13,584 research outputs found
Non-Markovian incoherent quantum dynamics of a two-state system
We present a detailed study of the non-Markovian two-state system dynamics
for the regime of incoherent quantum tunneling. Using perturbation theory in
the system tunneling amplitude , and in the limit of strong system-bath
coupling, we determine the short time evolution of the reduced density matrix
and thereby find a general equation of motion for the non-Markovian evolution
at longer times. We relate the nonlocality in time due to the non-Markovian
effects with the environment characteristic response time. In addition, we
study the incoherent evolution of a system with a double-well potential, where
each well consists several quantized energy levels. We determine the crossover
temperature to a regime where many energy levels in the wells participate in
the tunneling process, and observe that the required temperature can be much
smaller than the one associated with the system plasma frequency. We also
discuss experimental implications of our theoretical analysis.Comment: 10 pages, published versio
Development of optical data processing techniques applicable to detection and study of meteor trails
Development of coherent optical data processing techniques applicable to detection of meteor trails and examination of propertie
Corotation Resonance and Diskoseismology Modes of Black Hole Accretion Disks
We demonstrate that the corotation resonance affects only some
non-axisymmetric g-mode oscillations of thin accretion disks, since it is
located within their capture zones. Using a more general (weaker radial WKB
approximation) formulation of the governing equations, such g-modes, treated as
perfect fluid perturbations, are shown to formally diverge at the position of
the corotation resonance. A small amount of viscosity adds a small imaginary
part to the eigenfrequency which has been shown to induce a secular instability
(mode growth) if it acts hydrodynamically. The g-mode corotation resonance
divergence disappears, but the mode magnitude can remain largest at the place
of the corotation resonance. For the known g-modes with moderate values of the
radial mode number and axial mode number (and any vertical mode number), the
corotation resonance lies well outside their trapping region (and inside the
innermost stable circular orbit), so the observationally relevant modes are
unaffected by the resonance. The axisymmetric g-mode has been seen by Reynolds
& Miller in a recent inviscid hydrodynamic accretion disk global numerical
simulation. We also point out that the g-mode eigenfrequencies are
approximately proportional to m for axial mode numbers |m|>0.Comment: 16 pages, no figures. Submitted to The Astrophysical Journa
Development of PAN (personal area network) for Mobile Robot Using Bluetooth Transceiver
In recent years, wireless applications using radio frequency (RF) have been rapidly evolving in personal computing and communications devices. Bluetooth technology was created to replace the cables used on mobile devices. Bluetooth is an open specification and encompasses a simple low-cost, low power solution for integration into devices. This research work aim was to provide a PAN (personal area network) for computer based mobile robot that supports real-time control of four mobile robots from a host mobile robot. With ad hoc topology, mobile robots may request and establish a connection when it is within the range or terminated the connection when it leaves the area. A system that contains both hardware and software is designed to enable the robots to participate in multi-agent robotics system (MARS). Computer based mobile robot provide operating system that enabled development of wireless connection via IP address
Local community on trial
While plenty has been written about the reinvention of the social by the Third Way as a new governmentality of control, consensus, and social integration, less has been said about its subtle elision of social and the local, and the implications of this elision for urban and regional regeneration. This is the theme taken up by this paper, beginning with a critical appraisal of the recent turn by New Labour to community cohesion and social capital as a means of overcoming local poverty and disadvantage. It shows how the social has come to be redefined as community, localized, and thrown back at hard-pressed areas as both cause and solution in the area of social, political, and economic regeneration. The second half of the paper develops an alternative designation of the local-social that is less instrumentalist, decidedly a-moral (though equally ethical), agonistically political, and geographically unconstrained. It argues for a return to ideas of agonistic democracy and the society of commitments and connections so thoroughly repudiated by new versions of market social democracy
Thermally assisted adiabatic quantum computation
We study the effect of a thermal environment on adiabatic quantum computation
using the Bloch-Redfield formalism. We show that in certain cases the
environment can enhance the performance in two different ways: (i) by
introducing a time scale for thermal mixing near the anticrossing that is
smaller than the adiabatic time scale, and (ii) by relaxation after the
anticrossing. The former can enhance the scaling of computation when the
environment is superohmic, while the latter can only provide a prefactor
enhancement. We apply our method to the case of adiabatic Grover search and
show that performance better than classical is possible with a superohmic
environment, with no a priori knowledge of the energy spectrum.Comment: 4 pages, 2 figures, Final version to appear in PR
Systematic Topology Analysis and Generation Using Degree Correlations
We present a new, systematic approach for analyzing network topologies. We
first introduce the dK-series of probability distributions specifying all
degree correlations within d-sized subgraphs of a given graph G. Increasing
values of d capture progressively more properties of G at the cost of more
complex representation of the probability distribution. Using this series, we
can quantitatively measure the distance between two graphs and construct random
graphs that accurately reproduce virtually all metrics proposed in the
literature. The nature of the dK-series implies that it will also capture any
future metrics that may be proposed. Using our approach, we construct graphs
for d=0,1,2,3 and demonstrate that these graphs reproduce, with increasing
accuracy, important properties of measured and modeled Internet topologies. We
find that the d=2 case is sufficient for most practical purposes, while d=3
essentially reconstructs the Internet AS- and router-level topologies exactly.
We hope that a systematic method to analyze and synthesize topologies offers a
significant improvement to the set of tools available to network topology and
protocol researchers.Comment: Final versio
Eicosapentaenoic Acid (EPA) from Fish Oil and Margarine as Bioactive Compound for Anti-inflammation in Occupational Dermatitis
Occupational dermatitis (OCD) is a skin inflammatory disease caused by allergens and irritant agents in the workplace. The disease is related to hypersensitivity reaction, which is correlated with an immunological mechanism (allergic contact dermatitis) and a nonimmunological mechanism (irritant contact dermatitis). Patients with atopic history (rhinitis allergy, asthma, and atopic dermatitis) have a higher risk of contracting OCD. Atopic individuals suffer from barrier skin damage that increases the risk of allergen and irritant penetration. Inflammatory reaction involves T-helper 1 (Th1), which produces cytokine tumor necrosis factor alpha (TNF-α) and interferon-γ (INF-γ), while T-helper 2 (Th2) produces interleukin (IL-4, IL-6, IL-8, IL-10). Eicosapentaenoic acid (EPA) is an omega-3 substance from polyunsaturated free fatty acids (PUFAs)that has been shown to have an anti-inflammatory effect and the ability to decrease macrophage accumulation. In the inflammatory process, EPA inhibits IL-6, IL-8, and TNF-α, which are mediated by the free fatty acid-binding proteins (FABPs). The aim of this study was to determine the bioactivity compound of EPA for anti-inflammatory agents and its target, based on in silico screening. The bioinformatic tools based on reverse docking used in this study were the PubChem compound database, the protein target prediction database, PharmMapper, SwissTargetPrediction, molecular docking software PyRx 0.8, ligand docking, and binding site analysis using PyMOL software. Docking and binding site analysis showed that EPA was able to interact withFABPs, with the binding affinity of EPA with FABP 4 higher (–4.2 kcal/mol) than that of hydrocortisone with FABP 4 (–7.4 kcal/mol). EPA has the same binding site and relative bonding power as the FABPs; thus, it has potential as an alternative anti-inflammatory medicine in OCD.
Keywords: occupational dermatitis, eicosapentaenoic acid (EPA), free fatty acid binding proteins (FABPs), reverse dockin
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