478 research outputs found
Exchange-correlation functionals from the strongly-interacting limit of DFT: Applications to model chemical systems
We study model one-dimensional chemical systems (representative of their
three-dimensional counterparts) using the strictly-correlated electrons (SCE)
functional, which, by construction, becomes asymptotically exact in the limit
of infinite coupling strength. The SCE functional has a highly non-local
dependence on the density and is able to capture strong correlation within
Kohn- Sham theory without introducing any symmetry breaking. Chemical systems,
however, are not close enough to the strong-interaction limit so that, while
ionization energies and the stretched H2 molecule are accurately described,
total energies are in general way too low. A correction based on the exact next
leading order in the expansion at infinite coupling strength of the
Hohenberg-Kohn functional largely improves the results.Comment: 9 pages, 6 figures. Submitted to PCCP's Themed Collection on Density
Functional Theory and its Application
Transport and interaction blockade of cold bosonic atoms in a triple-well potential
We theoretically investigate the transport properties of cold bosonic atoms
in a quasi one-dimensional triple-well potential that consists of two large
outer wells, which act as microscopic source and drain reservoirs, and a small
inner well, which represents a quantum-dot-like scattering region. Bias and
gate "voltages" introduce a time-dependent tilt of the triple-well
configuration, and are used to shift the energetic level of the inner well with
respect to the outer ones. By means of exact diagonalization considering a
total number of six atoms in the triple-well potential, we find diamond-like
structures for the occurrence of single-atom transport in the parameter space
spanned by the bias and gate voltages. We discuss the analogy with Coulomb
blockade in electronic quantum dots, and point out how one can infer the
interaction energy in the central well from the distance between the diamonds.Comment: 18 pages, 6 figure
Spin-orbit effects in GaAs quantum wells: Interplay between Rashba, Dresselhaus, and Zeeman interactions
The interplay between Rashba, Dresselhaus and Zeeman interactions in a
quantum well submitted to an external magnetic field is studied by means of an
accurate analytical solution of the Hamiltonian, including electron-electron
interactions in a sum rule approach. This solution allows to discuss the
influence of the spin-orbit coupling on some relevant quantities that have been
measured in inelastic light scattering and electron-spin resonance experiments
on quantum wells. In particular, we have evaluated the spin-orbit contribution
to the spin splitting of the Landau levels and to the splitting of charge- and
spin-density excitations. We also discuss how the spin-orbit effects change if
the applied magnetic field is tilted with respect to the direction
perpendicular to the quantum well.Comment: 26 pages (with 3 figures included
Transcript expression of vesicular glutamate transporters in lumbar dorsal root ganglia and the spinal cord of mice – Effects of peripheral axotomy or hindpaw inflammation
Using specific riboprobes, we characterized the expression of vesicular glutamate transporter (VGLUT)1–VGLUT3 transcripts in lumbar 4–5 (L4–5) dorsal root ganglions (DRGs) and the thoracolumbar to lumbosacral spinal cord in male BALB/c mice after a 1- or 3-day hindpaw inflammation, or a 7-day sciatic nerve axotomy. Sham animals were also included. In sham and contralateral L4–5 DRGs of injured mice, VGLUT1-, VGLUT2- and VGLUT3 mRNAs were expressed in ∼45%, ∼69% or ∼17% of neuron profiles (NPs), respectively. VGLUT1 was expressed in large and medium-sized NPs, VGLUT2 in NPs of all sizes, and VGLUT3 in small and medium-sized NPs. In the spinal cord, VGLUT1 was restricted to a number of NPs at thoracolumbar and lumbar segments, in what appears to be the dorsal nucleus of Clarke, and in mid laminae III–IV. In contrast, VGLUT2 was present in numerous NPs at all analyzed spinal segments, except the lateral aspects of the ventral horns, especially at the lumbar enlargement, where it was virtually absent. VGLUT3 was detected in a discrete number of NPs in laminae III–IV of the dorsal horn. Axotomy resulted in a moderate decrease in the number of DRG NPs expressing VGLUT3, whereas VGLUT1 and VGLUT2 were unaffected. Likewise, the percentage of NPs expressing VGLUT transcripts remained unaltered after hindpaw inflammation, both in DRGs and the spinal cord. Altogether, these results confirm previous descriptions on VGLUTs expression in adult mice DRGs, with the exception of VGLUT1, whose protein expression was detected in a lower percentage of mouse DRG NPs. A detailed account on the location of neurons expressing VGLUTs transcripts in the adult mouse spinal cord is also presented. Finally, the lack of change in the number of neurons expressing VGLUT1 and VGLUT2 transcripts after axotomy, as compared to data on protein expression, suggests translational rather than transcriptional regulation of VGLUTs after injury.Fil: Malet, Mariana. Universidad Austral. Facultad de Ciencias Biomédicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vieytes, C. A.. Universidad Austral. Facultad de Ciencias Biomédicas; ArgentinaFil: Lundgren, K. H.. University of Cincinnati; Estados UnidosFil: Seal, R. P.. University of Pittsburgh; Estados UnidosFil: Tomasella, María Eugenia. Universidad Austral. Facultad de Ciencias Biomédicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Seroogy, K. B.. University of Cincinnati; Estados UnidosFil: Hökfelt, T.. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Gebhart, G. F.. University of Pittsburgh; Estados UnidosFil: Brumovsky, Pablo Rodolfo. Universidad Austral. Facultad de Ciencias Biomédicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Pittsburgh; Estados Unido
Evolution of CODYRUN from Thermal Simulation to Coupled Thermal and Daylight Simulation Software
AbstractCODYRUN is a multi-zone software integrating thermal building simulation, airflow, and pollutant transfer. Described in numerous publications, this software was originally used for the passive design of buildings, both for research and teaching purposes. In this context, the data treated were mainly concerned with volumes (zones), surfaces and thicknesses (walls and windows), materials, and systems, with the aim to determine temperatures, heat fluxes, energy consumed, air transfers, and so on.The question thus arose as to the integration of indoor lighting conditions into the simulation. Hence, previous data structures had to be amended to incorporate the spatial positioning of entities (walls, windows, and artificial lighting sources) through vertexes. A set of procedures was also developed for polygons as well as calculating natural and artificial lighting.The results of this new daylighting module were then compared with other results of simulation codes and experimental cases both in artificial and natural environments. Excellent agreements were obtained, such as the values for luminous efficiencies in a tropical and humid climate.A simulation exercise was conducted in a classroom located in Reunion Island (French overseas territory in the Indian Ocean), thus confirming the interest for thermal and daylighting designs in low-energy buildings
RETURNEES: WHO ARE THEY, WHY ARE THEY (NOT) COMING BACK AND HOW SHOULD WE DEAL WITH THEM? Assessing Policies on Returning Foreign Terrorist Fighters in Belgium, Germany and the Netherlands. Egmont Paper 101, February 2018
Some 5000 men, women and children have travelled from Europe to Syria and Iraq since 2012. An estimated 1500 of these foreign terrorist fighters (FTF) have returned so far. Belgium, Germany and the Netherlands represent a third of European FTF and returnees. This report looks into the evolution of policies on returning foreign fighters in these three countries, comparing responses with regard to fighters that are still in the conflict zone, policies to deal with returnees in prison and attitudes towards the children of foreign fighters. It is the very first systematic and in-depth study into national approaches and policies vis-à-vis returnees. Its added value lies in the wealth of data, including data that has not been published before, and in the comparative angle
Stevin numbers and reality
We explore the potential of Simon Stevin's numbers, obscured by shifting
foundational biases and by 19th century developments in the arithmetisation of
analysis.Comment: 22 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1104.0375, arXiv:1108.2885, arXiv:1108.420
Spectrum and Variability of Mrk501 as observed by the CAT Imaging Telescope
The CAT Imaging Telescope has observed the BL Lac object Markarian 501
between March and August 1997. We report here on the variability over this time
including several large flares. We present also preliminary spectra for all
these data, for the low emission state, and for the largest flare.Comment: 4 pages, 4 figures, Late
Very High Energy Gamma-ray spectral properties of Mrk 501 from CAT Cerenkov telescope observations in 1997
The BL Lac object Mrk 501 went into a very high state of activity during
1997, both in VHE gamma-rays and X-rays. We present here results from
observations at energies above 250 GeV carried out between March and October
1997 with the CAT Cerenkov imaging Telescope. The average differential spectrum
between 30 GeV and 13 TeV shows significant curvature and is well represented
by phi_0 * E_TeV^{-(alpha + beta*log10(E_TeV))}, with: phi_0 = 5.19 +/- 0.13
{stat} +/- 0.12 {sys-MC} +1.66/-1.04 {sys-atm} * 10^-11 /cm^2/s/TeV alpha =
2.24 +/- 0.04 {stat} +/- 0.05 {sys} beta = 0.50 +/- 0.07 {stat} (negligible
systematics). The TeV spectral energy distribution of Mrk 501 clearly peaks in
the range 500 GeV-1 TeV. Investigation of spectral variations shows a
significant hardness-intensity correlation with no measurable effect on the
curvature. This can be described as an increase of the peak TeV emission energy
with intensity. Simultaneous and quasi-simultaneous CAT VHE gamma-ray and
BeppoSAX hard X-ray detections for the highest recorded flare on 16th April and
for lower-activity states of the same period show correlated variability with a
higher luminosity in X-rays than in gamma-rays. The observed spectral energy
distribution and the correlated variability between X-rays and gamma-rays, both
in amplitude and in hardening of spectra, favour a two-component emission
scheme where the low and high energy components are attributed to synchrotron
and inverse Compton (IC) radiation, respectively.Comment: Submitted to Astronomy and Astrophysics, 8 pages including 6 figures.
Published with minor change
Ten Misconceptions from the History of Analysis and Their Debunking
The widespread idea that infinitesimals were "eliminated" by the "great
triumvirate" of Cantor, Dedekind, and Weierstrass is refuted by an
uninterrupted chain of work on infinitesimal-enriched number systems. The
elimination claim is an oversimplification created by triumvirate followers,
who tend to view the history of analysis as a pre-ordained march toward the
radiant future of Weierstrassian epsilontics. In the present text, we document
distortions of the history of analysis stemming from the triumvirate ideology
of ontological minimalism, which identified the continuum with a single number
system. Such anachronistic distortions characterize the received interpretation
of Stevin, Leibniz, d'Alembert, Cauchy, and others.Comment: 46 pages, 4 figures; Foundations of Science (2012). arXiv admin note:
text overlap with arXiv:1108.2885 and arXiv:1110.545
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