960 resultados para Anomalies in field and string theories
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Increases in plasma cholesterol are associated with progressive increases in the risk of atherosclerotic cardiovascular disease. In humans plasma cholesterol is contained primarily in apolipoprotein B-based low density lipoprotein (LDL). Cells stop making the high-affinity receptor responsible for LDL removal as they become cholesterol replete; this slows removal of LDL from plasma and elevates plasma LDL. As a result of this delayed uptake, hypercholesterolemic individuals not only have more LDL but have significantly older LDL. Oxidative modification of LDL enhances their atherogenicity. This study sought to determine whether increased time spent in circulation, or aging, by lipoprotein particles altered their susceptibility to oxidative modification. Controlled synchronous production of distinctive apolipoprotein B lipoproteins (yolk-specific very low density lipoproteins; VLDLy) with a single estrogen injection into young turkeys was used to model LDL aging in vivo. VLDLy remained in circulation for at least 10 days. Susceptibility to oxidation in vitro was highly dependent on lipoprotein age in vivo. Oxidation, measured as hexanal release from n-6 fatty acids in VLDLy, increased from 13.3 +/- 5.5 nmol of 2-day-old VLDLy per ml, to 108 +/- 17 nmol of 7-day-old VLDLy per ml. Oxidative instability was not due to tocopherol depletion or conversion to a more unsaturated fatty acid composition. These findings establish mathematically describable linkages between the variables of LDL concentration and LDL oxidation. The proposed mathematical models suggest a unified investigative approach to determine the mechanisms for acceleration of atherosclerotic cardiovascular disease risk as plasma cholesterol rises.
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The receptor tyrosine kinases (RTKs) c-kit and platelet-derived growth factor receptor alpha chain (PDG-FRa) are encoded at the white spotting (W) and patch (Ph) loci on mouse chromosome 5. While W mutations affect melanogenesis, gametogenesis, and hematopoiesis, the Ph mutation affects melanogenesis and causes early lethality in homozygotes. W-sash (Wsh) is an expression mutation and blocks c-kit expression in certain cell types and enhances c-kit expression in others, including at sites important for early melanogenesis. We have determined the effect of Ph on c-kit expression during embryogenesis in Ph heterozygotes. Immunohistochemical analysis revealed enhanced c-kit expression in several cell types, including sites important for early melanogenesis. We propose that in both Wsh and Ph mutant mice c-kit misexpression affects early melanogenesis and is responsible for the pigment deficiency. Moreover, we have defined the organization of the RTKs in the W/Ph region on chromosome 5 and characterized the Wsh mutation by using pulsed-field gel electrophoresis. Whereas the order of the RTK genes was determined as Pdgfra-c-kit-flk1, analysis of the Wsh mutation revealed that the c-kit and Pdgfra genes are unlinked in Wsh, presumably because of an inversion of a small segment of chromosome 5. The Ph mutation consists of a deletion including Pdgfra and the 3' deletion endpoint of Ph lies between Pdgfra and c-kit. Therefore, positive 5' upstream elements controlling c-kit expression in mast cells and some other cell types are affected by the Wsh mutation and negative elements are affected by both the Wsh and the Ph mutation.
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La ricerca di nuove strategie per la rigenerazione ossea rappresenta un focus di interesse centrale per migliorare la gestione di casi clinici complessi nell’ambito della chirurgia orale e maxillo-facciale. Uno degli approcci più utilizzati in tale contesto si basa sull’utilizzo di molecole con proprietà osteoinduttive e molte sostanze sono state fino ad oggi sperimentate. E’ noto in letteratura che gli androgeni svolgono un ruolo chiave nella regolazione della morfogenesi ossea e nel mantenimento della sua omeostasi durante il corso della vita. Questo lavoro di tesi nasce dall’ipotesi che la somministrazione locale di tali ormoni, eventualmente combinata a materiali da innesto, possa favorire la guarigione di difetti ossei. Stando a questa premessa, sono stati valutati gli effetti dello steroide sintetico Stanozololo sulla rigenerazione ossea in diversi settings sperimentali. La tesi è strutturata secondo un percorso che segue le fasi della ricerca, attraverso sperimentazioni in vitro e in vivo; ogni capitolo può essere approcciato come uno studio a sé stante, corrispondente ad una determinata tappa dell’iter sperimentale. Sulla base di questi intenti, viene fornito inizialmente un quadro d’insieme circa gli effetti degli androgeni sull’osso. A seguire, è presentata una sperimentazione in vitro nella linea cellulare SaOS-2. Infine, è proposta un’innovativa metodologia di analisi per lo studio della rigenerazione ossea nel modello di ratto, ove viene testata la somministrazione locale di Stanozololo combinato a materiale da innesto.
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We investigate the critical properties of the four-state commutative random permutation glassy Potts model in three and four dimensions by means of Monte Carlo simulations and a finite-size scaling analysis. By using a field programmable gate array, we have been able to thermalize a large number of samples of systems with large volume. This has allowed us to observe a spin-glass ordered phase in d=4 and to study the critical properties of the transition. In d=3, our results are consistent with the presence of a Kosterlitz-Thouless transition, but also with different scenarios: transient effects due to a value of the lower critical dimension slightly below 3 could be very important.
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The last two decades have been marked by a growing public awareness of family violence. Research by social scientists has suggested that family violence is widespread (Gelles and Straus, 1988). It is estimated that every year 1.8 to 4 million women are physically abused by their partners (Novello, 1992). In fact, more women are abused by their husbands or boyfriends than are injured in car accidents, muggings, or rapes (Jaffe, Wolfe, and Wilson, 1990). A recent prevalence study by Fantuzzo, Boruch, Beriama, Atkins, and Marcus (1997) found that children were disproportionately present in households where there was a substantial incident of adult female assault. Experts estimate that 3.3 to 10 million children are exposed to marital violence each year (Carlson, 1984; Straus, 1991). Until recently, most researchers did not consider the impact of parental conflict on the children who witness this violence. The early literature in this field primarily focused on the incidence of violence against women and the inadequate response of community agencies (Jaffe et al, 1990). The needs of children were rarely considered. However, researchers have become increasingly aware that children exposed to marital violence are victims of a range of psychological maltreatment (e.g., terrorizing, isolation;Hart, Brassared & Karlson, 1996) and are at serious risk for the development of psychological problems (Fantuzzo, DePaola, Lambert, Martino, Anderson, and Sutton, 1991). Jouriles, Murphy and O'Leary (1989) found that children of battered women were four times more likely to exhibit psychopathology as were children living in non-violent homes. Further, researchers have found associations between childhood exposure to parental violence and the expression of violence in adulthood (Carlson, 1990). Existing research suggests that children who have witnessed marital violence manifest numerous emotional, social, and behavioral problems (Sternberg et al., 1993; Fantuzzo et al., 1991; Jaffe et al, 1990). Studies have found that children of battered women exhibit more internalizing and externalizing behavior problems than non-witnesschildren (Hughes and Fantuzzo, 1994; McCloskey, Figueredo, and Koss, 1995). In addition, children exposed to marital violence have been found to exhibit difficulties with social problem-solving, and have lower levels of social competence than nonwitnesses (Rosenberg, 1987; Moore, Pepler, Weinberg, Hammond, Waddell, & Weiser, 1990). Other reported difficulties include low self esteem (Hughes, 1988), poor school performance (Moore et al., 1990) and problems with aggression (Holden & Ritchie, 1991; Jaffe, Wolfe, Wilson, & Zak, 1986). Further, within the last decade, researchers have found that some children are traumatized by the witnessing experience, showing elevated levels of posttraumatic stress symptoms (Devoe & Graham-Bermann, 1997; Rossman, Bingham, & Emde, 1996; Kilpatrick, Litt, & Williams, 1997). These findings corroborate clinical reports that describe many exposed children as experiencing trauma reactions. It appears that the negative effects of witnessing marital violence are numerous and varied, ranging from mild emotional and behavioral problems to clinically significant levels of posttraumatic stress symptoms. These incidence figures and research findings indicate that children's exposure to violence is a significant problem in our nation today and has serious implications for the future.
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ALICE is one of four major experiments of particle accelerator LHC installed in the European laboratory CERN. The management committee of the LHC accelerator has just approved a program update for this experiment. Among the upgrades planned for the coming years of the ALICE experiment is to improve the resolution and tracking efficiency maintaining the excellent particles identification ability, and to increase the read-out event rate to 100 KHz. In order to achieve this, it is necessary to update the Time Projection Chamber detector (TPC) and Muon tracking (MCH) detector modifying the read-out electronics, which is not suitable for this migration. To overcome this limitation the design, fabrication and experimental test of new ASIC named SAMPA has been proposed . This ASIC will support both positive and negative polarities, with 32 channels per chip and continuous data readout with smaller power consumption than the previous versions. This work aims to design, fabrication and experimental test of a readout front-end in 130nm CMOS technology with configurable polarity (positive/negative), peaking time and sensitivity. The new SAMPA ASIC can be used in both chambers (TPC and MCH). The proposed front-end is composed of a Charge Sensitive Amplifier (CSA) and a Semi-Gaussian shaper. In order to obtain an ASIC integrating 32 channels per chip, the design of the proposed front-end requires small area and low power consumption, but at the same time requires low noise. In this sense, a new Noise and PSRR (Power Supply Rejection Ratio) improvement technique for the CSA design without power and area impact is proposed in this work. The analysis and equations of the proposed circuit are presented which were verified by electrical simulations and experimental test of a produced chip with 5 channels of the designed front-end. The measured equivalent noise charge was <550e for 30mV/fC of sensitivity at a input capacitance of 18.5pF. The total core area of the front-end was 2300?m × 150?m, and the measured total power consumption was 9.1mW per channel.
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We address the electronic structure and magnetic properties of vacancies and voids both in graphene and graphene ribbons. By using a mean-field Hubbard model, we study the appearance of magnetic textures associated with removing a single atom (vacancy) and multiple adjacent atoms (voids) as well as the magnetic interactions between them. A simple set of rules, based on the Lieb theorem, link the atomic structure and the spatial arrangement of the defects to the emerging magnetic order. The total spin S of a given defect depends on its sublattice imbalance, but some defects with S=0 can still have local magnetic moments. The sublattice imbalance also determines whether the defects interact ferromagnetically or antiferromagnetically with one another and the range of these magnetic interactions is studied in some simple cases. We find that in semiconducting armchair ribbons and two-dimensional graphene without global sublattice imbalance, there is a maximum defect density above which local magnetization disappears. Interestingly, the electronic properties of semiconducting graphene ribbons with uncoupled local moments are very similar to those of diluted magnetic semiconductors, presenting giant Zeeman splitting.
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International mobility in search of amenity spaces for long-stay tourism is a growing phenomenon. U.S. citizens have practiced this lifestyle migration for decades to Latin American countries, especially to Mexico. British citizens move to Spain for similar reasons. In this paper we make a comparative analysis of these two international contexts in order to gain greater insight into the diversity and breadth of this type of migration. The study uses quantitative surveys administered at each field site. First, we analyze the phenomenon of U.S. citizens’ mobility to Mazatlán, Mexico. Second, we analize citizens from the United Kingdom residing in El Campello, Spain. In particular we compare their socio-demographic profiles, transnational practices and some patterns of social integration.
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Today, the requirement of professional skills to university students is constantly increasing in our society. In our opinion, the content offered in official degrees need to be nourished with different variables, enriching their global professional knowledge in a parallel way; that is why, in recent years, there is a great multiplicity of complementary courses at university. One of the most socially demanded technical requirements within the architectural, design or engineering field is the management of 3D drawing software, becoming an indispensable reality in these sectors. Thus, this specific training becomes essential over two-dimension traditional design, because the inclusion of great possibilities of spatial development that go beyond conventional orthographic projections (plans, sections or elevations), allowing modelling and rotation of the selected items from multiple angles and perspectives. Therefore, this paper analyzes the teaching methodology of a complementary course for those technicians in the construction industry interested in computer-aided design, using modelling (SketchupMake) and rendering programs (Kerkythea). The course is developed from the technician point of view, by learning computer management and its application to professional development from a more general to a more specific view through practical examples. The proposed methodology is based on the development of real examples in different professional environments such as rehabilitation, new constructions, opening projects or architectural design. This multidisciplinary contribution improves criticism of students in different areas, encouraging new learning strategies and the independent development of three-dimensional solutions. Thus, the practical implementation of new situations, even suggested by the students themselves, ensures active participation, saving time during the design process and the increase of effectiveness when generating elements which may be represented, moved or virtually tested. In conclusion, this teaching-learning methodology improves the skills and competencies of students to face the growing professional demands of society. After finishing the course, technicians not only improved their expertise in the field of drawing but they also enhanced their capacity for spatial vision; both essential qualities in these sectors that can be applied to their professional development with great success.
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A suitable knowledge of the orientation and motion of the Earth in space is a common need in various fields. That knowledge has been ever necessary to carry out astronomical observations, but with the advent of the space age, it became essential for making observations of satellites and predicting and determining their orbits, and for observing the Earth from space as well. Given the relevant role it plays in Space Geodesy, Earth rotation is considered as one of the three pillars of Geodesy, the other two being geometry and gravity. Besides, research on Earth rotation has fostered advances in many fields, such as Mathematics, Astronomy and Geophysics, for centuries. One remarkable feature of the problem is in the extreme requirements of accuracy that must be fulfilled in the near future, about a millimetre on the tangent plane to the planet surface, roughly speaking. That challenges all of the theories that have been devised and used to-date; the paper makes a short review of some of the most relevant methods, which can be envisaged as milestones in Earth rotation research, emphasizing the Hamiltonian approach developed by the authors. Some contemporary problems are presented, as well as the main lines of future research prospected by the International Astronomical Union/International Association of Geodesy Joint Working Group on Theory of Earth Rotation, created in 2013.
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This study presents the results of a systematic literature review on the combined field of Accessibility and Massive Open Online Courses (MOOCs), covering the time period from 2008 to 2016.
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no.32(1936)
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Light confinement and controlling an optical field has numerous applications in the field of telecommunications for optical signals processing. When the wavelength of the electromagnetic field is on the order of the period of a photonic microstructure, the field undergoes reflection, refraction, and coherent scattering. This produces photonic bandgaps, forbidden frequency regions or spectral stop bands where light cannot exist. Dielectric perturbations that break the perfect periodicity of these structures produce what is analogous to an impurity state in the bandgap of a semiconductor. The defect modes that exist at discrete frequencies within the photonic bandgap are spatially localized about the cavity-defects in the photonic crystal. In this thesis the properties of two tight-binding approximations (TBAs) are investigated in one-dimensional and two-dimensional coupled-cavity photonic crystal structures We require an efficient and simple approach that ensures the continuity of the electromagnetic field across dielectric interfaces in complex structures. In this thesis we develop \textrm{E} -- and \textrm{D} --TBAs to calculate the modes in finite 1D and 2D two-defect coupled-cavity photonic crystal structures. In the \textrm{E} -- and \textrm{D} --TBAs we expand the coupled-cavity \overrightarrow{E} --modes in terms of the individual \overrightarrow{E} -- and \overrightarrow{D} --modes, respectively. We investigate the dependence of the defect modes, their frequencies and quality factors on the relative placement of the defects in the photonic crystal structures. We then elucidate the differences between the two TBA formulations, and describe the conditions under which these formulations may be more robust when encountering a dielectric perturbation. Our 1D analysis showed that the 1D modes were sensitive to the structure geometry. The antisymmetric \textrm{D} mode amplitudes show that the \textrm{D} --TBA did not capture the correct (tangential \overrightarrow{E} --field) boundary conditions. However, the \textrm{D} --TBA did not yield significantly poorer results compared to the \textrm{E} --TBA. Our 2D analysis reveals that the \textrm{E} -- and \textrm{D} --TBAs produced nearly identical mode profiles for every structure. Plots of the relative difference between the \textrm{E} and \textrm{D} mode amplitudes show that the \textrm{D} --TBA did capture the correct (normal \overrightarrow{E} --field) boundary conditions. We found that the 2D TBA CC mode calculations were 125-150 times faster than an FDTD calculation for the same two-defect PCS. Notwithstanding this efficiency, the appropriateness of either TBA was found to depend on the geometry of the structure and the mode(s), i.e. whether or not the mode has a large normal or tangential component.
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This paper offers a picture of the obligations existing under international and European law in respect of the loss of nationality. It describes international instruments including obligations in this field with direct relevancy for the loss of nationality of Member States of the European Union, but also obligations regarding loss of nationality in regional non-European treaties. Attention is given to two important judicial decisions of the European Court of Justice (Janko Rottmann) and the European Court of Human Rights (Genovese v Malta) regarding nationality. Special attention is devoted to Article 15 of the Universal Declaration of Human Rights, which forbids the arbitrary deprivation of nationality. A survey is provided of possible sub-principles that can be derived from this rule. Finally, some observations are made on the burden of proof in cases of loss of nationality.
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The strength model of self-control assumes that all acts of self-control (e.g., emotion regulation, persistence) are empowered by a single global metaphorical strength that has limited capacity. This strength can become temporarily depleted after a primary self-control act, which, in turn, can impair performance in subsequent acts of self-control. Recently, the assumptions of the strength model of self-control also have been adopted and tested in the field of sport and exercise psychology. The present review paper aims to give an overview of recent developments in self-control research based on the strength model of self-control. Furthermore, recent research on interventions on how to improve and revitalize self-control strength will be presented. Finally, the strength model of self-control has been criticized lately, as well as expanded in scope, so the present paper will also discuss alternative explanations of why previous acts of self-control can lead to impaired performance in sport and exercise.