597 research outputs found
Информационные технологии в управлении интеллектуальным капиталом организации
The report examines how organization can use information technologies for management of intellectual capital
A benzene interference single-electron transistor
Interference effects strongly affect the transport characteristics of a
benzene single-electron transistor (SET) and for this reason we call it
interference SET (I-SET). We focus on the effects of degeneracies between
many-body states of the isolated benzene. We show that the particular current
blocking and selective conductance suppression occurring in the benzene I-SET
are due to interference effects between the orbitally degenerate states.
Further we study the impact of reduced symmetry due to anchor groups or
potential drop over the molecule. We identify in the quasi-degeneracy of the
involved molecular states the necessary condition for the robustness of the
results.Comment: 17pages, 9 figures, revised versio
On the sensitivity of the energy of vanishing flow towards mass asymmetry of colliding nuclei
We demonstrate the role of the mass asymmetry in the energy of vanishing flow
by studying asymmetric reactions throughout the periodic table and over entire
colliding geometry. Our results, which are almost independent of the system
size and as well as of the colliding geometries indicate a sizable effect of
the asymmetry of the reaction on the energy of vanishing flow
Simulated Annealing Clusterization Algorithm for Studying the Multifragmentation
We present the details of the numerical realization of the recently advanced
algorithm developed to identify the fragmentation in heavy ion reactions. This
new algorithm is based on the Simulated Annealing method and is dubbed as
Simulated Annealing Clusterization Algorithm [SACA]. We discuss the different
parameters used in the Simulated Annealing method and present an economical set
of the parameters which is based on the extensive analysis carried out for the
central and peripheral collisions of Au-Au, Nb-Nb and Pb-Pb. These parameters
are crucial for the success of the algorithm. Our set of optimized parameters
gives the same results as the most conservative choice, but is very fast. We
also discuss the nucleon and fragment exchange processes which are very
important for the energy minimization and finally present the analysis of the
reaction dynamics using the new algorithm. This algorithm is can be applied
whenever one wants to identify which of a given number of constituents form
bound objects.Comment: 36 pages, 15 figures, submitted to Journal of Computational Physic
A normal genetic variation modulates synaptic MMP-9 protein levels and the severity of schizophrenia symptoms
Abstract Matrix metalloproteinase 9 (MMP‐9) has recently emerged as a molecule that contributes to pathological synaptic plasticity in schizophrenia, but explanation of the underlying mechanisms has been missing. In the present study, we performed a phenotype‐based genetic association study (PGAS) in > 1,000 schizophrenia patients from the Göttingen Research Association for Schizophrenia (GRAS) data collection and found an association between the MMP‐9 rs20544 C/T single‐nucleotide polymorphism (SNP) located in the 3′untranslated region (UTR) and the severity of a chronic delusional syndrome. In cultured neurons, the rs20544 SNP influenced synaptic MMP‐9 activity and the morphology of dendritic spines. We demonstrated that Fragile X mental retardation protein (FMRP) bound the MMP‐9 3′UTR. We also found dramatic changes in RNA structure folding and alterations in the affinity of FMRP for MMP‐9 RNA, depending on the SNP variant. Finally, we observed greater sensitivity to psychosis‐related locomotor hyperactivity in Mmp‐9 heterozygous mice. We propose a novel mechanism that involves MMP‐9‐dependent changes in dendritic spine morphology and the pathophysiology of schizophrenia, providing the first mechanistic insights into the way in which the single base change in the MMP‐9 gene (rs20544) influences gene function and results in phenotypic changes observed in schizophrenia patients
The importance of initial-final state correlations for the formation of fragments in heavy ion collisions
Using quantum molecular dynamics simulations, we investigate the formation of
fragments in symmetric reactions between beam energies of E=30AMeV and 600AMeV.
After a comparison with existing data we investigate some observables relevant
to tackle equilibration: dsigma/dErat, the double differential cross section
dsigma/pt.dpz.dpt,... Apart maybe from very energetic E>400AMeV and very
central reactions, none of our simulations gives evidence that the system
passes through a state of equilibrium. Later, we address the production
mechanisms and find that, whatever the energy, nucleons finally entrained in a
fragment exhibit strong initial-final state correlations, in coordinate as well
as in momentum space. At high energy those correlations resemble the ones
obtained in the participant-spectator model. At low energy the correlations are
equally strong, but more complicated; they are a consequence of the Pauli
blocking of the nucleon-nucleon collisions, the geometry, and the excitation
energy. Studying a second set of time-dependent variables (radii,
densities,...), we investigate in details how those correlations survive the
reaction especially in central reactions where the nucleons have to pass
through the whole system. It appears that some fragments are made of nucleons
which were initially correlated, whereas others are formed by nucleons
scattered during the reaction into the vicinity of a group of previously
correlated nucleons.Comment: 45 pages text + 20 postscript figures Accepted for publication in
Physical Review
A temporal study of oxygen-rich pulsating variable AGB star, T Cep: Investigation on dust formation and dust properties
Pulsation is believed to be the leading cause of dusty mass loss from
Asymptotic Giant Branch (AGB) stars. We present a temporal study of T Cep, a
long-period Mira variable, using seven ISO SWS spectra, covering a 16-month
period over a single pulsation cycle. The observed spectral dust features
change over the pulsation cycle of this Mira. In general, the overall apparent
changes in spectral features can be attributed to changes in the dust
temperature, resulting from the intrinsic pulsation cycle of the central star.
However, not all feature changes are so easily explained. Based on direct
comparison with laboratory spectra of several potential minerals, the dust is
best explained by crystalline iron-rich silicates. These findings contradict
the currently favored dust formation hypotheses.Comment: This article has been accepted for publication in The Astrophysical
Journal. It is tentatively scheduled for the May 10, 2011, v732 -2 issu
Addressing the ‘hypoxia paradox’ in severe COVID-19: literature review and report of four cases treated with erythropoietin analogues
Background: Since fall 2019, SARS-CoV-2 spread world-wide, causing a major pandemic with estimated ~ 220 million subjects affected as of September 2021. Severe COVID-19 is associated with multiple organ failure, particularly of lung and kidney, but also grave neuropsychiatric manifestations. Overall mortality reaches > 2%. Vaccine development has thrived in thus far unreached dimensions and will be one prerequisite to terminate the pandemic. Despite intensive research, however, few treatment options for modifying COVID-19 course/outcome have emerged since the pandemic outbreak. Additionally, the substantial threat of serious downstream sequelae, called ‘long COVID’ and ‘neuroCOVID’, becomes increasingly evident. Main body of the abstract: Among candidates that were suggested but did not yet receive appropriate funding for clinical trials is recombinant human erythropoietin. Based on accumulating experimental and clinical evidence, erythropoietin is expected to (1) improve respiration/organ function, (2) counteract overshooting inflammation, (3) act sustainably neuroprotective/neuroregenerative. Recent counterintuitive findings of decreased serum erythropoietin levels in severe COVID-19 not only support a relative deficiency of erythropoietin in this condition, which can be therapeutically addressed, but also made us coin the term ‘hypoxia paradox’. As we review here, this paradox is likely due to uncoupling of physiological hypoxia signaling circuits, mediated by detrimental gene products of SARS-CoV-2 or unfavorable host responses, including microRNAs or dysfunctional mitochondria. Substitution of erythropoietin might overcome this ‘hypoxia paradox’ caused by deranged signaling and improve survival/functional status of COVID-19 patients and their long-term outcome. As supporting hints, embedded in this review, we present 4 male patients with severe COVID-19 and unfavorable prognosis, including predicted high lethality, who all profoundly improved upon treatment which included erythropoietin analogues. Short conclusion: Substitution of EPO may—among other beneficial EPO effects in severe COVID-19—circumvent downstream consequences of the ‘hypoxia paradox’. A double-blind, placebo-controlled, randomized clinical trial for proof-of-concept is warrante
Mid-Infrared Imaging and Modelling of the Dust Shell around Post-AGB star HD 187885 (IRAS 19500-1709)
We present 10 and 20 micron images of IRAS 19500-1709 taken with the
mid-infrared camera, OSCIR, mounted on the Gemini North Telescope. We use a 2-D
dust radiation transport code to fit the spectral energy distribution from UV
to sub-mm wavelengths and to simulate the images.Comment: 4 pages, 5 figures. To appear in "Asymmetric Planetary Nebulae III",
eds. M.Meixner, J.Kastner, N.Soker & B.Balick. 2004, ASP Conference Serie
Transport through a double quantum dot system with non-collinearly polarized leads
We investigate linear and non-linear transport in a double quantum dot system
weakly coupled to spin-polarized leads.
In the linear regime, the conductance as well as the non-equilibrium spin
accumulation are evaluated in analytic form. The conductance as a function of
the gate voltage exhibits four peaks of different height, with mirror symmetry
with respect to the charge neutrality point. As the polarization angle is
varied, the position and shape of the peaks changes in a characteristic way
which preserves the electron-hole symmetry of the problem. In the nonlinear
regime negative differential conductance features occur for non collinear
magnetisations of the leads. In the considered sequential tunneling limit, the
tunneling magneto resistance (TMR) is always positive with a characteristic
gate voltage dependence for non-collinear magnetization. If a magnetic field is
added to the system, the TMR can become negative.Comment: 18 pages, 13 figures, 5 tables; revised published versio
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