Dissertations / Theses on the topic 'Intrinsic propertie'
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Tsifoutidis, George. "Intrinsic properties of Hellenic “Marls”." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5704/.
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Post-alpine deposits cover substantial areas of Hellas. The fine grained facies of these deposits, comprise a wide range of over consolidated materials of varying grading and mineralogy. On average, however, these deposits cover different depositional environments and may be classed as silty clays and clayey silts of low to intermediate plasticity containing calcite in their mineralogical suite. Such deposits have been collectively known to practising engineers as marls. A concerted effort to collect field and laboratory data and interpret the behaviour of these materials was recently launched in view of the involvement of the aforesaid mentioned deposits in a series of geotechnical problems. This thesis aspires to contribute to this knowledge and provide a framework on which the field performance of such materials may be interpreted. To that end, disturbed and high quality undisturbed samples from the geologically dissimilar areas of Korinthos, Preveza-Igoumenitsa road axis and Amalias- Goumeron were obtained and tested in order to ascertain their physical characteristics and mineralogical composition. Further, engineering properties which are independent of stress history, i.e. intrinsic, of the materials sampled, were determined. These were the residual strength as determined by ring shearing and the compressibility of reconstituted samples. The performance of the samples was assessed in terms of grain size distribution and mineralogy. The results show that any attempt to explain or predict intrinsic properties of Hellenic fine grained calcareous sediments without taking simultaneous account of gradation and mineralogy is incomplete and therefore inaccurate.
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Hille, Laura [Verfasser], and Dietmar [Akademischer Betreuer] Trenk. "Intrinsic properties of reticulated platelets." Freiburg : Universität, 2020. http://d-nb.info/122441652X/34.
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Ren, Zhe. "Intrinsic Properties of "Case" and Potential Biomedical Applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1554409704895456.
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Häusser, Michael. "Intrinsic properties and synaptic inhibition of substantia nigra neurones." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306691.
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Duc, Tran Thien. "Electronic properties of intrinsic defects and impurities in GaN." Doctoral thesis, Linköpings universitet, Halvledarmaterial, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-121710.
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With its outstanding properties such as a wide direct bandgap (3.4 eV), high electron mobility and high breakdown voltage, GaN and its alloys with In and Al are considered as one of the most important semiconductors for optoelectronic devices and high-power and high-frequency transistors. The most important application of GaN today is high-brightness blue LEDs, which is used for white LEDs. With the discovery of GaN-based blue LED, Isamu Akasaki, Hiroshi Amano and Shuji Nakamura were awarded the Nobel Prize in 2014. Intrinsic defects and impurities are important in semiconductors since they influence the electronic properties. An impurity is one or several foreign atoms in the host crystal while an intrinsic defect is an imperfection in the host’s crystal lattice. Normally, impurities and intrinsic defects can be introduced either intentionally or unintentionally into semiconductors during the growth process, during processing of the device or from the working environment. Especially for GaN, due to the lack of native substrates, most of the GaN-based device structures are fabricated on foreign substrates such as silicon carbide (SiC) or sapphire (Al2O3). Growth on foreign substrates gives rise to high threading dislocation densities, and they can give rise to electronically active intrinsic defects that influence the performance of the device. This thesis is focused on electrical characterization of intrinsic defects and impurities in GaN grown by halide vapor phase epitaxy (HVPE) and metalorganic vapor phase epitaxy (MOCVD). In the first part of the thesis, impurities and intrinsic defects in freestanding thick HVPE grown GaN and Mg-doped MOCVD grown GaN is studied. In thick HVPE grown GaN, six electron traps were detected, where two of them were introduced by the polishing process. For three of the traps, the temperature dependence of the electron capture cross section was studied. From their electron capture properties, it was suggested that the traps are associated with point defects. In Mg-doped MOCVD grown GaN, one hole trap of high concentration was observed. The hole emission rate is enhanced by increasing electric field and by study the emission process in detail by simulation, it is suggested that the emission process is governed by both the Poole-Frenkel effect and phonon-assisted tunneling. In the second part, intrinsic defects in GaN introduced intentionally by electron irradiation with different fluences have been studied. In electron irradiated HVPE grown GaN, three electron-irradiation-induced electron traps appeared after 2 MeV electron irradiation at a fluence of 1 × 1014 cm2. Due to the annealing behavior, two of the levels were suggested to be related to primary intrinsic defects. In addition, the temperature dependence of the electron capture cross sections for three levels in electron-irradiated GaN was studied. The temperature dependence of one of them showed that the electron capturing is governed by a cascade capturing process, whereas no temperature dependence was observed for the other levels. The thermal stability of electron traps introduced by 2 MeV electron irradiation was studied. Isochronal annealing shows that most of the defects, which has been associated to nitrogen vacancies, annealed out already at 550 K and by using isothermal annealing the activation energy of one of the process was determined. By minority carrier spectroscopy and deep level transient spectroscopy, hole and electron traps in as-grown and 2 MeV ntype electron irradiated GaN were studied. One hole trap was observed in the as-grown material. By electron irradiation, it was observed that the concentration increases. Simultaneously, the concentration of two electron traps increases. Due to the low introduction rate of one of the electron traps, it is suggested that the defect is associated with a primary defect decorating extended structural defects. The high introduction rate of the hole trap suggests that the defect is associated with a primary intrinsic defect or a complex.
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Golda, Stephanie DuPont. "Intrinsic Properties of Bone as Predictors of Differential Survivorship." Thesis, University of Missouri - Columbia, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13877144.
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Investigating intrinsic properties as determinants of bone survival has major implications in forensic anthropology. It is useful in the incomplete recovery of a skeleton to know if certain bones that are missing are those that are expected to be missing. Assuming complete recovery, individual skeletal parts should have different recovery probabilities. This research examines the differential survivorship of human skeletal remains based on intrinsic properties (density, size, and shape) of bone. Fifty skeletons from the William M. Bass Forensic Skeletal Collection at the University of Tennessee-Knoxville were measured to determine bone length (cm) and shape (sphere, disc, rod, or blade) for twenty skeletal elements. Density measures (HUs) of skeletal parts were recorded for 11 skeletons from the Texas State University Donated Skeletal Collection. These intrinsic variables were then compared to recovery frequencies from a forensic sample of Arizona-Sonoran desert border crossers (n=380). This study found a correlation between bone length and frequency (rS= 0.46) and significant differences in the mean recovery frequencies for shapes (p < 0.05). Though no correlation was found for skeletal part density and frequency (rS= -0.21), structurally dense midshafts of long bones are recovered with a greater frequency than their corresponding epiphyseal ends (p < 0.001). Furthermore, structurally dense crania have the highest survivorship potential (89%). This study substantiates differences in mean recovery frequencies for skeletal elements according to anatomical location (p < 0.05). Anatomical regions and recovery frequencies were used to produce a simple taphonomic model. Educating law enforcement on the value and appearance of high survivorship bones in the taphonomic model is a recommendation to improve policy and practice.
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Chan, Lok-Chi. "Metaphysical Naturalism and the Ignorance of Categorical Properties." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/16555.
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The purpose of this dissertation is to investigate the connections between metaphysical naturalism and the categorical ignorance thesis – offered by Rae Langton (1998), David Lewis (2009), Frank Jackson (1998), and Simon Blackburn (1990) – and determine whether the latter will challenge the former. According to metaphysical naturalism, the actual world contains only metaphysically natural things. According to the categorical ignorance thesis, all we can know about things are their dispositional properties, but the categorical properties that bear these properties remain in principle unknowable. In this dissertation, I will determine whether the ignorance of categorical properties – as Rae Langton (1998), David Braddon-Mitchell and Frank Jackson (2007), John Foster (1993) and Alyssa Ney (2007) argue (or worry about) – is consistent with metaphysical naturalism (or physicalism), and whether it will lead to a scepticism about the metaphysical naturalness of categorical properties, which will, in turn, significantly decrease the probability that metaphysical naturalism is true. Being attracted to metaphysical naturalism, the categorical ignorance thesis, and also the philosophical position that the two theses are consistent, I will argue that the answer to the former question is yes, and that the answer to the latter question is no. Russellian Monism, an influential doctrine in philosophy of mind that is relevant to the topic, will also be considered. According to the doctrine, our first-person experiences are constituted by their categorical bases in some manner that is not (solely) via the dispositions borne by these bases. Some philosophers, such as Bertrand Russell (1992/1927a, 1927b), thus consider categorical properties to be knowable through our acquaintance with those experiences. On the other side, some philosophers, such as Daniel Stoljar (2001a, 2001b, 2006), David Chalmers (1996), and Galen Strawson (2013), argue that Russellian Monism is compatible with metaphysical naturalism (or physicalism). In this dissertation, I will determine whether the acquaintance view put forward by some Russellian Monists, understood as an objection to the categorical ignorance thesis, is true and whether it is compatible with metaphysical naturalism; I will argue that the answers to both questions are no.
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Tennigkeit, Frank. "Intrinsic membrane properties affecting signal transformation in auditory thalamic neurons." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34633.pdf.
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Deardorff, Adam S. "Regulation of Motoneuron Firing Properties: Intrinsic and Circuit-Based Mechanisms." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1432851525.
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Him, Aydin. "Intrinsic membrane properties and plasticity in medial vestibular nucleus neurones." Thesis, University of Edinburgh, 2002. http://hdl.handle.net/1842/23049.
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This thesis describes in vitro electrophysiological experiments on horizontal brainstem slices containing medial vestibular nucleus (MVN) from young adult and aged rats. The whole-cell patch clamp recording technique was used in MVN slices of young adult rats to study intrinsic membrane properties and spike firing characteristics of rostral MVN neurones and their role in vestibular compensation, the behavioral recovery that follows damage to the vestibular receptors or nerve of one inner ear. Extracellular recordings were made in MVN slices of young and aged rats to study age-related changes in the intrinsic activity and GABA receptor sensitivity of MVN neurones. MVN neurones were classified into Type A and Type B cells based on their action potential shapes. Type B cells were further grouped into Type BDP cells, which showed depolarising plateau potentials, and Type BLTS cells, which showed low threshold spikes, according to their firing behaviours in response to depolarising and hyperpolarising current pulses. The results showed that significant adaptive changes take place in intrinsic membrane properties and firing characteristics of specific subpopulations of vestibular neurones in the rostral region of the ipsilateral MVN during vestibular compensation following unilateral labyrinthectomy (UL). Type B cells had significantly higher resting discharges and more depolarised resting membrane potentials in post-UL slices, while Type A cells did not show any change in their in vitro firing rates and resting membrane potential. However, after UL, a greater number of Type A cells expressed spike frequency accommodation, and there was a significant increase in the gain of Type A cells. Significantly more Type B cells showed low threshold spikes in MVN slices of labyrinthectomised rats suggesting that T-type calcium currents were up-regulated in some MVN cells during vestibular compensation. Up-regulation of intrinsic excitability in Type B cells and changes in dynamic membrane properties of Type A cells could be important in vivo in recovery of neuronal activity of MVN cells which are silenced soon after UL.
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Austin, Shane. "The impact of PGC-1alpha on the intrinsic properties of mitochondria." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110743.
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PGC-1alpha is a key factor controlling mitochondrial biogenesis. In this thesis, we demonstrate that PGC-1alpha is also a central regulator of the intrinsic properties of mitochondria. Using mitochondria isolated from muscle tissues of MCK- PGC-1alpha Tg mice that ectopically express PGC-1alpha under the control of the muscle creatine kinase promoter, we observed significant changes in their intrinsic properties compared with wild-type controls. The results illustrate that PGC-1alpha changes the respiratory and ROS generation capacities of mitochondria, while maintaining their topology/sidedness of ROS production. Additionally, PGC-1alpha did not alter the fraction of electrons escaping the respiratory chain to react with oxygen during oxygen consumption, ensuring a tight coupling between the respiratory and ROS generation capacities of mitochondria. These changes in the intrinsic properties of mitochondria upon ectopic expression of PGC-1alpha were accompanied by modifications in the expression of several components of the respiratory chain. Together, these data reveal that PGC-1alpha does not only change the number of mitochondria in cells but also the intrinsic properties of individual mitochondria within the cell.PGC-1alpha est un facteur clé contrôlant la biogénèse mitochondriale. Dans cette thèse, nous démontrons que PGC-1alpha est aussi un régulateur important des propriétés intrinsèques des mitochondries. Utilisant des mitochondries isolées de tissus musculaires de souris transgéniques MCK-PGC-1alpha qui expriment ectopiquement PGC-1alpha sous le contrôle du promoteur de la créatine kinase musculaire, nous avons observé des changements significatifs à leurs propriétés intrinsèques comparativement à des mitochondries de souris sauvages. Spécifiquement, nous démontrons que PGC-1alpha change les capacités respiratoires et génératrices d'espèces réactives oxygénées (ROS) des mitochondries, bien qu'il maintienne leur topologie de production de ROS. De plus, PGC-1alpha n'altère pas la fraction d'électrons qui s'échappent de la chaine respiratoire pour ensuite réagir avec l'oxygène durant le processus de consommation d'oxygène, assurant un couplage étroit entre les capacités respiratoires et génératrices de ROS des mitochondries. Ces changements des propriétés intrinsèques des mitochondries suivant l'expression ectopique de PGC-1alpha ont été accompagnés de modification de l'expression de plusieurs composantes de la chaine respiratoire. Ensemble, ces données révèlent que PGC-1alpha change non seulement le nombre de mitochondries dans les cellules, mais aussi les propriétés intrinsèques des mitochondries individuelles.
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Tran, Duc Long. "Impact of intrinsic granular porosity on the durability properties of concrete." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30021.
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La préservation des ressources naturelles et la limitation des émissions de CO2 sont une contribution au développement durable. Dans le cadre de la conception du béton, cette contribution consiste à utiliser des granulats locaux ou recyclés. Cependant, ces derniers peuvent être poreux et de faible qualité. La communauté scientifique est d'accord sur le fait que la porosité intrinsèque des granulats modifie les propriétés de transport du béton, mais dans quelle mesure reste une question. L'objectif de la thèse est d'analyser l'impact de la porosité intrinsèque des granulats grossiers, principalement sur les propriétés de durabilité du béton. Dans une compréhension préliminaire et en vue d'accentuer les phénomènes se produisant dans le béton, un programme expérimental est conçu pour le modèle élémentaire (EM), qui est composé de pâte et de gravier. L'impact de la nature des granulats (poreux et non poreux), de l'état d'humidité et du volume ainsi que de la nature du liant, est analysé sur i) la porosité de l'eau du modèle élémentaire, ii) la structuration de l'interface pâte-granulat. Ensuite, à l'échelle du béton, les matériaux ont été conçus avec le même squelette de granulats (même sable) et la même teneur équivalente en liant. Les conceptions variaient selon la nature des granulats, l'état d'humidité, la nature du liant, la variation du rapport eau/ciment et l'incorporation d'adjuvants chimiques (plastifiant ou superplastifiant). L'impact de la porosité des granulats grossiers sur les propriétés à l'état frais (affaissement, densité apparente et teneur en air emprisonné) et à l'état durci (résistance à la compression, porosité de l'eau, absorption d'eau, perméabilité aux gaz, migration des chlorures, carbonatation accélérée et teneur en portlandite) a été étudié. Les principaux résultats montrent que l'état d'humidité des agrégats et la nature du liant sont les premiers facteurs qui conditionnent la structuration de l'interface pâte/agrégats au sein du modèle élémentaire. La nécessité d'utiliser des agrégats poreux en surface saturée et sèche est particulièrement mise en évidence. À l'échelle du béton, les propriétés à l'état frais sont influencées par la porosité des granulats et le rapport eau/liant (W/B). Cependant, pour un rapport eau/liant fixe correspondant à une consistance fluide, les variations des propriétés à l'état frais mesurées lors de l'incorporation de granulats poreux ne dépendent pas de la nature du liant. Dans le béton durci, la porosité des granulats joue un rôle important dans la porosité de l'eau et la perméabilité à l'air du béton, quelle que soit la nature du liant. Pour les autres propriétés de durabilité (absorption d'eau, migration de Clo, carbonatation et résistance à la compression), la nature du liant l'emporte sur la porosité des granulatsThe preservation of natural resources and the limitation of CO2 emissions are a contribution to sustainable development. In the context of the concrete design, this contribution consists in using local or recycled aggregates. However, local or recycled aggregates can be porous and of low quality.The scientific community agrees that the intrinsic porosity of aggregates changes the transport properties of concrete, but to what extent is still a question. The objective of the thesis is to analyze the impact of intrinsic coarse aggregate porosity on mainly the durability properties of concrete. In a preliminary understanding and with a view to accentuating phenomena occurring in the concrete, an experimental program is designed for elementary model (EM), which is composed of paste and gravel. The impact of the aggregate nature (porous and non-porous), moisture state and volume together with the binder nature, is analyzed on i) the water porosity of EM, ii) the structuration of the paste-aggregate interface. Next, at concrete scale, materials were designed with the same skeleton of aggregates (same sand) and the same equivalent binder content. The designs varied by the aggregate nature, moisture state, the binder nature, the variation of water/cement ratio and the incorporation of chemical admixtures (plasticizer or superplasticizer). The impact of coarse aggregate porosity on properties in the fresh state (slump, apparent density and entrapped air content) and in the hardened state (compressive strength, water porosity, water absorption, gas permeability, chloride migration, accelerated carbonation and Portlandite content) was studied. The main results show that the moisture state of aggregate and the binder nature are the first factors that condition the structuring of the paste/aggregate interface within the elementary model. The necessity to use porous aggregates in saturated surface dry is particularly highlighted. At the scale of concrete, the properties in the fresh state are influenced by the aggregate porosity and the water/binder (W/B) ratio. However, for a fixed W/B ratio corresponding to fluid consistency, the variations in the fresh properties measured when porous aggregates are incorporated do not depend on the binder nature. In hardened concrete, porosity of aggregate plays an important role in water porosity and air permeability of concrete whatever the nature of binder. For other durability properties (water absorption, Clo migration, carbonation and compressive strength), the nature of binder overcome leading in comparison to the porosity of aggregate
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Zaka, Yasin. "Properties of intrinsic and doped amorphous silicon produced by R.F. Sputtering." Thesis, Aston University, 1985. http://publications.aston.ac.uk/12036/.
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Ring, Kenneth M. "Intrinsic and substrate dependent properties of polycrystalline barium titanate thin films /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p9952670.
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Lee, Jonathan Cheuk Fung. "Intrinsic electrophysiological properties of interstitial cells of Cajal and smooth muscle cells." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ66217.pdf.
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Sigurbjornsson, Omar Freyr. "Vibrational dynamics of icy aerosol particles : phase transitions and intrinsic particle properties." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2795.
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Phase transitions and other intrinsic properties (shape, size, architecture) of molecularly structured aerosol particles are important for understanding their role in planetary atmospheres and for technical applications. By combining bath gas cooling with time resolved mid-infrared spectroscopy and modeling, information is obtained on dynamic processes and intrinsic properties of fluoroform and ethane aerosol particles.
The distinct infrared spectral features of fluoroform aerosol particles make it a particularly suitable model system. Homogeneous crystallization rates of the sub-micron sized aerosol particles are determined (JV = 10⁸ - 10¹⁰ cm-³s-¹ or JS = 10³ – 10⁵ cm-²s-¹ at a temperature of T = 78 K), and the controversial question regarding volume versus surface nucleation in freezing aerosols is addressed. It is demonstrated that current state of the art measurements of droplet ensembles cannot distinguish between the two mechanisms due to inherent experimental uncertainties. The evolution of particle shape from spherical supercooled droplets to cube-like crystalline particles and eventually to elongated crystalline particles is recorded and analyzed in detail with the help of vibrational exciton model calculations.
Phase behaviour of pure ethane aerosols and ethane aerosols formed in the presence of other ice nuclei under conditions mimicking Titan’s atmosphere provide evidence for the formation of supercooled liquid ethane aerosol droplets, which subsequently crystallize. The observed homogeneous freezing rates (JV = 10⁷ – 10⁹ cm-³s-¹) imply that supercooled ethane could play a similar role in ethane rich regions of Titan’s atmosphere as supercooled water does in the Earth’s atmosphere.
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Ganassin, Alberto [Verfasser], Wolfgang [Gutachter] Schuhmann, and Aliaksandr [Gutachter] Bandarenka. "Intrinsic catalytic properties of electrocatalysts / Alberto Ganassin ; Gutachter: Wolfgang Schuhmann, Aliaksandr Bandarenka." Bochum : Ruhr-Universität Bochum, 2017. http://d-nb.info/1129452468/34.
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Lindroos, Robert. "A simplied Medium SpinyNeuron-model with retained intrinsic characteristics and plateau properties." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-143499.
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This master thesis studies how a morphological reduction aects theperformance of a biophysically detailed model of a medium spiny neuron. Themorphological reduction is done using a MATLAB toolbox developed forautomatic 3-dimensional morphological reduction. Two versions of the toolboxare developed in which dierent criteria are used during the merge. Theevaluation of the two toolboxes shows that keeping the absolute distance to thesoma of the branching points and the surface area of the dendrites gives a moreaccurate result than if these criteria are not used. These criteria are implementedin Toolbox 2. In total 8 models with dierent maximal compartment length arethen constructed using Toolbox 2. The number of compartments in the resultingmodels range from 1/2 to 1/10 of the compartments in the original model. Furtherthe performance of the reduced models are evaluated against the original model.The results of this evaluation shows that an increasing compartment length givesa decrease in consistency with the response of the original model. However theresponse of all models are largely similar to the original model.I detta examensarbete studeras hur en biofysikt detaljerad modell av en mediumspiny neuron (direkt oversatt "medellang taggig neuron") paverkas av en reduceringav dess strukturella komplexitet. Denna strukturella reduktion gar till saatt fragmenten som formar modellen slas samman och bildar nya fragment. Denya fragmenten far da en langd motsvarande summan av de sammanslagna fragmentenslangd. For att underlatta den strukturella reduktionen utvecklas ocksa enverktygslada till MATLAB. Verktygsladan ar byggd for att automatiskt reduceraden 3-dimensionella strukturen av en modell baserat pa vissa kriterier. Tva versionerav vertygsladan utvecklas i vilka kriterierna som anvands vid reduktionenskiljer sig fran varandra. Utvarderingen av de bada versionerna visar att omavstandet mellan cellkarnan och de dendritiska forgreningspunkterna samt dentotala dendritiska arean ar konstant sa uppnas ett battre resultat an om dessakriterier inte uppfylls. Dessa kriterier implementeras i den andra versionen avvertygsladan, Toolbox 2. Med hjalp av Toolbox 2 tillverkas sedan 8 reducerademodeller som alla har reducerad struktur men olika maximal langd pa fragmenten.De reducerade Modellerna ar uppbyggda av mellan 1/2 och 1/10 av antalet fragmenti den ursprungliga modellen. De reducerade modellerna jamfors sedan medden ursprungliga modellen. Resultatet av jamforelsen visar att med okad fragmentlangd kommer ocksa en gradvis storre avvikelse fran den ursprungliga modellen.Detta till trots gav alla reducerade modeller en overraskande bra respons ialla test de utsattes for.
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Fuentealba, Durand Pablo José. "Intrinsic and Synaptic Membrane Properties of Neurons in the Thalamic Reticular Nucleus." Thesis, Université Laval, 2004. http://www.theses.ulaval.ca/2004/22126/22126.pdf.
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Le noyau réticulaire thalamique (RE) est une structure qui engendre des fuseaux, une oscillation bioélectrique de marque pendant les stades précoces du sommeil. De multiples propriétés neuronales, intrinsèques et synaptiques, sont impliquées dans la génération, la propagation, le maintien et la terminaison des ondes en fuseaux. D’un autre côté, ce rythme constitue un état spécial de l’activité du réseau qui est généré par le réseau lui-même et affecte les propriétés cellulaires du noyau RE. Cette étude se concentre sur ces sujets: comment les propriétés cellulaires et les propriétés du réseau sont inter-reliées et interagissent pour engendrer les ondes fuseaux dans les neurones du RE et leurs cibles, les neurones thalamocorticaux.
La présente thèse fournit de nouvelles évidences montrant le rôle fondamental joué par les neurones du noyau RE dans la genèse des ondes en fuseaux, dû aux synapses chimiques établies par ces neurones. La propagation et la synchronisation de l’activité sont modulées par les synapses électriques entre les neurones réticulaires thalamiques, mais aussi par les composantes dépolarisantes secondaires des réponses synaptiques évoquées par le cortex. De plus, la forme générale et la terminaison des oscillations thalamiques sont probablement contrôlées en grande partie par les neurones du RE, lesquels expriment une conductance intrinsèque leurs procurant une membrane avec un comportement bistable. Finalement, les oscillations thalamiques en fuseaux sont aussi capables de moduler les propriétés membranaires et l’activité des neurones individuels du RE.The thalamic reticular nucleus (RE) is a key structure related to spindles, a hallmark bioelectrical oscillation during early stages of sleep. Multiple neuronal properties, both intrinsic and synaptic, are implicated in the generation, propagation, maintenance and termination of spindle waves. On the other hand, this rhythm constitutes a special state of network activity, which is generated within, and affects single-cell properties of the RE nucleus. This study is focused on these topics: how cellular and network properties are interrelated and interact to generate spindle waves in the pacemaking RE neurons and their targets, thalamocortical neurons. The present thesis provides new evidence showing the fundamental role played by the RE nucleus in the generation of spindle waves, due to chemical synapses established by its neurons. The propagation and synchronization of activity is modulated by electrical synapses between thalamic reticular neurons, but also by the secondary depolarizing component of cortically-evoked synaptic responses. Additionally, the general shaping and probably the termination of thalamic oscillations could be controlled to a great extent by RE neurons, which express an intrinsic conductance endowing them with membrane bistable behaviour. Finally, thalamic spindle oscillations are also able to modulate the membrane properties and activities of individual RE neurons.
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Hoppe, Konrad. "Complex networks with node intrinsic fitness : on structural properties and contagious phenomena." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/10345.
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Complex networks is a vibrant research field and has received much attention over the last decade. Central to this area is the question of how networks around us are constructed. The essential notion of network research is that these systems are assembled in a decentralised way, thus no central agent is planning the network beforehand. Despite this lack of central coordination, many networks present intriguing universalities, such as broad degree distributions, in the form of power-laws. The subject of study in this thesis is a class of networks that are constructed by a node intrinsic variable, called fitness. The way these networks grow could be called a rich-get-richer mechanism. The fitter a node is, the more likely it is to acquire new connections inside the network. Several aspects that are directly connected to these networks are explored in this thesis. In the first part, the properties of growing networks that are driven by fitness are investigated and it is shown that the introduction of growth leads to a topological structure that is different from its static counterpart. In the subsequent chapter, percolation on fitness driven networks is studied. The results give insights into possible mechanisms that can stabilise systems. Furthermore, the theory can be used to identify vulnerable structures around us. In the following chapter, the world trade network is discussed. This numerical investigation highlights possible improvements to the methodology to make statistical analysis more robust. That chapter is followed by an analysis of time-varying networks. Time-varying networks represent an interesting construct that allows a formulation of stochastic processes on the same time-scale as the evolution of the network itself. This possibility is highly relevant to the investigation of epidemics, for instance. In the last chapter, a study of a system of clusters and their self-organised formation is presented.
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Longford, Francis G. J. "Modelling surface thermodynamics and intrinsic optical properties of the air-water interface." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/419052/.
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Intrinsic surface sampling techniques are used to analyse MD simulations of the air-water interface in order to investigate reports of anomalous optical behaviour recently uncovered by ellipsometry. In doing so, a new approach to calculating surface thermodynamic properties has been described and an overlooked finite size e↵ect a↵ecting surface tension measurements has been uncovered. A correction has also been developed to reduce a fitting bias in the intrinsic sampling method (ISM), which leads to a non-Gaussian distribution of mean curvature at interfacial molecular coordinates on a parametrised intrinsic surface. Consequently, it is now possible to reduce artefacts that prevent successful mapping back of the intrinsic density to the global density at high resolutions via convolution along the axis normal to the interface. A further method has been developed to estimate the local linear optical properties of interface regions, with application to the prediction of ellipsometry experiments. The e↵ective medium approximation for the dielectric permittivity of a system possessing a non-homogeneous polarisation density distribution is combined with an intrinsic surface technique describing the structure of the interface region as a Fourier series. It is concluded that employing the this description allows for optical properties of the air-water interface to be revealed from classical molecular dynamics simulations that are distinct from other polar solvents (methanol), and lie in agreement with new experimental data. This investigation also provides new pathways to determine a more robust description of the intrinsic surface and explores new simulation tools using extended capillary wave theories.
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Mitin, V. F., P. M. Lytvyn, V. V. Kholevchuk, L. A. Matveeva, V. V. Mitin, O. S. Kulyk, and E. F. Venger. "Ge/GaAs(100) Thin Films: Large Effect of Film Growth Rate and Thicknesses on Surface Morphology, Intrinsic Stresses and Electrical Properties." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35066.
Full textAbstract:
We found out and studied a profound effect of film growth rate on the electrical properties, intrinsic
stresses and surface morphology of thin Ge films grown on GaAs(100). This effect is essential and has to be
accounted for when developing and producing devices based on the Ge/GaAs heterostructure. All the Ge
films under investigation were single-crystalline and epitaxially-grown on the GaAs(100) substrates. However,
the transport phenomena in Ge films grown at low and high deposition rate differed drastically.
Those obtained at low deposition rate were p-type and high resistant. They had a low concentration of free
charge carriers and thermally activated conductivity, which is characteristic of heavily doped and strongly
(in the limiting case, fully) compensated semiconductors. Although such films were single-crystalline, their
conductivity was percolation-type. The Ge films obtained at high deposition rate were n-type and low resistant.
They had high concentration of free charge carriers. The temperature dependence of conductivity
in such films was weak or practically absent, which is characteristic of degenerate heavily doped semiconductors.
Besides, the surface morphology cardinally differed for films obtained at low and high deposition
rate. At low film growth rates, surfaces with developed relief were observed whose valleys and ridges
formed grains of irregular shape with pronounced substructure. As the film thickness grew, the surface relief
became essentially pronounced. At rather high film deposition rates, contrary to the above, the Ge film
surface was fine-grained and smooth; the surface relief practically did not depend on the film thickness. As
the deposition rate went down, the intrinsic stresses in films essentially decreased. The results obtained
were analyzed from the viewpoint of formation of compositional and morphological inhomogeneities, and
fluctuations of electrostatic potential at low growth rates. Such potential fluctuations modulate Ge energy
bands leading to appearance of potential relief and deep tails of density of states in the Ge bandgap.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35066
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Sousa, Felipe Domingos de. "Physicochemical properties of plant hemicelluloses." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=12378.
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CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel SuperiorIn this work six galactomannans (Adenanthera pavonina, Caesalpinia pulcherrima, Delonix regia, Dimorphera mollis, Prosopis glandulosa, Schizolobium parahyba) and three xyloglucans (Hymenaea courbaril, Mucuna sloanei e Tamarindus indica) were isolated from seed endosperm and cotyledon, respectively, by aqueous extraction followed by precipitation with ethanol. Yield of extraction, monosaccharide ratio, macromolecular parameters as well as molar mass distribution were determined and compared to guar gum (Cyamopsis tetragonoloba), LBG (Ceratonia siliqua) and xanthan (Xanthomonas campestris). Extraction yield in relation to seed mass ranged from 7.0 to 40.63%, with xyloglucan yields higher than the galactomannans ones. Schizolobium parahyba and Caesalpinia pulcherrima galactomannans presented the lowest protein content of 0.05% e 0.08%, respectively. The Mw values ranged from 0.09 â 3.37 x107 g mol-1 Flow curves of hemicelluloses solutions at 1% (w:v) were measured by varying the shear rate from 0.1 to 100 s-1. The resulting data were fit to the Power law e Herschel-Bulkley models. All the hemicelluloses presented shear-thinning behavior. Galactomannan and xyloglucans with different monosaccharide ratio showed similar consistency index; it may be influenced of the galactose distribution pattern on the chains and the interactions among the polysaccharides molecules. Rheological properties were compared and the results suggest new hemicelluloses sources which offer more profound applications in areas such as materials science, medicine e biology.
As hemiceluloses sÃo polissacarÃdeos presentes na parede celular de vegetais, onde funcionam como polissacarÃdeos de reserva e possuem uma cadeia principal composta por ligaÃÃes β-(1→4) em configuraÃÃo equatorial. Neste trabalho, hemiceluloses de sementes foram avaliadas quanto as suas propriedades reolÃgicas. Como resultado, galactomananas endospÃrmicas de Adenanthera pavonina, Caesalpinia pulcherrima, Delonix regia, Dimorphera mollis, Prosopis glandulosa e Schizolobium parahyba e xiloglucanas cotiledonÃrias de Hymenaea courbaril, Mucuna sloanei e Tamarindus indica foram isoladas por extraÃÃo aquosa, seguida por precipitaÃÃo em etanol. O rendimento das extraÃÃes, razÃo monossacarÃdica, parÃmetros macromoleculares, assim como distribuiÃÃo de massa molar foram determinados e comparados Ãs jà comercializadas goma guar (Cyamopsis tetragonoloba), LBG (Ceratonia siliqua) e goma xantana (Xanthomonas campestris). O rendimento das extraÃÃes em relaÃÃo à massa das sementes mostrou um intervalo de 7,0 a 40,63%, com os maiores valores para as xiloglucanas. Galactomananas de Schizolobium parahyba e Caesalpinia pulcherrima apresentaram os menores percentuais de proteÃnas, 0,05% e 0,08%, respectivamente. Valores de Mw variaram dentro de um intervalo entre 0,09 â 3,37 x107 g mol-1. Curvas de fluxo das soluÃÃes de hemiceluloses a 1% (m:v) foram obtidas pela variaÃÃo da taxa de cisalhamento entre 0,1 a 100 s-1. Os dados obtidos foram analisados pelos modelos de Lei das PotÃncias e Hershel-Bulkley demonstrando carÃter pseudoplÃstico para todas as hemiceluloses estudadas nessa concentraÃÃo. Galactomananas e xiloglucanas com diferentes razÃes monossacarÃdicas apresentaram Ãndice de consistÃncia similar, provavelmente influenciado pelo padrÃo de distribuiÃÃo de galactose nas cadeias e as interaÃÃes entre as molÃculas desses polissacarÃdeos. As propriedades reolÃgicas foram comparadas e os resultados sugerem novas fontes de hemiceluloses que permitem mais aplicaÃÃes em Ãreas como ciÃncia dos materiais, medicina e biologia.
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Camp, John L. "3-D Model Characterization and Identification from Intrinsic Landmarks." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1323135521.
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Katterwe, Sven-Olof. "Properties of small Bi2Sr2CaCu2O8 intrinsic Josephson junctions: confinement, flux-flow and resonant phenomena." Doctoral thesis, Stockholms universitet, Fysikum, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-62583.
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In this thesis, intrinsic Josephson junctions, naturally formed in the strongly anisotropic high-temperature superconductor Bi2Sr2CaCu2O8 (Bi-2212), are studied experimentally. For this purpose, small mesa structures are fabricated on the surface of single crystals using micro- and nano-fabrication tools, focused ion beam is used to reduce the area of the mesa-structures down to ≈ 1 × 1 μm2. The properties of charge transport across copper-oxide layers inside the mesas are studied by intrinsic tunneling spectroscopy. Temperature, bias and magnetic field dependences of current-voltage characteristics are examined. In the main part of the thesis, the behavior of intrinsic Josephson junctions in magnetic fields B parallel to the copper-oxide planes is studied. Parallel magnetic fields penetrate the junctions in the form of Josephson vortices (fluxons). At high magnetic fields, fluxons are arranged in a regular lattice and are accelerated by a sufficient high transport current. As the fluxon lattice is moving through the mesa, it emits electromagnetic waves in the important THz frequency range. Properties of Bi-2212 mesas in this flux-flow regime are studied in this thesis. The following new observations were made during the course of this work: a crossover from thermal activation above Tc to quantum tunneling below Tc is seen in the interlayer transport-mechanism, the Fraunhofer pattern of Ic(B) is observed clearly in Bi-2212, superluminal electromagnetic cavity resonances and phonon-polaritons are observed in Bi-2212. It is argued that the employed technique for miniaturization of mesas and the obtained results can be useful for a better understanding of fundamental properties of high-temperature superconductors and for the realizations of coherent flux-flow oscillators and coherent phonon-polariton generators in the important THz frequency range.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 6: Manuscript.
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Golea, Mostefa. "AB(2)C(4) semiconducting compounds crystal growth, intrinsic defects and optical properties." Thesis, University of Ottawa (Canada), 1988. http://hdl.handle.net/10393/5374.
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Guda, Kurumurthy. "The effect of interactions on intrinsic properties of polariton condensates in semiconductor microcavities." Thesis, University of Sheffield, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.632726.
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Steinhaus, Thomas. "Determination of intrinsic material flammability properties from material tests assisted by numerical modelling." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/3273.
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Computational Fluid Dynamics (CFD) codes are being increasingly used in the field of fire safety engineering. They provide, amongst other things, velocity, species and heat flux distributions throughout the computational domain. The various sub-models associated with these have been developed sufficiently to reduce the errors below 10%-15%, and work continues on reducing these errors yet further. However, the uncertainties introduced by using material properties as an input for these models are considerably larger than those from the other sub-models, yet little work is being done to improve these. Most of the data for these material properties comes from traditional (standard) tests. It is known that these properties are not intrinsic, but are test-specific. Thus, it can be expected that the errors incurred when using these in computations can be significant. Research has been held back by a lack of understanding of the basic factors that determine material flammability. The term “flammability” is currently used to encompass a number of definitions and “properties” that are linked to standardised test methodologies. In almost all cases, the quantitative manifestations of “flammability” are a combination of material properties and environmental conditions associated with the particular test method from which they were derived but are not always representative of parameters linked intrinsically with the tested material. The result is that even the best-defined parameters associated with flammability cannot be successfully introduced into fire models to predict ignition or fire growth. The aim of this work is to develop a new approach to the interpretation of standard flammability tests in order to derive the (intrinsic) material properties; specifically, those properties controlling ignition. This approach combines solid phase and gas modelling together with standard tests using computational fluid dynamics (CFD), mass fraction of flammable gases and lean flammability limits (LFL). The back boundary condition is also better defined by introducing a heat sink with a high thermal conductivity and a temperature dependant convective heat transfer coefficient. The intrinsic material properties can then be used to rank materials based on their susceptibility to ignition and, furthermore, can be used as input data for fire models. Experiments in a standard test apparatus (FPA) were performed and the resulting data fitted to a complex pyrolysis model to estimate the (intrinsic) material properties. With these properties, it should be possible to model the heating process, pyrolysis, ignition and related material behaviour for any adequately defined heating scenario. This was achieved, within bounds, during validation of the approach in the Cone Calorimeter and under ramped heating conditions in the Fire Propagation Apparatus (FPA). This work demonstrates that standard flammability and material tests have been proven inadequate for the purpose of obtaining the “intrinsic” material properties required for pyrolysis models. A significant step has been made towards the development of a technique to obtain these material properties using test apparatuses, and to predict ignition of the tested materials under any heating scenario. This work has successfully demonstrated the ability to predict the driving force (in-depth temperature distribution) in the ignition process. The results obtained are very promising and serve to demonstrate the feasibility of the methodology. The essential outcomes are the “lessons learnt”, which themselves are of great importance to the understanding and further development of this technique. One of these lessons is that complex modelling in conjunction with current standard flammability test cannot currently provide all required parameters. The uncertainty of the results is significantly reduced when using independently determined parameters in the model. The intrinsic values of the material properties depend significantly on the accuracy of the model and precision of the data.
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Prole, David L. "Intrinsic functional properties of neuronal KCNQ2/KCNQ3 potassium channels : insights into channel structure." Thesis, University of Bristol, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400272.
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Lu, Cong. "Epitaxial growth and intrinsic magnetic properties of magnetic thin films on semiconductor materials." Thesis, University of York, 2013. http://etheses.whiterose.ac.uk/9987/.
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Spin electronics, or spintronics, is an emergent interdisciplinary area whereby the spin degree of freedom in electronic devices is employed. One of the most important topics of spintronics is to develop magnetic/semiconductor hybrid materials for the next generation spin devices such as Spin-FET. This dissertation investigates the magnetic properties of magnetic thin films deposited on semiconductor substrate. Fe and Ni films have been deposited onto GaAs substrate with different substrate treatment. Both single and poly crystalline samples were developed during the process, and the magnetic properties were compared to explore the differences. The origin of a uniaxial magnetic anisotropy (UMA) from the crystal symmetry of the bcc Fe, observed in Fe/GaAs (100) has been investigated. Another major work for this thesis is the Artemis TR-ARPES (time resolved – angular resolved photoemission spectroscopy) project in Rutherford Appleton Laboratory. Successful MBE growth was achieved for the first time during the Artemis TR-ARPES project, followed by static and time-resolved MOKE, and time-resolved photoemission measurements. Preliminary time-resolved photoemission spectroscopy measurements has been performed on the single crystal Fe samples, which is the world first result in term of the study of the time-dependent valence band structures using direct photoemission technique from a metallic material. The research finally extended to the CoFeB film on GaAs substrate. The discovery of uniaxial magnetic anisotropy of this amorphous film make it one of the hottest topic in research. XMCD measurements were conducted and the results went through a series of calculations gives an indication of the relation between magnetic moment to the anisotropy. TEM inspections offers a clear look at the interface of the samples.
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Semeniuk, Daniel J. "Cell growth regulation is an intrinsic property of the alpha-fetoprotein molecule." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0028/NQ50299.pdf.
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Lemieux, Maxime. "The slow oscillation as an intrinsic and emergent property of the neocortex." Doctoral thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25573.
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Le sommeil est présent chez pratiquement tous les animaux mais a atteint le plus haut niveau d’organisation chez les mammifères et les oiseaux avec le sommeil à ondes lentes et le sommeil paradoxal. De nombreuses études ont suggéré que le sommeil est généré par le cerveau pour ses propres besoins. L’oscillation lente est une caractéristique électroencéphalographique du sommeil à ondes lentes se traduisant par une alternance entre des états actif et silencieux du réseau thalamocortical. Elle a attiré le focus de plusieurs études étant donné son implication dans la plasticité synaptique et la consolidation de la mémoire. Plusieurs questions restent néanmoins en suspens. Quel est le rôle du thalamus dans l’oscillation lente? Quelles conditions mènent à l’état silencieux? Y a-t-il une variabilité entre espèces dans la synchronisation des ondes lentes? Dans la première étude de cette thèse, nous montrons que le thalamus est crucial à la genèse et à la propagation de l’oscillation lente alors que le cortex a la propriété intrinsèque de la restaurer en absence d’afférence fonctionnelle. Dans la seconde étude, nous nous intéressons aux conditions qui mènent à l’initiation des états silencieux dans le néocortex. Nous avons trouvé que l’inhibition dépendante du chlore est impliquée dans la terminaison des états actifs et que les afférences thalamocorticales jouent un rôle dans la synchronisation des états silencieux. Dans la troisième étude, nous comparons le niveau de synchronisation de l’oscillation lente dans les régions somatosensorielle et associative du néocortex chez le chat et le lapin. Nous rapportons que la synchronisation de l’oscillation lente corrèle avec le niveau de gyrification du cortex cérébral et le niveau hiérarchique dans le traitement de l’information d’une région néocorticale. Nous concluons que l’oscillation lente est une propriété intrinsèque du néocortex qui émerge du dialogue entre le néocortex et le thalamus, de la balance entre l’inhibition et l’excitation dans le réseau néocortical et dont la synchronisation a évolué avec le développement du cortex cérébral.Sleep is a defining feature of animals that achieved the highest degree of organization in mammals with two distinct types of sleep: the slow wave sleep (SWS) and the rapid eye movements sleep. A large body of evidences suggests that the sleep is generated by the brain to fulfill its own need. Among the electroencephalographic signatures of SWS and anesthesia, the slow oscillation (< 1 Hz), a rhythmic alternation of active and silent states of the thalamocortical network, has attracted a lot of attention owing to its implication in synaptic plasticity and memory consolidation. Several questions remain unanswered on the mechanisms underlying the slow oscillation. For instance, what is the role of the thalamus in the slow oscillation? Which conditions lead to the onset of the silent state? Is there inter-species variability in the synchronization? In the first study of this thesis, we have investigated the respective contribution of the neocortex and the thalamus in the generation of the slow oscillation. We report that the thalamus is crucial to the generation and propagation of the active states of the slow oscillation while the neocortex has the intrinsic ability to recover the slow oscillation in absence of afferents. In the second study, we address the question regarding the conditions that lead to the onset of the silent state in the neocortex. We have found that chloride-mediated inhibition and functional thalamocortical afferents are involved in terminating the active states. In the third study, we compare the synchronization of the slow oscillation in the somatosensory and associative cortices of cats and rabbits. We have found that the synchronization of the slow waves correlates with the level of gyrification of the cerebral cortex and the hierarchical level of information processing of a neocortical region. We conclude that the slow oscillation is an intrinsic property of the neocortex that emerges from the dialogue between the neocortex and thalamus, the balance of inhibition and excitation in the neocortical network and that the synchronization of the slow oscillation evolved with the development of the cerebral cortex.
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Darhmaoui, Hassane. "Critical currents and intrinsic properties of Y¦1Ba¦2Cu¦3O¦7-¦delta thin films." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq22972.pdf.
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Csatorday, Peter 1973. "Studies of intrinsic properties of gamma ray bursts detected by the HETE-II satellite." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/39294.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, February 2007.Includes bibliographical references (p. 141-146).
Analysis of HETE-II data is discussed with the aim of understanding the intrinsic properties of gamma-ray bursts (GRBs). A technique is developed that allows the simultaneous estimation of source and background counts during a burst with coded aperture instruments such as the Wide-field X-ray Monitor (WXM) on HETE-II. A closely related photon-by-photon statistical bootstrap analysis is then described that can be used to compute the non-Gaussian error distribution of GRB temporal statistics. This is applied to the T90 and To.45 duration measures. The distribution of T90 has been extensively studied since the availability of the BATSE gamma-ray burst catalogs and is widely believed to be log-normally distributed. It is shown that intrinsically, GRBs may in fact have a much narrower distribution, and the wide log-normal may primarily be due to measurement artifacts. Computation of the TO.45 parameter enables the inference of redshifts through the recently discovered Liso-Epk-TO.45 relation. This in turn allows the compilation of a flux-limited sample of bursts with redshifts that is free of the observational selection effects inherent in spectroscopic catalogs. This analysis is performed for 31 WXM bursts and redshift-corrected distributions of T90 and T0.45 are computed.
(cont.) It is shown for the first time that the distribution of T0.45 can be modeled by an exponential distribution. The redshifts calculated through the Liso-Epk-TO.45 relation are also used to calculate the implied isotropic luminosities. The normalized luminosity function and redshift distribution of gamma-ray bursts are derived using the non-parametric methods of Lynden-Bell and Efron & Petrosian. The results imply strong evidence for luminosity evolution with redshift and are consistent with prior studies based on BATSE bursts. Concordance cosmology (QA = 0.7, QM = 0.3, Ho=70 km s-1 Mpc-1) is assumed throughout the analysis. Effects of log-normal errors in the redshifts are estimated using Monte-Carlo methods. Results indicate that a fraction close to 10% of GRBs are to be expected at high redshifts (> 5) in consonance with theoretical predictions of high-redshift Swift detections.
by Peter Csatorday.
Ph.D.
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Omar, Ahmad. "Disentangling the Intrinsic Attributes and the Physical Properties in Cobalt-based Quaternary Heusler Compounds." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-199751.
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Heusler compounds are cubic intermetallics with a wide range of interesting properties, which are closely related to the structure of the material. In addition, several exotic physical phenomena have been predicted for different compositions in the family, but have not been experimentally realized. By and large, the lack of success in realization of various properties are due to the issues with intrinsic material attributes, which have been difficult to resolve as the relationship between them is not well understood. The aim of this work has been to unravel the entanglement between the intrinsic material attributes of cobalt-based quaternary Heusler compounds such as the structure, defects (disorder), chemical inhomogeneities etc., and the resulting physical properties.
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Yoon, Im T. (Im Taek). "Anisotropy of conduction electrons in n-InSb and extrinsic and intrinsic properties of HgCdTe." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc332803/.
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The anistropy of the orbital and spin properties of conduction electrons in InSb has been measured simultaneously using a cyclotron-resonance type experiment. This represents the first time that the anistropy of effective mass in InSb has been directly measured using an optical method.
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Chen, Qian. "Evolution, interaction, and intrinsic properties of dislocations in intermetallics anisotropic 3D dislocation dynamics approach /." [Ames, Iowa : Iowa State University], 2008.
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Kirch, Nienkotter Rocha Bruna. "Intrinsic variations in geometric properties of nonlinear equivalent strut models for infill-RC frames." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2019. https://ro.ecu.edu.au/theses/2187.
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Reinforced concrete frames infilled with unreinforced masonry are commonly used in structures worldwide. The interaction between the frame and the infill panel is usually ignored in engineering practice, and the masonry infill is not considered as a structural element. However, observations made after the occurrence of strong earthquakes have shown that the bare frame and infill-frame behave differently when subjected to in-plane lateral loads. Extensive research has been conducted on the behaviour of infill-frames when laterally loaded. This research focuses on the analysis of infill-frames using the equivalent strut modelling method, whereby an infill-frame is simplified, and the infill panel is replaced by one or more compressive strut elements. A large number of strut models have been proposed in the literature, but recent studies have demonstrated that it is not possible to apply one strut model to all infill-frame structures. It has been found that changing the properties of an infill-frame can also change the geometric properties of struts, namely width, location and number of struts in an equivalent strut model. For this reason, recent studies have proposed a case-specific strut modelling approach. In the current study, a macro script available in the literature that can be used to generate a detailed finite element (FE) model has been applied to construct and analyse a number of infill-frames with different material and geometric properties. Sensitivity analyses on some of these infill-frames have also been conducted by varying the material properties of the infill, and the amount and distribution of vertical loads on the frame. The results of detailed FE analyses, more specifically contours of the compressive principal stresses, have been used to define the geometric properties of the struts of case-specific strut models for each of the infill-frames. Equivalent strut models were then analysed and compared. Further, the proposed strut models were applied to other infill-frames selected for this study; two strut models from the literature were also applied to these infill-frames. It was concluded that the geometric properties of, and the vertical load on an infill-frame can be related to the geometric properties of its equivalent strut model. In contrast, a variation of up to 25% in the masonry material properties did not have a significant effect on the strut properties. It was shown that casespecific strut modelling is a versatile and generic technique that can adequately replicate the highly nonlinear behaviour of infill-frames regardless of their geometric or material properties. By expanding the current research, it is hoped that a rigorous classification of infill-frames and their relevant equivalent strut models can be developed to assist structural engineers in their everyday design tasks.
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Komori, Sachio. "Epitaxial Growth and Superconducting Properties of 1212 Copper Oxides." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215546.
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Reifler, Ellen Sarah. "Investigation of Intrinsic and Tunable Properties of Two-Dimensional Transition-Metal Dichalcogenides for Optical Applications." Research Showcase @ CMU, 2018. http://repository.cmu.edu/dissertations/1182.
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Since the scotch-tape isolation of graphene, two-dimensional (2D) materials have been studied with increasing enthusiasm. Two-dimensional transition-metal dichalcogenides are of particular interest as atomically thin semiconductors. These materials are naturally transparent in their few-layer form, have direct band gaps in their monolayer form, exhibit extraordinary absorption, and demonstrate unique physics, making them promising for efficient and novel optical devices. Due to the two-dimensional nature of the materials, their properties are highly susceptible to the environment above and below the 2D films. It is critical to understand the influences of this environment on the properties of 2D materials and on the performance parameters of devices made with the materials. For transparent optical devices requiring electrical contacts and gates, the effect of transparent conducting oxides on the optical properties of 2D semiconductors is of particular importance. The ability to tune the optical properties of 2D transition-metal dichalcogenides could allow for improved control of the emission or absorption wavelength of optical devices made with the materials. Continuously tuning the optical properties of these materials would be advantageous for variable wavelength devices such as photodetectors or light emitters. This thesis systematically investigates the intrinsic structural and optical properties of two-dimensional transition-metal dichalcogenide films, the effect of substrate-based optical interference on the optical emission properties of the materials, and demonstrates methods to controllably tune the luminescence emission of the materials for future optical applications. This thesis advances the study of these materials toward integration in future efficient and novel optical devices. The specific transition metal dichalcogenides investigated here are molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2), tungsten disulfide (WS2), and tungsten diselenide (WSe2). The thickness-dependence of the intrinsic in-plane crystal structure of these materials is elucidated with high-resolution transmission electron microscopy; thickness-dependent optical properties are studied using Raman and photoluminescence spectroscopies. This thesis investigates the optical interference effects from substrates with transparent conducting oxide layers on the optical properties of few-layer MoS2 films. An understanding of these effects is critical for integrating MoS2 into efficient optical devices. We predict contributions of optical interference effects to the luminescence emission of few-layer MoS2 films. The predictions are experimentally verified. We also demonstrate the use of optical interference effects to tune the wavelength and intensity of the luminescence emission of few-layer MoS2. This thesis explores the use of electric fields applied perpendicular to the films to continuously and reversibly tune the band gap of few-layer MoS2 for future variable wavelength devices. To facilitate integration into devices, we demonstrate electric fieldinduced band gap tuning by applying electric fields with a pair of transparent or semitransparent conducting layers, and without the need for direct electrical contact to the MoS2 films. The observed band gap tuning is attributed to the Stark Effect. We discuss challenges to maximizing the effect of electric field-induced band gap tuning. We demonstrate that optical interference effects do not prevent observation of band gap tuning via applied electric fields. We successfully combine two luminescence emission tuning methods: optical interference effects and electric field effects.
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Balu, Ramani. "Intrinsic and Synaptic Properties of Olfactory Bulb Neurons and Their Relation to Olfactory Sensory Processing." Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1173540900.
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Wang, Di. "Ion channels and intrinsic membrane properties of locomotor network neurons in the lamprey spinal cord." Stockholm : Department of Neuroscience, Karolinska Institutet, 2009. http://diss.kib.ki.se/2009/978-91-7409-722-1/.
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Hayes, John A. "Phenotypic properties and intrinsic currents of neurons involved in the neural generation of mammalian breathing." W&M ScholarWorks, 2007. https://scholarworks.wm.edu/etd/1539623329.
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Breathing is essential for mammalian life. Although there is an emerging consensus that the inspiratory respiratory rhythm is generated in a lower brainstem region known as the preBotzinger Complex (preBotC), the mechanism of rhythmogenesis is still unclear. Additionally, the modulation of intrinsic currents within preBotC neurons has yet to be fully elucidated. This dissertation addresses both of these issues and relies on imaging, electrophysiological, and modeling techniques. The first chapter examines the size and composition of the preBotC. The chapter also decribes the means by which substance P (SP) excites the vast majority of preBotC neurons by illustrating the characteristics of the SP-activated current (/SP) in these neurons. In the subsequent chapter, we characterize a voltage-dependent potassium current that is involved in maintaining stable rhythms during normal fictive breathing. The third chapter presents a mathematical model of heterogeneous and rhythmogenic neurons that initiate network bursts. We show how this behavior relies on feedback synaptic connections within the network that reinforces activity, i.e., recurrent-excitation. We also compare model results to experimental data and make testable predictions. The final chapter elaborates on the discussion of /SP from the first chapter and presents evidence suggesting that a cyclic adenosine monophosphate (cAMP)-modulated non-specific cation channel may account for the depolarizing response in preBotC neurons from several neuromodulators. Altogether, this dissertation advances the field's understanding on several fronts. We have distinguished possible functional roles of neurons from electrophysiological characteristics, estimated the number of neurons necessary for rhythmogenesis, characterized /SP , and clarified the distribution of SP-sensitive receptors among inspiratory neurons. We have identified and characterized a voltage-dependent potassium currrent important for inspiratory activity and analyzed its role. We have also described in detail how rhythmic bursts form from recurrent excitation and how this relates to experimental data. Finally, we have identified and begun characterizing a potentially important and novel mechanism for the modulation of membrane potentials in critical inspiratory neurons.
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Xue, Wei xue. "Measurements of Cellular Intrinsic Magnetism with Cell Tracking Velocimetry and Separation with Magnetic Deposition Microscopy." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461231847.
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Fave, Sebastian Philipp. "Investigative Application of the Intrinsic Extended Finite Element Method for the Computational Characterization of Composite Materials." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50483.
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Computational micromechanics analysis of carbon nanotube-epoxy nanocomposites, containing aligned nanotubes, is performed using the mesh independent intrinsic extended finite element method (IXFEM). The IXFEM employs a localized intrinsic enrichment strategy to treat arbitrary discontinuities defined through the level-set method separate from the problem domain discretization, i.e. the finite element (FE) mesh. A global domain decomposition identifies local subdomains for building distinct partition of unities that appropriately suit the approximation. Specialized inherently enriched shape functions, constructed using the moving least square method, enhance the approximation space in the vicinity of discontinuity interfaces, maintaining accuracy of the solution, while standard FE shape functions are used elsewhere. Comparison of the IXFEM in solving validation problems with strong and weak discontinuities against a standard finite element method (FEM) and analytic solutions validates the enriched intrinsic bases, and shows anticipated trends in the error convergence rates. Applying the IXFEM to model composite materials, through a representative volume element (RVE), the filler agents are defined as individual weak bimaterial interfaces. Though a series of RVE studies, calculating the effective elastic material properties of carbon nanotube-epoxy nanocomposite systems, the benefits in substituting the conventional mesh dependent FEM with the mesh independent IXFEM when completing micromechanics analysis, investigating effects of high filler count or an evolving microstructure, are demonstrated.Master of Science
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Romer, Shannon Hunt. "The Organization of Kv2.1 ChannelProteins in the Membrane of Spinal Motoneurons:Regulation by Injury and Cellular Activity." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1425136084.
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Laghari, Gul Mohammad. "Preparation and properties of polybenzodioxane PIM-1 and its copolymers with poly(ethylene glycol)." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/preparation-and-properties-of-polybenzodioxane-pim1-and-its-copolymers-with-polyethylene-glycol(1b728ac9-9362-415d-ae6a-61dd3ffde884).html.
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This thesis describes the synthesis of soluble Polymer of Intrinsic Microporosity (PIM-1), fluoro-endcapped PIM-1 (F-PIM-1) and copolymers of F-PIM-1 with poly(ethylene glycol) monomethyl ether (MeOPEG). The main aim of the project was to alter the porosity of microporous PIM-1 in three ways: (a) synthesis of copolymers of F-PIM-1 with MeOPEG (b) blending of PIM-1 with MeOPEG in various proportions; and (c) adsorption of MeOPEG from aqueous solution byPIM-1. PIM-1 and F-PIM-1 were synthesized by step growth polymerization of tetrafluoroterephthalonitrile (TFTPN) with 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane (THSB), using the conventional method and a newly reported high shear mixing method. F-PIM-1 oligomers were then coupled to poly(ethylene glycol) monomethyl ether (MeOPEG). The products were analyzed by NMR, IR, MALDI ToF MSS, TGA and polystyrene based GPC as well as multidetector GPC techniques. The high shear technique generally produced high molar mass products and yields. This method was also more successful for copolymerization.Blending of PIM-1 and MeOPEG in different proportions resulted in macrophase separation. Copolymer products were used to facilitate mixing of blends (as compatibilizers), however only 5% of MeOPEG could be solubilised into a PIM-1 phase. The effect of compatibilizer was found to be affected by interaction between PIM-1 and copolymer. However, N2 adsorption studies showed that after thermal removal of MeOPEG, PIM-1 regained stable porosity with significant BET surface area.Fluorescence studies were aimed at applications of PIM-1 and copolymers in sensors. PIM-1 and copolymers, spin-coated on the polyester-based substrate Melinex, were studied with and without methanol treatment in an environment of different solvent vapours. The effect of time and volume on wavelength shift and change in intensity was studied. Polar solvents tended to cause a red shift with decrease in intensity while less polar solvents behaved otherwise. Based on fluorescence experiments, solvent profiles for PIM-1 and copolymers were established.
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Dirba, Imants [Verfasser], Oliver [Akademischer Betreuer] Gutfleisch, and Rainer [Akademischer Betreuer] Niewa. "Fe8Nx Thin Films and Nanoparticles: from Intrinsic Properties Towards Magnetic Applications / Imants Dirba ; Oliver Gutfleisch, Rainer Niewa." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/113486597X/34.
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Bammann, Rodrigo Roberto. "Differential effects of serotonin and nitric oxide on the intrinsic properties and network activity of cortical neurons." Thesis, University of Leicester, 2015. http://hdl.handle.net/2381/31981.
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Serotonin (5HT) and nitric oxide (NO) are important signalling molecules with roles in behavioural control and various psychological conditions. Various lines of evidence suggest interactions between 5HT and NO signalling, however little is known about their interaction in modulating intrinsic properties of cortical neurons and the effects on the neuronal network activity in the cortex. This project studied the effects of 5HT and NO on cultured neurons isolated from Wistar rat cortices. 5HT and NO produced diverse responses in cortical neurons, reflecting the heterogeneity of cortical neuron types. Neither 5HT nor NO appeared to significantly modulate glutamate induced depolarisations. However, they affected the number of APs elicited by the glutamate response, hinting at the possible modulation of intrinsic membrane properties. Subsequently, k-Means clustering based on 10 electrophysiological parameters was used to divide cultured cortical neurons into 10 different cell types with consistent firing properties. 5HT and NO had diverse, cell-type specific effects on neuronal excitability and cellular parameters in these cell types. Furthermore, 5HT and NO showed complex interactions between each other, suggesting modulatory cross-talk. Using ODQ to block soluble guanylate cyclase activity suggests that NO effects are mediated not only by sGC/cGMP signalling, but also S-nitrosylation. Comparing results obtained in cell culture to data from acute cortical slices showed similarities in basic cellular properties. However, 5HT and NO effects on pyramidal cell properties differed markedly between slices and cultures. At the network level, 5HT increased the spontaneous EPSC frequency in pyramidal neurons through 5HT2 receptors, whereas NO had no effect. Interestingly, NO was able to reduce the 5HT induced increase in EPSC frequency when inhibitory synaptic interactions were blocked, possibly by modulating 5HT1 receptor function. The results obtained demonstrate the interaction between 5HT and NO in modulating both intrinsic membrane properties and neocortical network activity.
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Lund, Anna. "Material properties of recycled PET in beverage containers." Thesis, KTH, Fiber- och polymerteknologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-296504.
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PET har under lång tid använts för flasktillverkning eftersom den är lätt, har goda barriäregenskaper och kan enkelt bearbetas industriellt. På senare tid har miljömedvetenheten ökat i samhället och därmed efterfrågan på återvunnet material, däribland PET-flaskor. Redan idag tillverkas flaskor med helt återvunnen PET. Återvunnen PET har dock kvalitetsproblem. Därför uppstår frågan hur materialegenskaperna hos 100% återvunna PET-flaskor påverkas av upprepade återvinningscykler. I den här rapporten undersöks hur den kemiska strukturen och egenskaperna förändras hos materialen allt eftersom fler återvinningscykler genomförs. Tre olika återvunna PET-material används för att ge ett bredare undersökningsunderlag och dessa tre material jämförs sedan sinsemellan samt med jungfrulig PET (icke-återvunnen PET) som referens. Egenskaperna analyseras med DSC för att ge information om termiska egenskaper, ATR-FTIR utförs för att detektera nedbrytning och förändring i den kemiska strukturen, dragprovning görs för att se hur återvinningen påverkar de mekaniska egenskaperna hos materialen och slutligen analyseras även den inneboende viskositeten hos de återvunna materialen. Examensarbetet visar på en markant minskning av inneboende viskositet med antalet återvinningscykler. Dessutom kan viss nedbrytning hos den kemiska strukturen ses via ATR-FTIR fastän inte så tydligt. Även en tendens till minskad kristallinitet med återvinning kan ses med DSC. En minskning i kristallinitet möjliggör produktion av mer transparenta flaskor, vilket ofta är eftertraktat. Emellertid får materialet försämrade barriäregenskaper. Dock krävs mer forskning för att kunna dra några slutsatser gällande materialegenskaper i industriell skala.PET has been used in bottle production for a long time since it is lightweight, easily processable and has good barrier properties. In recent years, the awareness of environmental issues has increased and thereby the demand for recycled materials, including PET bottles. Already today PET bottles with 100% recycled PET are produced. However, recycled PET bottles have quality problems. Thereby, the question arises how the material properties of 100% recycled PET bottles are affected when subjected to multiple recycling loops. In this report the changes in chemical structure and material properties of the materials are investigated as more recycling loops are performed. Three different recycled PET materials are used to give a broader base of information. These materials are compared to each other and to virgin PET (not recycled PET) as a reference. The materials are analysed with DSC to give information about the thermal properties, ATR-FTIR to detect changes in the chemical structure, tensile testing to see how the recycling affects the mechanical properties of the material and finally the intrinsic viscosity is analysed for the recycled materials. In this master thesis a clear decrease in intrinsic viscosity with increasing number of recycling loops can be observed. In addition, some degradation of the chemical structure can be seen through ATR-FTIR, although not very clearly. Also, a decrease in crystallinity with the number of recycling loops can be seen from DSC. A decrease in crystallinity enables production of more transparent bottles, which is often desired, although the material will have reduced barrier properties. However, more research is required to draw any conclusions regarding the material properties on an industrial scale.