrument. Peripheral aberrations are affected by accommodation, myopia, age, orthokeratology, spherical intraocular lens implantation and laser in situ keratomileusis. These factors affect the magnitudes and patterns of most aberrations considerably (especially coma and spherical aberration) across the studied visual field. The changes in aberrations across the field may influence peripheral detection and motion perception. However, further research is required to investigate how the changes in aberrations influence peripheral detection and motion perception and consequently peripheral vision task performance.
6
Merriman, Carolyn. "Peripheral Vascular System (PVS)." Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etsu-works/8533.
Full text
7
Gordienko, P. O. "Structure of peripheral nerves." Thesis, Sumy State University, 2017. http://essuir.sumdu.edu.ua/handle/123456789/53954.
Full textAbstract:
Introduction. The problem of a structure of peripheral nerves is one of the scientific directions in anatomy. The attention of scientists was drawn to this problem from 1912-1913 when doctrines about constancy of topography of bunches of nervous fibers in a nerve trunk moved forward. Further researches on a problem of a structure of peripheral nerves were directed to detection of regularities of the course of nervous conductors.
8
Wilmshurst, Jo. "Peripheral neuropathies of childhood." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/10746.
Full textAbstract:
Includes synopsis.<br>Incldues bibliographical references (p. 195-220).<br>Peripheral nerve disease was described by Galen (AD 130-200) over a thousand years ago.(3) Detailed anatomical illustrations were documented by Andreas Vesalius in his major work 'De humani corporis fabrica' in 1543.(4) Over the last two centuries an explosion in knowledge in the area has occurred, with a further exponential increase in the last 20 years mostly related to understandings in the field of molecular genetics.(5) Although some degree of diagnostic closure was possible for a number of the hereditary peripheral neuropathies, this has not been the end point of knowledge but only the beginning.
9
Teh, Hashim Haji Wan. "Peasants under peripheral capitalism." Bangi : Universiti Kebangsaan Malaysia, 1988. http://catalog.hathitrust.org/api/volumes/oclc/25748506.html.
Full textAbstract:
Revision of the author's Thesis (doctoral)--University of Manchester, 1982.<br>"Issued under the auspices of the Institute of Southeast Asian Studies in Singapore." Includes bibliographical references (p. [199]-205).
10
Mercadal, Cavaller Borja. "Electroporation and peripheral nerve stimulation." Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/667854.
Full textAbstract:
This thesis aimed at addressing questions within the fields of electroporation and peripheral nerve stimulation and, in particular, those that arise from the interaction between the two phenomenona. On the one hand, electroporation can have various direct and indirect effects in the neuronal functions. This thesis investigates the possible role of electroporation in pulsed radiofrequency treatments for chronic pain. On the other hand, during electroporation based treatments, electrical stimulation of peripheral nerves appears as an unwanted effect causing muscle contractions and acute pain. This thesis analyzes the rationale behind the use of bipolar pulses to mitigate this effect and the implications of such approach in irreversible electroporation treatments. In addition, this thesis provides a theoretical framework to explain a series of results that were in apparent contradiction with the common knowledge of the electroporation phenomenon. Finally, this thesis presents a neuromuscular model to study the recruitment patterns in intramuscular electrical stimulation.<br>Aquesta tesi té com a objectiu resoldre qüestions en els camps de l’electroporació i l’estimulació dels nervis perifèrics, i sobretot, aquelles que es deriven de l’interacció entre els dos fenòmens. L’electroporació pot tenir diversos efectes directes o indirectes en les funcions neuronals. En aquesta tesi s’investiga el possible paper de l’electroporació en els tractaments de radiofreqüència polsada. D’altra banda, durant els tractaments basats en l’electroporació, l’estimulació elèctrica dels nervis perifèrics apareix com a efecte secundari causant contraccions musculars i dolor. En aquesta tesi s’analitza com l’ús de polsos bipolar pot mitigar aquests efectes i quines implicacions té aquesta estratègia en els tractaments d’electroporació irreversible. En aquesta tesi també es presenta un marc teòric per explicar una sèrie de resultats que entren en aparent contradicció amb els nostres coneixements sobre l’electroporació. Finalment, es presenta un model neuromuscular que permet estudiar la resposta d’un múscul quan és estimulat mitjançant elèctrodes intramusculars.
11
Norman, Kelly Robert. "Encryption of Computer Peripheral Devices." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1232.pdf.
Full text
12
Lundström, Linda. "Wavefront Aberrations and Peripheral Vision." Doctoral thesis, KTH, Tillämpad fysik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4385.
Full textAbstract:
Failing eyesight causes a dramatic change in life. The aim of this project is to help people with large central visual field loss to better utilize their remaining vision. Central visual field loss means that the person has to rely on peripheral vision since the direct vision is lost, often due to a dysfunctional macula. In these cases, a full restoration of vision would require replacement or repair of the damaged retinal tissue, which is not yet possible. Instead, the present study seeks to improve peripheral vision by enhancing the image quality on the remaining functional part of the retina by optical corrections. The off-axis optics of the human eye often suffers from large optical errors, which together with the lower sampling density of the retina explain the limited visual function in the periphery. The dominating aberrations are field curvature and oblique astigmatism, which induce an effective eccentric refractive error. However, the irregular character of the aberrations and the limited neural function in the periphery will make it difficult to find the optimal refractive correction; the conventional subjective refraction, for example, is not suitable for subjects with large central visual field loss. Within the work of this thesis a Hartmann-Shack wavefront sensor has been constructed for oblique aberration measurements. Wavefront sensing is an objective method to assess detailed information about the optical errors in the human eye. Theory and methods have been developed to allow accurate off-axis measurements of the large aberrations, enable eccentric fixation, and handle the elliptical pupil. The study has mainly concentrated on sphero-cylindrical correction of peripheral vision. Peripheral resolution and detection acuity thresholds have been evaluated for seven subjects with central visual field loss and ten control subjects with normal vision. Five of the subjects with field loss showed improved resolution acuity with eccentric refractive correction compared to their habitual central correction, whereas little change was found for the control subjects. These results demonstrate that correction of peripheral optical errors can be beneficial to people with large central visual field loss in situations where a normal healthy eye does not experience any improvements. In conclusion, it is worthwhile to investigate the peripheral refractive errors in low-vision rehabilitation of central visual field loss and prescribe spectacle correction when those errors are large.<br>QC 20100809
13
Chapman, Katie. "Peripheral inflammation after experimental stroke." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518434.
Full text
14
Lundström, Linda. "Wavefront aberrations and peripheral vision /." Stockholm : Department of Applied Physics, Royal Institute of Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4385.
Full text
15
Kindstrand, Eva. "Peripheral neuropathy in Lyme borreliosis /." Stockholm, 1999. http://diss.kib.ki.se/1999/91-628-3940-3/.
Full text
16
Graça, LuiÌs. "Mechanisms of peripheral transplantation tolerance." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249470.
Full text
17
Houlden, Henry James. "The genetics of peripheral neuropathy." Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412633.
Full text
18
Bell, Nicola Jane. "Peripheral tachykinins and tachykinin receptors." Thesis, University of Reading, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428305.
Full text
19
Hamilton, Sara M. "ATP and peripheral sensory systems." Thesis, King's College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325538.
Full text
20
Adeoye, Opeolu M. D. "Peripheral Leukocytes and Intracerebral Hemorrhage." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1353100438.
Full text
21
Ross, Jessica L. "Peripheral Mechanisms of Ischemic Myalgia." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504803397585968.
Full text
22
Lambert, Hayley M. "Emotion Discrimination in Peripheral Vision." TopSCHOLAR®, 2018. https://digitalcommons.wku.edu/theses/2087.
Full textAbstract:
The recognition accuracy of emotion in faces varies depending on the discrete emotion being expressed and the location of the stimulus. More specifically, emotion detection performance declines as facial stimuli are presented further out in the periphery. Interestingly, this is not always true for faces depicting happy emotional expressions, which can be associated with maintained levels of detection. The current study examined neurophysiological responses to emotional face discrimination in the periphery. Two event-related potentials (ERPs) that can be sensitive to the perception of emotion in faces, P1 and N170, were examined using EEG data recorded from electrodes at occipitotemporal sites on the scalp. Participants saw a face presented at a 0° angle of eccentricity, at a 10° angle of eccentricity, or at a 20° angle of eccentricity, and responded whether the face was a specific emotion or neutral. Results showed that emotion detection was higher when faces were presented at the center of the display than at 10° or 20° for both happy and angry expressions. Likewise, the voltage amplitude of the N170 component was greater when faces were presented at the center of the display than at 10° or 20°. Further exploration of the data revealed that high intensity expressions were more easily detected at each location and elicited a larger amplitude N170 than low intensity expressions for both emotions. For a peripheral emotion discrimination task like that which was employed in the current study, emotion cues seem to enhance face processing at peripheral locations.
23
Gordon, Cheryl. "Screening for Peripheral Artery Disease." ScholarWorks, 2015. https://scholarworks.waldenu.edu/dissertations/1780.
Full textAbstract:
Peripheral artery disease (PAD) affects 8 to 10 million Americans, and the incidence of PAD is expected to increase as the population ages. A high percentage of the PAD is undiagnosed prior to the onset of a serious cardiovascular event; therefore, the inability to screen and diagnose for PAD in the early stages could hinder efforts to decrease adverse consequences of cardiovascular disease. Individuals with PAD have a 3 to 5 times increased risk of cardiovascular disease (CVD) mortality when compared to people without PAD. Guided by the Stetler model, the purpose of this project was to evaluate the relationship between level of PAD, as measured by skin perfusion pressure, and HbA1c using secondary data obtained from charts of patients within the clinic setting. Data included patient gender, age, degree of PAD, and HbA1c. A Pearson's correlation investigated the relationship between the patients' HbA1c and level of PAD. There was a significant relationship between HbA1c and LT PAD (r = .21, p =.009). There was no relation in RT PAD (r =.01, n = 149, p = .90). There was a significant relationship between HbA1c and age (r = .34, p = .00). Ultimately, the goal of this study was to improve PAD recognition, encourage early intervention, and facilitate effective preventive methods. Critical limb ischemia might be delayed or prevented if it is
identified earlier by screening methodologies. Early identification and treatment of PAD can improve the quality of life and care for individuals suffering with PAD.
24
Ozdemir, Esin. "Different Definitions Of." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606217/index.pdf.
Full textAbstract:
The definition of the periphery can be made in in different ways, based on the concepts emphisized in different theoretical discussions. Correspondingly, different peripheries appear in Europe from the perspectives of these different definitions. The thesis puts forward five different definitions of the periphery<br>definition of the periphery based on income and income growth differentials<br>definition of the periphery by using economic structure, employment and population potentials<br>definition of the periphery based on welfare conditions<br>definition of the periphery based on externalities<br>and definition of the periphery based on endogenous growth dynamics. All these definitions produce different core-periphery maps of Europe. The evidence is based on the use of cluster analysis to identify different groups of regions homogenous in terms of variables that belong to every one of these five definitions. The result confirms that there are different peripheries in Europe. One region that is categorised as core can fall into a peripheral group in a different clasification. This shows that there is not only one type of periphery in Europe, but that different peripheries appear in case of the usage of different variables. The thesis also argues that there is a need for regional policies that do not the define the periphery as a homogenous area by considering only income differentials, but that identifies different peripheries that have different needs and problems, and devise instruments accordingly.
25
Jaisankar, Durgasri. "Influence of testing methods on the evaluation of peripheral ocular optics and peripheral visual performance." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/226479/1/Durgasri%20Jaisankar%20Thesis.pdf.
Full textAbstract:
Peripheral (out-to-the-side) vision is important for general mobility and tasks such as driving. This study evaluated appropriateness of testing methods used to measure peripheral optics and visual performance. Peripheral optics measurements depended on the instrument used to measure them. The choice of either head or eye movements to set up peripheral optics measurements was not critical, even when contact lenses were worn. The nature of targets, in terms of size and abrupt or gradual loss of contrast near the edge, affected peripheral detection. To measure peripheral contrast detection accurately in the presence of blur, fine spatial frequency sampling was required.
26
MELFI, SIMONA. "NEW SIGNALING PATHWAYS REGULATING SCHWANN CELLS OF THE PERIPHERAL NERVOUS SYSTEM: IMPLICATIONS IN PERIPHERAL NEUROPATHIES." Doctoral thesis, Università degli Studi di Milano, 2018. http://hdl.handle.net/2434/564819.
Full textAbstract:
The origin, development and maturation of Schwann cells (SCs), the main glial cells of
the peripheral nervous system (PNS), are a set of complicated and intriguing processes.
These multifactorial processes take place following a precise and unique coordination
between different molecules and intracellular signaling, that interact with a complex of
endogenous and exogenous signals. Among these, there are integrins, neuregulins,
growth factors, hormones, neurotransmitters and intracellular pathway, including
protein kinase A and protein kinase C (PKA and PKC), serine/threonine kinase 1
(AKT), extracellular regulated MAPK/mitogen-activated protein kinase 1
(ERK/MAPK), Hippo, mechanistic target of rapamycin (mTOR), etc.
This thesis is focused on some novel intracellular signaling pathways involved in the
SCs development and maturation, from their origin to the acquisition of the myelinating
or repairing phenotype.
The first part of the thesis focuses on a proto-oncogene, the non-receptor tyrosine kinase
SRC (SRC), and the focal adhesion kinase (FAK), which are intermediate pathways
known to play a role in the control of adhesion, motility, and migration of SCs. It has
been investigated whether these pathways are regulated by allopregnanolone (ALLO),
a neuroactive steroid of peculiar interest for the control of SCs maturation.
The second part of this thesis focuses on the study of the Hippo signaling pathway,
known to be a key regulator of proliferation, apoptosis, control of organ size and
crucial for cancer proliferation. Hippo pathway has been studied in SCs, where it is
linked to Merlin (an oncosuppressor protein) and Yes associated protein/tafazzin
(YAP/TAZ) factors. Interestingly, these mechanisms were responsive to physical and
environmental challenges. Lastly, the third part of this thesis move on studying the role of the g-aminobutyric acid
(GABA) system in the control of peripheral myelination. In particular, the whole
expression profile was investigated in conditional knock out mice for the B1 subunit of
the GABA-B receptor (GABA-B R), with a specific deletion in SCs. By the use of
microarray technology, several genes resulted up- or downregulated in SCs, opening
new perspectives on the possible targets downstream GABA-B R in SCs.
Overall, these results highlight new aspects of the SCs biology, shedding light on
unraveled mechanisms and underlying their importance in the development and
maturation of these specialized cells of the PNS. This may be of pharmacological and
therapeutically interest, in order to identify reliable approaches for the treatment of
PNS diseases.
27
Moller, Kristian. "Pituitary adenylate cyclase activating peptide (PACAP) an experimental study on the expression and regulation in the peripheral nervous system /." Lund : Dept. of Physiology and Neuroscience, neuroendocrine Cell Biology, Lund University, 1997. http://books.google.com/books?id=Fw5rAAAAMAAJ.
Full text
28
Herrmann, Susan E. "A cross-sectional study of the peripheral circulation in patients with nephrosis." Thesis, Curtin University, 2000. http://hdl.handle.net/20.500.11937/2160.
Full textAbstract:
Background: Lipid abnormalities are a common feature of the nephrotic syndrome that is also characterised by oedema, hypoalbuminaemia, proteinuria, and hypercoagulability. Concern has arisen over the increased incidence of cardiovascular disease that has been reported in individuals with nephrotic syndrome, particularly since the syndrome may occur early in life and become a chronic illness. The presence of proteinuria is a prognostic indicator for the progression of renal disease, but its possible contribution as a cardiovascular risk factor in patients with nephrotic syndrome is not known. In contrast, disordered lipoprotein metabolism, in isolation, is a conventional risk factor for the development of atherosclerosis. An early phase of atherosclerosis, vascular endothelial dysfunction, has been identified. Endothelial function can be measured non-invasively using ultrasonography and plethysmography allowing the impact of risk factors to be assessed in vivo.Aim: To test the hypothesis that endothelial dysfunction occurs in the nephrotic syndrome primarily as a consequence of dyslipidaemia.Methods: A cross-sectional design was used to study vascular function of the peripheral circulation in 45 individuals: fifteen patients with nephrosis (NP), 15 control subjects with primary hyperlipidaemia (HL) and 15 normolipidaernic controls (NC). The groups were matched for age, gender and body mass index. The NP group and the HL group had similar serum lipid and lipoprotein concentrations. High-resolution ultrasonography assessed endothelial function of the brachial artery. This non-invasive technique measured post- ischaemic flow-mediated dilatation (FMD) and endothelium-independent vasodilatation in response to glyceryl trinitrate (GTNMD). Post-ischaemic microcirculatory function was measured using venous occlusion strain gauge plethysmography.Results: Post-ischaemic FMD of the brachial artery was significantly lower in the NP and HL groups, compared with the NC group, with no significant difference found between the former two groups. There were no significant differences in GTNMD of the brachial artery, or in microcirculatory responses. In the patients with nephrosis, non-esterified free fatty acids were inversely associated with FMD, and maximal blood flow with insulin resistance.Conclusion: Dyslipidaemia is associated with endothelial dysfunction in patients with nephrosis and provides a plausible basis for the increased risk of cardiovascular disease observed in individuals with nephrotic syndrome.
29
Segura, Castell Mónica. "Peripheral blood biomarkers in Psychiatric Diseases." Doctoral thesis, Universitat Internacional de Catalunya, 2012. http://hdl.handle.net/10803/83727.
Full textAbstract:
Actually, there is a strong incidence of psychiatric diseases, representing a 13% of total burden diseases and 450 million of people affected. The etiology of psychiatric diseases remains unknown. However, scientific evidences suggest a maldevelopment of nervous system (NS). The diagnosis is inaccurate, and international manuals (ICD-10 and DSM-IV) identify pathologies according to a list of symptoms but no underlying biological cause of disease. The aim of the thesis is to identify potential biomarkers -related to the development of NS- in peripheral blood of psychiatric patients diagnosed as different mental diseases, such as autism spectrum disorders (ASD), schizophrenia and bipolar disorders. It is intended to contribute with the improvement of diagnostic, prognostic and treatment of subjects.
The thesis is divided into 4 chapters: 1) study of neurotrophins in ASD, where the results show the relationship of this family of molecules with the disease, 2) study of Latrophilin-3 (LPHN3) in the TEA, which was obtained in association with lower cognitive level of ASD, 3) study of the Eph-receptor A4 in the pathology of schizophrenia and bipolar disorder, results of which show no association, and finally 4) study of Ankyrin-3 (ANK3) in schizophrenia and bipolar disorder, which shown a relationship with bipolar disorder but not with schizophrenia.<br>Actualment, hi ha una forta incidència de les patologies psiquiàtriques, representant un 13% del total de les malalties i 450 milions de persones afectades. L’etiologia de les patologies psiquiàtriques és desconeguda. Tot i així, evidències científiques suggereixen un mal desenvolupament del sistema nerviós (SN). El diagnòstic és poc precís, i els manuals internacionals (ICD-10 i DSM-IV) identifiquen les patologies d’acord a un llistat de símptomes, però sense cap causa biològica subjacent de la patologia. L’objectiu de la tesi és la identificació de biomarcadors potencials –relacionats en el desenvolupament del SN- en sang perifèrica de pacients diagnosticats amb diferents patologies mentals, com ara els trastorns de l’espectre autista (TEA), esquizofrènia i desordres bipolars. És pretén contribuir amb la millora del diagnòstic, el pronòstic i el tractament de les persones que les pateixen.
La tesi s’estructura en 4 capítols: 1) estudi de les neurotrofines en els TEA, on els resultats evidencien la relació d’aquesta família de molècules amb la patologia, 2) estudi de la Latrofilina-3 (LPHN3) en els TEA, on s’ha obtingut associació amb el nivell cognitiu més baix dels TEA, 3) estudi del receptor EPH A4 en les patologies d’esquizofrènia i desordres bipolars, resultats del qual no mostren associació i, per últim 4) estudi de la Ankirina-3 (ANK3) en l’esquizofrènia i els desordres bipolars, en el qual si que es troba una relació amb els desordres bipolars, però no amb l’esquizofrènia.<br>Actualmente, hay una fuerte incidencia de las patologías psiquiátricas, representando un 13% del total de las enfermedades y 450 millones de personas afectadas. La etiología de las patologías psiquiátricas es desconocida. Aún así, evidencias científicas sugieren un mal desarrollo del sistema nervioso (NS). El diagnóstico es poco preciso, y los manuales internacionales (ICD-10 y DSM-IV) identifican las patologías de acuerdo a un listado de síntomas, pero sin ninguna causa biológica subyacente de la patología. El objetivo de la tesis es la identificación de biomarcadores potenciales –relacionados con el desarrollo del SN- en sangre periférica de pacientes diagnosticados con diferentes patologías mentales, como son los trastornos del espectro autista (TEA), esquizofrenia y desordenes bipolares. Se pretende contribuir en la mejora del diagnóstico, el pronóstico i el tratamiento de las personas que las padecen.
La tesis se estructura en 4 capítulos: 1) estudio de las neurotrofinas en los trastornos del espectro autista (TEA), en el cual los resultados evidencian la relación de esta familia de moléculas con la patología, 2) estudio de la Latrofilina-3 (LPHN3) en los TEA, donde se ha obtenido una asociación con el nivel cognitivo más bajo de los TEA, 3) estudio del receptor EPH A4 en las patologías de la esquizofrenia y los desordenes bipolares, resultados del cual no muestran asociación y, por último 4) estudio de la Ankirina-3 (ANK3) en la esquizofrenia y los desordenes bipolares, en el cual si que se ha encontrado una relación con los desordenes bipolares, pero no con la esquizofrenia.
30
Dodla, Mahesh Chandra. "Bioengineered Scaffolds for Peripheral Nerve Regeneration." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14504.
Full textAbstract:
Nerve autografts are widely used clinically to repair nerve grafts. However, nerve grafts have many limitations, such as, availability of donor nerve grafts, and loss of function at donor site. To overcome these problems, we have used a tissue engineering approach to design three-dimensional (3D) agarose scaffolds containing gradients of laminin-1 (LN-1) and nerve growth factor (NGF) to mimic in vivo conditions to promote nerve regeneration in rats.
To determine the effect of LN-1 gradients on neurite extension in vitro, dorsal root ganglia (DRG) from chick embryos were cultured in 3D hydrogels. A gradient of LN-1 molecules in agarose gels was made by diffusion technique. LN-1 was then immobilized to the agarose hydrogels using a photo-crosslinker, Sulfo-SANPAH (Sulfosuccinimidyl-6-[4-azido-2-nitrophenylamino] hexanoate). Anisotropic scaffolds with three different slopes of LN-1 gradients were used. Isotropic scaffolds with uniform concentrations of LN-1, at various levels, were used as a positive control. DRG cultured in anisotropic scaffolds with optimal slope of LN-1 gradient extended neurites twice as fast as DRG in optimal concentration in isotropic scaffolds. Also, in the anisotropic scaffolds the faster growing neurites were aligned along the direction of LN-1 gradient.
To promote nerve regeneration in vivo, tubular polysulfone guidance channels containing agarose hydrogels with gradients of LN-1 and NGF (anisotropic scaffolds) were used to bridge 20-mm nerve gaps in rats. Nerve autografts were used as positive controls and isotropic scaffolds, with uniform concentration of LN-1 and NGF, were used as negative controls. After 4-months, the rats were sacrificed and nerve histology was done to test for nerve regeneration. Only anisotropic scaffolds and nerve autografts contained evidence of axonal regeneration. Both groups had similar numbers of myelinated axons and similar axonal-diameter distribution. However, nerve graft group performed better in functional outcome as measured by relative gastrocnemius muscle weight (RGMW) and electrophysiology. Optimization of performance of anisotropic scaffolds by varying the LN-1 and NGF concentration gradients might lead to development of scaffolds that can perform as well as nerve auotgrafts for nerve regeneration over long nerve gaps.
31
Habekost, Bonne. "Neuroplasticity induced by peripheral nerve stimulation." Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/3062.
Full textAbstract:
Non-invasive methods have been developed to induce plastic changes in the sensorimotor cortex. These rely on stimulating pairs of afferent nerves. By associative stimulation (AS) of two afferent nerves, excitability changes in the motor cortex occur as indicated by studies reporting changes in motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS). Repetitive stimulation of those nerves has a potential in rehabilitation and treatment of neurological disorders like stroke or spinal cord injury. Despite promising results and applications in human subjects using these methods, little is understood about the underlying basis for the changes which are seen. In the present study, behavioural, electrophysiological and immunohistochemical assessments were performed before and after paired associative and non-associative (NAS) median and ulnar nerve stimulation. Two macaque monkeys were trained to perform a skilled finger abduction task using refined behavioural methods. Monkeys were not able to move their thumb and index finger as selectively after one hour of paired AS as indicated by an increased number of errors and decreased performance measures. NAS however decreased error numbers and led to increased performances. Additionally, I recorded from identified pyramidal tract neurons and unidentified cells in primary motor cortex (M1), in two macaque monkeys before and after one hour of AS (and NAS) of the median and ulnar nerve. Cell discharge was recorded in response to electrical stimulation of each nerve independently. Some cells in M1 showed changed firing rates in response to nerve stimulation after AS (and NAS). Subsequently, structural changes in response to one week of paired AS were investigated. The laminar-specific density of parvalbumin-positive interneurons, perineuronal nets and the colocalisation of these two entities changed on the stimulated (in comparison to the non-stimulated) sensorimotor cortex. These findings suggest that the sensorimotor cortex undergoes plastic changes in response to AS (and NAS).
32
Welbourne, Lauren Elizabeth. "Peripheral factors affecting human colour perception." Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/14319/.
Full textAbstract:
Human colour perception is mediated by multiple factors. These include: the external environment, physiological structures within the eye, and the neuronal pathways that originate in the eye. The aim of this thesis was to further investigate the impact of three main factors on both the perception and cortical representation of colour. These factors were: the external, changing seasonal environment, genetically determined differences in the number of photoreceptor types, and spatial filters inherent to cortical and pre-cortical luminance and chromatic pathways. Novel findings and methods were demonstrated in this thesis: 1) For the first time, it was found that natural seasonal changes in the chromatic environment (in York, UK) affect the perception of unique yellow; this finding supports the existence of a slow normalisation mechanism, which is governed by changes in the average chromatic environment. 2) Genetically atypical individuals, who have fewer photoreceptor types (dichromats), demonstrated no differences in achromatic contrast discrimination thresholds compared to colour-normal trichromats. Therefore, for this particular measure, dichromats do not appear to benefit from increased neuronal resources from ‘unused’ chromatic pathway populations. A multi-channel LED system was developed to allow the isolation of photoreceptor responses in individuals with an additional photoreceptor type (tetrachromats). Modelling of this system indicated that precision in the cone spectra used to generate the stimulus, relative to the observer’s actual cone sensitivities (i.e. peak wavelength sensitivities), is crucial for successful isolation of the cones. 3) fMRI-based population receptive field (pRF) mapping was used to measure pRF sizes in the pre-cortical channels. Between the pathways, no differences in pRF sizes were found, however, differences in fMRI measures of spatial frequency sensitivity were observed. These data indicate that spatial frequency tuning in early visual cortex may be decoupled from population receptive field sizes.
33
Wallace, Victoria C. J. "Peripheral nerve demyelination and neuropathic pain." Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/27605.
Full textAbstract:
Chronic neuropathic pain, characterised by allodynia (perception of innocuous stimuli as painful) and hyperalgesia (facilitated responses to painful stimuli), is poorly understood and is usually resistant to classical analgesics. Such abnormal pain phenomena can be associated with human demyelinating conditions such as Charcot-Marie-Tooth disease. Using mouse models of peripheral nerve demyelination, we have provided evidence for the consequent establishment of neuropathic pain and investigated possible underlying mechanisms. The first model investigated was the Prx-null mouse. The murine periaxin gene (Prx) is expressed in Schwann cells and encodes L- and S-periaxin, two abundant PDZ-domain proteins thought to have a role in stabilisation of myelin in the peripheral nervous system (PNS). Prx-null mice show progressive demyelination in peripheral nerves and electrophysiological investigations indicate the presence of spontaneous action potential discharge; abnormal activity thought to be critical for the development of persistent pain states. Consistent with the time course of demyelination, Rrx-null mice display an increased behavioural reflex sensitivity to cutaneous mechanical and noxious thermal stimulation. To further investigate the link between demyelination of peripheral nerves and neuropathic pain, we have also characterised a novel model of focal peripheral nerve demyelinating neuropathy. Focal demyelination of the sciatic or saphenous nerve was induced with lysolecithin (lysophosphatidylcholine) and resulted in an increased behavioural reflex sensitivity to both thermal and mechanical tests, peaking at 9-14 days following treatment. Nerve morphology was investigated using light and electron microscopy, which revealed 30-40% demyelination of the treated nerve, (without lysolecithin-treated axon loss) coinciding with peak behavioural changes. Changes in the excitability of saphenous nerves were revealed, with spontaneous action potential discharge of 2-3 impulses per second present at peak behavioural change. No associated change in peripheral activation thresholds or conduction velocity was observed. In both models, immunohistochemical investigations revealed no cell loss in the dorsal root ganglia (DRG) and no evidence for axonal damage. Similar methods revealed changes in the expression of neuropeptide Y, and the sodium channels Nav1.3 and Nav1.8 in DRG neurones. Such changes may account for increased nerve excitability and are known to occur in other models of nerve injury. However, these changes in the demyelinating models occur in a more restricted manner, specifically in the cells of formerly myelinated fibres. Intrathecal injections of the selective NMDA receptor antagonist, [R]-CPP, indicated that NMDA receptor-dependent changes are crucial for the development of a neuropathic pain-like state following peripheral nerve demyelination. Intrathecal administration of pharmacological agents indicated a role for the transcription factor NFkB in the production of the behavioural reflex sensitivity of lysolecithin-treated mice, as well as identifying the endogenous cannabinoid system as an effective inhibitory regulator and potential analgesic target. This study describes the first mouse models of peripheral nerve demyelination designed for the study of neuropathic pain and reveals phenotypic changes in DRG, which may contribute to the development of a neuropathic pain-like state. Therefore, these models may be useful for the evaluation of novel therapeutic targets for the treatment of demyelination-associated neuropathic pain.
34
Rosén, Robert. "Peripheral Vision : Adaptive Optics and Psychophysics." Doctoral thesis, KTH, Biomedicinsk fysik och röntgenfysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-120077.
Full textAbstract:
This thesis is about our peripheral vision. Peripheral vision is poor compared to central vision, due to both neural and optical factors. The optical factors include astigmatism, defocus and higher order aberrations consisting mainly of coma. Neurally, the density of ganglion cells decreases towards the periphery, which limits the sampling density. The questions that this thesis attempts to answer are how much and under which circumstances correction of optical errors can improve peripheral vision. For this, an adaptive optics system has been constructed with a wavefront sensor and a deformable mirror working in closed loop to perform real-time correction of optical errors. To investigate vision, psychophysical routines utilizing Bayesian methods have been evaluated and modified for peripheral vision to handle the presence of aliasing, fixation instability and rapid fatigue. We found that correcting both refractive errors and higher order aberrations improved peripheral low-contrast resolution acuity. \\ We looked at two specific topics in peripheral vision research in particular: Central visual field loss and myopia development. Persons with central visual field loss have to rely on their remaining peripheral vision, and it is of great interest to understand whether optical correction can offer them any benefits. In a case study on a single subject, we found meaningful improvements in vision with both optimized refractive correction as well as additional benefits with aberration correction. These improvements were larger than for comparable healthy subjects with a similar magnitude of aberrations. When it comes to myopia development, an interesting hypothesis is that peripheral optics affect and guide the emmetropization process. We have found an asymmetric depth of field in the periphery for myopic subjects, caused by their higher order aberrations, and presented a model on how this asymmetry may influence the emmetropization process.<br><p>QC 20130327</p>
35
Taylor, Anna. "Peripheral mechanisms of trigeminal neuropathic pain." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97105.
Full textAbstract:
Trigeminal neuropathic pain is a unique type of neuropathic pain resulting from damage to primary afferents of the trigeminal nerve that innervates the head and neck region. It is characterized by intractable, unremitting pain in the absence of any overt tissue damage, and represents a significant clinical and societal burden. A thorough understanding of the mechanisms driving this condition is required to adequately treat, and ideally cure, this condition. The skin of the lower lip is innervated by several classes of primary afferents, including myelinated Aβ fibers, thinly myelinated Aδ fibers, and unmyelinated C fibers, which together are able to transduce the variety of innocuous and noxious stimuli encountered in the environment. Nociceptive stimuli are largely mediated by the unmyelinated C fibers, which have been further divided into 2 groups based on neurochemical and anatomical criteria, called the peptidergic and non-peptidergic C fibers. Given that nerve lesions initiating neuropathic pain conditions most often occur in the periphery, changes in the peripheral nervous system following nerve injury are particularly relevant in driving this aberrant pain condition. Therefore, the overall objective of this thesis is to explore the peripheral changes in an animal model of trigeminal neuropathic pain. The results of this thesis are presented in three chapters. The pattern of innervation of non-peptidergic C fibers in the skin of uninjured rats has been described, as well as how this fiber population changes following nerve injury. Concomitant ectopic autonomic fibers were observed in close apposition to the regenerating sensory fibers, and correlated with the behavioral phenotype of the animals. GDNF levels in the skin rapidly increased following nerve injury, and provided a possible mechanism for the ectopic parasympathetic fibers and regenerating non-peptidergic C fibers. Ablation of the non-peptidergic C fibers led to specific sprouting of parasympathetic fibers, but no change in behavior, however ablation of non-peptidergic fibers in neuropathic animals led to an exacerbated pain response. These results suggest an important role for non-peptidergic fibers and autonomic sprouting in neuropathic pain, and identifies GDNF as a potential factor for mediating these changes.<br>La douleur trigeminale neuropathique est une forme unique de douleur qui résulte d'un dommage aux afférents primaires du nerf trijumeau innervant la région de la tête et du coup. Cette douleur constante qui se manifeste en l'absence d'un dommage aux tissus périphériques représente un fardeau social et économique important. Une compréhension rigoureuse des mécanismes qui mènent à cette condition sera nécessaire pour mieux la traiter et préférablement la guérir.La peau de la lèvre inferieure est innervée par des afférents primaires appartenant à différentes classes, incluant les fibres myélinisées Aβ, les fibres légèrement myélinisées Aδ, ainsi que les fibres C non myélinisées. Ensemble, ces fibres peuvent transmettre une variété de stimuli nociceptifs ou inoffensifs tels que rencontrés dans l'environnement. Les stimuli nociceptifs sont majoritairement transmis par les fibres C non myélinisées, lesquelles peuvent être divisées en 2 catégories, peptidergiques ou non peptidergiques, selon des critères neurochimiques et anatomiques. Puisque les lésions nerveuses qui déclenchent la douleur neuropathique se produisent le plus souvent en périphérie, les changements au niveau du système nerveux périphérique sont centraux au développement de la condition douloureuse. Ceci étant dit, l'objectif général de cette thèse est d'explorer les changements périphériques qui se produisent dans un model animal de douleur trigeminale neuropathique.Les résultats de cette thèse sont présentés dans trois chapitres. L'innervation de la peau par les fibres C non peptidergiques chez le rat normal a d'abord été décrite. Ensuite, les changements subis par cette population suivant un dommage au nerf ont été documentés. Suite à un dommage nerveux périphérique, des fibres autonomiques ectopiques ont été observées en proximité des fibres sensorielles en régénération, et ce changement corrélait temporellement avec le phénotype comportemental des animaux. Les niveaux cutanés de GDNF ont rapidement augmenté après le dommage nerveux, fournissant un mécanisme potentiel permettant la régénération des fibres C non peptidergiques et la migration ectopique des fibres parasympathiques. L'ablation des fibres C non peptidergiques a déclenché la pousse des fibres parasympathiques sans changer le comportement des animaux. Par contre, l'ablation de ces fibres chez des animaux neuropathiques a exacerbé la réponse douloureuse de ceux-ci.Ces résultats suggèrent une participation importante des fibres C non peptidergiques et de la migration autonomique dans la douleur neuropathique. De plus, GDNF est rapporté comme étant un facteur pouvant produire ces changements.
36
Racz, Karoly. "Peripheral dopaminergic mechanisms in experimental hypertension." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72776.
Full text
37
Willis, Fenella Mai. "Optimising peripheral blood progenitor cell mobilisation." Thesis, St George's, University of London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511964.
Full text
38
Fitzgerald, J. J. "Electrical interfacing to regenerating peripheral nerve." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599056.
Full textAbstract:
A mathematical model of the electrical behaviour of an axon in a microchannel was constructed and showed that microchannel confinement results in signal amplification. Next a series of silicon discs containing precisely etched arrays of microchannels covering a range of dimensions were implanted between the cut stumps of rat sciatic nerves and the success of axon regeneration through the channels evaluated. Single prototype channels were then used to test the electrical properties of microchannels in vitro. Strands of rat ventral motor root were placed into the channels and amplified APs were recorded from electrodes in the channel walls. The prediction of the mathematical model were validated, and techniques for reducing noise in the recorded signal were explored. Microchannels were also evaluated in vitro as stimulating devices, where the confinement for the extracellular space was shown to result in extremely small stimulus current requirements. Finally, in order to test regenerated axons in microchannels, implants containing arrays of microchannels cast in silicone were implanted into rat sciatic nerve. After allowing time for regeneration, ultrafine needle electrodes pushed through the sides of the arrays were used to record and stimulate. It was possible to record endogenous muscle spindle APs from the channels, and by delivering stimulus current into the channels single motor units in the <i>tibialis anterior</i> muscle could be activated.
39
Williams, Craig. "Peripheral muscle fatigue during intense exercise." Thesis, University of Chichester, 2005. http://eprints.chi.ac.uk/840/.
Full textAbstract:
The role of adenine nucleotide metabolism is central to the electro-mechanical processes in muscular contraction. Interventions which alter the cellular micro-environment can impact on the fatigue response during exercise possibly mediated by the balance between ATP and ADP. This thesis examined the response of biochemical and physiological markers of muscle fatigue in dietary interventions aimed to alter the cellular environment. Contractile measures included force and relaxation times from contractions of the knee extensors, whilst biochemical markers included anunonia and lactate after voluntary isometric and incremental cycle exercise. Evoked contractile measurements afforded experimental objectivity independent of voluntary intervention whilst the voluntary measures afforded greater transferability. In Chapter 3 the relaxation time response to a train of evoked fatiguing contractions varied depending on the choice of relaxation method (upper exponential, lower exponential, 60-40 exponential, 100-75,95-45,75-37.5,75-25%). Methods describing the earlier portions of the relaxation curve slowed less during fatigue than those comprising the latter portions. Intra-session variability ranged from 1.3 to 5.02% and inter-session variation ranged from 2.85 to 6.97% dependent upon the adopted relaxation method. Such variability was comparable with other laboratories demonstrating significant intervention-induced changes. This has implications for future studies in the choice of relaxation method and magnitude of change necessary for identification of intervention-induced changes. In chapter 4 the magnitudes of change in MVC and time to fatigue in a voluntary isometric contraction between creatine and placebo supplementation were -3% and 2% respectively. The fatigue-induced slowing of evoked relaxation times was greater by -4% and these changes were not significant. The differences in markers of adenine nucleotide degradation after creatine and placebo supplementation were also insignificant. In chapter 5 the creatine supplementation-induced change in the decline in evoked force during a fatiguing train was -1 % but was insignificant. For the voluntary and evoked relaxation times, in chapter 5, the magnitude of changes between placebo and creatine supplementation were <1 %, and insignificant. The ingestion of NaHCO, accelerated the loss of evoked force during a fatiguing train, with a trend towards shorter relaxation times that was only evident in the 100-75% method. Bicarbonate ingestion resulted in higher plasma lactate but had minimal effect on markers of adenine nucleotide degradation. The rate of evoked force loss was greater when muscle glycogen stores were reduced by exercise and low CHO diet and this trend was reversed by additionally supplementing with creatine, but this was not associated with similar trends in markers of nucleotide degradation during incremental cycling. A novel finding of this study was that reducing muscle glycogen resulted in a more severe slowing of relaxation times that was reversed when combined with creatine supplementation. In this thesis the changes in the biochemical markers of ADP homeostasis (NH,) by dietary interventions were insignificant. However, the force and relaxation time responses may highlight the functional importance of maintaining ADP homeostasis. The fatigue-induced slowing of evoked relaxation times was different depending on the chosen method. Despite a smaller relative slowing during fatigue the 100-75% method appeared to be most sensitive to dietary interventions.
40
Scott, Adrian Roy. "Peripheral blood flow and diabetes mellitus." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303002.
Full text
41
Calcutt, N. A. "Peripheral nerve dysfunction in diabetic rodents." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384339.
Full text
42
Wink, Brian. "Spatial coding in human peripheral vision." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296632.
Full text
43
Hilditch, A. "Pharmacological characterisation of peripheral dopamine receptors." Thesis, Open University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.352607.
Full text
44
Oxenham, Andrew John. "Psychophysical consequences of peripheral auditory nonlinearity." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388481.
Full text
45
Sexton, J. E. "Peripheral mechanisms of touch and pain." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1475391/.
Full textAbstract:
This thesis uses transgenic approaches to alter expression of candidate mechanosensors in physiological and pathological conditions to determine their contribution to the sensations of touch and pain. Transient receptor potential (TRP) ion channels have highly conserved roles in sensory function and a great deal of evidence implicates them in the process of mechanotransduction. Their propensity to form heteromeric complexes as well as the functional redundancy they exhibit makes them difficult to study. We used animals with global deletion of multiple canonical TRP (TRPC) channels to minimise the effects of these features and found that TRPC1, TRPC3, TRPC5 and TRPC6 have a modality specific and combinatorial role in innocuous mechanosensation. Next, we looked at the role of TRPC channels and TRPA1 and TRPV1 in mechanical hypersensitivity in the monosodium-iodoacetate (MIA) model of Osteoarthritis (OA). The results show TRPC3, TRPC6 and TRPV1 do not contribute to mechanical hypersensitivity in OA. However, TRPA1 appears to be necessary for the full manifestation of OA induced mechanical hypersensitivity. We also investigated the role of Annexin A6 in mechanosensation and OA. The Annexin A6 protein binds to NMB-1, a blocker of mechanically activated currents. We found that it negatively regulates mechanosensation and that by overexpressing the protein using a gene therapy approach we are able to partially attenuate mechanical hypersensitivity in the MIA model of OA. Finally, we investigated the role of ASIC4 in pain and mechanosensation through generation and behavioural characterisation of a global knockout mouse. The function of ASIC4 is largely unknown but in vitro it regulates expression and function of other ASIC subunits, some of which have roles in noxious and mechanosensory processes. We found a role for ASIC4 in formalin induced pain and in visceral inflammation which is the first report of a somatosensory function for this poorly understood protein.
46
Buelow, Deborah Ann. "Peripheral memory : New York's forgotten landscape." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59106.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2010.<br>"June 2010." Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 141-149).<br>Hart Island, New York City's largest public burial ground, reveals an alternate history of the city through the lens of the interment of the abject. Historically, the state has provided for remains not otherwise cared for through what are commonly referred to as "potter's fields" - municipally owned burial grounds for the poor, the friendless, the alien, and the unknown. The location and lack of iconography act to erase the memories of so-called abject members of society rather than preserve them. New York City houses the country's largest of these municipal burial grounds on Hart Island, remotely situated away from the city. The management of these burials is left to the Department of Correction, which daily ships inmates from nearby Riker's Island to bury unknown members of society. Although since 1869 approximately three quarters of a million bodies have been interred there through the penal system, many of New York's inhabitants are not aware of its existence. A major contributing factor to the absence of public knowledge is the lack of information either about the phenomenon of the potter's field or about Hart Island itself. Reference to Hart Island today is limited to on-line curiosity blogs and op-ed columns in the daily newspapers, but even then references are infrequent. Yet the area of the island is equivalent to fifty New York City blocks - a large swath of land to be ignored in a dense urban context. This thesis addresses the landscape of Hart Island, which acts as a depository for identity shaped through memory. Urban landscapes reveal social and cultural biases in their physical characteristics. Identity is made evident through, or paradoxically denied by, these terrains. Hart Island exemplifies one such landscape of negated identity. By looking at the history of Hart Island and its physical relationship to the constructed city, this thesis uncovers socioeconomic disparities that manifest themselves even in death.<br>by Deborah Ann Buelow.<br>S.M.
47
Déjardin, Theophile P. E. "New strategies for peripheral nerve regeneration." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/5013/.
Full textAbstract:
Nerve repair is still a major challenge in surgery, regenerative medicine and tissue engineering even if progress has been made over the last 30 years. Functional recovery after severe lesions to a nerve is often incomplete and rarely totally successful. In this thesis I present a multi-disciplinary approach to improve the regenerative potential of “nerve repair tubes” that aim to reconnect wounded nerves and refine or replace autologous nerve graft, the clinical current gold standard. The efficacy of such tubes has already been shown in the clinic especially for small gap injuries, but the outcomes are still limited, and ought to be improved by e.g. micro/nano-topography, growth factor delivery systems, supportive cells or active features such as electrical stimulation, which have individually been shown to enhance nerve regeneration. In this study organotypic cultures of dorsal root ganglions (DRG) isolated from neonatal rats were used throughout as an in vitro model of nerve regeneration. Here I tested different devices in combination with growth factors to contribute to the fundamental and technical knowledge necessary to improve the regenerative potential of such tubes. I investigated the interaction between surface features and growth factors in their joined influence on regenerating DRGs. For this polydimethylsiloxane (PDMS), a polymer with adjustable elasticity was used together with photolithography to build devices of different stiffness with different surface microgrooves, on which DRG could be grown. To optimise the use of nerve growth factor (NGF) in conjunction with these devices, and to show how NGF interacts with stiffness and topography the reaction of the DRG was tested. To ease the making of three-dimensional internally microstructured tubes I have developed up a novel, timesaving, fabrication technique for polycaprolactone (PCL) “Swiss roll” nerve repair tubes. This technique improves the reproducibility of the scaffold, and using DRG its potential for nerve regeneration is being demonstrated. The influence of time-variant, balanced, pulsed electric stimulation is a potentially useful means to influence nerve regeneration. To narrow down the parameter space the effect of various electric fields was tested in their effect on DRG regeneration using commercially available devices. In collaboration with Christopher Martin from the School of Engineering, novel custom-made devices that allowed us to quantify the directional response of the regenerating axons were developed, and the guidance effect of pulsed alternating current (AC) electrical fields on regenerating DRGs axons was investigated in vitro. This approach allows in principle to transfer the use of this nerve guiding strategy to potentially improve nerve repair tubes.
48
Zilic, Leyla. "Development of acellular porcine peripheral nerves." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/15777/.
Full textAbstract:
Peripheral nerve injuries can lead to a major loss of function and affect quality of life. Current autologous treatments and commercially available products such as nerve guide conduits all have limitations. The aim of this study was to develop biocompatible, non-immunogenic nerve grafts using low concentration SDS to decellularise porcine peripheral nerves. Initially the porcine nerve anatomy was defined. Acellular nerves were then used as the basis for an in vitro study of perfused flow within the tissue for the introduction of Schwann cells - as the delivery of these cells is reported to stimulate axon regeneration. Furthermore, an in vivo study using a rat sciatic nerve injury model was conducted to evaluate the regenerative capacity of acellular porcine grafts. Histology confirmed an absence of cells and retention of the native nerve histioarchitecture. DNA levels were reduced by >95 % throughout the decellularised tissue. Immunohistochemistry showed retention of important extracellular matrix proteins such as collagen, laminin and fibronectin. In vitro biocompatibility studies indicated the acellular nerves were not cytotoxic to human dermal fibroblasts and primary rat Schwann cells. Uniaxial tensile testing showed a significant increase in ultimate tensile strength (UTS) and strain between native and acellular nerve tissues. In addition, mechanical testing of the nerves revealed porcine peroneal nerves to have a higher UTS value in comparison to the porcine tibial nerves. Analysis of the nerves using transmission electron microscopy concluded that the mechanical properties of nerves could not be determined exclusively by their ultrastructure or collagen fibril diameter. Porcine acellular nerve grafts were used as an in vitro and in vivo model for the introduction of primary rat Schwann cells. The in vitro nerve model confirmed that reseeded Schwann cells under perfusion maintained their phenotype and had a lower rate of cell death when compared to static conditions. A rat sciatic nerve in vivo gap injury model demonstrated that porcine grafts were able to promote axonal regeneration; however, they were not as effective as the autologous graft. In summary, acellular peripheral nerve tissue was found to have excellent potential for development of a tissue engineered graft to aid peripheral nerve regeneration.
49
Dooley, Sharon T. "Peripheral IV Infiltration and Extravasation Prevention." Mount St. Joseph University Dept. of Nursing / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=msjdn1619174321310464.
Full text
50
White, Kevin Scott. "MODELING INTERFASCICULAR INTERFACES FOR PERIPHERAL NERVES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1347023787.
Full text