4,156 research outputs found
Limits of Binaries That Can Be Characterized by Gravitational Microlensing
Due to the high efficiency of planet detections, current microlensing planet
searches focus on high-magnification events. High-magnification events are
sensitive to remote binary companions as well and thus a sample of
wide-separation binaries are expected to be collected as a byproduct. In this
paper, we show that characterizing binaries for a portion of this sample will
be difficult due to the degeneracy of the binary-lensing parameters. This
degeneracy arises because the perturbation induced by the binary companion is
well approximated by the Chang-Refsdal lensing for binaries with separations
greater than a certain limit. For binaries composed of equal mass lenses, we
find that the lens binarity can be noticed up to the separations of
times of the Einstein radius corresponding to the mass of each lens. Among
these binaries, however, we find that the lensing parameters can be determined
only for a portion of binaries with separations less than times of
the Einstein radius.Comment: 5 pages, 3 figures, 1 tabl
Biochemical, haematological and histopathological studies of extract of Ageratum conyzoides L. in Sprague Dawley rats
This study was conducted to evaluate the safety potential of the leaf extract of Ageratum conyzoides Linnaeus in Sprague Dawley (SD) rats using biochemical, haematological and histological indices of toxicity. Four groups of seven male SD rats per group were used for the study. To group A was administered 0.25% CMC-Na/ kg body weight and was used as the control group, while groups B, C and D were respectively administered with 500, 1000 and 1500 mg/kg body weight of the ethanolic leaf extract of A. conyzoides by gastric intubation for 14 days. Animals were subsequently anaesthetized, blood samples were collected for biochemical and haematological assays; organs were isolated and weighed, while the liver, kidney and spleen were processed for histopathological studies. Aspartate
amino transferase, lactate dehydrogenase, creatine kinase and alkaline phosphatase were significantly (p < 0.05) reduced in the groups treated with 1000 and 1500 mg/kg body weight of the extract. Furthermore, there was a significant (p < 0.05) elevation in white blood cell count, mean platelet volume and % platelet distribution width. Histopathological studies indicated various degrees of hepatocellular necrosis in all the treated groups accompanied by significant increases in the weight of liver and spleen. The results showed that the ethanolic leaf extract of A. conyzoides significantly alters the
biomarkers of cardiac and skeletal muscle disorders, and higher doses could induce liver cell injury
Oxyphyllones A and B, novel sesquiterpenes with an unusual 4,5-secoeudesmane skeleton from Alpinia oxyphylla
Two novel 4,5-secoeudesmane sesquiterpenoids, oxyphyllones A (1) and B (2) were isolated from the fruits of Alpinia
oxyphylla. Their structures were established by spectroscopic methods including 1D and 2D NMR spectra. These two compounds
are the first example of naturally occurring sesquiterpenoids with a 4,5-secoeudesmane skeleton in the family of Zingiberaceae and
oxyphyllone A (1) is the first 4,5-secoeudesmane type of 13-norsesquiterpenoid. Compounds 1 and 2 exhibited no cytotoxicities
against three cancer cell lines at 10 mg/mL
Properties of Central Caustics in Planetary Microlensing
To maximize the number of planet detections, current microlensing follow-up
observations are focusing on high-magnification events which have a higher
chance of being perturbed by central caustics. In this paper, we investigate
the properties of central caustics and the perturbations induced by them. We
derive analytic expressions of the location, size, and shape of the central
caustic as a function of the star-planet separation, , and the planet/star
mass ratio, , under the planetary perturbative approximation and compare the
results with those based on numerical computations. While it has been known
that the size of the planetary caustic is \propto \sqrt{q}, we find from this
work that the dependence of the size of the central caustic on is linear,
i.e., \propto q, implying that the central caustic shrinks much more rapidly
with the decrease of compared to the planetary caustic. The central-caustic
size depends also on the star-planet separation. If the size of the caustic is
defined as the separation between the two cusps on the star-planet axis
(horizontal width), we find that the dependence of the central-caustic size on
the separation is \propto (s+1/s). While the size of the central caustic
depends both on and q, its shape defined as the vertical/horizontal width
ratio, R_c, is solely dependent on the planetary separation and we derive an
analytic relation between R_c and s. Due to the smaller size of the central
caustic combined with much more rapid decrease of its size with the decrease of
q, the effect of finite source size on the perturbation induced by the central
caustic is much more severe than the effect on the perturbation induced by the
planetary caustic. Abridged.Comment: 5 pages, 4 figures, ApJ accepte
Microlensing Detections of Planets in Binary Stellar Systems
We demonstrate that microlensing can be used for detecting planets in binary
stellar systems. This is possible because in the geometry of planetary binary
systems where the planet orbits one of the binary component and the other
binary star is located at a large distance, both planet and secondary companion
produce perturbations at a common region around the planet-hosting binary star
and thus the signatures of both planet and binary companion can be detected in
the light curves of high-magnification lensing events. We find that identifying
planets in binary systems is optimized when the secondary is located in a
certain range which depends on the type of the planet. The proposed method can
detect planets with masses down to one tenth of the Jupiter mass in binaries
with separations <~ 100 AU. These ranges of planet mass and binary separation
are not covered by other methods and thus microlensing would be able to make
the planetary binary sample richer.Comment: 5 pages, two figures in JPG forma
EM Decay of X(3872) as the charmonium
The recently BaBar results raise the possibility that X(3872) has negative
parity. This makes people reconsider assigning X(3872) to the state. In this paper we give a general form of the wave function of
mesons. By solving the instantaneous Bethe-Salpeter equation, we get
the mass spectrum and corresponding wave functions. We calculate
electromagnetic decay widths of the first state which we assume to be
the X(3872) particle. The results are keV, eV and keV. The ratio of branch fractions
of the second and first channel is about 0.002, which is inconsistent with the
experimental value . So X(3872) is unlikely to be a
charmonium state. In addition, we obtain a relatively large decay width for
channel which is keV.Comment: Revised versio
Mobile resistome of human gut and pathogen drives anthropogenic bloom of antibiotic resistance
BACKGROUND:The impact of human activities on the environmental resistome has been documented in many studies, but there remains the controversial question of whether the increased antibiotic resistance observed in anthropogenically impacted environments is just a result of contamination by resistant fecal microbes or is mediated by indigenous environmental organisms. Here, to determine exactly how anthropogenic influences shape the environmental resistome, we resolved the microbiome, resistome, and mobilome of the planktonic microbial communities along a single river, the Han, which spans a gradient of human activities. RESULTS:The bloom of antibiotic resistance genes (ARGs) was evident in the downstream regions and distinct successional dynamics of the river resistome occurred across the spatial continuum. We identified a number of widespread ARG sequences shared between the river, human gut, and pathogenic bacteria. These human-related ARGs were largely associated with mobile genetic elements rather than particular gut taxa and mainly responsible for anthropogenically driven bloom of the downstream river resistome. Furthermore, both sequence- and phenotype-based analyses revealed environmental relatives of clinically important proteobacteria as major carriers of these ARGs. CONCLUSIONS:Our results demonstrate a more nuanced view of the impact of anthropogenic activities on the river resistome: fecal contamination is present and allows the transmission of ARGs to the environmental resistome, but these mobile genes rather than resistant fecal bacteria proliferate in environmental relatives of their original hosts. Video abstract
Could Fractional Exhaled Nitric Oxide Test be Useful in Predicting Inhaled Corticosteroid Responsiveness in Chronic Cough? A Systematic Review
© 2016 Background Fractional exhaled nitric oxide (FENO) is a safe and convenient test for assessing T H 2 airway inflammation, which is potentially useful in the management of patients with chronic cough. Objective To summarize the current evidence on the diagnostic usefulness of FENO for predicting inhaled corticosteroid (ICS) responsiveness in patients with chronic cough. Methods A systematic literature review was conducted to identify articles published in peer-reviewed journals up to February 2015, without language restriction. We included studies that reported the usefulness of FENO (index test) for predicting ICS responsiveness (reference standard) in patients with chronic cough (target condition). The data were extracted to construct a 2 à 2 accuracy table. Study quality was assessed with Quality Assessment of Diagnostic Accuracy Studies 2. Results We identified 5 original studies (2 prospective and 3 retrospective studies). We identified considerable heterogeneities in study design and outcome definitions, and thus were unable to perform a meta-analysis. The proportion of ICS responders ranged from 44% to 59%. Sensitivity and specificity ranged from 53% to 90%, and from 63% to 97%, respectively. The reported area under the curve ranged from abou t 0.60 to 0.87; however, studies with a prospective design and a lower prevalence of asthma had lower area under the curve values. None measured placebo effects or objective cough frequency. Conclusions We did not find strong evidence to support the use of FENO tests for predicting ICS responsiveness in chronic cough. Further studies need to have a randomized, placebo-controlled design, and should use validated measurement tools for cough. Standardization would facilitate the development of clinical evidence
Therapeutic Effect of Repurposed Temsirolimus in Lung Adenocarcinoma Model
Lung cancer is one of the major cause of cancer-related deaths worldwide. The poor prognosis and resistance to both radiation and chemotherapy urged the development of potential targets for lung cancer treatment. In this study, using a network-based cellular signature bioinformatics approach, we repurposed a clinically approved mTOR inhibitor for renal cell carcinomans, temsirolimus, as the potential therapeutic candidate for lung adenocarcinoma. The PI3K-AKT-mTOR pathway is known as one of the most frequently dysregulated pathway in cancers, including non-small-cell lung cancer. By using a well-documented lung adenocarcinoma mouse model of human pathophysiology, we examined the effect of temsirolimus on the growth of lung adenocarcinoma in vitro and in vivo. In addition, temsirolimus combined with reduced doses of cisplatin and gemcitabine significantly inhibited the lung tumor growth in the lung adenocarcinoma mouse model compared with the temsirolimus alone or the conventional cisplatinâgemcitabine combination. Functional imaging techniques and microscopic analyses were used to reveal the response mechanisms. Extensive immunohistochemical analyses were used to demonstrate the apparent effects of combined treatments on tumor architecture, vasculature, apoptosis, and the mTOR-pathway. The present findings urge the further exploration of temsirolimus in combination with chemotherapy for treating lung adenocarcinoma
Weak localization and electron-electron interactions in Indium-doped ZnO nanowires
Single crystal ZnO nanowires doped with indium are synthesized via the
laser-assisted chemical vapor deposition method. The conductivity of the
nanowires is measured at low temperatures in magnetic fields both perpendicular
and parallel to the wire axes. A quantitative fit of our data is obtained,
consistent with the theory of a quasi-one-dimensional metallic system with
quantum corrections due to weak localization and electron-electron
interactions. The anisotropy of the magneto-conductivity agrees with theory.
The two quantum corrections are of approximately equal magnitude with
respective temperature dependences of T^-1/3 and T^-1/2. The alternative model
of quasi-two-dimensional surface conductivity is excluded by the absence of
oscillations in the magneto-conductivity in parallel magnetic fields.Comment: 13 pages, Corrected forma
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