2,024 research outputs found
Knowledge Structure of Korean Medical Informatics: A Social Network Analysis of Articles in Journal and Proceedings
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NMHCs and halocarbons in Asian continental outflow during the Transport and Chemical Evolution over the Pacific (TRACE-P) Field Campaign: Comparison with PEM-West B
We present an overview of the spatial distributions of nonmethane hydrocarbons (NMHCs) and halocarbons observed over the western north Pacific as part of the NASA GTE Transport and Chemical Evolution over the Pacific (TRACEâP) airborne field campaign (FebruaryâApril 2001). The TRACEâP data are compared with earlier measurements from the Pacific Rim during the Pacific Exploratory MissionâWest B (PEMâWest B), which took place in FebruaryâMarch 1994, and with emission inventory data for 2000. Despite the limited spatial and temporal data coverage inherent to airborne sampling, mean levels of the longerâlived NMHCs (including ethane, ethyne, and benzene) were remarkably similar to our results during the PEMâWest B campaign. By comparison, mixing ratios of the fire extinguisher Halonâ1211 (CF2ClBr) increased by about 50% in the period between 1994 and 2001. Southern China (south of 35°N), and particularly the Shanghai region, appears to have been a substantial source of Halonâ1211 during TRACEâP. Our previous analysis of the PEMâWest B data employed methyl chloroform (CH3CCl3) as a useful industrial tracer. However, regulations have reduced its emissions to the extent that its mixing ratio during TRACEâP was only oneâthird of that measured in 1994. Methyl chloroform mixing ratio âhot spots,â indicating regions downwind of continuing emissions, included outflow from the vicinity of Shanghai, China, but particularly high emission ratios relative to CO were observed close to Japan and Korea. Tetrachloroethene (C2Cl4) levels have also decreased significantly, especially north of 25°N, but this gas still remains a useful indicator of northern industrial emissions. Methyl bromide (CH3Br) levels were systematically 1â2 pptv lower from 1994 to 2001, in accord with recent reports. However, air masses that had been advected over Japan and/or South Korean port cities typically exhibited elevated levels of CH3Br. As a consequence, emissions of CH3Br from Japan and Korea calculated employing CH3Br/CO ratios and scaled to CO emission inventory estimates, were almost as large as for all of south China (south of 35°N). Total east Asian emissions of CH3Br and CH3Cl were estimated to be roughly 4.7 Gg/yr and 167 Gg/yr, respectively, in 2001
Inclusive decays of into - and -wave charmonium states
Inclusive S- and P-wave charmonium productions in the bottomonium ground
state decay are calculated at the leading order in the strong coupling
constant and quarkonium internal relative velocity in the
framework of the NRQCD factorization approach. We find the contribution of
followed by is
also very important to the inclusive production in the
decays, which maybe helpful to the investigation of the color-octet mechanism
in the inclusive production in the decays in the forthcoming
LHCb and SuperB. As a complementary work, we also study the inclusive
production of , and in the decays, which may help
us understand the X(3940) and X(3872) states.Comment: 7 pages, 2 figure
Excited heavy tetraquarks with hidden charm
The masses of the excited heavy tetraquarks with hidden charm are calculated
within the relativistic diquark-antidiquark picture. The dynamics of the light
quark in a heavy-light diquark is treated completely relativistically. The
diquark structure is taken into account by calculating the diquark-gluon form
factor. New experimental data on charmonium-like states above open charm
threshold are discussed. The obtained results indicate that X(3872), Y(4260),
Y(4360), Z(4248), Z(4433) and Y(4660) could be tetraquark states with hidden
charm.Comment: 11 page
New aspects of the BMN correspondence beyond the planar limit
Motivated by recent disagreements in the context of AdS/CFT, we study the
non-planar sector of the BMN correspondence. In particular, we reconsider the
energy shift of states with two stringy excitations in light-cone string field
theory and explicitly determine its complete perturbative contribution from the
impurity-conserving channel. Surprisingly, our result neither agrees with
earlier leading order computations, nor reproduces the gauge theory prediction.
More than that, it features half-integer powers of the effective gauge coupling
representing a qualitative difference to gauge theory. Based on
supersymmetry we argue that the above truncation is not suited for conclusive
tests of the BMN duality.Comment: 20 pages, 1 figur
The open-charm radiative and pionic decays of molecular charmonium Y(4274)
In this work, we investigate the decay widths and the line shapes of the
open-charm radiative and pionic decays of Y(4274) with the
molecular charmonium assignment. Our calculation
indicates that the decay widths of and
can reach up to 0.05 keV and 0.75 keV,
respectively. In addition, the result of the line shape of the photon spectrum
of shows that there exists a very sharp
peak near the large end point of photon energy. The line shape of the pion
spectrum of is similar to that of the pion
spectrum of , where we also find a very
sharp peak near the large end point of pion energy. According to our
calculation, we suggest further experiments to carry out the search for the
open-charm radiative and pionic decays of Y(4274).Comment: 7 pages, 6 figures, 1 table. Published versio
1-- and 0++ heavy four-quark and molecule states in QCD
We estimate the masses of the 1^{--} heavy four-quark and molecule states by
combining exponential Laplace (LSR) and finite energy (FESR) sum rules known
perturbatively to lowest order (LO) in alpha_s but including non-perturbative
terms up to the complete dimension-six condensate contributions. This approach
allows to fix more precisely the value of the QCD continuum threshold (often
taken ad hoc) at which the optimal result is extracted.
We use double ratio of sum rules (DRSR) for determining the SU(3) breakings
terms. We also study the effects of the heavy quark mass definitions on these
LO results.
The SU(3) mass-splittings of about (50 - 110) MeV and the ones of about (250
- 300) MeV between the lowest ground states and their 1st radial excitations
are (almost) heavy-flavour independent.
The mass predictions summarized in Table 4 are compared with the ones in the
literature (when available) and with the three Y_c(4260,~4360,~4660) and
Y_b(10890) 1^{--} experimental candidates. We conclude (to this order
approximation) that the lowest observed state cannot be a pure 1^{--}
four-quark nor a pure molecule but may result from their mixings. We extend the
above analyzes to the 0^{++} four-quark and molecule states which are about
(0.5-1) GeV heavier than the corresponding 1^{--} states, while the splittings
between the 0^{++} lowest ground state and the 1st radial excitation is about
(300-500) MeV. We complete the analysis by estimating the decay constants of
the 1^{--} and 0^{++} four-quark states which are tiny and which exhibit a
1/M_Q behaviour.
Our predictions can be further tested using some alternative non-perturbative
approaches or/and at LHCb and some other hadron factories.Comment: 13 pages, 15 figures, 4 tables, version to appear in PLB (more
general choice of the interpolating currents, estimate of the four-quark
meson decay constants, new references added, slight numerical changes for the
0++ mass predictions
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Twelve-Month Suicidal Symptoms and Use of Services Among Adolescents: Results From the National Comorbidity Survey
Objective
The study assessed the prevalence of suicidal ideation, suicide plans, and suicide attempts as well as patterns of mental health service use among adolescents.
Methods
Data came from the National Comorbidity SurveyâAdolescent Supplement, a nationally representative sample of 10,123 adolescents aged 13 to 18 years who participated in computer-assisted, face-to-face interviews between February 2001 and January 2004. Prevalences of suicidal thoughts and behaviors in the past year were determined. Past-year use of any mental health treatment and receipt of four or more visits from one provider among youths with suicidal ideation, plans, or attempts were also assessed. Associations were evaluated by using logistic regression.
Results
During the course of 12 months, 3.6% of adolescents reported suicidal ideation without a plan or attempt, .6% reported a suicide plan without an attempt, and 1.9% made a suicide attempt. Overall, two-thirds of adolescents with suicidal ideation (67.3%) and half of those with a plan (54.4%) or attempt (56.9%) did not have any contact with a mental health specialist in the past year. Different predictors of use of care were identified for each group.
Conclusions
Adolescent suicidality often is untreated in the United States. Increased outreach efforts to improve treatment access for youths with suicidal ideation and attempts are needed.Psycholog
Identification of plasma lipid biomarkers for prostate cancer by lipidomics and bioinformatics
Background:
Lipids have critical functions in cellular energy storage, structure and signaling. Many individual lipid molecules have been associated with the evolution of prostate cancer; however, none of them has been approved to be used as a biomarker. The aim of this study is to identify lipid molecules from hundreds plasma apparent lipid species as biomarkers for diagnosis of prostate cancer.
Methodology/Principal Findings:
Using lipidomics, lipid profiling of 390 individual apparent lipid species was performed on 141 plasma samples from 105 patients with prostate cancer and 36 male controls. High throughput data generated from lipidomics were analyzed using bioinformatic and statistical methods. From 390 apparent lipid species, 35 species were demonstrated to have potential in differentiation of prostate cancer. Within the 35 species, 12 were identified as individual plasma lipid biomarkers for diagnosis of prostate cancer with a sensitivity above 80%, specificity above 50% and accuracy above 80%. Using top 15 of 35 potential biomarkers together increased predictive power dramatically in diagnosis of prostate cancer with a sensitivity of 93.6%, specificity of 90.1% and accuracy of 97.3%. Principal component analysis (PCA) and hierarchical clustering analysis (HCA) demonstrated that patient and control populations were visually separated by identified lipid biomarkers. RandomForest and 10-fold cross validation analyses demonstrated that the identified lipid biomarkers were able to predict unknown populations accurately, and this was not influenced by patient's age and race. Three out of 13 lipid classes, phosphatidylethanolamine (PE), ether-linked phosphatidylethanolamine (ePE) and ether-linked phosphatidylcholine (ePC) could be considered as biomarkers in diagnosis of prostate cancer.
Conclusions/Significance:
Using lipidomics and bioinformatic and statistical methods, we have identified a few out of hundreds plasma apparent lipid molecular species as biomarkers for diagnosis of prostate cancer with a high sensitivity, specificity and accuracy
Spectroscopy of Mesons with Heavy Quarks
I will give a concise overview of mesons with heavy quarks including p-wave
charmed mesons and charmonium (or charmonium-like) states such as X(3872),
Y(4260), X(3940), Y(3940), Z(3930) etc. The effect from the nearby S-wave open
channels on the quark model spectrum is emphasized.Comment: Plenary talk at INPC2007, http://inpc2007.riken.jp/P/P5-zhu.pd
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