9,002 research outputs found
Two-site dynamical mean field theory for the dynamic Hubbard model
At zero temperature, two-site dynamical mean field theory is applied to the
Dynamic Hubbard model. The Dynamic Hubbard model describes the orbital
relaxation that occurs when two electrons occupy the same site, by using a
two-level boson field at each site. At finite boson frequency, the appearance
of a Mott gap is found to be enhanced even though it shows a metallic phase
with the same bare on-site interaction in the conventional Hubbard model.
The lack of electron-hole symmetry is highlighted through the quasi-particle
weight and the single particle density of states at different fillings, which
qualitatively differentiates the dynamic Hubbard model from other conventional
Hubbard-like models.Comment: 13 pages, 15 figure
A finite difference solution for the cylindrical expansion of a gas cloud into vacuum
Finite difference method for solution of cylindrical expansion of gas cloud into vacuu
Environmental determinants of landmine detection by dogs: Findings from a large-scale study in Afghanistan
This articleâs purpose is to examine the strengths and weaknesses of mine-detection dogs in different environments. The experiments employed a total of 39 dogs in Afghanistan between October 2002 and July 2003. The results are discussed here
Optical conductivity for a dimer in the Dynamic Hubbard model
The Dynamic Hubbard Model represents the physics of a multi-band Hubbard
model by using a pseudo-spin degree of freedom to dynamically modify the
on-site Coulomb interaction. Here we use a dimer system to obtain analytical
results for this model. The spectral function and the optical conductivity are
calculated analytically for any number of electrons, and the distribution of
optical spectral weight is analyzed in great detail. The impact of polaron-like
effects due to overlaps between pseudo-spin states on the optical spectral
weight distribution is derived analytically. Our conclusions support results
obtained previously with different models and techniques: holes are less mobile
than electrons.Comment: 11 pages, 4 figure
Use of remote sensing for hydrological parameterisation of Alpine catchments
International audiencePhysically-based water balance models require a realistic parameterisation of land surface characteristics of a catchment. Alpine areas are very complex with strong topographically-induced gradients of environmental conditions, which makes the hydrological parameterisation of Alpine catchments difficult. Within a few kilometres the water balance of a region (mountain peak or valley) can differ completely. Hence, remote sensing is invaluable for retrieving hydrologically relevant land surface parameters. The assimilation of the retrieved information into the water balance model PROMET is demonstrated for the Toce basin in Piemonte/Northern Italy. In addition to land use, albedos and leaf area indices were derived from LANDSAT-TM imagery. Runoff, modelled by a water balance approach, agreed well with observations without calibration of the hydrological model. Keywords: PROMET, fuzzy logic based land use classification, albedo, leaf area inde
Dissecting the Workforce and Workplace for Clinical Endocrinology, and the Work of Endocrinologists Early in Their Careers
[Excerpt] No national mechanism is in place for an informed, penetrating, and systematic assessment of the physician workforce such as that achieved by the National Science Foundation (NSF) for the periodic evaluation of the nationâs scientists and engineers. Likewise, knowledge of the workforce for clinical research is enigmatic and fragmentary despite the serial recommendations of âblue-ribbonâ panels to establish a protocol for the recurrent assessment of clinical investigators early in their careers. Failure to adopt a national system for producing timely, high-quality data on the professional activities of physicians limits the application of improvement tools for advancing clinical investigation and ultimately improving clinical practice.
The present study was designed as a pilot project to test the feasibility of using Web-based surveys to estimate the administrative, clinical, didactic, and research work of subspecialty physicians employed in academic, clinical, federal, and pharmaceutical workplaces. Physician members of The Endocrine Society (TES) were used as surrogate prototypes of a subspecialty workforce because of their manageable number and investigative tradition. The results establish that Web-based surveys provide a tool to assess the activities of a decentralized workforce employed in disparate workplaces and underscore the value of focusing on physician work within the context of particular workplaces within a subspecialty. Our report also provides a new and timely snapshot of the amount and types of research performed by clinically trained endocrinologists and offers an evidenced-based framework for improving the investigative workforce in this medical subspecialty
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