2,313 research outputs found
Correlation potentials for molecular bond dissociation within the self-consistent random phase approximation
Self-consistent correlation potentials for H and LiH for various
inter-atomic separations are obtained within the random phase approximation
(RPA) of density functional theory. The RPA correlation potential shows a peak
at the bond midpoint, which is an exact feature of the true correlation
potential, but lacks another exact feature: the step important to preserve
integer charge on the atomic fragments in the dissociation limit. An analysis
of the RPA energy functional in terms of fractional charge is given which
confirms these observations. We find that the RPA misses the derivative
discontinuity at odd integer particle numbers but explicitly eliminates the
fractional spin error in the exact-exchange functional. The latter finding
explains the accurate total energy in the dissociation limit.Comment: 9 pages, 10 figure
Exchange-correlation orbital functionals in current-density-functional theory: Application to a quantum dot in magnetic fields
The description of interacting many-electron systems in external magnetic
fields is considered in the framework of the optimized effective potential
method extended to current-spin-density functional theory. As a case study, a
two-dimensional quantum dot in external magnetic fields is investigated.
Excellent agreement with quantum Monte Carlo results is obtained when
self-interaction corrected correlation energies from the standard local
spin-density approximation are added to exact-exchange results. Full
self-consistency within the complete current-spin-density-functional framework
is found to be of minor importance.Comment: 5 pages, 2 figures, submitted to PR
The European Network for Translational Research in Atrial Fibrillation (EUTRAF): objectives and initial results.
Atrial fibrillation (AF) is the most common sustained arrhythmia in the general population. As an age-related arrhythmia AF is becoming a huge socio-economic burden for European healthcare systems. Despite significant progress in our understanding of the pathophysiology of AF, therapeutic strategies for AF have not changed substantially and the major challenges in the management of AF are still unmet. This lack of progress may be related to the multifactorial pathogenesis of atrial remodelling and AF that hampers the identification of causative pathophysiological alterations in individual patients. Also, again new mechanisms have been identified and the relative contribution of these mechanisms still has to be established. In November 2010, the European Union launched the large collaborative project EUTRAF (European Network of Translational Research in Atrial Fibrillation) to address these challenges. The main aims of EUTRAF are to study the main mechanisms of initiation and perpetuation of AF, to identify the molecular alterations underlying atrial remodelling, to develop markers allowing to monitor this processes, and suggest strategies to treat AF based on insights in newly defined disease mechanisms. This article reports on the objectives, the structure, and initial results of this network
The Use of Repatriate Knowledge in Austrian Banks
Repatriates are mostly an underestimated resource within a company. Repatriates could contribute to sustained competitive advantage of firms as a rare and imperfectly imitable resource, if firms would fully employ their knowledge. In extant literature, we find four major categories of expatriate knowledge: market specific knowledge, personal skills (Adler 2000, Antal 2000, Downes/Thomas, 1999, Kühlmann/Stahl 1995), job related management skills, and network skills (Antal 2000, Downes/Thomas 1999, Kühlmann/Stahl 1995). In an explorative qualitative case study in Austrian commercial banks, we collected data about the knowledge acquired by expatriates using narrative interview techniques. From the perspective of the interviewed repatriates, the existent categories could be confirmed and an additional category of importance was found that so far was not identified in the literature: the general management capacity of expatriates was substantially enhanced during their assignment abroad
Experimental and computational analyses reveal that environmental restrictions shape HIV-1 spread in 3D cultures
Here, using an integrative experimental and computational approach, Imle et al. show how cell motility and density affect HIV cell-associated transmission in a three-dimensional tissue-like culture system of CD4+ T cells and collagen, and how different collagen matrices restrict infection by cell-free virions
Die Spektren der Protonen aus (d,p)-Reaktionen an schweren Kernenbei Deuteronenenergien unter 12 MeV.
The proton spectra of the (d,p)-reactions on heavy nuclei show, in addition to the low energy continuum and the gross structure at higher energies, a pronounced proton group. The relative intensity of the proton group increases with decreasing energy of the primary deuterons. The dependence of the spectra on the atomic number of the target and the energy dependence and angular distribution for gold have been measured. The results are explained in terms of the properties of the nuclear surface
First Demonstration of a Pixelated Charge Readout for Single-Phase Liquid Argon Time Projection Chambers
Liquid Argon Time Projection Chambers (LArTPCs) have been selected for the
future long-baseline Deep Underground Neutrino Experiment (DUNE). To allow
LArTPCs to operate in the high-multiplicity near detector environment of DUNE,
a new charge readout technology is required. Traditional charge readout
technologies introduce intrinsic ambiguities, combined with a slow detector
response, these ambiguities have limited the performance of LArTPCs, until now.
Here, we present a novel pixelated charge readout that enables the full 3D
tracking capabilities of LArTPCs. We characterise the signal to noise ratio of
charge readout chain, to be about 14, and demonstrate track reconstruction on
3D space points produced by the pixel readout. This pixelated charge readout
makes LArTPCs a viable option for the DUNE near detector complex.Comment: 13 pages, 9 figure
Elastic scattering of 11,8 MEV deuterons from several elements
The angular distributions of 11.8 MeV deuterons elastically scattered from C, Mg, Al, Ti, Fe, Ni, Cu, Zn, Zr, Nb, Rh, Pd, Ag, Cd, In, Sn, Ta and Au have been measured. The detector is capable of electronically separating deuterons from other ions which may enter the detector. The data has been taken in 2 degree steps between 20° and 165°. The structure in the angular distribution observed with the light target elements vanishes with increasing atomic weight. An exception is observed between A=90 and A=120
Reduced dose of subcutaneous cladribine induces identical response rates but decreased toxicity in pretreated chronic lymphocytic leukaemia
Purpose To study the efficacy and the safety of cladribine (2-chlorodeoxyadenosine, 2-CDA) administered as 24-hour infusions or as subcutaneous bolus injections at two different doses to patients with relapsing or refractory chronic lymphocytic leukaemia (CLL). Patients and methods In this non randomised 2-cohort study, 20 patients with pretreated CLL received cladribine at a dose of 0.7 mg/kg/cycle as continuous i.v. infusions over seven days (group 1) and 35 patients were treated at a reduced dose of 0.5 mg/kg/cycle given as s.c. bolus injections for five days (group 2). After two cycles of four week duration, response was assessed. In the case of progressive disease, therapy was discontinued, otherwise a maximum of four additional cycles were administered until best response. Results A total of 130 cycles were administered (group 1: 41, group 2: 89). Patient characteristics in both groups were comparable. The median dose intensities were 0.172 mg/kg per week and 0.123 mg/kg per week for groups 1 and 2, respectively (P ≤ 0.0001). The overall response rate for all 55 patients was 38% (95% confidence interval (95% CI): 25%-52%), with 5% CR and 33% PR. Response was similar in both patient groups (35% in group 1, 40% in group 2). No association between cladribine dose intensity and response rate was found, and there was no difference between patients relapsing after or refractory to previous therapies (11 of 24 vs. 10 of 31). Median remission duration was six months in both groups. Toxicity, in particular infections (all WHO grades, 34% in group 1 versus 7% in group 2) and myelosuppression (grade 1-4 neutropenia, 72% versus 41% of cladribine cycles) were statistically significantly more frequent in group 1. Conclusion Cladribine is active in heavily pretreated patients with chronic lymphocytic leukaemias. Dose reduction by 29% led to similar response and remission duration, but to a significant decrease of myelotoxicity and risk of infection. Cladribine administered as s.c. bolus injections at 0.5 mg/kg per cycle is safe and this dose level should not be exceeded in this patient populatio
Dynamic heterogeneities in the out-of-equilibrium dynamics of simple spherical spin models
The response of spherical two-spin interaction models, the spherical
ferromagnet (s-FM) and the spherical Sherrington-Kirkpatrick (s-SK) model, is
calculated for the protocol of the so-called nonresonant hole burning
experiment (NHB) for temperatures below the respective critical temperatures.
It is shown that it is possible to select dynamic features in the
out-of-equilibrium dynamics of both models, one of the hallmarks of dynamic
heterogeneities. The behavior of the s-SK model and the s-FM in three
dimensions is very similar, showing dynamic heterogeneities in the long time
behavior, i.e. in the aging regime. The appearence of dynamic heterogeneities
in the s-SK model explicitly demonstrates that these are not necessarily
related to {\it spatial} heterogeneities. For the s-FM it is shown that the
nature of the dynamic heterogeneities changes as a function of dimensionality.
With incresing dimension the frequency selectivity of the NHB diminishes and
the dynamics in the mean-field limit of the s-FM model becomes homogeneous.Comment: 16 pages, 8 figure
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