3,649 research outputs found
The Many Electron Ground State of the Adiabatic Holstein Model in Two and Three Dimensions
We present the complete ground state phase diagram of the Holstein model in
two and three dimension considering the phonon variables to be classical. We
first establish the overall structure of the phase diagram by using exact
diagonalisation based Monte Carlo (ED-MC) on small lattices and then use a new
``travelling cluster'' approximation (TCA) for annealing the phonon degrees of
freedom on large lattices. The phases that emerge include a Fermi liquid (FL),
with no lattice distortions, an insulating polaron liquid (PL) at strong
coupling, and a charge ordered insulating (COI) phase around half- filling. The
COI phase is separated from the Fermi liquid by a regime of phase coexistence
whose width grows with increasing electron-phonon coupling. We provide results
on the electronic density of states, the COI order parameter, and the spatial
organisation of polaronic states, for arbitrary density and electron-phonon
coupling. The results highlight the crucial role of spatial correlations in
this strong coupling problem.Comment: Final versio
Einstein static universes are unstable in generic f(R) models
We study Einstein static universes in the context of generic f(R) models. It
is shown that Einstein static solutions exist for a wide variety of modified
gravity models sourced by a barotropic perfect fluid with equation of state
w=p/rho, but these solutions are always unstable to either homogeneous or
inhomogeneous perturbations. Our general results are in agreement with specific
models investigated in that past. We also discuss how our techniques can be
applied to other scenarios in f(R) gravity.Comment: 7 pages, 2 figures. Minor corrections. Minor changes and references
added to match version accepted by Phys. Rev.
Impact of ATM Service on Customer Perception and Satisfaction of Indian Banks
. Indian banking sector has completely changed. It has undergone much technological advancement that makes banking easy. Technological advancements are important but at the end what build customer satisfaction is proper management, employee behavior and customer relationship handling. Customer satisfaction is a sum of many variables that is many factors together leads to customer satisfaction. This modern electronic banking has completely changed the concept and functioning of banking system in India. Indian banking has moved from cash economy to cheque to and finally to the use of plastic cards. The customer satisfaction is dependent on customer awareness to a lot of extent. An unaware customer has less knowledge and therefore they cannot use the facilities completely even if they have it at their disposal. Customers prefer public sector banks when they are looking for trust and security and reliability. When it comes to speed, advancements and up gradation people shits from public sector banks to private sector banks. Customer gets satisfied only when they get quality service from the brand they are dealing with. This is very important for the marketers or the service providers as this leads to consumer satisfaction which benefits them and this brings loyalty to the brand enhancing the brand positioning. This research is important because new modern era has made people technology savvy they start their day with technology and end with technology therefore it is important to see the perception of users towards various factors of ATM. This research is conducted to see the highlighting factors that have direct impact on ATM services
Tumors in von Hippel–Lindau Syndrome: From Head to Toe—Comprehensive State-of-the-Art Review
Von Hippel–Lindau syndrome (VHL) is an autosomal-dominant hereditary tumor disease that arises owing to germline mutations in the VHL gene, located on the short arm of chromosome 3. Patients with VHL may develop multiple benign and malignant tumors involving various organ systems, including retinal hemangioblastomas (HBs), central nervous system (CNS) HBs, endolymphatic sac tumors, pancreatic neuroendocrine tumors, pancreatic cystadenomas, pancreatic cysts, clear cell renal cell carcinomas, renal cysts, pheochromocytomas, paragangliomas, and epididymal and broad ligament cystadenomas. The VHL/hypoxia-inducible factor pathway is believed to play a key role in the pathogenesis of VHL-related tumors. The diagnosis of VHL can be made clinically when the characteristic clinical history and findings have manifested, such as the presence of two or more CNS HBs. Genetic testing for heterozygous germline VHL mutation may also be used to confirm the diagnosis of VHL. Imaging plays an important role in the diagnosis and surveillance of patients with VHL. Familiarity with the clinical and imaging manifestations of the various VHL-related tumors is important for early detection and guiding appropriate management. The purpose of this article is to discuss the molecular cytogenetics and clinical manifestations of VHL, review the characteristic multimodality imaging features of the various VHL-related tumors affecting multiple organ systems, and discuss the latest advances in management of VHL, including current recommendations for surveillance and screening
Theoretical prediction of multiferroicity in double perovskite YNiMnO
We put forward double perovskites of the RNiMnO family (with a
rare-earth atom) as a new class of multiferroics on the basis of {\it ab
initio} density functional calculations. We show that changing from La to Y
drives the ground-state from ferromagnetic to antiferromagnetic with
spin patterns. This E-type ordering
breaks inversion symmetry and generates a ferroelectric polarization of few
. By analyzing a model Hamiltonian we understand the microscopic
origin of this transition and show that an external electric field can be used
to tune the transition, thus allowing electrical control of the magnetization.Comment: 4 pages, 3 figure
Background independent quantization and wave propagation
We apply a type of background independent "polymer" quantization to a free
scalar field in a flat spacetime. Using semi-classical states, we find an
effective wave equation that is both nonlinear and Lorentz invariance
violating. We solve this equation perturbatively for several cases of physical
interest, and show that polymer corrections to solutions of the Klein-Gordon
equation depend on the amplitude of the field. This leads to an effective
dispersion relation that depends on the amplitude, frequency and shape of the
wave-packet, and is hence distinct from other modified dispersion relations
found in the literature. We also demonstrate that polymer effects tend to
accumulate with time for plane-symmetric waveforms. We conclude by discussing
the possibility of measuring deviations from the Klein-Gordon equation in
particle accelerators or astrophysical observations.Comment: 15 pages, minor revision to match PRD versio
Leakage of old carbon dioxide from a major river system in the Canadian Arctic
The Canadian Arctic is warming at an unprecedented rate. Warming-induced permafrost thaw can lead to mobilization of aged carbon from stores in soils and rocks. Tracking the carbon pools supplied to surrounding river networks provides insight on pathways and processes of greenhouse gas release. Here, we investigated the dual-carbon isotopic characteristics of the dissolved inorganic carbon (DIC) pool in the main stem and tributaries of the Mackenzie River system. The radiocarbon (14C) activity of DIC shows export of “old” carbon (2,380 ± 1,040 14C years BP on average) occurred during summer in sampling years. The stable isotope composition of river DIC implicates degassing of aged carbon as CO2 from riverine tributaries during transport to the delta; however, information on potential drivers and fluxes are still lacking. Accounting for stable isotope fractionation during CO2 loss, we show that a large proportion of this aged carbon (60 ± 10%) may have been sourced from biospheric organic carbon oxidation, with other inputs from carbonate weathering pathways and atmospheric exchange. The findings highlight hydrologically connected waters as viable pathways for mobilization of aged carbon pools from Arctic permafrost soils
- …