Dissertations / Theses on the topic 'Single spike'
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Miller, Christopher L. "Variation in single kernel hardness within the wheat spike." Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/925.
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Benda, Jan. "Single neuron dynamics." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2002. http://dx.doi.org/10.18452/14684.
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Das Neuron ist das zentrale Element in der Informationsverarbeitung im Nervensystem. In dieser Arbeit werden verschiedene Aspekte der Spikegenerierung sowohl theoretisch als auch experimentell untersucht. Phasen-Rotatoren verschiedener Komplexität werden zur Vorhersage von Spikezeitpunkten vorgestellt. Die Kennlinie eines Neurons wird dabei als wichtiger Parameter für diese Modelle verwendet, damit diese leicht auf echte Neurone anwendbar sind. Die Phasenantwortkurve als ein zweiter wichtiger Aspekt der Spikedynamik wird zur Erweiterung der Modelle verwendet. Solange ein Neuron in seinem überschwelligen Bereich gereizt wird, erweisen sich die Phasenrotatoren als gute Beschreibung des Spikeverhaltens. Es wird jedoch gezeigt, daß bei einer Stimulierung mit Strömen, die um die Schwelle des Neurons herum fluktuieren, diese Modelle, genauso wie alle anderen eindimensionalen Modelle einschließlich des Intergrate-and-fire Neurons, versagen. Feuerraten Adaptation kann in vielen Neuronen beobachtet werden. Es wird ein allgemeines phänomenologisches Modell für die Feuerrate adaptierender Neurone aus den Eigenschaften verschiedene Ionenströme, die Adaptation verursachen, hergeleitet. Dieses Modell ist durch die Kennlinien und einer Adaptations-Zeitkonstanten vollständig definiert. Mit Hilfe des Modells können die Eigenschaften der Adaptation als Hochpassfilter quantifiziert werden. Weiterhin wird die Rolle der Adaptation bei der Unterdrückung von Hintergrundrauschen diskutiert. Sowohl die Phasenrotatoren als auch das Adaptationsmodell werden an auditorischen Rezeptorzellen der Wanderheuschrecke und dem AN1, ein primäres auditorisches Interneuron der Grille {Teleogryllus oceanicus}, getestet. In beiden Fällen stimmen die Modelle gut mit den experimentelle Daten überein. Es wird mit Hilfe der Modelle gezeigt, daß Adaptation in den Rezeptorzellen durch Ionenströme des Spikegenerators verursacht wird, während in dem Interneuron der Eingang schon adaptatiert. Zusätzlich wird der Einfluß der Feuerraten-Adaptation auf die Gesangserkennung analysiert.The single neuron is the basic element of information processing in nervous systems. In this thesis several properties of the dynamics of the generation of spikes are investigated theoretically as well as experimentally. Phase oscillators of different complexity are introduced as models to predict the timing of spikes. The neuron's intensity-response curve is used as a basic parameter in these models to make them easily applicable to real neurons. As a second important aspect of the spiking dynamics, the neuron's phase-resetting curve is used to extend the models. The phase oscillators turn out to be a good approximation of the spiking behavior of a neuron as long as it is stimulated in its super-threshold regime. However, it is shown by comparison with conductance-based models that these models, as well as all other one-dimensional models including the common integrate-and-fire model, fail, if the neuron is stimulated with currents fluctuating around its threshold. Spike-frequency adaptation is a common feature of many neurons. For various ionic currents, as a possible reason for adaptation, a general phenomenological model for the firing rate of adapting neurons is derived from their biophysical properties. This model is defined by the neuron's intensity-response curves and an adaptation time-constant. By means of this model the high-pass properties of spike-frequency adaptation can be quantified. Also the role of adaptation in supression of background noise is discussed. Both the phase oscillators and the adaptation-model are tested on auditory receptor neurons of locusts and the AN1, a primary auditory interneuron of the cricket {Teleogryllus oceanicus}. In both cases the models are in good agreement with the experimental data. By means of the models it is shown that adaptation in the receptor neurons is caused by ionic currents of the spike generator while in the interneuron it is the input which is already adapting. In addition, the influence of spike-frequency adaptation on the recognition of courtship songs is analysed.
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Du, Nan, Mahdi Kiani, Christian G. Mayr, Tiangui You, Danilo Bürger, Ilona Skorupa, Oliver G. Schmidt, and Heidemarie Schmidt. "Single pairing spike-timing dependent plasticity in BiFeO3 memristors with a time window of 25ms to 125µs." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-171458.
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Memristive devices are popular among neuromorphic engineers for their ability to emulate forms of spike-driven synaptic plasticity by applying specific voltage and current waveforms at their two terminals. In this paper, we investigate spike-timing dependent plasticity (STDP) with a single pairing of one presynaptic voltage spike and one postsynaptic voltage spike in a BiFeO3 memristive device. In most memristive materials the learning window is primarily a function of the material characteristics and not of the applied waveform. In contrast, we show that the analog resistive switching of the developed artificial synapses allows to adjust the learning time constant of the STDP function from 25ms to 125μs via the duration of applied voltage spikes. Also, as the induced weight change may degrade, we investigate the remanence of the resistance change for several hours after analog resistive switching, thus emulating the processes expected in biological synapses. As the power consumption is a major constraint in neuromorphic circuits, we show methods to reduce the consumed energy per setting pulse to only 4.5 pJ in the developed artificial synapses.
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Malvestio, Irene. "Detection of directional interactions between neurons from spike trains." Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/666226.
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An important problem in neuroscience is the assessment of the connectivity
between neurons from their spike trains. One recent approach developed for
the detection of directional couplings between dynamics based on recorded
point processes is the nonlinear interdependence measure L. In this thesis we
first use the Hindmarsh-Rose model system to test L in the presence of noise
and for different spiking regimes of the dynamics. We then compare the
performance of L against the linear cross-correlogram and two spike train
distances. Finally, we apply all measures to neuronal spiking data from an
intracranial whole-night recording of a patient with epilepsy. When applied
to simulated data, L proves to be versatile, robust and more sensitive than
the linear measures. Instead, in the real data the linear measures find more
connections than L, in particular for neurons in the same brain region and
during slow wave sleep.Un problema important en la neurociència és determinar la connexió entre neurones utilitzant dades dels seus trens d’impulsos. Un mètode recent que afronta la detecció de connexions direccionals entre dinàmiques utilitzant processos puntuals és la mesura d’interdependència no lineal L. En aquesta tesi, utilitzem el model de Hindmarsh-Rose per testejar L en presència de soroll i per diferents règims dinàmics. Després comparem el desempenyorament de L en comparació al correlograma lineal i a dues mesures de trens d’impulsos. Finalment, apliquem totes aquestes mesures a dades d’impulsos de neurones obtingudes de senyals intracranials electroencefalogràfiques gravades durant una nit a un pacient amb epilèpsia. Quan utilitzem dades simulades, L demostra que és versàtil, robusta i més sensible que les mesures lineals. En canvi, utilitzant dades reals, les mesures lineals troben més connexions que L, especialment entre neurones en la mateixa àrea del cervell i durant la fase de son d’ones lentes.
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Landry, Richard Spencer Jr. "Simulating the Affects of Glutamatergic Afferents on the Firing Pattern of Midbrain Dopamine Neurons." ScholarWorks@UNO, 2006. http://scholarworks.uno.edu/td/299.
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A computational model of a midbrain dopamine neuron was extended in this study to include a response to random excitatory afferent input by incorporating the receptor components AMPA and NMDA. In a diagonal band where average glutamatergic and tonic gabaergic input is roughly balanced, both single spike firing and bursting can be observed. Simulated SK channel block strengthens the correlation between pattern and rate and increases the number of spikes fired in bursts by increasing the spikes per burst. A simulated doubling of the AMPA/NMDA ratio leads to a frequency increase that becomes more prominent at high firing rates, and an increase in the percent spikes fired in bursts. Changes in pattern and rate are poorly correlated in the model. Manipulations of the neuron greatly depend on the background level of synaptic inputs, suggesting that interpretation of population data from dopamine neurons requires taking variability into account rather than averages.
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Herrera-Valdez, Marco Arieli. "Relationship Between Nearly-Coincident Spiking and Common Excitatory Synaptic Input in Motor Neurons." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/196051.
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The activities of pairs of mammalian motor neurons (MNs) receiving varying degrees of common excitatory synaptic input were simulated to study the relationship between nearly-coincident spiking and common excitatory drive. The somatic membrane potential of each MN was modeled using a single compartment model. Each MN was modeled toreceive synaptic contacts from hundreds of pre-synaptic fibers. The percentage of pre-synaptic fibers that diverged to supply both MNs of a pair with common synaptic input could be varied from 0 (no common inputs) to 100% (all common inputs). Spikes trains on separate re-synaptic fibers were independent of one another and were modeled as realizations of renewal processes with mean firing rates (10 - 50Hz) resembling that associated with supra-spinal input. Maximum synaptic conductances and time constants were varied across synapsesto match experimentally observed somatic EPSPs. The number of active pre-synaptic fibers to each MN was adjusted in order that the firingrates of MNs were between 8 and 15 Hz. For each common input condition, 100 s of concurrent spiking activity of the MNs was usedto construct cross-correlation histograms. The sizes of the central peaks in the histograms were quantified using both the k' (Ellaway and Murthy 1985) and CIS (Nordstrom et al. 1992) indices ofsynchrony. Monotonically increasing linear relationships between the proportion of common synaptic input and the magnitude of synchronywere observed for both indices. For example, the model predicted that 10% common input would yield a CIS value of 0.27 whereas 100% commoninput would yield a CIS value of 1.5. These values are within the range of values observed experimentally. These results, therefore,provide a means to translate measures of nearly-coincident spiking into plausible renditions of synaptic connectivity.
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Telenczuk, Bartosz. "Crossing the scales." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://dx.doi.org/10.18452/16404.
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Während seiner normalen Funktion generiert das Gehirn starke elektrische Signale, die technisch gemessen werden können. Das schon seit über einem Jahrhundert bekannte Phänomen ermöglicht es die Signalverarbeitung im Gehirn räumlich und zeitlich zu beobachten. Heute versteht man die zellulären Prozesse die zur Generierung der elektrischen Signale in einzelnen Neuronen führen. Jedoch rekrutieren die meisten neuronalen Ereignisse große Populationen von Zellen, dessen Aktivität zeitlich und räumlich koordiniert ist. Diese Koordinierung führt dazu, dass ihre elektrische Aktivität auch weit von den Quellen gemessen werden kann, sodass die Beobachtung des Gehirns auch nicht invasiv auf der Schädeloberfläche mittels dem sogenannten Elektroenzephalogramm (EEG) möglich ist. Der zeitliche Verlauf des Signals hängt nicht nur von den Eigenschaften einzelner Zellen ab sondern auch von ihrer Wechselwirkung mit anderen Neuronen, die oft komplex oder gar nicht bekannt ist. Diese Komplexität verhindert die Auswertung der gemessen Signale im Bezug auf die Anzahl von aktiven Neuronen, die Art der Antwort (Inhibition, Exzitation), die Synchronisationsstärke und den Einfluss anderer aktiver Prozesse (wie zum Beispiel: Lernen, Aufmerksamkeit usw.). In dieser Arbeit werden die Zusammenhänge zwischen diesen mikroskopischen Parametern (einzelne Neurone) und ihrer makroskopischen Wirkung (EEG) experimentell, datenanalytisch und theoretisch untersucht.During its normal function the brain generates strong and measurable electric signals. This phenomenon, which has been known for more than a century, makes it possible to investigate the signal processing in the brain. Nowadays the cellular processes taking part in the generation of the electric signals are well understood. However, most of the neuronal events recruit large populations of cells, whose activities are coordinated spatially and temporally. This coordination allows for summation of activities generated by many neurons leading to extracellular electric signals that can be recorded non-invasively from the scalp by means of electroencephalography (EEG). The temporal structure of the EEG signal does not depend only on the properties of single neurons, but also on their interactions that may be very complex. The complexity hinders the evaluation of the recoded signal with respect to the number of active neurons, the type of response, the degree of synchronisation and the contribution of other processes (such as, learning and attention). In the thesis, the relations between the microscopic (single-neuron) and their macroscopic (EEG) properties will be investigated by means of experimental, data-analytic and theoretical approaches.
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Blankenburg, Sven. "Theoretical mechanisms of information filtering in stochastic single neuron models." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17577.
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Die vorliegende Arbeit beschäftigt sich mit Mechanismen, die in Einzelzellmodellen zu einer frequenzabhängigen Informationsübertragung führen können. Um dies zu untersuchen, werden Methoden aus der theoretischen Physik (Statistische Physik) und der Informationstheorie angewandt. Die Informationsfilterung in mehreren stochastischen Neuronmodellen, in denen unterschiedliche Mechanismen zur Informationsfilterung führen können, werden numerisch und, falls möglich, analytisch untersucht. Die Bandbreite der betrachteten Modelle erstreckt sich von reduzierten strombasierten ’Integrate-and-Fire’ (IF) Modellen bis zu biophysikalisch realistischeren leitfähigkeitsbasierten Modellen. Anhand numerischer Untersuchungen wird aufgezeigt, dass viele Varianten der IF-Neuronenmodelle vorzugsweise Information über langsame Anteile eines zeitabhängigen Eingangssignals übertragen. Der einfachste Vertreter der oben genannten Klasse der IF-Neuronmodelle wird dahingehend erweitert, dass ein Konzept von neuronalem ’Gedächtnis’, vermittelst positiver Korrelationen zwischen benachbarten Intervallen aufeinander- folgender Spikes, integriert wird. Dieses Model erlaubt eine analytische störungstheoretische Untersuchung der Auswirkungen positiver Korrelationen auf die Informationsfilterung. Um zu untersuchen, wie sich sogenannte ’unterschwelligen Resonanzen’ auf die Signalübertragung auswirken, werden Neuronenmodelle mit verschiedenen Nichtlinearitäten anhand numerischer Computersimulationen analysiert. Abschließend wird die Signalübertragung in einem neuronalen Kaskadensystem, bestehend aus linearen und nichtlinearen Elementen, betrachtet. Neuronale Nichtlinearitäten bewirken eine gegenläufige Abhängigkeit (engl. "trade-off") zwischen qualitativer, d.h. frequenzselektiver, und quantitativer Informations-übertragung, welche in allen von mir untersuchten Modellen diskutiert wird. Diese Arbeit hebt die Gewichtigkeit von Nichtlinearitäten in der neuronalen Informationsfilterung hervor.Neurons transmit information about time-dependent input signals via highly non-linear responses, so-called action potentials or spikes. This type of information transmission can be frequency-dependent and allows for preferences for certain stimulus components. A single neuron can transmit either slow components (low pass filter), fast components (high pass filter), or intermediate components (band pass filter) of a time-dependent input signal. Using methods developed in theoretical physics (statistical physics) within the framework of information theory, in this thesis, cell-intrinsic mechanisms are being investigated that can lead to frequency selectivity on the level of information transmission. Various stochastic single neuron models are examined numerically and, if tractable analytically. Ranging from simple spiking models to complex conductance-based models with and without nonlinearities, these models include integrator as well as resonator dynamics. First, spectral information filtering characteristics of different types of stochastic current-based integrator neuron models are being studied. Subsequently, the simple deterministic PIF model is being extended with a stochastic spiking rule, leading to positive correlations between successive interspike intervals (ISIs). Thereafter, models are being examined which show subthreshold resonances (so-called resonator models) and their effects on the spectral information filtering characteristics are being investigated. Finally, the spectral information filtering properties of stochastic linearnonlinear cascade neuron models are being researched by employing different static nonlinearities (SNLs). The trade-off between frequency-dependent signal transmission and the total amount of transmitted information will be demonstrated in all models and constitutes a direct consequence of the nonlinear formulation of the models.
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Darling, Ryan Daniel. "Single Cell Analysis of Hippocampal Neural Ensembles during Theta-Triggered Eyeblink Classical Conditioning in the Rabbit." Miami University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=miami1225460517.
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Nguyen, Van Dong. "Speciation analysis of butyl- and phenyltin compounds in environmental samples by GC separation and atomic spectrometric detection." Doctoral thesis, Umeå : Department of Chemistry, Umeå University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-892.
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Errico, Carmine. "Determination of the influence of SRG anchors on the bond behavior of SRG/FRCM strips bonded to a quasi-brittle substrate." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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The use of FRCM composites (Fiber Reinforced Cementitious Matrix) is becoming more and more widespread. The inorganic matrix guarantees many advantages, especially when dealing with masonry substrates, including a good compatibility from both a physical and a chemical point of view and the lower sensitivity to debonding phenomena at the interface.
Compared to FRP composites, which presents many data in the literature, FRCM composites must be studied in detail and research in this field has only begun in recent years. This work deals with an important problem: the realization of an anchorage system to improve the strength of composites and allow their use even in the absence of adequate development length.
In this study, the effectiveness of the anchorage system and the interaction with an externally bonded FRCM were studied on masonry columns. The columns were tested until failure condition in the Laboratory of Structural and Geotechnical Engineering (DICAM – LISG) of the University of Bologna, via del Lazzaretto 15/5, Bologna.
Test results demonstrate that the introduction of additional anchorages improves the effectiveness of the FRCM composites in terms of resistance and loading capacity.
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Kurz, Thorben Andreas. "Development of techniques for single dendritic spine analysis." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-148813.
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Kurz, Thorben Andreas [Verfasser], and Alexander [Akademischer Betreuer] Borst. "Development of techniques for single dendritic spine analysis : spinomics / Thorben Andreas Kurz. Betreuer: Alexander Borst." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2012. http://d-nb.info/102706616X/34.
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Ambati, Divya V. "Effect of Design Variables on Biomechanics of Lumbar Spine Implanted with Single, Multilevel and Hybrid Posterior Dynamic Stabilization Systems." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1290226430.
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Morris, Tracy Louise. "Investigation of thoracic spine kinematics in adult sports participants with chronic groin pain during a single leg drop landing task." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86314.
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Thesis (MScPhysio)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Chronic groin pain is widespread across many sporting disciplines. The aim of our research was to determine if there are kinematic differences of the thoracic spine in active sports people with chronic groin pain, compared with healthy controls. A cross-sectional descriptive design was followed. Participants were required to complete six single leg drop landings with each leg from a 20cm height. The study was done in the 3D Movement Analysis Laboratory at the University of Stellenbosch. Ten male participants with unilateral or bilateral chronic groin pain of more than 3 months duration and 10 asymptomatic males, matched for age and sports participation, were recruited. The main outcome measures were: thoracic spine angle at initial foot contact, maximum thoracic spine angle, range of movement (ROM) (difference between the minimum and maximum values) and thoracic spine angle at lowest vertical point of the pelvis. This was assessed in all 3 movement planes: the sagittal plane (X plane), the coronal plane (Y plane) and the transverse plane (Z plane). The results of our study showed that for the unilaterally affected groin pain group, the cases landed in significantly more thoracic flexion (P<0.001 with large effect size) and were in significantly more thoracic flexion still at the lowest point. Peak thoracic flexion was significantly more in the cases than the controls. (P<0.001 with medium effect size) The same was true for the bilaterally affected group when landing on the most painful side, although this was not statistically significant. There were no significant differences in the frontal or transverse planes. In the bilaterally painful group, axial rotation ROM was significantly reduced when landing on either leg (worst affected side: P=0.040 with medium effect size and least affected side: p=0.006 with large effect size). The same occurred in the unilaterally affected group, although this was not statistically significant. Our study suggests that, in participants with chronic groin pain, there is greater thoracic forward flexion away from neutral during landing and that total axial rotation ROM during landing is diminished.
AFRIKAANSE OPSOMMING: Kroniese liespyn kom dikwels en in verskeie sportsoorte voor. Die doel van ons studie was om te bepaal of daar kinematiese verskille van die torakale werwelkolom is in aktiewe sportmense met chroniese liespyn, in vergelyking met gesonde kontroles. ‘n Dwars-deursnit beskrywende studiemetode is gevolg, en uitgevoer in die 3D Beweging Analise Laboratorium, Universiteit van Stellenbosch. Deelnemers moes ses landings op een been doen, met elke been, vanaf 'n 20cm hoogte. Tien mans met eensydige of bilaterale chroniese liespyn vir langer as 3 maande, en 10 asimptomatiese mans (ooreenstemmende ouderdom en sport deelname) het deelgeneem. Die hoof uitkomste wat gemeet is, was torakale werwelkolom krommingshoek by aanvanklike voet-kontak, maksimum torakale werwelkolom krommingshoek, omvang van beweging (OVB) (verskil tussen die minimum en maksimum waardes) en torakale werwelkolom krommingshoek by die laagste punt van die bekken. Dit is beoordeel in al 3 beweging vlakke: die sagittale (X) vlak, die koronale/frontale (Y) vlak en die transversale (Z) vlak. Die resultate van die studie het getoon dat, in die eensydig-geaffekteerde liespyn groep, die deelnemers in beduidend meer torakale fleksie geland het(P < 0.001, met 'n groot effekgrootte), asook met aansienlik meer torakale fleksie by die laagste punt na landing. Piek torakale fleksie was aansienlik meer in die liespyn-gevalle as in die kontroles. (P < 0.001, met middelmatige effekgrootte ) Dieselfde het vir die bilateraalgeaffekteerde groep gegeld wanneer hulle op hul mees pynlike kant geland het, hoewel dit nie statisties beduidend was nie. Daar was geen betekenisvolle verskille in die frontale of transversale vlakke van beweging nie. In die bilateraal pynlike groep, was aksiale rotasie OVB aansienlik verminder wanneer die gevalle op hul pynlikste been óf op hul minder pynlike been geland het ( mees pynlike been : P = 0,040, met 'n middelmatige effekgrootte en minder pynlike been : p = 0,006, met 'n groot effekgrootte ). Dieselfde het in die eensydig-geaffekteerde groep gebeur, hoewel dit nie statisties beduidend was nie. Ons studie dui daarop dat, in deelnemers met chroniese liespyn, daar meer torokale fleksie weg van neutraal tydens landing is en dat die totale aksiale rotasie OVB tydens die landing verminder is, in vergelyking met die kontrolegroep.
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Küffner, Mercedes [Verfasser], and Michael [Akademischer Betreuer] Frotscher. "Ultrastructural analysis of spine apparatus in CA3 pyramidal neurons following single cell electroporation in Synaptopodin Knockout - mice = Elektronenmikroskopische Untersuchung des Spine-Apparats in CA3 Pyramidenzellen mittels Einzelzell-Elektroporation in Synaptopodin-defizienten Mäusen." Freiburg : Universität, 2013. http://d-nb.info/1115495283/34.
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Dare, Michael Robert. "Investigation of hip kinematics in adult sports participants during single leg drop landing with chronic groin pain." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86334.
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Thesis (MScPhysio)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Introduction-Groin injuries are among the top six most cited injuries in soccer and account for 10-18 per cent of all injuries reported in contact sport. Groin pain can result from a variety of pathologies, but according to literature, 63 per cent of groin pain is due to adductor pathology. Objective-The objective of this study was to explore if there are kinematic differences in the hip joint in sports participants with groin pain compared to matched healthy controls. Study design A cross sectional, descriptive study was conducted. Study setting-The study was conducted at the FNB -3D motion analysis laboratory at the University of Stellenbosch, South Africa. Outcome variables-The dependent variables included hip kinematics in the sagittal, frontal and transverse planes at foot strike, lowest vertical point of the pelvis and total range of hip motion during a single leg drop landing. Methodology-The study sample comprised 20 male club level soccer-and, rugby players, running and cycling participants between the ages of 18-55 years of age. Ten of the subjects had chronic groin pain and the other ten were healthy matched controls. An eight-camera Vicon system was used to analyse the kinematics of the hip joint during single leg drop landing. For the purpose of comparison, the data was analysed for participants with unilateral groin pain and matched controls (n=14) and participants with bilateral groin pain and controls (n=6). The full set of data was subdivided for analysis into three distinct sub-groups. Unilaterally injured groin cases (n=7) were matched with seven healthy controls for analysis. Bilaterally injured groin cases (n=3) were matched with three healthy controls. Results-Cases with unilateral groin pain at initial contact had significantly more abduction of the hip joint when compared to controls (p<0.05). The effect size of this difference was large (0.94). Cases with unilateral groin pain also demonstrated greater hip internal rotation while the controls had external rotation (p<0.05) during a drop landing activity. Bilaterally injured groin cases landed with significantly (p=?) greater ranges of hip flexion as well as in significantly (p=?) more hip abduction during a drop landing activity. They also demonstrated greater total range of motion in the frontal plan when compared to controls. Groin pain cases overall demonstrated greater ranges of motion and tended to land in more abduction compared to controls. Conclusion-This study found that during a single leg drop landing, sports participants with unilateral chronic groin pain landed with significantly greater hip abduction and exhibited larger total range of motion in the transverse plane, which may indicate impaired stability of the hip complex when compared to controls.
AFRIKAANSE OPSOMMING: Inleiding-Liesbeserings is een van die top ses mees prominente sokker beserings. Dit beloop 10-18 persent van alle beserings wat in kontaksport aangemeld word. Liespyn kan die gevolg wees van ‘n verskeidenheid patologië, maar volgens die literatuur is 63 persent van liespyn as gevolg adduktor patologie. Doelwitte-Die doelwit van hierdie studie was om ondersoek in te stel of daar enige kinematiese veranderinge in die heupgewrig is in spelers met liespyn in vergelyking met dieselfde vergelykbare spelers sonder liespyn. Studie Ontwerp-‘n Deursnit, beskrywende studie was onderneem. Studie Omgewing-Die studie was uitgevoer by die FNB-3D bewegingsanalise laboratorium van die Stellenbosch Universiteit, Suid-Afrika. Uitkomsveranderlikes-Die afhanklike veranderlikes het in gesluit die heup kinematika in die sagitale, frontale en transvers vlakke met voet kontak endie laagste vertikale punt van die pelvis sowel as die totale heup omvang van beweging gedurende een been landing. Metodologie-Die studie populasie het bestaan uit 20 manlike sokker- en, rugbyspelers, hardlopers en fietsryers tussen die ouderdomme van 18 en 55 jaar. Tien van die deelnemers het kroniese liespyn gehad en die ander tien in die gelyke gesonde groep was sonder liespyn. Die agt kamera Vicon sisteem was gebruik om die kinematika van die heupgewrig te analseer tydens een been landing. Vir die doel om ‘n vergelyking te kan maak, was die data geanaliseer van deelnemers met unilaterale liespyn en die vergelykende groep sonder liespyn (n=14) en deelnemers met bilaterale liespyn en hulle vergelykende groep sonder liespyn (n=6).. Die volledige stel data was onderverdeel in drie afsonderlike sub groepe. Vir die analiese was unilaterale liesbeserings (n=7) vergelyk met sewe deelnemers sonder liespyn in die kontrolegroep. Deelnemers met bilaterale liesbeserings (n=3) was vergelyk met drie in die kontrolegroep. Resultate-Die deelnemers met unilaterale liespyn het met eerste kontak beduidend meer abduksie van die heupgewrig gehad in vergelyking met die kontrolegroep (p<0.05). Die effek van hierdie verskil was groot (0.94). Die deelnemers met unilaterale liespyn het ook ‘n grooter interne rotasie getoon, terwyl die kontrole groep meer eksterne rotasie gedemonstreer het (p<0.05) met landing. Deelnemers met bilaterale liespyn het beduidend (p=?) meer heup fleksie en abduksie omvang van beweging tydens landing. Hulle het ook ‘n groter totale heup omvang van beweging in die frontale vlak gehad in vergelyking met die kontrolegroep. Deelnemers met liespyn het oor die algemeen ‘n grooter omvang van beweging getoon, en was geneig om met meer abduksie van die heup te land as die kontrolegroep. Gevolgtrekking-Die studie toon dat deelnemers met kroniese unilaterale liespyn, tydens een been landing, beduidende meerheup abduksie toon en dat die heup in die transverse vlak meer totale omvang van beweging gebruik wat kan dui op onstabiliteit in die heupkompleks in vergelyking met die kontrolegroep.
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Chen, Jian Hua [Verfasser], Peter Jomo [Akademischer Betreuer] Walla, Reinhard [Akademischer Betreuer] Jahn, and Andreas [Akademischer Betreuer] Janshoff. "Spatial-temporal actin dynamics during synaptic plasticity of single dendritic spine investigated by two-photon fluorescence correlation spectroscopy / Jian Hua Chen. Gutachter: Reinhard Jahn ; Andreas Janshoff. Betreuer: Peter Jomo Walla." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://d-nb.info/1045776246/34.
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Chen, Jian Hua Verfasser], Peter Jomo [Akademischer Betreuer] [Walla, Reinhard [Akademischer Betreuer] Jahn, and Andreas [Akademischer Betreuer] Janshoff. "Spatial-temporal actin dynamics during synaptic plasticity of single dendritic spine investigated by two-photon fluorescence correlation spectroscopy / Jian Hua Chen. Gutachter: Reinhard Jahn ; Andreas Janshoff. Betreuer: Peter Jomo Walla." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://nbn-resolving.de/urn:nbn:de:gbv:7-11858/00-1735-0000-0022-609F-1-7.
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Mayo, Andrew. "A biomechanical study of top screw pullout in anterior scoliosis correction constructs." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/17152/1/Andrew_Elton_Mayo_Thesis.pdf.
Full textAbstract:
Top screw pullout is a significant problem in anterior scoliosis correction, with rates of 5-15% reported in the literature. The Mater Misericordiae Hospital in Brisbane currently has a series of 125 patients with scoliosis treated by thoracoscopic anterior fusion, instrumentation and correction between April 2000 and August 2007. In this series 11 top screws are known to have pulled out (a rate of 8.8%), with six occurring in the first week, and all within 6 weeks, suggesting that the problem is one of excessive static force rather than fatigue.
This thesis describes a biomechanical investigation into the mechanics of vertebral body screw pullout in anterior scoliosis surgical constructs. Previous biomechanical studies of vertebral body screws have evaluated their resistance to either straight pullout or cephalo-caudad compression forces, however the aim of this study was to assess screw resistance to more realistic loading conditions, namely pullout of initially angled screws, and pullout where the motion path is an arc rather than a straight axial pullout, as would be expected in a single rod anterior construct.
The first series of experiments involved straight and angled pullout tests using synthetic bone. In the angled tests, both locked and free-to-pivot configurations were tested. The second series of experiments tested the effect of cephalo-caudad pre-compression (the actual deformity correction step performed during surgery) on subsequent axial pullout strength. A third series of experiments performed arc pullouts using synthetic bone, and the final series of experiments tested the pullout resistance of a newly proposed screw position configuration against the standard screw positioning using ovine lumbar vertebrae.
Synthetic bone testing revealed that for initially angled pullout, resistance is greatest as the screw angle approaches 0 (ie a direct axial pullout). Cephalo-caudad pre-compression reduced subsequent pullout strength for cases where a staple was not used under the screw head, but if a staple was used the pre-compression did not decrease pullout force significantly. Arc pullout resistance was greatest when the screw was angled at 10 cephalad, and the mean pullout strength for the proposed screw configuration using ovine lumbar vertebrae (1864N) was almost double that of the standard screw positioning (993N).
The clinical implication of this study is that top screw pullout resistance can be maximised by placing the top screw as close as possible to the top endplate and the bottom screw as close as possible to the bottom endplate, although this will have detrimental effects on the pullout of the second screw should the top screw pull out. Screw angulation is a less important factor but any angulation should be in a cephalad direction and around 10º in magnitude. The experimental results also suggest that the use of a staple may play a role in preventing cephalo-caudad pre-compression forces from reducing screw resistance to subsequent pullout forces.
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Mayo, Andrew. "A biomechanical study of top screw pullout in anterior scoliosis correction constructs." Queensland University of Technology, 2007. http://eprints.qut.edu.au/17152/.
Full textAbstract:
Top screw pullout is a significant problem in anterior scoliosis correction, with rates of 5-15% reported in the literature. The Mater Misericordiae Hospital in Brisbane currently has a series of 125 patients with scoliosis treated by thoracoscopic anterior fusion, instrumentation and correction between April 2000 and August 2007. In this series 11 top screws are known to have pulled out (a rate of 8.8%), with six occurring in the first week, and all within 6 weeks, suggesting that the problem is one of excessive static force rather than fatigue.
This thesis describes a biomechanical investigation into the mechanics of vertebral body screw pullout in anterior scoliosis surgical constructs. Previous biomechanical studies of vertebral body screws have evaluated their resistance to either straight pullout or cephalo-caudad compression forces, however the aim of this study was to assess screw resistance to more realistic loading conditions, namely pullout of initially angled screws, and pullout where the motion path is an arc rather than a straight axial pullout, as would be expected in a single rod anterior construct.
The first series of experiments involved straight and angled pullout tests using synthetic bone. In the angled tests, both locked and free-to-pivot configurations were tested. The second series of experiments tested the effect of cephalo-caudad pre-compression (the actual deformity correction step performed during surgery) on subsequent axial pullout strength. A third series of experiments performed arc pullouts using synthetic bone, and the final series of experiments tested the pullout resistance of a newly proposed screw position configuration against the standard screw positioning using ovine lumbar vertebrae.
Synthetic bone testing revealed that for initially angled pullout, resistance is greatest as the screw angle approaches 0 (ie a direct axial pullout). Cephalo-caudad pre-compression reduced subsequent pullout strength for cases where a staple was not used under the screw head, but if a staple was used the pre-compression did not decrease pullout force significantly. Arc pullout resistance was greatest when the screw was angled at 10 cephalad, and the mean pullout strength for the proposed screw configuration using ovine lumbar vertebrae (1864N) was almost double that of the standard screw positioning (993N).
The clinical implication of this study is that top screw pullout resistance can be maximised by placing the top screw as close as possible to the top endplate and the bottom screw as close as possible to the bottom endplate, although this will have detrimental effects on the pullout of the second screw should the top screw pull out. Screw angulation is a less important factor but any angulation should be in a cephalad direction and around 10º in magnitude. The experimental results also suggest that the use of a staple may play a role in preventing cephalo-caudad pre-compression forces from reducing screw resistance to subsequent pullout forces.
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Chazeau, Anael. "Rôle de l’organisation du cytosquelette d’actine branché et des adhésions N-cadhérine dans la dynamique des épines dendritiques." Thesis, Bordeaux 2, 2012. http://www.theses.fr/2012BOR21967/document.
Full textAbstract:
Les épines dendritiques sont de petites protrusions post-synaptiques présentant des changements morphologiques corrélés avec la plasticité synaptique. Elles ont pour origine les filopodes dendritiques qui s’élargissent lors du contact avec l’axone. Ces changements morphologiques impliquent une grande variété de molécules dont des protéines associées à l’actine et des protéines d’adhésion. Cependant, comment ces différentes protéines sont coordonnées dans le temps et l’espace est encore largement méconnu. De plus, les techniques de microscopie conventionnelle ne permettent pas d’étudier l’organisation et la dynamique de ces protéines dans les épines dont la taille est proche de la limite de resolution. L’objectif de ma thèse a donc été d’explorer le rôle des protéines associées à l’actine ainsi que celui des protéines d’adhésion N-cadhérines dans l’organisation et la dynamique du cytosquelette d’actine des épines dendritiques. Dans une première étude, nous avons suivi la motilité des filopodes et épines dendritiques de neurones en visualisant l’actine-GFP. Nous avons couplé cette approche avec : 1) une technique de piégeage optique de microsphères recouvertes de N-cadhérines ou des substrats micro-imprimés également recouverts de N-cadhérines afin de contrôler temporellement et spatialement les adhésions cadhérine-cadhérine, 2) la stimulation pharmacologique de la myosine II afin d’induire la contraction F-actine/myosine et 3) l’expression de mutants de N-cadhérine non adhésifs. Nous avons ainsi démontré que la stabilisation des filopodes en épines était dépendante de l’engagement d’un embrayage moléculaire entre les adhésions trans-synaptiques N-cadhérine et le flux rétrograde d’actine généré par les myosines II. Dans une deuxième étude, nous avons utilisé la microscopie super-résolutive (PALM et dSTORM) et le suivi de protéines individuelles (sptPALM) pour étudier l’organisation et la dynamique à l’échelle nanométrique des protéines à l’origine des réseaux d’actine branchés dans les épines. Ainsi, nous avons caractérisé la localisation et la dynamique de l’actine, du complexe Arp2/3, du complexe WAVE, d’IRSp53, de VASP et de Rac-1. Nous avons montré que, contrairement aux structures motiles classiques comme lamellipode, le réseau d’actine branché dans les épines n’ést pas formé aux extrémités protrusives puis incorporé dans un flux rétrograde d’actine. Ce réseau est initié à la PSD puis croît vers l’extérieur afin de générer les protrusions membranaires responsablent des changements morphologiques de l’épine. Nos résultats montrent également qu’un contrôle strict de l’activité de Rac-1 est nécessaire au maintien de la morphologie des épines dendritiques et de l’architecture du réseau d’actine branché. L’ensemble de mon travail souligne l’importance du rôle de l’organisation à l’échelle nanométrique du réseau d’actine branché et des adhésions N-cadhérine dans la dynamique et la formation des épines dendritiques. Ces résultats pourraient avoir un rôle important dans la compréhension des changements morphologiques lors de la plasticité synaptiqueDendritic spines are tiny post-synaptic protrusions exhibiting changes in morphology correlated with synaptic plasticity. They originate from motile dendritic filopodia, which enlarge after contacting axons. These morphological changes involve a wide number of molecular actors, including actin-binding proteins, and adhesion molecules. However, how these various molecular components are coordinated temporally and spatially to tune changes in spine shape remains unclear. Furthermore, conventional photonic microscopy techniques could not achieved the spatial resolution required to study the dynamic nanoscale organization of these proteins within the micron size dendritic spines. The objective of my Ph.D. was to unravel how actin-binding proteins and N-cadherin adhesion regulate the organization and dynamics of F-actin network in dendritic spines. In a first study, we measured the motility of dendritic filopodia and spines by time lapse imaging of actin-GFP in primary hippocampal neurons. We combined those measurements with: 1) manipulation of N-cadherin coated beads with optical tweezers, or micropatterns to control the timing and location of nascent N-cadherin adhesions, 2) pharmacological stimulation of myosin II to trigger contraction of the F-actin/myosin network and 3) expression of non-adhesive N-cadherin mutants to compete for the interaction between N-cadherin adhesion and F-actin. Using these different approaches we demonstrated that the stabilization of dendritic filopodia into mature spines was dependent on the engagement of a molecular clutch between trans-synaptic N-cadherin adhesions and the myosin driven F-actin flow. In a second study, we used super resolution microscopy (PALM and dSTORM) and single protein tracking (sptPALM) to study the dynamic nanoscale organizations of branched actin networks within dendritic spines. Using these technics, we characterized within dendritic spines, the localization and dynamics of actin, Arp2/3 complex, WAVE complex, IRSp53, VASP and Rac-1. We established that, opposite to classical motile structures such as the lamellipodium, branched F-actin networks in dendritic spines are not formed at the tip of membrane protrusions and incorporated in a retrograde flow. On the contrary, they are growing outwards from the PSD generating membrane protrusions responsible for spine motility. We also show that a thigh control of Rac1 activity is required to maintain dendritic spine morphology and branched actin network organization. Altogether, these studies point out the role of the nanoscale functional organization of F-actin networks and its linkage to adhesion proteins in the regulation of dendritic spine formation and dynamics. These findings may have important implications in the understanding of spine morphology changes driven by synaptic activity
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Yang, Fuchan, and 楊富全. "Unsupervised Spike Sorting with Improved Single-Linkage Method." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/76462628804011661813.
Full textAbstract:
碩士國立交通大學
電機與控制工程系所
95
Spike sorting is the one of the based in many neuroscience researches. The targets of spike sorting are to research the action potential of neuron and to classify the difference spikes produced by difference neurons. The recorded neuron signals is often diffusion and astronomical. It may also record the signals produced by two or more neurons. A lot of neuron signals make the procedure of spike sorting slow and weighty. Hence the spike sorting needs much artificial operations to complete. Many researches attach importance to the accuracy of classification and the performance under the simulate situation. The first lead to the lack of convenience, and the later lacks the test of real applications to support. Hence the spike sorting can’t conveniently be used for signal analysis. The thesis uses a new spike sorting method for multiunit neuron signals. The method respectively use wavelet transform and principal components analysis to extract the spike waveform features. Then the spike classification method is based on improved signal linkage method and grey theory to arrive automatically procedure. The procedure is unsupervised and reasonable and hence it can make a fast, effective and convenient spike sorting method. The method is tested by strict simulation spikes and compared with some other classification methods. Subsequently the method analyzes the neuron signals recorded from human. The results also show that the method of the thesis has an unsupervised spike sorting procedure.
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Chuang, Chung-Ting, and 莊仲庭. "Biomechanical analysis of take-off spike movement by single-foot." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/98482240037652424042.
Full textAbstract:
碩士國立臺北教育大學
體育學系碩士班
95
The purpose of this study was to investigate the kinematics and kinetics parameters change of human body take-off spike movement by single-foot in women’s volleyball players. Five female volleyball players (ages：21.4±3.05yrs , weight：66.2±4.66kg , height：172±4.64cm,practice experience: 11.4±1.95 yrs ; mean±SD) were served as subject for the study. Two CPL MS25K high speed cameras（100Hz）was synchronized with an AMTI force platform（1000Hz） to collect the biomechanical parameters of taking-off spike movement by single-foot . The images were processed with Kwon motion analysis system to obtain kinematics parameters of run-up period, take-off period, and air-motion period, and the values were analyzed with Dasy Lab 6.0 software to obtain kinetics parameters changes of take-off period. After comparing with previously report, conclusion was as follow: when players use take-off spike movement by single-foot, the strides should increase progressively after observing the ball’s direction, and raise the height of jump by getting faster horizontal and vertical velocity of body gravity. In order to avoid increasing the time of take-off, the body gravity is inadvisable to drop so much. In air motion period, player’s movement of arm swing will influences the time of spike, if we emphasize the quick offensive, it should reduce the movement of arm swing to decrease the time of spike. When spiking, the joint of elbow should flex by a little range to make forearm powerful.
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Quang, Trong-Nha, and 廣眾雅. "Single-Stage Current-Fed Power Factor Correction Converters with Low Voltage Spike." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/26277710377739885342.
Full textAbstract:
博士國立臺灣科技大學
電子工程系
102
Previous studies on the single-stage power factor correction (PFC) converters expose some shortcomings such as high voltage spike on power devices, discontinuous conduction mode (DCM) input current and switching frequency variation. These undesired factors cause efficiency limitation, high electromagnetic interference (EMI) intensity and high-voltage high-cost power device use. In this dissertation, three topologies are proposed for PFC applications. For low power applications, two topologies named current-fed flyback and zero-voltage-switching (ZVS) current-fed flyback PFC converters featuring voltage-spike-free on MOSFET, high power quality and ZVS achievement are proposed. For high power applications, a novel current-fed full-bridge (CFFB) PFC converter is proposed to improve efficiency, input current quality and reduce common mode (CM) noise. Utilizing quasi z-source configuration, the voltage spike on the MOSFETs is effectively eliminated by capacitive clamping circuit without power loss consumption. Low voltage MOSFETs with low on-resistance Rds(on) are used to improve efficiency. The input current is continuous conduction mode (CCM) operation. Additionally, to evaluate the conducted EMI behavior, the differential mode (DM) loop and CM loop models are also thoroughly analyzed and presented in this study. Several laboratory prototypes of the conventional PFC converters and proposed PFC converters were built to compare their performances and demonstrate the circuit feasibility. The experimental results showed that the proposed topologies completely eliminated the voltage spikes on the MOSFETs. The efficiency improved by using low Rds(on) MOSFETs. The input current was CCM operation.
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Narayana, Gopalakrishna. "Investigation of an Axisymmetric Spiked Body in a Hypersonic Shock Tunnel." Thesis, 2019. https://etd.iisc.ac.in/handle/2005/4401.
Full textAbstract:
The forefront research in the regime of hypersonic flow is intended to focus on improving the overall performance of the existing aerospace vehicles. A high-speed vehicle experiences a high level of aerodynamic heating and drag. These vehicles are also characterised by shock impingement on the body and shock-shock interaction closer to the body surface, which cause pressure and thermal loading. With the addition of a spike on the main body, the flow field over high-speed vehicles can be changed drastically, which would create an impact on the heat flux and aerodynamic drag at hypersonic speed. The aerospike with a hemispherical blunt body and the sharp tip spike over a flat-faced cylinder are two types of spike configurations with different flow phenomenon that are studied
in this investigation.
The first part of the study focuses on exploring the possibility of addressing aerodynamic drag and heat transfer on a body by placing an aerospike at the nose (i.e., stagnation region) of the high-speed vehicle and as a result, wave drag of a vehicle is considerably reduced. However, this can lead to an increase in heat transfer at localized spots of the main body. An attempt is made in the current study
to reduce these localized high heat transfer spots and evaluate the variation in both heat transfer and drag on the body, by modifying the spike configuration through the addition of a smaller hemisphere midway along length of the aerospike. In this regard, shock tunnel experiments and computational studies are carried out on this modified spike configuration, termed a double-disk spike or double
spike. The experimental results show that the heat transfer rate near the localized spot of the blunt body with spike decreases for a double spike in comparison with a single disk spike. The decrease in heat transfer varies from 5% to 30% depending on the double spike configuration (i.e. varying cap radius and length of the spike). To supplement these results, the 3D Finite Volume solver, HiFUN
(High-Resolution Flow Solver on Unstructured mesh) is used and it showed a good trend in heat transfer and drag compared with experiment.
In the second part, an investigation is carried out to understand the unsteady flow phenomenon exhibited by certain types of spiked bodies (Pulsation and Oscillation) which are characteristics by a shock-shock interaction, which in turn depends on spike length and blunt body shape. This unsteady flow separation leads to pressure and heat transfer fluctuations of high amplitude and frequency.
Pulsation is characterised by the formation of a separation zone at the spike with a conical shock engulfing it, which grows in size and collapses, and this cycle continues. Pulsating flow is observed for shorter spike length (0.2< L/D < 1.25). Oscillations for the longer spike (1.25 < L/D<2.5), are identified by a small change in the size of the conical separated flow region and an oscillating conical
shock engulfing the body. An attempt is made to measure heat flux for these types of unsteady flows, which would provide additional insight and lead to a better understanding of the flow phenomena. Experiments are carried out on a sharp-tipped spike attached to a flat-faced cylinder in a shock tunnel at Mach 5.7. Provision is made to vary the spike length, with L/D = 0.75, 1, 1.25, 1.5 and 2 and results
are discussed in detail. The measured heat transfer using a platinum thin-film sensor varied around 100 W/cm2 to 10 W/cm2
for a pulsation case (L/D = 0.75). For the oscillation case all except the corner gauge, indicated the heat transfer varied between 50 W/cm2 and 5 W/cm2. Last gauge shows higher heat transfer values of around 120 W/cm2 to 10 W/cm2 , indicating the shock interaction around this region. Schlieren visualization is used to complement the experimental heat transfer data. To understand the effect of Mach number on pulsation and oscillation heat transfer measurements are carried out at Mach number of 8.2 in a shock tunnel. The suppression of the pulsation and oscillations fluctuations are obtained by attachment of a disc halfway along the length of the spike mounted in front of the flat-faced cylinder which is observed through a heat transfer and schlieren visualisation.ISRO
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Harward, Stephen Cannada. "BDNF-TrkB Signaling in Single-Spine Structural Plasticity." Diss., 2016. http://hdl.handle.net/10161/12096.
Full textAbstract:
Multiple lines of evidence reveal that activation of the tropomyosin related kinase B (TrkB) receptor is a critical molecular mechanism underlying status epilepticus (SE) induced epilepsy development. However, the cellular consequences of such signaling remain unknown. To this point, localization of SE-induced TrkB activation to CA1 apical dendritic spines provides an anatomic clue pointing to Schaffer collateral-CA1 synaptic plasticity as one potential cellular consequence of TrkB activation. Here, we combine two-photon glutamate uncaging with two photon fluorescence lifetime imaging microscopy (2pFLIM) of fluorescence resonance energy transfer (FRET)-based sensors to specifically investigate the roles of TrkB and its canonical ligand brain derived neurotrophic factor (BDNF) in dendritic spine structural plasticity (sLTP) of CA1 pyramidal neurons in cultured hippocampal slices of rodents. To begin, we demonstrate a critical role for post-synaptic TrkB and post-synaptic BDNF in sLTP. Building on these findings, we develop a novel FRET-based sensor for TrkB activation that can report both BDNF and non-BDNF activation in a specific and reversible manner. Using this sensor, we monitor the spatiotemporal dynamics of TrkB activity during single-spine sLTP. In response to glutamate uncaging, we report a rapid (onset less than 1 minute) and sustained (lasting at least 20 minutes) activation of TrkB in the stimulated spine that depends on N-methyl-D-aspartate receptor (NMDAR)-Ca2+/Calmodulin dependent kinase II (CaMKII) signaling as well as post-synaptically synthesized BDNF. Consistent with these findings, we also demonstrate rapid, glutamate uncaging-evoked, time-locked release of BDNF from single dendritic spines using BDNF fused to superecliptic pHluorin (SEP). Finally, to elucidate the molecular mechanisms by which TrkB activation leads to sLTP, we examined the dependence of Rho GTPase activity - known mediators of sLTP - on BDNF-TrkB signaling. Through the use of previously described FRET-based sensors, we find that the activities of ras-related C3 botulinum toxin substrate 1 (Rac1) and cell division control protein 42 (Cdc42) require BDNF-TrkB signaling. Taken together, these findings reveal a spine-autonomous, autocrine signaling mechanism involving NMDAR-CaMKII dependent BDNF release from stimulated dendritic spines leading to TrkB activation and subsequent activation of the downstream molecules Rac1 and Cdc42 in these same spines that proves critical for sLTP. In conclusion, these results highlight structural plasticity as one cellular consequence of CA1 dendritic spine TrkB activation that may potentially contribute to larger, circuit-level changes underlying SE-induced epilepsy.
Dissertation
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Shi-Tin, Lin, and 林式庭. "Study of Single-electron Transistor Model for SPICE Analysis." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/59323458785523715586.
Full textAbstract:
碩士國立暨南國際大學
電機工程學系
91
Due to the rapid progress in nano-fabrication technologies, various nano devices have been successfully fabricated. Among them, single-electron devices have drawn many researchers’ attention due to their very promising characteristics, such as ultimate low power consumption, down-scalability to nano-scale, high density and high switching speed. Basic logic circuits constructed with single electron devices as the basic building unit have been practically implemented. Therefore, the need for new circuit simulator that can simulate single- electron circuits is urgent. If the simulator can be combined with the existing circuits simulator such as SPICE, one can further simulate those hybrid circuits that include both the single electron devices and the conventional circuit elements. Since single electron simulators based on Monte Carlo method usually involve complicated calculations and take very long computation time, in this thesis we focus on single-electron transistors’ macro model and analytical model suitable for SPICE analysis. Based on the existing macro model and analytical model found in the literature, we developed an improved macro model and an improved analytical model for single electron transistors that can be used in SPICE circuit analysis. When compared with the well-accepted Monte Carlo single electron simulator SIMON 2.0, we found that both of our proposed models can correctly predict the terminal characteristics of single electron transistors with little computation time. We also applied our proposed macro model to single electron inverters and a practical single electron XOR logic gates and obtained the voltage transfer characteristics and output waveforms successfully. In this thesis, we also reported the fabrication of a nanowire transfer resistor by using atomic force microscopy based on scanning probe lithography. From the measured characteristics of the nanowire transfer resistor, we found that they are quite different from those of the single electron transistors. We believed that it is worthy of further study of the nature of the nanowire transfer resistor.
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Blakeney, Carmen. "The effect of a single versus multiple cervical spine manipulations on peak torque of the rotator cuff muscles in asymptomatic subjects with cervical spine fixation." Thesis, 2009. http://hdl.handle.net/10321/457.
Full textAbstract:
Submitted in partial compliance with the requirements for the Masters Degree in Technology: Chiropractic at the Durban University of Technology, 2009.Aim: The aim of the study was to assess the effect of a single versus multiple cervical spine manipulations, over a two week period, on peak torque of the rotator cuff muscles utilizing the Cybex Orthotron II Isokinetic Rehabilitation System. This study was a pre and post experimental investigation. Method: Forty asymptomatic (in terms of neck and shoulder pain) male chiropractic students were stratified into two equal groups of twenty subjects to ensure that each group consisted of an equal number of subjects from each year of study. All subjects underwent a familiarisation session on the Cybex Orthotron II Isokinetic Rehabilitation System. Group One received a single manipulation. Rotator cuff peak torque was measured pre-manipulation, immediately post manipulation and at a two-week follow up. Group Two received four manipulations over a two week period. Rotator cuff peak torque was measured pre and immediately post the first manipulation. A third rotator cuff peak torque measurement was taken two weeks after the first manipulation. Results: There was no statistically significant effect of a single or multiple manipulations on rotator cuff peak torque (abduction, adduction, internal rotation and external rotation). Inter-group analysis revealed a trend of an effect for abduction as the single manipulation increased at the two-week follow up and the multiple manipulation group decreased; however, this was not statistically significant. Conclusion: No statistically significant results were found possibly due to small sample size and the fact that objective measurements were only taken at the beginning and the end of the research processes and not at regular intervals throughout the study.Further studies are needed to determine the effects of multiple manipulations on peripheral muscle activity, including the treatment of symptomatic patients with rotator cuff pathology. It is also recommended that EMG readings be done in conjunction with peak torque measures to determine muscle activity.
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Gregory, Diane Elizabeth. "The Influence of the Tensile Material Properties of Single Annulus Fibrosus Lamellae and the Interlamellar Matrix Strength on Disc Herniation and Progression." Thesis, 2009. http://hdl.handle.net/10012/4525.
Full textAbstract:
Low back pain is highly prevalent in the developed world, with 80% of the population being affected at some point in their lives. Herniation, a common injury to the intervertebral disc, is characterized as the posterior migration of the nucleus pulposus through the layers of the annulus fibrosus. Various risk factors have been associated with the development of disc herniation, but the mechanisms are largely not understood. For example, exposure to vibration has been linked to the occurrence of herniation, yet our understanding of this association is not clear. It is hypothesized that vibration cyclically loads the tissues of the intervertebral disc until failure occurs as a result of fatigue. Tissues at risk of fatigue failure may include the intra-lamellar matrix, the connective tissue found between collagen fibres within a single lamella, and the inter-lamellar matrix, the connective tissue found between adjacent lamellae. In order to determine the mechanistic link between vibration and herniation, a firm understanding of the properties of the intervertebral disc as well as the intra and inter-lamellar matrices are of utmost importance. Further, it is important to determine these properties under physiological loading scenarios. This thesis consists of five studies, which have each provided a unique piece to the intervertebral disc herniation puzzle in order to better understand this mechanistic link. First, it was discovered that annular tissue is subject to significantly higher stresses and is stiffer under biaxial strain as compared to uniaxial strain. Biaxial strain is more representative of the in vivo loading scenario and provides more accurate information regarding scenarios that the annulus can tolerate and those that can result in injury. It was also revealed that, when strained at physiological strain rates (up to 4%/sec), these mechanical properties do not change such that they are independent of strain rate. Therefore, when strained at varying rates akin to voluntary movement, the annulus is not subject to higher stresses or altered stiffness. Second, the effect of vibration, an acknowledged risk factor for herniation, was examined on the mechanical properties of the intra and inter-lamellar matrices. It was discovered that vibration altered these matrices such that they were more extensible and strained to greater magnitudes, yet did not reach higher stresses before failing. It was hypothesized that this increased extensibility was due to damage to elastin, as elastin assists in minimizing tissue deformation and helps tissues recover from tensile strain. The final study assessed the effect of exposure to vibration on the development of disc herniation. The initiation of herniation was observed in a significantly greater number of intervertebral discs exposed to vibration as compared to a control condition. Although epidemiological studies had documented a correlation between exposure to vibration and herniation, this was the first study to conclude that exposure to vibration is in fact a mechanical risk factor for the development of herniation and increases the incidence of herniation. Further, based on the findings of the mechanical properties of the intra and inter-lamellar matrices, and in particular the observed 15-20 times greater failure strength of the intra as compared to inter-lamellar matrix, it would appear that the inter-lamellar matrix, and thus delamination, may be the weakest link in the herniation pathway.
This thesis has uncovered new information regarding physiological mechanical properties of the annulus. Further, new information regarding the intra and inter-lamellar matrices was obtained, improving our understanding of the healthy disc. Last, by subjecting the disc to a known risk factor for herniation, hypotheses were generated regarding the initiation and progression of disc herniation, specifically related to the roles of the intra and inter-lamellar matrices.
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Chen, Jian Hua. "Spatial-temporal actin dynamics during synaptic plasticity of single dendritic spine investigated by two- photon fluorescence correlation spectroscopy." Doctoral thesis, 2013. http://hdl.handle.net/11858/00-1735-0000-0022-609F-1.
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Rogers, Tamara. "The effect of a single application of muscle energy technique on pressure pain thresholds in the lumbar spine." Thesis, 2005. https://vuir.vu.edu.au/887/.
Full textAbstract:
Muscle energy technique (MET) is commonly used by osteopaths and other manual therapists in the treatment of spinal and joint pain, but there has been little investigation of its effectiveness on pain reduction, particularly in the lumbar region. The aim of this study was to investigate the immediate effect of a single application of MET on pressure pain thresholds (PPT) in the lumbar spine in an asymptomatic population. Fifty-nine asymptomatic volunteers (40 female, 19 male) were recruited from the Victoria University student population. The lumbar spinous process reported as most sensitive to manual springing by each subject was marked using a skin pencil. An electronic algometer was used to determine the PPT at this level. Subjects were directed to another room and were randomly assigned to a single application of either a rotational MET or a sham "functional" treatment. Following intervention, subjects returned for re-measurement of PPT by an examiner who was blinded to the treatment intervention. Following intervention, a small significant increase in PPT was found in the MET group, whereas a non-significant decrease in PPT occurred in the sham group. When the difference scores of the two groups were analysed using an independent t-test, a significant difference between the groups was found, and a large between-group effect size was calculated. A single application of rotational MET to the lumbar spine did produce a significant increase in PPT in this asymptomatic population. Caution must be used when interpreting this result because the change in PPT was small and within the error range of the testing equipment. Future research is recommended in symptomatic populations. This minor thesis was written by a post-graduate student as part of the requirements of the Master of Health Science (Osteopathy) program.
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Rogers, Tamara. "The effect of a single application of muscle energy technique on pressure pain thresholds in the lumbar spine." 2005. http://eprints.vu.edu.au/887/1/Rogers_et.al_2005.pdf.
Full textAbstract:
Muscle energy technique (MET) is commonly used by osteopaths and other manual therapists in the treatment of spinal and joint pain, but there has been little investigation of its effectiveness on pain reduction, particularly in the lumbar region. The aim of this study was to investigate the immediate effect of a single application of MET on pressure pain thresholds (PPT) in the lumbar spine in an asymptomatic population. Fifty-nine asymptomatic volunteers (40 female, 19 male) were recruited from the Victoria University student population. The lumbar spinous process reported as most sensitive to manual springing by each subject was marked using a skin pencil. An electronic algometer was used to determine the PPT at this level. Subjects were directed to another room and were randomly assigned to a single application of either a rotational MET or a sham "functional" treatment. Following intervention, subjects returned for re-measurement of PPT by an examiner who was blinded to the treatment intervention. Following intervention, a small significant increase in PPT was found in the MET group, whereas a non-significant decrease in PPT occurred in the sham group. When the difference scores of the two groups were analysed using an independent t-test, a significant difference between the groups was found, and a large between-group effect size was calculated. A single application of rotational MET to the lumbar spine did produce a significant increase in PPT in this asymptomatic population. Caution must be used when interpreting this result because the change in PPT was small and within the error range of the testing equipment. Future research is recommended in symptomatic populations. This minor thesis was written by a post-graduate student as part of the requirements of the Master of Health Science (Osteopathy) program.
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Ceong, Hailey Hyekyeong. "The morphosyntax of clause typing: single, double, periphrastic, and multifunctional complementizers in Korean." Thesis, 2019. http://hdl.handle.net/1828/10815.
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In this dissertation I provide an account of the distribution of Korean clause-typing markers from the perspective of a formal typological model, the Universal Spine Hypothesis (Wiltschko, 2014, 2017). Although Korean clause-typing markers have both syntactic properties (expressing force/mood, Chomsky 2000, 2001) and pragmatic properties (expressing speech styles, Sohn 1999), my investigation focuses on the morphosyntactic properties of clause-typing markers in single-layered and double-layered CPs. I detail their ability to transmit clause type, their compatibility with TAM elements, and their incompatibility with subordinators and speech act elements. My central claim is that, through an association with the linking spine (i.e., CP in generative grammar), clause-typing markers, including ta and e, construct Korean language-specific categories. Clause-typing markers interact with a syntactic domain encoding the common ground of speech participants, the grounding spine. My dissertation has two major findings. First, the morphophonological realization of C is obligatory in both finite and non-finite clauses. I therefore propose a Clause Complementation Parameter (CCP)—all clauses must have a complementizer, and a C must have a correspondent PF realization. This accounts for the expletive-like dummy complementizers e and ci which can fill the head of the three basic clause types. Second, functional elements selecting clause-typing markers support the existence of syntactic projections above the traditional CP. For instance, iterative ko and hearsay y in reiterated and hearsay utterances, respectively, must be associated with the syntactic domain above CP. I argue that along with polite yo and intonation, they construct Korean language-specific categories through their association with the three universal categorizers k: linking, k: grounding, and k: responding. This is formulated as [RespP [GroundP [LinkingP [AnchoringP …-ssPAST] -taDECL] -yHEARSAY] (-yoPOLITE) -↑].
Investigations of the distributions of periphrastic irrealis clause-typing markers and multifunctional clause-typing markers contribute to our understanding of the multifaceted nature of category C: the periphrastic irrealis markers show that C with T can restrict the person feature on the subject. The interpretations of multifunctional markers in different morphosyntactic contexts show that their properties emerge in two ways: through interaction with local elements in the domain or by virtue of their association with hierarchically distinct domains. Assuming the Universal Spine Hypothesis, I have accounted for the morphosyntactic properties of Korean clause-typing markers by proposing language-specific categories considering the functional layers. This dissertation offers a more complete account of Korean grammar but also will provide an explanation for cross-linguistic differences in encoding of clause-typing—Units of Languages change how C appears.Graduate
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Lee, Seok-Jin. "Spatiotemporal Dynamics of Calcium/calmodulin-dependent Kinase II in Single Dendritic Spines During Synaptic Plasticity." Diss., 2011. http://hdl.handle.net/10161/3818.
Full textAbstract:
Synaptic plasticity is the leading candidate for the cellular/molecular basis of learning and memory. One of the key molecules involved in synaptic plasticity is Calcium/calmodulin-dependent Kinase II (CaMKII). Synaptic plasticity can be expressed at a single dendritic spine independent of its neighboring dendritic spines. Here, we investigated how long the activity of CaMKII lasts during synaptic plasticity of single dendritic spines. We found that CaMKII activity lasted ~2 minutes during synaptic plasticity and was restricted to the dendritic spines undergoing synaptic plasticity while nearby dendritic spines did not show any change in the level of CaMKII activity. Our experimental data argue against the persistent activation of CaMKII in dendritic spines undergoing synaptic plasticity and suggest that the activity of CaMKII is a spine-specific biochemical signal necessary for synapse-specificity of synaptic plasticity. We provide a biophysical explanation of how spine-specific CaMKII activation can be achieved during synaptic plasticity. We also found that CaMKII is activated by highly localized calcium influx in the proximity of Voltage-dependent Calcium Channels (VDCCs) and a different set of VDCCs and their respective Ca2+ nanodomains are responsible for the differential activation of CaMKII between dendritic spines and dendritic shafts.
Dissertation
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Rowley, Neil Charles. "The relative effectiveness of a single dry needle insertion compared to multiple fanning dry needle insertions in the treatment of myofasciitis in the cervical and upper thoracic spine." Thesis, 2001. http://hdl.handle.net/10321/1863.
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A thesis presented in partial compliance with the requirements for the Master's Degree in Technology: Chiropractic, Technikon Natal, 2001.Myofascial Pain Syndrome (MPS) is a clinical syndrome of soft tissue pain arising from skeletal muscle. It is manifested by characteristic trigger points (TrPs) in palpable taut bands of muscle fibres with typical referred pain patterns, restricted range of motion and local twitch responses. Treatment of MPS appears to be aimed at disrupting the reverberating neural circuits responsible for the self-perpetuation of the pain-spasm pain cycle. This occurs through inactivating the active TrP through releasing the taut bands with various techniques including massage, ischaemie compression, spray and stretch, ultrasound, hydrocollator moist heat, trigger point injection, dry needling, and TENS. There are many treatments available yet little research substantiating efficiency of one specific therapy over another, with the result that choice of treatment often becomes based on personal preferences rather than clinical evidence. Among many authors, dry needling has been shown to be an effective form of treatment. The therapeutic effect of dry needling relies on the mechanical disruption or direct stimulation of the TrP and that the strongest analgesic effect is achieved when the most painful spot is precisely reached with a fme needle, normally an acupuncture needle. This immediate analgesia produced by needle puncture of a TrP has been termed the
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