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1
Obermeier, Michael. "Untersuchungen an Pistolenkrebsen (Alpheus heterochaelis Say 1818) zur Bedeutung von Wasserströmen und chemischer Signale in intraspezifischen Interaktionen." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969864477.
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Bergk, Beate. "De-Haas-van-Alphen-Untersuchungen nichtmagnetischer Borkarbidsupraleiter." Doctoral thesis, Berlin Logos-Verl, 2010. http://d-nb.info/1002009383/04.
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Bergk, Beate. "de Haas-van Alphen Untersuchungen nichtmagnetischer Borkarbidsupraleiter." Doctoral thesis, Technische Universität Dresden, 2009. https://tud.qucosa.de/id/qucosa%3A25240.
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Im Rahmen dieser Doktorarbeit werden de Haas-van Alphen-Untersuchungen an den nichtmagnetischen Borkarbidsupraleitern LuNi2B2C und YNi2B2C präsentiert. Aus den Quantenoszillationen in der normalleitenden Phase in Kombination mit Bandstrukturrechnungen konnten Informationen über die verzweigte Fermiflächenarchitektur und über die Elektron-Phonon-Kopplung der Borkarbide gewonnen werden. Die Kopplung ist stark anisotrop und fermiflächenabhängig. Dies spricht für einen Mehrbandmechanismus der Supraleitung in der Materialklasse.
Zusätzlich konnten de Haas-van-Alphen-Oszillationen mehrerer Fermiflächen unterhalb von Bc2 tief in der Shubnikov-Phase beobachtet werden. Das Verhalten dieser Oszillationen lässt sich nicht mit bisher bekannten Theorien beschreiben. Allerdings weist das Bestehen der Oszillationen weit unterhalb von Bc2 auf ein Bestehen von elektronischen Zuständen in der Shubnikov-Phase hin.
4
Miller, Paul. "De Haas - van Alphen oscillation in the vortex state." Thesis, University of Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240525.
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BOUFELFEL, ALI. "DE HAAS - VAN ALPHEN EFFECT IN QUENCHED PLATINUM CRYSTALS." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184187.
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The oscillatory de Haas-van Alphen (DHVA) magnetization has been studied in Pt crystals containing more than 100 ppm vacancies. Magnetic fields as high as 75 kG were used. The oscillations were observed at temperatures as low as 0.45 k, and found to be strongly attenuated by the vacancies in this concentration range. The emphasis of this work is on the measurement of this attenuation for the purpose of studying conduction electron scattering due to single vacancies. Dingle (scattering) temperatures due to vacancies are reported for four cyclotron orbits with the field in a (110) plane, along with a new measurement of the cyclotron effective mass (m* = 2.31 ± 0.03) for the electron orbit 33° away from <100>. Vacancies were generated by quenching Pt single crystals from temperatures as high as 1730 °C in air, using a technique which minimizes the induced strain. The vacancy contribution to the electron scattering rate was separated by measuring the Dingle temperature in both quenched and annealed specimens which had been subjected to the same quenching process. The results suggest that there is only a moderate variation in this scattering rate over the s-p-like electron sheet of the Fermi surface. However, the scattering rate for the d-like open hole sheet, which contacts the Brillouin zone, is about 49% larger than that for the electron sheet. This anisotropy is attributed mainly to the lattice distortion around a vacancy and to the difference between the hole and electron wave-function symmetries.
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Read, Arthur Thomas. "Reversal and maintenance of claw asymmetry in the snapping shrimp Alpheus heterochelis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ35296.pdf.
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Goh, S. K. "Probing Mott delocalisation using the de Haas-van Alphen effect." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599463.
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The physics of Mott delocalisation is investigated from the perspective of Fermiology through a series of high resolution de Haas-van Alphen experiments. Two systems in which some or all electrons can be forced to Mott localise by an experimental tuning parameter were chosen. The first system is CeRh1-xCoxIn5 where the 4f electron of CeRhIn5 can be driven into a delocalised state by Co substitution. The Fermi surface of CeRh1-xCoxIn5 was studied for six different values of x. By measuring the angular dependence of de Haas-van Alphen frequencies, a Fermi surface sheet with f-electron character was observed to undergo an abrupt change in topology as x is varied. This reconstruction does not occur at the quantum critical concentration xc, where antiferromagnetism is suppressed to T = 0. Instead this sudden change occurs well below xc, deep inside the antiferromagnetic state. Across all concentrations, the quasiparticle effective mass of this sheet does not diverge, suggesting this critical behaviour is not exhibited equally on all parts of the Fermi surface. The second system of interest is the Mott insulator Ca2RuO4, which can be metallised at 0.6 GPa. A completely new setup, utilising a 10-turn signal pick-up coil in an anvil cell for field modulation measurements, was developed for performing de Haas-van Alphen experiments under pressure. This novel setup thus has the potential to reach much higher pressures than the existing piston-cylinder type setup, opening up a much bigger phase space for future exploration in materials physics. The newly developed method was tested using Sr2RuO4 and the results are in excellent agreement with a broad body of literature. Subsequently, the method was applied to study the metallic state of Ca2RuO4. De Haas-van Alphen signals were successfully recorded at high pressure using both the cryomagnetic system in Cambridge up to 18 T and a resistive magnet in National High Magnetic Field Laboratory in Tallahassee up to 31 T. Comparisons to band structure calculations were made.
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Bintley, D. "Unconventional superconductivity studied by the de Haas van Alphen effect." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399936.
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Haworth, Christopher. "The de Haas-van Alphen effect and the superconducting state." Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294551.
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Corcoran, Robin. "The de Haas van Alphen effect in type II superconductors." Thesis, University of Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294745.
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Fletcher, Jonathon David. "Penetration depth and de Haas - Van Alphen studies of magnesium diboride." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.495614.
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The recently discovered superconductor MgB2 has the highest critical-temperature (Tc) of any non-cuprate superconductor. It is also the first clear example of two gap superconductor. In this material, the presence of significant gap anisotropy, combined with Fermi surface sheets of different anisotropy leads to many unusual properties in the superconducting state. This thesis includes a study of the anisotropy in the London penetration depth, and that of Hc2 in MgB2. Unusually, these are both temperature dependent due to multi-gap effects.
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Harrison, Neil. "The de Haas-van Alphen effect in Y-Ba-Cu-O superconductors." Thesis, University of Bristol, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317152.
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Jaudet, Cyril. "Effet de Haas-van Alphen dans les supraconducteurs à haute température critique." Toulouse 3, 2009. http://thesesups.ups-tlse.fr/701/.
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Ce travail de thèse est basé sur des mesures d'oscillations quantiques de l'aimantation dans les supraconducteurs à haute température critique. Ces matériaux ont été découvert en 986 par Bednorz et Müller. Ils sont caractérisés par la présence de plans CuO2 dont on peut faire varier la concentration électronique. A faible dopage, ces systèmes se comportent comme un isolant, les électrons étant localisés par une forte répulsion coulombienne. A très fort dopage, ces systèmes retrouvent un comportement de type liquide de Fermi. Entre ces deux extrêmes, un dôme supraconducteur, dont la température critique maximum correspond au dopage dit optimum, apparaît. Différentes sondes expérimentales ont révélé, du côté sous-dopé, la présence d'une phase dite \emph{pseudogap}. La physique de ces systèmes soulève plusieurs questions fondamentales: quelle est la nature de cette phase \emph{pseudogap}, quel est le mécanisme d'appariement à l'origine de la supraconductivité. Au cours de cette thèse, nous avons développé un système de mesure de l'aimantation par cantilever piezorésistif sous champ magnétique intense à très basse température. Nos mesures ont révélé la présence d'oscillations quantiques de l'aimantation des deux cotés du diagramme de phase et ce pour la première fois. Ces oscillations prouvent l'existence d'une surface de Fermi fermée et cohérente qui évolue d'une large orbite de trou du côté sur-dopé à une surface de Fermi contenant une ou plusieurs petites poches du côté sous-dopé. De plus, la présence d'un battement de ces oscillations suggère la restauration de la cohérence selon l'axe c à très basse température du côté sous-dopé du diagramme de phase. Ces différents faits expérimentaux vont dans le sens d'un état fondamental de type liquide de Fermi. Le \emph{pseudogap} marquerait alors l'apparition d'une phase ordonnée en compétition avec la supraconductivitéThis thesis work is based on quantum oscillation measurements of the magnetization in high temperature superconductors. These materials were discovered in 1986 by Bednorz and Müller. They are characterized by the presence of CuO2 planes of which the electronic concentration can be changed. At low doping, these systems have insulating behavior, the electron being localised by strong Coulomb repulsion. At very high doping, these systems recover Fermi liquid behavior. Between these two extremes there is a superconducting dome at which the maximum critical temperature corresponding to a doping, called optimum, arises. Various experimental probes reveal, on the underdoped side, the presence of the so-called \emph{pseudogap} phase. The physics of this system raise several fundamental questions: What is the nature of this \emph{pseudogap} phase and what is the pairing mechanism at the origin of this superconductivity. During this thesis, we have developed a measurent system of the magnetization with a piezoresistive cantilever under high magnetic field and at very low temperature. Our measurements have revealed the presence of quantum oscillations of the magnetization for the first time on each side of the phase diagram. These oscillations attest of the existence of a closed and coherent Fermi surface which evolves from a huge orbit of holes on the overdoped side to a Fermi surface containing one or several small pockets on the underdoped side. Moreover, the presence of a beating in these oscillations suggest the restoration of the coherence along the c-axis at very low temperature and at very high magnetic field on the underdoped side. These different experimental facts are consistent with a Fermi liquid fundamental state. The \emph{pseudogap} is a hallmark of the appearance of an ordered phase in competition with superconductivity
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Alphei, Lukas-David [Verfasser]. "Reaktive Benetzungsphänomene am Beispiel der Si(1)/SiO2(s) Grenzfläche / Lukas-David Alphei." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2015. http://d-nb.info/1075258510/34.
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Hill, Robert W. "Measurements of Landau quantum oscillations in heavy fermion systems." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319091.
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Duncan, Kevin P. "The semiclassical theory of the de Haas-van Alphen oscillations in type-II superconductors." Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297817.
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Mercure, Jean-François. "The de Haas van Alphen effect near a quantum critical end point in Sr₃Ru₂O₇ /." St Andrews, 2008. http://hdl.handle.net/10023/683.
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Mercure, Jean-Francois. "The de Haas van Alphen effect near a quantum critical end point in Sr₃Ru₂O₇." Thesis, University of St Andrews, 2008. http://hdl.handle.net/10023/683.
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Highly correlated electron materials are systems in which many new states of matter can emerge. A particular situation which favours the formation of exotic phases of the electron liquid in complex materials is that where a quantum critical point (QCP) is present in the phase diagram. Neighbouring regions in parameter space reveal unusual physical properties, described as non-Fermi liquid behaviour. One of the important problems in quantum criticality is to find out how the Fermi surface (FS) of a material evolves near a QCP. The traditional method for studying the FS of materials is the de Haas van Alphen effect (dHvA). A quantum critical end point (QCEP) has been reported in the highly correlated metal Sr₃Ru₂O₇, which is tuned using a magnetic field high enough to perform the dHvA experiment. It moreover features a new emergent phase in the vicinity of the QCEP, a nematic type of electron ordering. The subject of this thesis is the study of the FS of Sr₃Ru₂O₇ using the dHvA effect. Three aspects were explored. The first was the determination of the FS at fields both above and below that where the QCEP arises. The second was the search for quantum oscillations inside the nematic phase. The third was a reinvestigation of the behaviour of the quasiparticle effective masses near the FS. In collaboration with angle resolved photoemission spectroscopy experimentalists, a complete robust model for the FS of Sr₃Ru₂O₇ at zero fields was determined. Moreover, the new measurements of the quasiparticle masses revealed that no mass enhancements exist anywhere around the QCEP, in contradiction with previous specific heat data and measurements of the A coefficient of the power law of the resistivity. Finally, we report dHvA oscillations inside the nematic phase, and the temperature dependence of their amplitude suggests strongly that the carriers consist of Landau quasiparticles.
19
Polyakov, Andrey. "Fermi-surface investigations of rare-earth transition-metal compounds." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-113653.
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The interplay of partially filled d- or f-electron shells with conduction-band electrons is a key ingredient in new rare-earth transition-metal compounds for the emergence of unusual electronic and magnetic properties. Among which unconventional superconductivity is one of the most studied. Despite many years of intensive experimental investigations and plenty promising theoretical models, unconventional superconductivity still remains hotly debated a very rich topic. One of the fundamental unsolved problems for condensed-matter physicists is the mechanism that causes the electrons to form anisotropic superconductivity.
Since electrons in the vicinity of the Fermi level are primarily responsible for superconductivity, in order to better understand the mechanism giving rise to this phenomenon and the origin of complex forces between correlated electrons, knowledge of the Fermi surface and band selective effective mass is essential. Of the many techniques used to study electronic band-structure properties, measurements of quantum oscillations in the magnetization, so-called de Haas-van Alphen (dHvA) effect, in combination with band-structure calculations is the traditional proven tool for studying Fermi-surface topology and quasiparticle effective mass.
In the present work, electronic structure and Fermi-surface properties of Ybsubstituted heavy fermion superconductor CeCoIn5 and iron based ternary phosphides LaFe2P2 and CeFe2P2 have been investigated by means of dHvA measurements. For these measurements, capacitive cantilever-torque magnetometry was utilized.
In Ce1−xYbxCoIn5, the evolution of the Fermi surface and effective mass was studied as a function of Yb concentration. The observed topology change is consistent with what is expected from the band-structure calculations. For a small Yb concentration, x = 0.1, the band-structure topology and the effective masses remain nearly unchanged compared to CeCoIn5. This contrasts clearly modified Fermi surfaces and light, almost unrenormalized effective masses for x = 0.2 and above. For LaFe2P2 and CeFe2P2, the obtained effective masses are light. Good agreement between the calculated and measured dHvA frequencies was identified only for LaFe2P2. However, for CeFe2P2 strong disagreement was observed. Moreover, different CeFe2P2 single crystals reveal different experimental results. In order to reconcile the results of the dHvA measurements and density-functional-theory calculations more work is necessary.
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Schiller, Martin. "Quantenoszillationsexperimente an quasi-zweidimensionalen organischen Metallen : (BEDT-TTF) 4 (Ni(dto) 2 ) und Kappa-(BEDT-TTF) 2 I 3 /." [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10067912.
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Weiß, Herbert Dieter. "Fermi surface studies on the organic superconductor Kappa-(BEDT-TTF) 2 Cu[N[CN] 2 ]Br and on the alkanline earth subnitride NaBa 3 Nby means of magneto-quantum oscillations." [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9218369.
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Pescinelli, Régis Augusto [UNESP]. "Dinâmica populacional do camarão Alpheus brasileiro Anker, 2012 (Decapoda: Caridea: Alpheidae) em Cananéia, extremo sul do estado de São Paulo, Brasil." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/131957.
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000851505.pdf: 1328033 bytes, checksum: 059f33005a4f430d1ccfe867ed388e6e (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O crescimento relativo, a maturidade sexual morfológica e funcional, o período reprodutivo, o recrutamento, a razão sexual, o pareamento heterossexual e a fecundidade de Alpheus brasileiro foram investigados. Os camarões foram coletados de março de 2013 a janeiro de 2014, manualmente, na zona intermareal estuarina de Cananéia, SP. Os indivíduos foram identifi4cados em relação ao sexo e mensurados quanto às estruturas: comprimento da carapaça (CC), comprimento do própodo do quelípodo (CPQ), largura do própodo do quelípodo (LPQ), altura do própodo do quelípodo (APQ), comprimento da segunda pleura abdominal (CP), comprimento do apêndice interno (CAI) e comprimento do apêndice masculino (CAM). Foram coletados 186 indivíduos durante o período, sendo 92 machos e 94 fêmeas. As relações que melhor demonstraram mudanças na taxa de crescimento entre jovens e adultos, as quais também utilizadas para estimar a maturidade sexual morfológica para machos e fêmeas, foram CPQ vs. CC e CP vs. CC, com maturidade estimada em 4,70 e 4,77 mm de CC respectivamente. A maturidade funcional encontrada foi 4,80 mm de CC. O período reprodutivo caracterizou-se como sazonal contínuo assim como o recrutamento, mostrando-se uma exceção ao padrão esperado para espécies tropicais e subtropicais. Não houve diferença significativa na razão sexual (M:F) (p > 0,05), provavelmente em função do comportamento de pareamento, no qual ocorre a formação de pares em espécies gonocóricas, favorecendo a distribuição igualitária entre machos e fêmeas. Durante, o estudo 42 pares (macho e fêmea) foram capturados. Os casais estiveram presentes na população em todos os meses estudados. O comportamento territorial é intenso e comumente encontrado nos camarões Alpheidae, portanto, a estratégia de pareamento pode garantir a sobrevivência e o sucesso reprodutivo dos casais. A fecundidade média calculada...
The aim of this study was to investigate the relative growth, the morphological and functional sexual maturity, the spawning period, recruitment, sex ratio, heterosexual pairing and fertility of the snapping shrimp Alpheus brasileiro. Shrimps were captured manually from March 2013 to January 2014 in the intertidal estuarine zone of Cananéia, SP. Individuals were identified according to sex and measured in relation to the carapace length (CL), propodus cheliped length (PCL), propodus cheliped width (PQW), propodus cheliped height (PQH), length of second abdominal pleura (PL), internal appendix length (IAL) and male appendage length (MAL). During the studied period, 186 individuals were collected, 92 males and 94 females. The relationships that best evidencied changes in growth rate between juveniles and adults were CPQ vs. CC and CP vs. DC. These relationships were used to estimate the morphological sexual maturity for males and females, which were 4.70 and 4.77 mm CW, respectively. The functional maturity was calculated in 4.80 mm CW. The reproductive period was characterized as seasonal continuous, as well as the recruitment, which is considered as an exception to the expected pattern for tropical and subtropical species. There was no statistically significant difference in sex ratio (M: F) (p> 0.05). This fact is probably due to the pairing behavior, in which the pair formation occurs in gonocoric species and favors equal distribution between males and females. During the study 42 pairs (male and female) were captured. Couples were present in the population in all months of sampling. Territorial behavior is intense and it is commonly found in Alpheidae shrimp, so the pairing strategy can ensure survival and reproductive success. The mean fertility calculated was 148.53 ± 93.37, related to 28 females. There was a positive correlation between the number of eggs and the carapace, Spearman correlation (p<0.05), highlighting a ...
CNPq: 30574/2013-9
FAPESP: 2013/12136-4
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Pescinelli, Régis Augusto. "Dinâmica populacional do camarão Alpheus brasileiro Anker, 2012 (Decapoda: Caridea: Alpheidae) em Cananéia, extremo sul do estado de São Paulo, Brasil /." Botucatu, 2015. http://hdl.handle.net/11449/131957.
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Orientador: Rogerio Caetano da CostaBanca: Marcelo Antonio Amaro Pinheiro
Banca: Alexandre Oliveira de Andrade
Resumo: O crescimento relativo, a maturidade sexual morfológica e funcional, o período reprodutivo, o recrutamento, a razão sexual, o pareamento heterossexual e a fecundidade de Alpheus brasileiro foram investigados. Os camarões foram coletados de março de 2013 a janeiro de 2014, manualmente, na zona intermareal estuarina de Cananéia, SP. Os indivíduos foram identifi4cados em relação ao sexo e mensurados quanto às estruturas: comprimento da carapaça (CC), comprimento do própodo do quelípodo (CPQ), largura do própodo do quelípodo (LPQ), altura do própodo do quelípodo (APQ), comprimento da segunda pleura abdominal (CP), comprimento do apêndice interno (CAI) e comprimento do apêndice masculino (CAM). Foram coletados 186 indivíduos durante o período, sendo 92 machos e 94 fêmeas. As relações que melhor demonstraram mudanças na taxa de crescimento entre jovens e adultos, as quais também utilizadas para estimar a maturidade sexual morfológica para machos e fêmeas, foram CPQ vs. CC e CP vs. CC, com maturidade estimada em 4,70 e 4,77 mm de CC respectivamente. A maturidade funcional encontrada foi 4,80 mm de CC. O período reprodutivo caracterizou-se como sazonal contínuo assim como o recrutamento, mostrando-se uma exceção ao padrão esperado para espécies tropicais e subtropicais. Não houve diferença significativa na razão sexual (M:F) (p > 0,05), provavelmente em função do comportamento de pareamento, no qual ocorre a formação de pares em espécies gonocóricas, favorecendo a distribuição igualitária entre machos e fêmeas. Durante, o estudo 42 pares (macho e fêmea) foram capturados. Os casais estiveram presentes na população em todos os meses estudados. O comportamento territorial é intenso e comumente encontrado nos camarões Alpheidae, portanto, a estratégia de pareamento pode garantir a sobrevivência e o sucesso reprodutivo dos casais. A fecundidade média calculada...
Abstract: The aim of this study was to investigate the relative growth, the morphological and functional sexual maturity, the spawning period, recruitment, sex ratio, heterosexual pairing and fertility of the snapping shrimp Alpheus brasileiro. Shrimps were captured manually from March 2013 to January 2014 in the intertidal estuarine zone of Cananéia, SP. Individuals were identified according to sex and measured in relation to the carapace length (CL), propodus cheliped length (PCL), propodus cheliped width (PQW), propodus cheliped height (PQH), length of second abdominal pleura (PL), internal appendix length (IAL) and male appendage length (MAL). During the studied period, 186 individuals were collected, 92 males and 94 females. The relationships that best evidencied changes in growth rate between juveniles and adults were CPQ vs. CC and CP vs. DC. These relationships were used to estimate the morphological sexual maturity for males and females, which were 4.70 and 4.77 mm CW, respectively. The functional maturity was calculated in 4.80 mm CW. The reproductive period was characterized as seasonal continuous, as well as the recruitment, which is considered as an exception to the expected pattern for tropical and subtropical species. There was no statistically significant difference in sex ratio (M: F) (p> 0.05). This fact is probably due to the pairing behavior, in which the pair formation occurs in gonocoric species and favors equal distribution between males and females. During the study 42 pairs (male and female) were captured. Couples were present in the population in all months of sampling. Territorial behavior is intense and it is commonly found in Alpheidae shrimp, so the pairing strategy can ensure survival and reproductive success. The mean fertility calculated was 148.53 ± 93.37, related to 28 females. There was a positive correlation between the number of eggs and the carapace, Spearman correlation (p<0.05), highlighting a ...
Mestre
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Siewert, Christiane. "Development of regulatory T cells and induction of mucosa-specific homing." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2007. http://dx.doi.org/10.18452/15697.
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Bei der Aufrechterhaltung des homeostatischen Gleichgewichts und der peripheren Selbst-Toleranz spielen CD4+CD25+ regulatorische T-Zellen (Tregs) eine wichtige Rolle. In Vorarbeiten wurden Subpopulationen von murinen CD4+ Tregs identifiziert, die sich durch die Expression des Integrins alphaE auszeichnen. Diese alphaE+ Treg Subpopulationen weisen einen Effektor/Memory-ähnlichen Phänotyp auf. In der vorliegenden Dissertation wurde untersucht, welche Bedingungen zur Entwicklung von alphaE+ Effektor/Memory Tregs in vivo führen und aus welchen Vorläuferzellen sie entstehen. Dabei zeigte sich, dass es sich bei den alphaE+ Tregs um Effektor/Memory T-Zellen handelt, die unter physiologischen Bedingungen in vivo ein hohes Maß an Zellteilung aufweisen, welche zum Teil abhängig von der bakteriellen Besiedelung des Darms ist. Darüber hinaus wurde beobachtet, dass alphaE+ Tregs nach oraler, antigen-spezifischer Aktivierung in den darm-assozierten lymphoiden Geweben sowohl aus konventionellen naiven CD4+ T-Zellen, als auch aus thymus-generierten naiven CD4+CD25+ Tregs entstehen können. Zusammenfassend deuten die erzielten Ergebnisse darauf hin, dass das spezifische mukosale Mikroenvironment sowohl die Expansion als auch Konvertierung von Tregs fördert und so eine wichtige Rolle für die Aufrechterhaltung der Homeostase von alphaE+Foxp3+ Tregs spielt. Zudem wurde in dieser Arbeit die Ausbildung von gewebespezifischen Homingrezeptor-Phänotypen von naiven CD4+CD25+ Tregs untersucht. In in vitro Kultur-Systemen zeigte sich, dass selektive Modulation von Tregs, ähnlich wie bei konventionellen T-Zellen, die Induktion von organspezifischen Migrationseigenschaften ermöglicht. So konnte eine effiziente Wanderung von Tregs in den Darm ausgelöst werden. Diese Daten legen den Schluss nahe, dass die Herstellung von Tregs mit spezifischen Wanderungseigenschaften eine Option für therapeutische Anwendungen in der adoptiven T-Zell Therapie sein könnte.Regulatory CD4+CD25+ T cells (Tregs) play an important role in immune homeostasis and in the maintenance of self-tolerance. Previously, subsets of murine CD4+ Tregs characterised by expression of the integrin alphaE had been identified. These alphaE+ Treg subsets display an effector/memory-like phenotype. In the present study the circumstances favouring in vivo generation of effector/memory-like alphaE+ Tregs were analysed. The results presented here show that alphaE+ effector/memory-like Treg subsets contain a large fraction of cycling cells under physiologic conditions in healthy mice. This in vivo proliferation depended, at least in part, on intestinal commensal microflora. Furthermore, it was observed that alphaE+ Tregs not only developed by differentiation of naive-like CD4+CD25+ Tregs, but were also generated de novo from naive CD4+ T cells in the gut-associated lymphoid tissue upon oral antigen delivery. Taken together, these results indicate that the mucosal microenvironment favours both expansion and conversion of Tregs and thereby represents an important mechanism for the homeostatic maintenance of alphaE+Foxp3+ Tregs. In addition, susceptibility of naive CD4+CD25+ Tregs to acquire tissue-specific homing receptor phenotypes was investigated. In vitro culture systems demonstrated that Tregs, similarly to conventional T cells, could be configured with organ-selective homing properties allowing efficient targeting into the gut. These results suggest that generation of Tregs with specific homing properties for therapeutic purposes in adoptive T cell therapy might be a feasible option.
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Pricopi, Lucia. "Etude de la masse effective des fermions lourds CeAl2 et CeRu2Si2 par mesures de l'effet de Haas-van Alphen sous champs magnétiques pulsés." Toulouse 3, 2001. http://www.theses.fr/2001TOU30044.
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Clayton, N. J. "Quantum oscillations in organic metals and superconductors." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326720.
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Bach, Alexandra P. R. "Instrumentation and thermometry for the study of heavy fermion compounds." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340154.
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Westerkamp, Tanja. "Quantenphasenübergänge in den Schwere-Fermionen-Systemen Yb(Rh_{1-x}M_x)_2Si_2 und CePd_{1-x}Rh_x." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1244202394324-81635.
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Die Betrachtung von Schwere-Fermionen-Systemen stellt ein wichtiges Themengebiet im Bereich der Festkörperphysik dar. Das Verhalten von Schwere-Fermionen-Systemen wird durch die starken Korrelationen der magnetischen Momente der ungepaarten Spins der f-Elektronen bestimmt. Experimentell zugängliche Messgrößen sind dadurch bei tiefen Temperaturen stark erhöht, so dass sich diese Systeme besonders gut zur Untersuchung von Grundzustandseigenschaften eignen. Zentrales Thema dieser Arbeit ist die Untersuchung zweier intermetallischer Seltenerd-Verbindungen in Bezug auf Quantenphasenübergänge. Diese treten am absoluten Nullpunkt der Temperatur als Funktion eines anderen Parameters wie Magnetfeld, Druck oder chemischer Substitution auf und sind bei endlicher Temperatur durch Abweichungen physikalischer Messgrößen von der durch L. D. Landau aufgestellten Theorie der Fermi-Flüssigkeiten nachzuweisen. Zu diesem Zweck wurden Tieftemperaturexperimente bis hinab zu 20mK und in Magnetfeldern bis zu 18T durchgeführt. Es wurden elektrischer Widerstand, magnetische Wechselfeldsuszeptibilität, Magnetostriktion und thermische Ausdehnung gemessenThe investigation of heavy-fermion systems marks an important subject in the research field of solid state physics. The behaviour of heavy-fermion systems is dominated by the strong correlations of the magnetic moments of the unpaired f-electron spins. At low temperatures, experimentally accessible variables are strongly enhanced so that these systems are especially suited to analyse ground state properties. The central topic of this thesis is the investigation of two intermetallic rare-earth compounds with regard to quantum phase transitions. The latter occur at zero temperature as a function of parameters such as magnetic field, pressure or chemical substitution. They are traceable at finite temperature due to deviations of physical variables from the theory of Fermi liquids established by L. D. Landau. For this purpose, low-temperature experiments were performed down to 20mK and in magnetic fields up to 18T. Electrical resistivity, magnetic ac susceptibility, magnetostriction and thermal expansion were measured
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Gozzoli, Manuel. "Intelligenza Artificiale: tecniche e applicazioni." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Westerkamp, Tanja. "Quantenphasenübergänge in den Schwere-Fermionen-Systemen Yb(Rh_{1-x}M_x)_2Si_2 und CePd_{1-x}Rh_x." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A23821.
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Die Betrachtung von Schwere-Fermionen-Systemen stellt ein wichtiges Themengebiet im Bereich der Festkörperphysik dar. Das Verhalten von Schwere-Fermionen-Systemen wird durch die starken Korrelationen der magnetischen Momente der ungepaarten Spins der f-Elektronen bestimmt. Experimentell zugängliche Messgrößen sind dadurch bei tiefen Temperaturen stark erhöht, so dass sich diese Systeme besonders gut zur Untersuchung von Grundzustandseigenschaften eignen. Zentrales Thema dieser Arbeit ist die Untersuchung zweier intermetallischer Seltenerd-Verbindungen in Bezug auf Quantenphasenübergänge. Diese treten am absoluten Nullpunkt der Temperatur als Funktion eines anderen Parameters wie Magnetfeld, Druck oder chemischer Substitution auf und sind bei endlicher Temperatur durch Abweichungen physikalischer Messgrößen von der durch L. D. Landau aufgestellten Theorie der Fermi-Flüssigkeiten nachzuweisen. Zu diesem Zweck wurden Tieftemperaturexperimente bis hinab zu 20mK und in Magnetfeldern bis zu 18T durchgeführt. Es wurden elektrischer Widerstand, magnetische Wechselfeldsuszeptibilität, Magnetostriktion und thermische Ausdehnung gemessen.The investigation of heavy-fermion systems marks an important subject in the research field of solid state physics. The behaviour of heavy-fermion systems is dominated by the strong correlations of the magnetic moments of the unpaired f-electron spins. At low temperatures, experimentally accessible variables are strongly enhanced so that these systems are especially suited to analyse ground state properties. The central topic of this thesis is the investigation of two intermetallic rare-earth compounds with regard to quantum phase transitions. The latter occur at zero temperature as a function of parameters such as magnetic field, pressure or chemical substitution. They are traceable at finite temperature due to deviations of physical variables from the theory of Fermi liquids established by L. D. Landau. For this purpose, low-temperature experiments were performed down to 20mK and in magnetic fields up to 18T. Electrical resistivity, magnetic ac susceptibility, magnetostriction and thermal expansion were measured.
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Balthes, Eduard. "Electron correlations in the 2D multilayer organic metal kappa-(BEDT-TTF) 2 I 3 in magnetic fields." [S.l. : s.n.], 2004. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-29283.
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Green, Alexander Christopher Maurice. "Correlated electrons in heavy fermion and double exchange systems." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312479.
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KUPFER, JOHN CARLTON. "A SEARCH FOR CHANGES IN THE BAND STRUCTURE OF EXTREMELY STRAIN-FREE MAGNESIUM-CADMIUM CRYSTALS AS A FUNCTION OF ALLOYING, IN THE DILUTE LIMIT (DE HAAS-VAN ALPHEN, FERMI SURFACE)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/187953.
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We report here a study of a specific doublet of de Haas-van Alphen frequencies in pure Mg and very dilute Mg(Cd) alloys with the magnetic field aligned with the c-axis. The work involved three stages. First, the use of extremely strain-free crystals, temperatures down to 40 millidegree Kelvin, large amplitude modulation, and the fast Fourier transform allowed the components of this doublet to be well resolved. This resolution allowed measurement of the changes in the cross-sectional area as a function of magnetic field orientation to verify the assignment of this doublet to the cap and monster arm junction at the top of the Brillouin zone. Third, with the magnetic field aligned with the c-axis, the splitting of this doublet offered a direct and sensitive indication of any symmetry breaking changes in the 0001 Fourier component of the ionic lattice potential in Mg upon the introduction of Cd. C. B. Friedberg's analysis of his electron interference lineshape data from the quantum interferometer in Mg had indicated that the energy of this band gap should increase by 40% with the introduction of 15 ppm Cd. Our data indicate that any change in the energy of the band gap must be at least three orders of magnitude smaller than that indicated by Friedberg. Our data are, in fact, consistent with there being no changes in the electronic band structure or the Fermi surface of Mg(Cd) alloys (with up to 0.02% (At) Cd), from that of pure Mg.
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Predrag, Kuzmanović. "Korelacija radioloških i strukturnih karakteristika građevinskih materijala." Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2020. https://www.cris.uns.ac.rs/record.jsf?recordId=114752&source=NDLTD&language=en.
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U ovoj doktorskoj disertaciji predstavljena je radiološka i strukturna karakterizacija građevinskih materijala koji se mogu naći u upotrebi u Srbiji. Izvršena je radiološka karakterizaicija ukupno 348 uzoraka: granita, fosfogipsa, sirovina u keramičkoj industriji, keramičkih pločica, betona, opeke, maltera, siporeksa, crepa i drugihgrađevinskih materijala opšte upotrebe. Radiološka karakterizacija je sprovedena merenjem koncentracija aktivnosti 226 Ra,232 Th i 40 K metodom gama spektrometrije, kao i ekshalacije radona iz selektovanih građevinskih materijala korišćenjem aktivnih uređaja RAD7, RTM 1688-2, AlphaGUard i AlphaE. Korišćenjem Monte Karlo simulacija izvršena je procena jačina apsorbovanih dozagama zračenja, uočena su odstupanja od teorijski procenjenih vrednosti i dati predlozi za korekciju. Izvršena je procena radijacionog rizika od korišćenja analiziranih građevinskih materijala u enterijeru, kao i za profesionalna lica pri radu sa sirovinskim materijalima. Ispitivane su mogućnosti upotrebe fosfogipsa kao NORM materijala u proizvodnji gips-karton ploča i opeke uz procenu radijacionog rizika od upotrebe. Napravljeno je 8 uzoraka opeke sa različitim udelog fosfogipsa i izvršena jeradiološka i strukturna karakterizacija dobijenih materijala. Ispitivane su varijacije koeficijenata emanacije radona iz građevinskih materijala tokom vremena, kao i uticaj efekata curenja i povratne difuzije koji dovode do tih varijacija. Ispitivan je takođe i uticaj strukture materijala u smislu mineraloškog i hemijskog satava i poroznosti na vrednosti koeficijenta emanacije radona. Meneraloška karakterizacija uzoraka izvršena je metodom rendgenske strukturne analize (XRD), a hemijska metodom rendgenske fluorescentne analize (XRF). Merenje ukupne efektivne poroznosti izvršeno je metodama apsorpcije vode i metodom živine porozimetrije. Na osnovu dobijenih rezultata uspostavljene su značajne korelacije između pojedinih radioloških i strukturnih parametara za analizirane uzorke građevinskih materijala.In this doctoral dissertation, the results of the radiological and structural characterization of building materials used in Serbia were presented. Radiological characterization of a total of 348 samples was performed, including granite, phosphogypsum, raw materials in the ceramic industry, ceramic tiles, concrete, brick, mortar, siporex, tiles, and other materials frequently used as building materials.Radiological characterization was performed by measuring activity concentrations of 226 Ra,232 Th, and 40 K by gamma spectrometry method, as well as radon exhalation from selected building materials using active devices RAD7, RTM 1688-2, AlphaGuard and AlphaE.Using Monte Carlo simulations, the absorbed gamma dose rates were estimated. Furthermore, the deviations from the theoretically estimated absorbed dose rates were observed, and suggestions for correction were given. An assessment of the radiation risk from the use of analyzed building materials in the interior, as well as for occupational workers working with raw materials was conducted.The possibilities of using phosphogypsum as a NORM material in the production of gypsum plasterboard and bricks were investigated, with an assessment of the radiation risk due to use of phosphogypsum as a component in the building materials. 8 samples of bricks with different proportions of phosphogypsum were made and radiological and structural characterization of the obtained materials was performed. Variations of radon emanation coefficients from building materials over time, as well as the influence of leakage and back diffusion effects leading to these variations, were investigated. The influence of the structure of the material in terms of mineral and chemical composition and porosity on the values of the radon emanation coefficient was also investigated. The mineralogical characterization of the samples was performed by the method of X-ray structural analysis (XRD), and the chemical characterization by the method of X-ray fluorescence analysis (XRF). The measurement of total effective porosity was performed by water absorption methods and mercury porosimetry method. Based on the obtained results, significant correlations were establishedbetween individual radiological and structural parameters for the analyzed samples of construction materials.
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Thomas, Olivier. "Contribution à l'étude des siliciures pour la microélectronique." Grenoble INPG, 1986. http://www.theses.fr/1986INPG0069.
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Elaboration de monocristaux de TaSi2, MoSi2, WSi2. Mesures de conductivité, magnétoconductivité; détermination de la surface de Fermi de MoSi2 par effet de Haas van Alphen. L'interaction du phosphore avec WSi2 a été étudiée par la métallurgie des poudres
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Albert, Stephan Gerhard [Verfasser], Dirk [Akademischer Betreuer] Grundler, and Christian [Akademischer Betreuer] Pfleiderer. "Torque magnetometry on graphene and Fermi surface properties of VB2 and MnB2 single crystals studied by the de Haas-van Alphen effect / Stephan Gerhard Albert. Gutachter: Dirk Grundler ; Christian Pfleiderer. Betreuer: Dirk Grundler." München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1070372412/34.
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Silva, Bruno Farias da. "Quantização de Landau e efeitos associados para átomos ultrafrios do tipo tripod na presença de uma campo magnético artificial." Universidade Federal da Paraíba, 2015. http://tede.biblioteca.ufpb.br:8080/handle/tede/7991.
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In this thesis, we propose an experimental setup for the study of Landau quantization and associated effects in a two-dimensional ultracold atomic gas. Gauge fields can emerge in the equation of motion for the optically addressed ultracold atoms. To this end, spatially dependent dark states are necessary for the internal states of the atoms. A tripod level scheme yields two degenerate dark states which can leads to either an Abelian U(1) U(1) gauge field or a non-Abelian SU(2) gauge field. Using a suitable laser configuration, we obtain a uniform U(1) U(1) magnetic field which causes the atoms organize themselves in Landau levels. The strength of the effective magnetic field depends on the relative intensity of the lasers beams at the atomic cloud. We estimate the degeneracy of the energy levels for an atomic gas formed by atoms of 87Rb. In addition, we establish the experimental conditions to reach the lowest Landau level regime. In the zero-temperature limit, we realize the emergence of magnetic oscillations in the atomic energy and its derivative as function of the inverse of the effective magnetic field (de Haas van Alphen effect). The period of the de Haas van Alphen oscillation allow us to determine area of the Fermi circle for the atomic gas via an Onsager-like relation. We also show that detuning the a laser from the two-photon resonance we generate a parabolic scalar potential that laterally confines the atoms. As a consequence, the Landau levels degeneracy is removed, since the energy spectrum depends explicitly on the transverse atomic momentum. We show that the Landau levels presents a reminiscent degeneracy when the boundaries conditions are considered. The residual degeneracy occurs when different energy levels overlap. We map the residual degeneracy points as a function of the effective magnetic field. Finally, we present an experimental scheme for observing the spin Hall effect for ultracold atoms in a tripod configuration.
Nesta tese, propomos um arranjo experimental para o estudo da quantização de Landau e efeitos associados em um gás atômico ultrafrio bidimensional. Campos de calibre podem surgir na equação de movimento para átomos ultrafrios oticamente vestidos. Para que isto ocorra, estados escuros espacialmente dependentes são necessários a partir dos estados internos dos átomos. Átomos numa configuração de níveis de energia do tipo tripod produzem dois estados escuros degenerados, que podem levar a campos de calibre Abelianos U(1) U(1) ou não-Abelianos SU(2). Utilizando uma configuração adequada de lasers, mostramos que é possível se produzir um campo magnético sintético uniforme U(1) U(1) que atua nos átomos neutros fazendo-os se organizarem em níveis de Landau. A intensidade do campo efetivo depende da intensidade relativa dos feixes de luz na nuvem atômica. Estimamos a degenerescência dos níveis de energia para um gás atômico formado por átomos de 87Rb e estabelecemos as condições experimentais para que seja atingido o regime em que todos os átomos populam unicamente o nível de Landau menos energético. Considerando o limite de temperatura nula, verificamos o surgimento de oscilações magnéticas na energia e em sua derivada como uma função do inverso do campo magnético efetivo (efeito de Haas van Alphen). O período da oscilação magnética nos permite determinar a área do círculo de Fermi para o gás atômico através de uma expressão similar a de Onsager para sistemas eletrônicos. Mostramos também que dessintonizando um dos lasers em relação à ressonância de dois fótons geramos um potencial escalar parabólico que faz com os átomos sejam lateralmente confinados. Isto resulta na remoção da degenerescência dos níveis de Landau, uma vez que a energia depende explicitamente do momento atômico transverso. Demonstramos que, aplicando condições periódicas de contorno ao sistema, temos o surgimento de uma degenerescência residual. A degenerescência remanescente ocorre quando diferentes níveis de energia se superpõem. Mapeamos os pontos de degenerescência como uma função do campo magnético efetivo. Por fim, apresentamos um esquema experimental para a observação do efeito spin Hall para átomos ultrafrios em uma configuração tripod.
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Diver, Andrew James. "The strongly correlated electron systems CeNiâ†2Geâ†2 and Srâ†2RuOâ†4." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364543.
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Hsiao, Pai-Yi. "Comportement critique des modèles de spin classiques sur des fractals : magnétisme orbital d'un gaz d'electrons bidimentionnel confiné par un potentiel harmonique." Paris 7, 2002. http://www.theses.fr/2002PA077099.
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(I) On étudie les comportements critiques du modèle d'Ising et dumodèle de Potts à 3 états sur des fractals par simulation Monte Carlo. Les résultats obtenus par l'analyse en tailles finies satisfont larelation d'hyperscaling avec la dimension de Hausdorff; ils différentdes développements en epsilon. L'universalité de la transition sur cesfractals est faible. De plus, on mesure les exposants dynamiques del'algorithme de Wolff et on met en évidence une nouvelle loi d'échelle que satisfait la distribution de taille des amas. (II) On étudie ungaz d'électrons 2D confiné par un potentiel harmonique et on introduitune formule de trace exacte en appliquant la théorie des résidus. Onpeut montrer que le magnétisme présente trois comportements différents:Diamagnétisme de Landau, Oscillation de Haas-van Alphen et Fluctuation mésoscopique. En appliquant la méthode des états cohérents, on peutdonner une formule pour le courant induit par le champ externe(I) We study the critical behavior of Ising model and 3-state Pottsmodel on fractals by Monte Carlo simulation. The results obtained byfinite size scaling satisfy the hyperscaling relation with the Hausdorffdimension, but differ from the prediction of epsilon-expansion. Theuniversality of these phase transions is shown to be weak. Moverover, we measure the dynamical exponents of the Wolff algorithm and establisha new scaling law for the size distribution of Wolff clusters. (II) Westudy a 2D electron gas confined by an harmonic potential and introducean exact trace formula in application of the residue theorem. We showthat the magnetism presents three different behaviors: Landau Diamagnetism,de Haas-van Alphen Oscillation and Mesoscopic Fluctuation. In applyingthe coherent state method, we give a formula for current density inducedby the external magnetic field
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Le, Touze Christophe. "Etude des propriétés associées aux ondes de densité de charge dans les bronzes oxygénés quasi-bidimensionnels (PO2)4(WO3)2m." Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10183.
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Nous avons etudie les proprietes associees aux ondes de densite de charge dans les bronzes quasi-bidimensionnels (po#2)#4(wo#3)#2#m (m=4, 5, 6, 7, 10, 11 et 12). Ces composes subissent des transitions de peierls a des temperatures t#p vers un etat d'onde de densite de charge caracterise par une distorsion periodique de reseau couplee a une modulation de la densite electronique. La chaleur specifique a ete mesuree pour les composes 4m entre 1,7k et 300k. Nous avons obtenu des termes lineaires en temperature anormalement eleves et qui augmentent avec m. Les temperatures de debye se situent autour de 250k et diminuent lorsque m augmente. Ce comportement pourrait etre du a la diminution de la liaison metallique ou (et) a l'augmentation du caractere bidimensionnel quand le parametre m croit. Des oscillations quantiques shubnikov-de haas et de haas-van alphen ont ete observees dans les composes m=4 et m=6 lors de mesures de magnetoresistance (m=4 et m=6) et de couple magnetique (m=6) effectuees a tres basse temperature et sous fort champ magnetique. Nous avons attribue ces phenomenes a l'existence de petites poches cylindriques subsistant sur la surface de fermi dans l'etat onde de densite de charge, plus petites pour le compose m=6 que pour le compose m=4: la surface de fermi est plus detruite dans le compose m=6 que dans le compose m=4. Le caractere de basse dimensionnalite pourrait donc augmenter avec m. Enfin, nous avons mesure la resistivite electrique des composes 10m2 en fonction de la temperature entre 4k et 800k. Cette etude nous a permis de differencier les composes a petit m des composes a grand m: contrairement aux premiers, dans le domaine des basses temperatures, les seconds ont une resistivite qui decroit a temperature croissante. Nous avons attribue l'augmentation en fonction de m de la resistivite a 300k (p(300k)) et du rapport de resistivite p(300k)/p(4k) a l'augmentation des interactions electrons-electrons via la diminution du nombre moyen d'electrons de conduction par atome de tungstene. D'autre part, nous pensons que l'absence d'anomalie tres marquee, caracteristique d'une transition de peierls, pour la plupart des composes a grand m, est due a des phenomenes de desordre empechant l'apparition d'un ordre a grande distance dans l'etat onde de densite de charge
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Bergk, Beate [Verfasser]. "De Haas-van Alphen-Untersuchungen nichtmagnetischer Borkarbidsupraleiter / von Beate Bergk." 2010. http://d-nb.info/1008647160/34.
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Legae, Alpheus Mogatusi. "Rights to Machavie (Matlwang) Village : a historical study, 1837-1991 / Alpheus Mogatusi Legae." Thesis, 1997. http://hdl.handle.net/10394/14092.
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This mini-dissertation investigates the validity of the right to land of the Barolong ba-ga Modiboa of Machavie Matlwang during the period of 183 7 - 1991 . Very few works on the resettlement of tribes in the former Western Transvaal have been published regarding the loss of people's right to land. Among others, there are descriptions on the Bakwena ba Mogopa who were relocated to Pachsdraai in Bophuthatswana in 1984. The process of relocating people and resettling them was a process of interaction involving the tribal councils, the Government of the Union of South Africa from 1910 and since 1961, the Republic of South Africa. The process of interaction to regain the right to land by the Barolong ba-ga Modiboa extends over three major periods. The first period is 1853 to 1900 in which the negotiations between the Trekker leaders and the Barolong ba-ga Modiboa over land can be regarded as a most important aspect that is also covered in this study. The second period is from 1900 to 1948 during which time the implementation by Government of laws regarding land played a vital role and in time became an important dispute between the white Government and its black inhabitants. This process is also covered in this dissertation. The third period followed after 1948 up to 1991 in which the process of interaction between the Barolong ba-ga Modiboa and the Potchefstroom Town Council concerning land reached a crisis. The Barolong were compelled to settle in various places and this process of relocation became commonly known as forced removals in the late 20th century. This process •of the resettlement of communities is a world-wide phenomenon affecting millions of people. The perception of the land rights as defined by the most important Native Land Act, 27 of 1913 and the Native Trust Land Act, 18 of 1936, classified black land into trust areas, released areas, and black spots. This classification automatically resulted in the (forced) resettlement of people. After 1948 it was even implemented in a stricter way by the implementation of stricter laws. This research, among others, indicates that the Barolong also settled in the former Orange Free State and the Zuid-Afrikaansche Republiek (former Transvaal Republic) before the Ndebeles and that the blacks, and the Barolong in particular, contributed to the defeat of Mzilikazi in order: to regain land in the former Western Transvaal, which they have occupied before the Ndebele's terrif Ying Difaqane/Mfeqane movement in the Highveld. As mentioned, this dissertation will cover the history of the Barolong ba-ga Modiboa, the process of obtaining land by them and whether they have a right to land. This will be done against the background of various Government acts with regard to land implemented in the 20th century. This discussion also considers the approaches to land and human rights world-wide.Thesis (MA (Geskiedenis)--PU for CHE, 1998
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Alpheis, Alexandra-Sabine [Verfasser]. "Molekularbiologische Untersuchungen an Hautpilzen der Arten Microsporum canis und Microsporum equinum / vorgelegt von Alexandra-Sabine Alpheis." 2001. http://d-nb.info/965163741/34.
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ZHENG, MING-XIU, and 鄭明修. "Studies on the mechanisms and behavioral ecology of pairing in the snapping shrimp Alpheus edwardsii (Audouin)." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/60273359230709996958.
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冼宜樂. "Studies on the biology of the snapping shrimp Alpheus brevicristatus （De Haan, 844）from the waters of Penghu." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/37845966693273090722.
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碩士國立海洋大學
漁業科學系碩士在職專班
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Summary 1. Snapping shrimps Alpheus brevicristatus inhabit in the segrass meadow or sandy bottoms at the intertidal zones of Peng-hu. They are commonly used as fishing baits or even for food if reach larger body sizes. 2. The results of investigations showed that Alpheus brevicristatus distributed at sixteen sites in Peng-hu so for. Its highest population density reached 5 ind. /m2 in Chi-to Bay. Four species of symbiont gobyfishes were discovered. Acentrogobius pflaumill was the most widely distributed and with must individuals. 3. The results of morphological characters measurements of male or female Alpheus brevicristatus : (1) The linear regression equations between body length (B. L.) and carapace length (C. L.): female : B. L. =-0.4583 + 3.0525 × C. L. (r2 = 0.9357, N= 487) and male: B. L. =1.404 + 2.7823 × C. L. (r2 = 0.8726, N=254). (2) The curve regression equations between body weight (B. W.) and body length larger (B. L.): Y= 0.0009 X2.9307, (r2 = 0.9782, N= 99) and male : Y= 0.0005 X3.2219, (r2 = 0.9520, N= 67) . The indiridnals with body lengths larger than 40mm are all female. 4. This study snggests that Alpheus brevicristatus in Peng-Hu should be perennial iteroparous life cycle. The gravid period is between February to December and with climax in May. However, annual temperature fluctuation is small and variation curve is slow. It will have extended gravid period and higher - fertility. The gravid period will be also extended with elevated monthly average temperature. 5. Under the controlled condition for artifical reproduction with salinity between 3.2-3.4% and with temperature between 24-27.5℃, it takes about 10days for larvae to hatch from the female gravid stage. It take 30days for larvae to go through 9 stages of zoea before metamorphosis to juveniles. The larvae of Alpheus brevicristatus are with common type developmental mode.
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Obermeier, Michael [Verfasser]. "Untersuchungen an Pistolenkrebsen (Alpheus heterochaelis Say 1818) zur Bedeutung von Wasserströmen und chemischer Signale in intraspezifischen Interaktionen / Michael Obermeier." 2003. http://d-nb.info/969864477/34.
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Forzani, Eugenio Angelo. "Characterization of the electronic properties of LaIrIn5: calculations, transport-, heat capacity- and de Haas-van Alphen-experiments." Doctoral thesis, 2007. http://hdl.handle.net/11858/00-1735-0000-0006-B451-0.
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Polyakov, Andrey. "Fermi-surface investigations of rare-earth transition-metal compounds." Doctoral thesis, 2012. https://tud.qucosa.de/id/qucosa%3A26909.
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The interplay of partially filled d- or f-electron shells with conduction-band electrons is a key ingredient in new rare-earth transition-metal compounds for the emergence of unusual electronic and magnetic properties. Among which unconventional superconductivity is one of the most studied. Despite many years of intensive experimental investigations and plenty promising theoretical models, unconventional superconductivity still remains hotly debated a very rich topic. One of the fundamental unsolved problems for condensed-matter physicists is the mechanism that causes the electrons to form anisotropic superconductivity.
Since electrons in the vicinity of the Fermi level are primarily responsible for superconductivity, in order to better understand the mechanism giving rise to this phenomenon and the origin of complex forces between correlated electrons, knowledge of the Fermi surface and band selective effective mass is essential. Of the many techniques used to study electronic band-structure properties, measurements of quantum oscillations in the magnetization, so-called de Haas-van Alphen (dHvA) effect, in combination with band-structure calculations is the traditional proven tool for studying Fermi-surface topology and quasiparticle effective mass.
In the present work, electronic structure and Fermi-surface properties of Ybsubstituted heavy fermion superconductor CeCoIn5 and iron based ternary phosphides LaFe2P2 and CeFe2P2 have been investigated by means of dHvA measurements. For these measurements, capacitive cantilever-torque magnetometry was utilized.
In Ce1−xYbxCoIn5, the evolution of the Fermi surface and effective mass was studied as a function of Yb concentration. The observed topology change is consistent with what is expected from the band-structure calculations. For a small Yb concentration, x = 0.1, the band-structure topology and the effective masses remain nearly unchanged compared to CeCoIn5. This contrasts clearly modified Fermi surfaces and light, almost unrenormalized effective masses for x = 0.2 and above. For LaFe2P2 and CeFe2P2, the obtained effective masses are light. Good agreement between the calculated and measured dHvA frequencies was identified only for LaFe2P2. However, for CeFe2P2 strong disagreement was observed. Moreover, different CeFe2P2 single crystals reveal different experimental results. In order to reconcile the results of the dHvA measurements and density-functional-theory calculations more work is necessary.
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Forzani, Eugenio Angelo [Verfasser]. "Characterization of the electronic properties of LaIrIn5 : calculations, transport-, heat capacity- and de Haas-van Alphen experiments / vorgelegt von Eugenio Angelo Forzani." 2007. http://d-nb.info/985718080/34.
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Schumann, Christian [Verfasser]. "Expansion von αEβ7+CD4+-T-Lymphozyten [AlphaE-beta7-CD4-T-Lymphozyten] in der bronchoalveolären Lavage als Marker für pulmonale Fibrosen : Beziehung zu interstitiellen Lungenkrankheiten und diagnostische Relevanz / von Christian Schumann." 2004. http://d-nb.info/971647712/34.
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