Effect of Weak Disorder on the BCS-BEC crossover in a two-dimensional Fermi Gas

In this article we study the two-dimensional (2D) ultracold Fermi gas with weak impurity in the framework of mean-field theory where the impurity is introduced through Gaussian fluctuations. We have investigated the role of the impurity by studying the experimentally accessible quantities such as condensate fraction and equation of state of the ultracold systems. Our analysis reveals that, at the crossover the disorder enhances superfluidity, which we attribute to the unique nature of the unitary region and to the dimensional effect.Comment: To appear in Int. J. Mod. Phys.

Investigating Dirty Crossover through Fidelity Susceptibility and Density of States

We investigate the BCS-BEC crossover in an ultracold atomic gas in the presence of disorder. The disorder is incorporated in the mean-field formalism through Gaussian fluctuations. We observe evolution to an asymmetric line-shape of fidelity susceptibility as a function of interaction coupling with increasing disorder strength which may point to an impending quantum phase transition. The asymmetric line-shape is further analyzed using the statistical tools of skewness and kurtosis. We extend our analysis to density of states (DOS) for a better understanding of the crossover in the disordered environment.Comment: 12 pages, 6 figures. To appear in Int. J. Mod. Phys.

Kalb-Ramond field interactions in a braneworld scenario

Electromagnetic and (linearized) gravitational interactions of the Kalb-Ramond (KR) field, derived from an underlying ten dimensional heterotic string in the zero slope limit, are studied in a five dimensional background Randall-Sundrum I spacetime with standard model fields confined to the visible brane having negative tension. The warp factor responsible for generating the gauge hierarchy in the Higgs sector is seen to appear inverted in the KR field couplings, when reduced to four dimensions. This leads to dramatically enhanced rotation, {\it far beyond observational bounds}, of the polarization plane of electromagnetic and gravitational waves, when scattered by a homogeneous KR background. Possible reasons for the conflict between theory and observation are discussed.Comment: 13 pages Latex, no figures, discussion and acknowledgements adde

Using experimental evolution to evaluate diversification of Pseudomonas fluorescens SBW25 in complex environments

Understanding the ecological conditions promoting diversification of lineages has been one of the major challenges in the field of evolutionary ecology. The ecological theory of adaptive radiation identified two potential conditions to divergence; selection resulting from differences between environments and from the interaction between species. So far, the best explained factor is differences between environmental features giving rise to divergence of lineages. Most of the other cases on adaptive radiation indicated that resource competition is an important process underlying diversification, although the roles of the other species interactions are not explicitly tested. Predation, for instance, is still underexplored, despite having both ecological and evolutionary impacts on prey populations. Role of predation on diversification remained unsettled, as field studies are challenging and experimental studies showed its modifying effect when selection is driven by resource competition. Importantly, the interacting effects of different ecological processes on diversification should be evaluated in detail. The aim of this thesis is to evaluate the importance of predation, and its effect on diversification when predation and resource competition are both present.  Eine der fundamentalen Fragen der Evolutionsökologie untersucht die Rolle ökologischer Bedingungen bei der Aufspaltung von Arten. Die Theorie der adaptiven Radiation benennt zwei mögliche Szenarien für diese Divergenz: Selektionsprozesse basierend auf der Interaktion zwischen den Arten sowie durch unterschiedliche Umweltbedingungen. Unterschiedliche Umweltbedingungen, die zur Artbildung führen sind bisher am besten erforscht. Die meisten anderen Szenarien adaptiver Radiation postulieren Ressourcenknappheit als weitere Hauptursache, die zur Aufsplittung von Arten führt, auch wenn die Rolle der Interaktionen zwischen den Arten bisher nicht explizit untersucht wurde. So ist beispielsweise ist die Rolle des Räuberverhalten trotz ihres großen ökologischen Einflusses auf Beutepopulationen in diesem Kontext weitestgehend unerforscht. Feldstudien zur Bedeutung von Räuber-Beute-Beziehung im Artbilungsprozess sind sehr schwierig durchzuführen, experimentelle Untersuchungen weisen auf darauf hin, dass der divergierende Einfluss primär dann zum tragen kommt, wenn Selektion durch Ressourcenknappheit getrieben wird. Besonders wichtig ist hierbei die Bedeutung möglicher Interaktionen verschiedener Selektionsprozesse im Detail zu analysieren. Das Ziel der hier vorliegenden Doktorarbeit ist es die Bedeutung von Räuber-Beute-Verhalten und seiner Bedeutung auf Artbildungsprozesse im Kontext von Ressourcenknappheit zu erforschen

Holography of Gravitational Action Functionals

Einstein-Hilbert (EH) action can be separated into a bulk and a surface term, with a specific ("holographic") relationship between the two, so that either can be used to extract information about the other. The surface term can also be interpreted as the entropy of the horizon in a wide class of spacetimes. Since EH action is likely to just the first term in the derivative expansion of an effective theory, it is interesting to ask whether these features continue to hold for more general gravitational actions. We provide a comprehensive analysis of lagrangians of the form L=Q_a^{bcd}R^a_{bcd}, in which Q_a^{bcd} is a tensor with the symmetries of the curvature tensor, made from metric and curvature tensor and satisfies the condition \nabla_cQ^{abcd}=0, and show that they share these features. The Lanczos-Lovelock lagrangians are a subset of these in which Q^{abcd} is a homogeneous function of the curvature tensor. They are all holographic, in a specific sense of the term, and -- in all these cases -- the surface term can be interpreted as the horizon entropy. The thermodynamics route to gravity, in which the field equations are interpreted as TdS=dE+pdV, seems to have greater degree of validity than the field equations of Einstein gravity itself. The results suggest that the holographic feature of EH action could also serve as a new symmetry principle in constraining the semiclassical corrections to Einstein gravity. The implications are discussed.Comment: revtex 4; 17 pages; no figure

Nanotechnology and COVID-19: Prevention, diagnosis, vaccine, and treatment strategies

In December 2019, Coronavirus pandemic (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) viruses, which affected the whole world, is emerged. The details on the epidemiology, infection source, transmission mode, and prognosis of SARS-CoV-2 gave in this review. Universal infection control standards such as hand hygiene, environmental cleanliness, use of personal protective equipment, and quarantine used to prevent the spread of COVID-19 without vaccine. However, many vaccine candidate studies carried out globally with using traditional and technological approaches. Innovations in technology allow the development of nanotechnological tools and the formation of systems that will inactivate SARS-CoV-2 in patients. It expected to include technologies that combine different disciplines, especially robotic applications, antimicrobial nanotechnology, and tissue engineering for the future treatment of COVID-19. This review-based work discusses the relationship of COVID-19 and nanotechnology based working principles

Electrocaloric effect of PMN-PT thin films near morphotropic phase boundary

The electrocaloric effect is calculated for PMN-PT relaxor ferroelectric thin film near morphotropic phase boundary composition. Thin film of thickness, ~240 nm, has been deposited using pulsed laser deposition technique on a highly (111) oriented platinized silicon substrate at 700°C and at 100 mtorr oxygen partial pressure. Prior to the deposition of PMN-PT, a template layer of LSCO of thickness, ~60 nm, is deposited on the platinized silicon substrate to hinder the pyrochlore phase formation. The temperature dependent P-E loops were measured at 200 Hz triangular wave operating at the virtual ground mode. Maximum reversible adiabatic temperature change, ΔT = 31 K, was calculated at 140°C for an external applied voltage of 18 V

Investigation of biferroic properties in La0.6Sr0.4MnO3/0.7 Pb(Mg1/3Nb2/3)O3 0.3 PbTiO3 epitaxial bilayered heterostructures

Epitaxial bilayered thin films consisting of La0.6Sr0.4MnO3 (LSMO) and 0.7 Pb(Mg1/3Nb2/3)O3 0.3 PbTiO3 (PMN-PT) layers of relatively different thicknesses were fabricated on LaNiO3 coated LaAlO3 (100) single crystal substrates by pulsed laser ablation technique. Ferroelectric and ferromagnetic characteristics of these heterostructures confirmed their biferroic nature. The magnetization and ferroelectric polarization of the bilayered heterostructures were enhanced with increasing PMN-PT layer thickness owing to the effect of lattice strain. Dielectric properties of these heterostructures studied over a wide range of temperature under different magnetic field strength suggested a possible role of elastic strain mediated magnetoelectric coupling behind the observed magneto-dielectric effect in addition to the influence of rearrangement of the interfacial charge carriers under an applied magnetic field