50 research outputs found
Entropic uncertainty measures for large dimensional hydrogenic systems
The entropic moments of the probability density of a quantum system in position and momentum spaces describe not only some fundamental and/or experimentally accessible quantities of the system but also the entropic uncertainty measures of R\xc3\xa9nyi type, which allow one to find the most relevant mathematical formalizations of the position-momentum Heisenberg\'s uncertainty principle, the entropic uncertainty relations. It is known that the solution of difficult three-dimensional problems can be very well approximated by a series development in 1/D in similar systems with a nonstandard dimensionality D; moreover, several physical quantities of numerous atomic and molecular systems have been numerically shown to have values in the large- D limit comparable to the corresponding ones provided by the three-dimensional numerical self-consistent field methods. The D-dimensional hydrogenic atom is the main prototype of the physics of multidimensional many-electron systems. In this work, we rigorously determine the leading term of the R\xc3\xa9nyi entropies of the Ddimensional hydrogenic atom at the limit of large D. As a byproduct, we show that our results saturate the known position-momentum R\xc3\xa9nyi-entropy-based uncertainty relations
THREE-DIMENSIONAL ASSESSMENT OF ON WATER ROWING TECHNIQUE: A METHODOLOGICAL STUDY
The analysis of rowing technique in training or competitive environments has been a challenge to biomechanists for some time now. Typically, two-dimensional assessments are carried out with fixed cameras mounted on-land next to a rowing course (Hay 1993) or by handheld cameras from an accompanying boat. Three-dimensional technique analysis were only presented for athletes rowing on an ergometer in a laboratory environment (Hofmijster et al. 2007). The purpose of this study was to develop and validate a system for three-dimensional kinematic analyses of on water rowing
Pengukuran Geolistrik Pada Daerah Rawan Gerakan Tanah di Kota Semarang untuk Identifikasi Bidang Gelincir_Turnitin
Characterization of a Li-6 loaded liquid organic scintillator for fast neutron spectrometry and thermal neutron detection
The characterization of a liquid scintillator incorporating an aqueous
solution of enriched lithium chloride to produce a scintillator with 0.40% Li-6
is presented, including the performance of the scintillator in terms of its
optical properties and neutron response. The scintillator was incorporated into
a fast neutron spectrometer, and the light output spectra from 2.5 MeV, 14.1
MeV, and Cf-252 neutrons were measured using capture-gated coincidence
techniques. The spectrometer was operated without coincidence to perform
thermal neutron measurements. Possible improvements in spectrometer performance
are discussed.Comment: Submitted to Applied Radiation and Isotopes. 11 pages, 7 figures, 3
tables. Revision addresses reviewers' comment
Virtual annihilation contribution to orthopositronium decay rate
Order alpha^2 contribution to the orthopositronium decay rate due to
one-photon virtual annihilation is found to be
delta Gamma = (alpha/pi)^2 (pi^2 ln(alpha) - 0.8622(9))Gamma_LO.Comment: 2 pages, no figure
Heterogeneity of mouse spleen dendritic cells: in vivo phagocytic activity, expression of macrophage markers, and subpopulation turnover
In the normal mouse spleen, two distinct populations of dendritic cells
(DC) are present that differ in microanatomical location. The major
population of marginal DC is found in the "marginal zone bridging
channels" and extends into the red pulp. The interdigitating cells (IDC)
are localized in the T cell areas in the white pulp. The aim of the
present study was to characterize these two splenic DC populations with
regard to their phenotype, in vivo phagocytic function, and turnover. Both
marginal DC and IDC are CD11c+ and CD13+, but only IDC are NLDC-145+ and
CD8alpha+. Notably, both populations, when freshly isolated, express the
macrophage markers F4/80, BM8, and Mac-1. To study the phagocytic capacity
of these cells, we employed the macrophage "suicide" technique by
injecting liposomes loaded with clodronate i.v. Marginal DC, but not IDC,
were eliminated by this treatment. Phagocytosis of DiI-labeled liposomes
by DC confirmed this finding. The two DC populations differed
significantly with regard to their turnover rates, as studied in a
transgenic mouse model of conditional depletion of DC populations with
high turnover. In these mice, marginal DC were completely eliminated, but
the IDC population remained virtually intact. From these data we conclude
that the marginal DC population has a high turnover, in contrast to the
IDC population. Taken together, the present results indicate that marginal
DC and IDC represent two essentially distinct populations of DC in the
mouse spleen. They differ not only in location, but also in phenotype,
phagocytic ability, and turnover
A gamma- and X-ray detector for cryogenic, high magnetic field applications
As part of an experiment to measure the spectrum of photons emitted in
beta-decay of the free neutron, we developed and operated a detector consisting
of 12 bismuth germanate (BGO) crystals coupled to avalanche photodiodes (APDs).
The detector was operated near liquid nitrogen temperature in the bore of a
superconducting magnet and registered photons with energies from 5 keV to 1000
keV. To enlarge the detection range, we also directly detected soft X-rays with
energies between 0.2 keV and 20 keV with three large area APDs. The
construction and operation of the detector is presented, as well as information
on operation of APDs at cryogenic temperatures
Biodiversity enhances ecosystem multifunctionality across trophic levels and habitats
The importance of biodiversity for the integrated functioning of ecosystems remains unclear because most evidence comes from analyses of biodiversity\u27s effect on individual functions. Here we show that the effects of biodiversity on ecosystem function become more important as more functions are considered. We present the first systematic investigation of biodiversity\u27s effect on ecosystem multifunctionality across multiple taxa, trophic levels and habitats using a comprehensive database of 94 manipulations of species richness. We show that species-rich communities maintained multiple functions at higher levels than depauperate ones. These effects were stronger for herbivore biodiversity than for plant biodiversity, and were remarkably consistent across aquatic and terrestrial habitats. Despite observed tradeoffs, the overall effect of biodiversity on multifunctionality grew stronger as more functions were considered. These results indicate that prior research has underestimated the importance of biodiversity for ecosystem functioning by focusing on individual functions and taxonomic groups
Radiative β decay of the free neutron
The theory of quantum electrodynamics predicts that the β decay of the neutron into a proton, electron, and antineutrino is accompanied by a continuous spectrum of emitted photons described as inner bremsstrahlung. While this phenomenon has been observed in nuclear β decay and electron-capture decay for many years, it has only been recently observed in free-neutron decay. We present a detailed discussion of an experiment in which the radiative decay mode of the free neutron was observed. In this experiment, the branching ratio for this rare decay was determined by recording photons that were correlated with both the electron and proton emitted in neutron decay. We determined the branching ratio for photons with energy between 15 and 340 keV to be (3.09±0.32)×10-3 (68% level of confidence), where the uncertainty is dominated by systematic effects. This value for the branching ratio is consistent with theoretical predictions. The characteristic energy spectrum of the radiated photons, which differs from the uncorrelated background spectrum, is also consistent with the theoretical spectrum
Two-loop corrections to the decay rate of parapositronium
Order corrections to the decay rate of parapositronium are
calculated. A QED scattering calculation of the amplitude for electron-positron
annihilation into two photons at threshold is combined with the technique of
effective field theory to determine an NRQED Hamiltonian, which is then used in
a bound state calculation to determine the decay rate. Our result for the
two-loop correction is in units of times the
lowest order rate. This is consistent with but more precise than the result
of a previous calculation.Comment: 26 pages, 7 figure