3,154 research outputs found
Digital three-state adiabatic passage
We explore protocols for three-state adiabatic passage where the tunnel matrix elements are varied digitally, rather than smoothly as is the case with conventional adiabatic passage. In particular, we focus on stimulated Raman adiabatic passage and related three-state schemes where the control is applied stepwise, with either equal spaced levels for the tunnel matrix elements or uniform pulse lengths. Our results show that the evolution typically shows the hallmarks of conventional adiabatic passage, although with additional resonances exhibiting no state transfer
Electronic transport in Si:P delta-doped wires
Despite the importance of Si:P delta-doped wires for modern nanoelectronics,
there are currently no computational models of electron transport in these
devices. In this paper we present a nonequilibrium Green's function model for
electronic transport in a delta-doped wire, which is described by a
tight-binding Hamiltonian matrix within a single-band effective-mass
approximation. We use this transport model to calculate the current-voltage
characteristics of a number of delta-doped wires, achieving good agreement with
experiment. To motivate our transport model we have performed
density-functional calculations for a variety of delta-doped wires, each with
different donor configurations. These calculations also allow us to accurately
define the electronic extent of a delta-doped wire, which we find to be at
least 4.6 nm.Comment: 13 pages, 11 figure
Are roadwork zones safe?
Increasing heavy traffic volumes and ageing of road infrastructure cause road pavement degradation, which leads to the need for repaving or rehabilitation activities – roadwork. As cars are much more enhanced than previous decade, drivers accept roadwork zone as a common condition. Work zones present more complex driving environment in consequence of possible accidents. Accidents in roadwork zones are significant problem in all European countries while noncompliance with speed limits is one of the major safety concerns. The article gives an overview of the existing traffic safety situation in roadwork zones through the EU countries. Analysis of traffic speed of different layout work zones and accidents statistics on the Lithuanian national road network is presented. Based on research this research. The most effective traffic calming measures are highlighted
Thyroid Hormone Mediated Modulation of Energy Expenditure
Thyroid hormone (TH) has diverse effects on mitochondria and energy expenditure (EE), generating great interest and research effort into understanding and harnessing these actions for the amelioration and treatment of metabolic disorders, such as obesity and diabetes. Direct effects on ATP utilization are a result of TH’s actions on metabolic cycles and increased cell membrane ion permeability. However, the majority of TH induced EE is thought to be a result of indirect effects, which, in turn, increase capacity for EE. This review discusses the direct actions of TH on EE, and places special emphasis on the indirect actions of TH, which include mitochondrial biogenesis and reduced metabolic efficiency through mitochondrial uncoupling mechanisms. TH analogs and the metabolic actions of T2 are also discussed in the context of targeted modulation of EE. Finally, clinical correlates of TH actions on metabolism are briefly presented
A study of collider signatures for two Higgs doublet models with a Pseudoscalar mediator to Dark Matter
Two Higgs doublet models with an additional pseudoscalar particle coupling to
the Standard Model and to a new stable, neutral particle, provide an attractive
and fairly minimal route to solving the problem of Dark Matter. They have been
the subject of several searches at the LHC. We study the impact of existing LHC
measurements on such models, first in the benchmark regions addressed by
searches and then after relaxing some of their assumptions and broadening the
parameter ranges considered. In each case we study how the new parameters
change the potentially visible signatures at the LHC, and identify which of
these signatures should already have had a significant impact on existing
measurements. This allows us to set some first constraints on a number of so
far unstudied scenarios.Comment: 20 pages, 9 figures; added EW constraints contours, extended
explanation of WW model-dependency, extended motivation for pseudoscalar
mediators, corrected typo
Metabolic effects of FGF-21: thermoregulation and beyond
Fibroblast growth factor (FGF)-21, a member of the FGF family, is a novel hormone involved in the control of metabolism by modulating glucose homeostasis, insulin sensitivity, ketogenesis, and promoting adipose tissue “browning.” Recent studies demonstrated that brown adipose tissue is not only a target for FGF-21, but is also a potentially important source of systemic FGF-21. These findings support the hypothesis that FGF-21 plays a physiologic role in thermogenesis and thermogenic recruitment of white adipose tissue by an autocrine–paracrine axis. This review examines the role of FGF-21 in thermogenesis from the perspective of cell-based, animal model, and human studies. We also present recent advances in the characterization of FGF-21’s regulation of metabolism
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