618 research outputs found
Possible open-charmed pentaquark molecule --- the bound state --- in the Bethe-Salpeter formalism
We study the -wave bound state in the Bethe-Salpeter formalism in
the ladder and instantaneous approximations. With the kernel generated by the
hadronic effective Lagrangian, two open-charmed bound states, which quantum
numbers are , and , ,
respectively, are predicted as new candidates of hadronic pentaquark molecules
in our formalism. If existing, they could contribute to the broad 3188 eV
structure near the five new narrow states observed recently by the
LHCb Collaboration.Comment: 8 pages, 4 figures, accepted by Eur. Phys. J.
Monic Testing of Web Services Based on Algebraic Specifications
Web services are designed to be discovered and composed dynamically, which implies that testing must also be done dynamically. This involves both the generation of test cases and the checking of test results. This paper presents algorithms for both of these using the technique of algebraic specification. It focuses in particular on the problem that web services, when they are third-party, have poor controllability and observability, and introduces a solution known as monic floating checkable test cases. A prototype tool has implemented the proposed testing technique and it is applied to a case study with a real industry application GoGrid, demonstrating that the technique is both applicable and feasible
EUCLIA - Exploring the UV/optical continuum lag in active galactic nuclei. I. a model without light echoing
The tight inter-band correlation and the lag-wavelength relation among
UV/optical continua of active galactic nuclei have been firmly established.
They are usually understood within the widespread reprocessing scenario,
however, the implied inter-band lags are generally too small. Furthermore, it
is challenged by new evidences, such as the X-ray reprocessing yields too much
high frequency UV/optical variations as well as it fails to reproduce the
observed timescale-dependent color variations among {\it Swift} lightcurves of
NGC 5548. In a different manner, we demonstrate that an upgraded inhomogeneous
accretion disk model, whose local {\it independent} temperature fluctuations
are subject to a speculated {\it common} large-scale temperature fluctuation,
can intrinsically generate the tight inter-band correlation and lag across
UV/optical, and be in nice agreement with several observational properties of
NGC 5548, including the timescale-dependent color variation. The emergent lag
is a result of the {\it differential regression capability} of local
temperature fluctuations when responding to the large-scale fluctuation. An
average speed of propagations as large as of the speed of light
may be required by this common fluctuation. Several potential physical
mechanisms for such propagations are discussed. Our interesting
phenomenological scenario may shed new light on comprehending the UV/optical
continuum variations of active galactic nuclei.Comment: 18 pages, 8 figures. ApJ accepted. Further comments are very welcome
Prediction of stroke risk in patients with transient ischemic attack: ABCD score and its derived scores
Transient Ischemic Attack (TIA) is a high-risk signal of acute ischemic cerebrovascular disease, indicates a significant increase in the risk of ischemic stroke, especially within 7 days. Risk assessment and stratification are important in patient with TIA. A variety of simple prediction scales were developed based on the risk factors for stroke in patients with TIA, such as the California scale, ABCD scale, and ABCD2 scale. Among them, the ABCD scale score is used most commonly, but as its application becomes more and more common, the defects of this scale are also increasingly apparent. In recent years, some derived scales of ABCD score were introduced in order to improve the sensitivity and specificity of prediction. This article reviews the evolution, contents, characteristics, and predictive value of the ABCD score and its derived scales in the prediction of the stroke risk in patients with TIA
An intrinsic link between long-term UV/optical variations and X-ray loudness in quasars
Observations have shown that UV/optical variation amplitude of quasars depend
on several physi- cal parameters including luminosity, Eddington ratio, and
likely also black hole mass. Identifying new factors which correlate with the
variation is essential to probe the underlying physical processes. Combining
~ten years long quasar light curves from SDSS stripe 82 and X-ray data from
Stripe 82X, we build a sample of X-ray detected quasars to investigate the
relation between UV/optical variation amplitude () and X-ray
loudness. We find that quasars with more intense X-ray radiation (com- pared to
bolometric luminosity) are more variable in UV/optical. Such correlation
remains highly significant after excluding the effect of other parameters
including luminosity, black hole mass, Ed- dington ratio, redshift, rest-frame
wavelength (i.e., through partial correlation analyses). We further find the
intrinsic link between X-ray loudness and UV/optical variation is gradually
more prominent on longer timescales (up to 10 years in the observed frame), but
tends to disappear at timescales < 100 days. This suggests a slow and long-term
underlying physical process. The X-ray reprocessing paradigm, in which
UV/optical variation is produced by a variable central X-ray emission
illuminating the accretion disk, is thus disfavored. The discovery points to an
interesting scheme that both the X-ray corona heating and UV/optical variation
is quasars are closely associated with magnetic disc turbulence, and the
innermost disc turbulence (where corona heating occurs) correlates with the
slow turbulence at larger radii (where UV/optical emission is produced).Comment: 9 pages, 4 figures, 1 table, accepted by Ap
5,5′,7,7′-TetraÂmethÂoxy-2,2′-ethano-1,1′-spiroÂbiindane
In the title compound, C23H26O4, there is a dihedral angle of 83.7 (6)° between the two benzene rings. The five-membered rings have chair conformations
Coexistence of aneurysmal subarachnoid hemorrhage and surgically identified pituitary apoplexy: a case report and review of the literature
INTRODUCTION: A ruptured aneurysm associated with a pituitary apoplexy is rare. We present the first case report of the coexistence of a ruptured posterior communicating aneurysm with a surgically discovered pituitary apoplexy where the pituitary apoplexy had not been diagnosed by a pre-operative computerized tomography scan. CASE PRESENTATION: A 31-year-old right-handed Chinese woman began to experience severe headache, vomiting and blurred vision which continued for two days. On admission to the hospital, a brain computerized tomography scan demonstrated a small amount of increased signal in the basal cisterns; no evidence of intrasellar and suprasellar lesions was seen. The appearance of her brain suggested aneurysmal subarachnoid hemorrhage. She had nuchal rigidity and reduced vision. There was no extra-ocular palsy and no other neurological deficit. Our patient had no stigmata of Cushing’s syndrome or acromegaly. During an interview for further history, she reported normal menses and denied reduced vision. Cerebral digital subtraction angiography was subsequently performed, which revealed a 6mm left posterior communicating aneurysm. Urgent left pterional craniotomy was performed. The left ruptured posterior communicating artery aneurysm was completely dissected prior to clipping. At surgery, a suprasellar mass was discovered, the tumor bulging the diaphragma sella and projecting anteriorly under the chiasm raising suspicion of a pituitary tumor. The anterior part of the tumor capsule was opened and a necrotic tumor mixed with dark old blood was removed. The appearance suggested pituitary apoplexy. Histopathology revealed pituitary adenoma with evidence of hemorrhagic necrosis. Our patient made a good recovery. CONCLUSION: Our case report proves that pituitary apoplexy can be coexistent with the rupture of a posterior communicating aneurysm. This association should be considered when evaluating any case of aneurysm. A normal computerized tomography scan does not exclude pituitary apoplexy. Pre-operative magnetic resonance imaging interpretation is required if a pituitary apoplexy is suspected. Craniotomy allows a coexisting aneurysm and pituitary apoplexy to be simultaneously treated
Methological quality of systematic reviews and meta-analyses on acupuncture for stroke: a review of review
Objective:
To assess the methodological quality of systematic reviews and meta-analyses regarding acupuncture intervention for stroke and the primary studies within them.
Methods:
Two researchers searched PubMed, Cumulative index to Nursing and Allied Health Literature, Embase, ISI Web of Knowledge, Cochrane, Allied and Complementary Medicine, Ovid Medline, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, Wanfang and Traditional Chinese Medical Database to identify systematic reviews and meta-analyses about acupuncture for stroke published from the inception to December 2016. Review characteristics and the criteria for assessing the primary studies within reviews were extracted. The methodological quality of the reviews was assessed using adapted Oxman and Guyatt Scale. The methodological quality of primary studies was also assessed.
Results:
Thirty-two eligible reviews were identified, 15 in English and 17 in Chinese. The English reviews were scored higher than the Chinese reviews (P=0.025), especially in criteria for avoiding bias and the scope of search. All reviews used the quality criteria to evaluate the methodological quality of primary studies, but some criteria were not comprehensive. The primary studies, in particular the Chinese reviews, had problems with randomization, allocation concealment, blinding, dropouts and withdrawals, intent-to-treat analysis and adverse events.
Conclusions:
Important methodological flaws were found in Chinese systematic reviews and primary studies. It was necessary to improve the methodological quality and reporting quality of both the systematic reviews published in China and primary studies on acupuncture for stroke
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