5,323 research outputs found
Effects of the intravenous administration of purine nucleosides guanosine or inosine against hemorrhagic shock in pigs
The Sri Lanka National Blindness, Visual Impairment and Disability Survey: rationale, objectives and detailed methodology
The luminosity function of field galaxies
Schmidt's method for construction of luminosity function of galaxies is
generalized by taking into account the dependence of density of galaxies from
the distance in the near Universe. The logarithmical luminosity function (LLF)
of field galaxies depending on morphological type is constructed. We show that
the LLF for all galaxies, and also separately for elliptical and lenticular
galaxies can be presented by Schechter function in narrow area of absolute
magnitudes. The LLF of spiral galaxies was presented by Schechter function for
enough wide area of absolute magnitudes: . Spiral galaxies differ slightly by
parameter . At transition from early spirals to the late spirals parameter in
Schechter function is reduced. The reduction of mean luminosity of galaxies is
observed at transition from elliptical galaxies to lenticular galaxies, to
early spiral galaxies, and further, to late spiral galaxies, in a bright end, .
The completeness and the average density of samples of galaxies of different
morphological types are estimated. In the range the mean number density of all
galaxies is equal 0.127 Mpc-3.Comment: 14 page, 8 figures, to appear in Astrophysic
A photonic quantum information interface
Quantum communication is the art of transferring quantum states, or quantum
bits of information (qubits), from one place to another. On the fundamental
side, this allows one to distribute entanglement and demonstrate quantum
nonlocality over significant distances. On the more applied side, quantum
cryptography offers, for the first time in human history, a provably secure way
to establish a confidential key between distant partners. Photons represent the
natural flying qubit carriers for quantum communication, and the presence of
telecom optical fibres makes the wavelengths of 1310 and 1550 nm particulary
suitable for distribution over long distances. However, to store and process
quantum information, qubits could be encoded into alkaline atoms that absorb
and emit at around 800 nm wavelength. Hence, future quantum information
networks made of telecom channels and alkaline memories will demand interfaces
able to achieve qubit transfers between these useful wavelengths while
preserving quantum coherence and entanglement. Here we report on a qubit
transfer between photons at 1310 and 710 nm via a nonlinear up-conversion
process with a success probability greater than 5%. In the event of a
successful qubit transfer, we observe strong two-photon interference between
the 710 nm photon and a third photon at 1550 nm, initially entangled with the
1310 nm photon, although they never directly interacted. The corresponding
fidelity is higher than 98%.Comment: 7 pages, 3 figure
Combustion in thermonuclear supernova explosions
Type Ia supernovae are associated with thermonuclear explosions of white
dwarf stars. Combustion processes convert material in nuclear reactions and
release the energy required to explode the stars. At the same time, they
produce the radioactive species that power radiation and give rise to the
formation of the observables. Therefore, the physical mechanism of the
combustion processes, as reviewed here, is the key to understand these
astrophysical events. Theory establishes two distinct modes of propagation for
combustion fronts: subsonic deflagrations and supersonic detonations. Both are
assumed to play an important role in thermonuclear supernovae. The physical
nature and theoretical models of deflagrations and detonations are discussed
together with numerical implementations. A particular challenge arises due to
the wide range of spatial scales involved in these phenomena. Neither the
combustion waves nor their interaction with fluid flow and instabilities can be
directly resolved in simulations. Substantial modeling effort is required to
consistently capture such effects and the corresponding techniques are
discussed in detail. They form the basis of modern multidimensional
hydrodynamical simulations of thermonuclear supernova explosions. The problem
of deflagration-to-detonation transitions in thermonuclear supernova explosions
is briefly mentioned.Comment: Author version of chapter for 'Handbook of Supernovae,' edited by A.
Alsabti and P. Murdin, Springer. 24 pages, 4 figure
Scanning-probe spectroscopy of semiconductor donor molecules
Semiconductor devices continue to press into the nanoscale regime, and new
applications have emerged for which the quantum properties of dopant atoms act
as the functional part of the device, underscoring the necessity to probe the
quantum structure of small numbers of dopant atoms in semiconductors[1-3].
Although dopant properties are well-understood with respect to bulk
semiconductors, new questions arise in nanosystems. For example, the quantum
energy levels of dopants will be affected by the proximity of nanometer-scale
electrodes. Moreover, because shallow donors and acceptors are analogous to
hydrogen atoms, experiments on small numbers of dopants have the potential to
be a testing ground for fundamental questions of atomic and molecular physics,
such as the maximum negative ionization of a molecule with a given number of
positive ions[4,5]. Electron tunneling spectroscopy through isolated dopants
has been observed in transport studies[6,7]. In addition, Geim and coworkers
identified resonances due to two closely spaced donors, effectively forming
donor molecules[8]. Here we present capacitance spectroscopy measurements of
silicon donors in a gallium-arsenide heterostructure using a scanning probe
technique[9,10]. In contrast to the work of Geim et al., our data show
discernible peaks attributed to successive electrons entering the molecules.
Hence this work represents the first addition spectrum measurement of dopant
molecules. More generally, to the best of our knowledge, this study is the
first example of single-electron capacitance spectroscopy performed directly
with a scanning probe tip[9].Comment: In press, Nature Physics. Original manuscript posted here; 16 pages,
3 figures, 5 supplementary figure
Generation of Functional CLL-Specific Cord Blood CTL Using CD40-Ligated CLL APC
PMCID: PMC3526610This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
A cost-effective method to quantify biological surface sediment reworking
We propose a simple and inexpensive method to determine the rate and pattern of surface sediment reworking by benthic organisms. Unlike many existing methods commonly used in bioturbation studies, which usually require sediment sampling, our approach is fully non-destructive and is well suited for investigating non-cohesive fine sediments in streams and rivers. Optical tracer (e.g., luminophores or coloured sand) disappearance or appearance is assessed through time based on optical quantification of surfaces occupied by tracers. Data are used to calculate surface sediment reworking (SSR) coefficients depicting bioturbation intensities. Using this method, we evaluated reworking activity of stream organisms (three benthic invertebrates and a fish) in laboratory microcosms mimicking pool habitats or directly in the field within arenas set in depositional zones. Our method was sensitive enough to measure SSR as low as 0.2 cm2.d-1, such as triggered by intermediate density (774 m-2) of Gammarus fossarum (Amphipoda) in microcosms. In contrast, complex invertebrate community in the field and a fish (Barbatula barabatula) in laboratory microcosms were found to yield to excessively high SSR (>60 cm2.d-1). Lastly, we suggest that images acquired during experiments can be used for qualitative evaluation of species-specific effects on sediment distribution
Prevalence of self-reported disability, activity limitation and social participation in Sri Lanka
Introduction
The World Health Organization estimates that 15% of the global population has a disability. Available evidence from Sri Lanka shows variable estimates of the magnitude of disability.
Objectives
Determine the prevalence of self-reported disability in the adult population aged ≥18 years, and associated risk factors in a nationally representative sample in Sri Lanka.
Methods
The Washington Group short questionnaire was used to identify persons with self-reported disability. Data were collected from responsible adults aged ≥18 years in the selected households. A four point-scale: “no difficulty”, “some difficulty”, “a lot of difficulty” and “cannot do at all” was used. Individuals screening positive for disability were administered an additional questionnaire on activity limitations, social participation and their health and financial concerns.
Results
Overall 41.5% (4131) [95% CI: 40.5-42.4] reported functional difficulty in at least one domain. The prevalence of disability, i.e. a lot of difficulty or cannot do at all was 3.8% (382) [95% CI: 3.5 – 4.2], while the prevalence of “some functional difficulty” was 37.6% (3749) [95% CI: 36.7-38.6].
The prevalence of disability increased with age and was higher among females, urban residents, and those with lower education and socio-economic status. Minor degrees of functional difficulties were more common among older people, females and people with lower education.
Conclusions
The prevalence of disability and varying degrees of functional difficulty is high among the adult population of Sri Lanka. Evidence shows that a strategic plan is required to address the magnitude of disability and functional limitations in Sri Lanka
Spin-orbit density wave induced hidden topological order in URu2Si2
The conventional order parameters in quantum matters are often characterized
by 'spontaneous' broken symmetries. However, sometimes the broken symmetries
may blend with the invariant symmetries to lead to mysterious emergent phases.
The heavy fermion metal URu2Si2 is one such example, where the order parameter
responsible for a second-order phase transition at Th = 17.5 K has remained a
long-standing mystery. Here we propose via ab-initio calculation and effective
model that a novel spin-orbit density wave in the f-states is responsible for
the hidden-order phase in URu2Si2. The staggered spin-orbit order 'spontaneous'
breaks rotational, and translational symmetries while time-reversal symmetry
remains intact. Thus it is immune to pressure, but can be destroyed by magnetic
field even at T = 0 K, that means at a quantum critical point. We compute
topological index of the order parameter to show that the hidden order is
topologically invariant. Finally, some verifiable predictions are presented.Comment: (v2) Substantially modified from v1, more calculation and comparison
with experiments are include
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