2,835 research outputs found
Information on the Pion Distribution Amplitude from the Pion-Photon Transition Form Factor with the Belle and BaBar Data
The pion-photon transition form factor (TFF) provides strong constraints on
the pion distribution amplitude (DA). We perform an analysis of all existing
data (CELLO, CLEO, BaBar, Belle) on the pion-photon TFF by means of light-cone
pQCD approach in which we include the next-to-leading order correction to the
valence-quark contribution and estimate the non-valence-quark contribution by a
phenomenological model based on the TFF's limiting behavior at both
and . At present, the pion DA is not definitely determined, it is
helpful to have a pion DA model that can mimic all the suggested behaviors,
especially to agree with the constraints from the pion-photon TFF in whole
measured region within a consistent way. For the purpose, we adopt the
conventional model for pion wavefunction/DA that has been constructed in our
previous paper \cite{hw1}, whose broadness is controlled by a parameter . We
fix the DA parameters by using the CELLO, CLEO, BABAR and Belle data within the
smaller region ( GeV), where all the data are consistent
with each other. And then the pion-photon TFF is extrapolated into larger
region. We observe that the BABAR favors which has the behavior close
to the Chernyak-Zhitnitsky DA, whereas the recent Belle favors which
is close to the asymptotic DA. We need more accurate data at large region
to determine the precise value of , and the definite behavior of pion DA can
be concluded finally by the consistent data in the coming future.Comment: 6 pages, 5 figures. Slightly changed and references update
The psychometric properties of the quick inventory of depressive symptomatology-self-report (QIDS-SR) in patients with HBV-related liver disease
Background: Comorbid depression in Hepatitis B virus (HBV) is common. Developing accurate and time efficient tools to measure depressive symptoms in HBV is important for research and clinical practice in China.
Aims: This study tested the psychometric properties of the Chinese version of the 16-item Quick Inventory of Depressive Symptomatology (QIDS-SR) in HBV patients.
Methods: The study recruited 245 depressed patients with HBV and related liver disease. The severity of depressive symptoms was assessed with the Montgomery-Asberg Depression Rating Scale (MADRS) and the QIDS-SR.
Results: Internal consistency (Cronbach’s alpha) was 0.796 for QIDS-SR. The QIDS-SR total score was significantly correlated with the MADRS total score (r=0.698, p.
Conclusions: The QIDS-SR (Chinese version) has good psychometric properties in HBV patients and appears to be useful in assessing depression in clinical settings
Molecular cloning and analysis of zebrafish voltage-gated sodium channel beta subunit genes: implications for the evolution of electrical signaling in vertebrates
<p>Abstract</p> <p>Background</p> <p>Action potential generation in excitable cells such as myocytes and neurons critically depends on voltage-gated sodium channels. In mammals, sodium channels exist as macromolecular complexes that include a pore-forming alpha subunit and 1 or more modulatory beta subunits. Although alpha subunit genes have been cloned from diverse metazoans including flies, jellyfish, and humans, beta subunits have not previously been identified in any non-mammalian species. To gain further insight into the evolution of electrical signaling in vertebrates, we investigated beta subunit genes in the teleost <it>Danio rerio </it>(zebrafish).</p> <p>Results</p> <p>We identified and cloned single zebrafish gene homologs for beta1-beta3 (<it>zbeta1-zbeta3</it>) and duplicate genes for beta4 (<it>zbeta4.1, zbeta4.2</it>). Sodium channel beta subunit loci are similarly organized in fish and mammalian genomes. Unlike their mammalian counterparts, <it>zbeta1 </it>and <it>zbeta2 </it>subunit genes display extensive alternative splicing. Zebrafish beta subunit genes and their splice variants are differentially-expressed in excitable tissues, indicating tissue-specific regulation of <it>zbeta1-4 </it>expression and splicing. Co-expression of the genes encoding zbeta1 and the zebrafish sodium channel alpha subunit Na<sub>v</sub>1.5 in Chinese Hamster Ovary cells increased sodium current and altered channel gating, demonstrating functional interactions between zebrafish alpha and beta subunits. Analysis of the synteny and phylogeny of mammalian, teleost, amphibian, and avian beta subunit and related genes indicated that all extant vertebrate beta subunits are orthologous, that beta2/beta4 and beta1/beta3 share common ancestry, and that beta subunits are closely related to other proteins sharing the V-type immunoglobulin domain structure. Vertebrate sodium channel beta subunit genes were not identified in the genomes of invertebrate chordates and are unrelated to known subunits of the <it>para </it>sodium channel in <it>Drosophila</it>.</p> <p>Conclusion</p> <p>The identification of conserved orthologs to all 4 voltage-gated sodium channel beta subunit genes in zebrafish and the lack of evidence for beta subunit genes in invertebrate chordates together indicate that this gene family emerged early in vertebrate evolution, prior to the divergence of teleosts and tetrapods. The evolutionary history of sodium channel beta subunits suggests that these genes may have played a key role in the diversification and specialization of electrical signaling in early vertebrates.</p
Efficient routing on complex networks
In this letter, we propose a new routing strategy to improve the
transportation efficiency on complex networks. Instead of using the routing
strategy for shortest path, we give a generalized routing algorithm to find the
so-called {\it efficient path}, which considers the possible congestion in the
nodes along actual paths. Since the nodes with largest degree are very
susceptible to traffic congestion, an effective way to improve traffic and
control congestion, as our new strategy, can be as redistributing traffic load
in central nodes to other non-central nodes. Simulation results indicate that
the network capability in processing traffic is improved more than 10 times by
optimizing the efficient path, which is in good agreement with the analysis.Comment: 4 pages, 4 figure
On the 2d Zakharov system with L^2 Schr\"odinger data
We prove local in time well-posedness for the Zakharov system in two space
dimensions with large initial data in L^2 x H^{-1/2} x H^{-3/2}. This is the
space of optimal regularity in the sense that the data-to-solution map fails to
be smooth at the origin for any rougher pair of spaces in the L^2-based Sobolev
scale. Moreover, it is a natural space for the Cauchy problem in view of the
subsonic limit equation, namely the focusing cubic nonlinear Schroedinger
equation. The existence time we obtain depends only upon the corresponding
norms of the initial data - a result which is false for the cubic nonlinear
Schroedinger equation in dimension two - and it is optimal because
Glangetas-Merle's solutions blow up at that time.Comment: 30 pages, 2 figures. Minor revision. Title has been change
Bioconversion of apple pomace into a multienzyme bio-feed by two mixed strains of Aspergillus niger M2 in solid state fermentation
Apple pomace is a wasted resource produced in large quantities and its
deposit has caused serious environmental problems, so it is
significance to make the full utilization of the residues. The
objectives of this work were to produce multienzyme bio-feed,
biodegrade the anti-nutritional factors such as pectin and tannins in
apple pomace, and obtain the nutritional enrichment of the fermented
substrate. The mixture of apple pomace and cottonseed powder (1:1,
w/w), supplemented with 1% (w/w) (NH4)2SO4 and 0.1% (w/w) KH2PO4, was
proved to be the optimum medium for the mixed strains of Aspergillus
niger M2 and M3 (2:1, w/w). The activities of pectinase, proteinase
and cellulase achieved 21168 u/g, 3585 u/g and 1208u/g, and the
biodegradation rates of pectin and tannins reached 99.0% and 66.1%,
respectively, when 0.4%(w/w) of the test fungiwere inoculated and
incubated at 30\ubaC for 48 hrs in solid state fermentation. The
utilization of apple pomace in the paper can be served as a model for
the similar waste recycling
Origin and Radiative Forcing of Black Carbon Aerosol: Production and Consumption Perspectives.
Air pollution, a threat to air quality and human health, has attracted ever-increasing attention in recent years. In addition to having local influence, air pollutants can also travel the globe via atmospheric circulation and international trade. Black carbon (BC), emitted from incomplete combustion, is a unique but representative particulate pollutant. This study tracked down the BC aerosol and its direct radiative forcing to the emission sources and final consumers using the global chemical transport model (MOZART-4), the rapid radiative transfer model for general circulation simulations (RRTM), and a multiregional input-output analysis (MRIO). BC was physically transported (i.e., atmospheric transport) from western to eastern countries in the midlatitude westerlies, but its magnitude is near an order of magnitude higher if the virtual flow embodied in international trade is considered. The transboundary effects on East and South Asia by other regions increased from about 3% (physical transport only) to 10% when considering both physical and virtual transport. The influence efficiency on East Asia was also large because of the comparatively large emission intensity and emission-intensive exports (e.g., machinery and equipment). The radiative forcing in Africa imposed by consumption from Europe, North America, and East Asia (0.01 Wm-2) was even larger than the total forcing in North America. Understanding the supply chain and incorporating both atmospheric and virtual transport may improve multilateral cooperation on air pollutant mitigation both domestically and internationally
Global Sulfur Dioxide Emissions and the Driving Forces
The presence of sulfur dioxide (SO_{2}) in the air is a global concern because of its severe environmental and public health impacts. Recent evidence from satellite observations shows rapid changes in the spatial distribution of global SO_{2} emissions, but such features are generally missing in global emission inventories that use a bottom-up method due to the lack of up-to-date information, especially in developing countries. Here, we rely on the latest data available on emission activities, control measures, and emission factors to estimate global SO2 emissions for the period 1960–2014 on a 0.1° × 0.1° spatial resolution. We design two counterfactual scenarios to isolate the contributions of emission activity growth and control measure deployment on historical SO_{2} emission changes. We find that activity growth has been the major factor driving global SO_{2} emission changes overall, but control measure deployment is playing an increasingly important role. With effective control measures deployed in developed countries, the predominant emission contributor has shifted from developed countries in the early 1960s (61%) to developing countries at present (83%). Developing countries show divergency in mitigation strategies and thus in SO_{2} emission trends. Stringent controls in China are driving the recent decline in global emissions. A further reduction in SO_{2} emissions would come from a large number of developing nations that currently lack effective SO_{2} emission controls
A general model for collaboration networks
In this paper, we propose a general model for collaboration networks.
Depending on a single free parameter "{\bf preferential exponent}", this model
interpolates between networks with a scale-free and an exponential degree
distribution. The degree distribution in the present networks can be roughly
classified into four patterns, all of which are observed in empirical data. And
this model exhibits small-world effect, which means the corresponding networks
are of very short average distance and highly large clustering coefficient.
More interesting, we find a peak distribution of act-size from empirical data
which has not been emphasized before of some collaboration networks. Our model
can produce the peak act-size distribution naturally that agrees with the
empirical data well.Comment: 10 pages, 10 figure
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