12,419 research outputs found
Practical use of reactor anti-neutrinos for nuclear safeguard in Vietnam
One of the most abundant man-made sources of low energy (few~MeVs) neutrinos,
reactor neutrino, is not only useful for studying neutrino properties, but it
is also used in practical applications. In this study, we investigate the
practical use of reactor neutrino detectors for nuclear safeguard in Vietnam,
specifically at the Dalat Nuclear Reactor, a future research facility, and
presumably commercial reactors with 500~kW, 10~MW, and 1000~MW thermal powers,
respectively. We compute the rate of observed inverted beta decay events, as
well as the statistical significance of extracting isotope composition under
the practical assumptions of detector mass, detection efficiency, and
background level. We find that a 1-ton detector mass can allow us to detect the
reactor's on-off transition state from a few hours to a few days, depending on
the standoff distance and reactor thermal power. We investigate how background
and energy resolution affect the precision of the extracted weapon-usable
isotope. We conclude that in order to distinguish the 10\%
variation of the in the 10~MW thermal power reactor, a
1-ton detector placed 50~m away must achieve 1\% background level. Increasing
the statistics by using a 10x larger detector or placing it times
closer to the reactor alleviates the requirement of the background level to
10\%
Stringent constraint on CPT violation with the synergy of T2K-II, NOA extension, and JUNO
Neutrino oscillation experiments have measured precisely the mass-squared
differences of three neutrino mass eigenstates, and three leptonic mixing
angles by utilizing both neutrino and anti-neutrino oscillations. The possible
CPT violation may manifest itself in the difference of neutrino and
anti-neutrino oscillation parameters, making these experiments promising tools
for testing CPT invariance. We investigate empirically the sensitivity of the
CPT test via the difference in mass-squared splittings () and in leptonic mixing angles () with the synergy of T2K-II, NOA
extension, and JUNO experiments. If the CPT symmetry is found to be conserved,
the joint analysis of the three experiments will be able to establish limits of
< and <
at 3 C. L. on the possible CPT violation. We find that with (), the dependence of the statistical
significance on the relevant parameters to exclude the CPT conservation is
marginal, and that, if the difference in the best-fit values of and measured by MINOS(+) and NOA
persists as the true, the combined analysis will rule out the CPT conservation
at 4 C. L.. With the (), the statistical significance to exclude CPT
invariance depends strongly on the true value of
. In case of maximal mixing of
, the CPT conservation will be excluded at 3 C. L. or more
if the difference in the best-fit values of and
remains as the true.Comment: 10 pages, 10 figure
Antimicrobial Electrodeposited Silver-Containing Calcium Phosphate Coatings
Biocompatible antimicrobial coatings may enhance the function of many orthopedic implants by combating infection. Hydroxyapatite is a choice mineral for such a coating as it is native to bone and silver would be a possible antimicrobial agent as it is also commonly used in biomedical applications. The aim of the research is to develop a silver-containing calcium phosphate (Ag/Ca-P) coating via electrochemical deposition on titanium substrates as this allows for controlled coating buildup on complex shapes and porous surfaces. Two different deposition approaches are explored: one-step Ag/Ca-P(1) deposition coatings, containing silver ions as microsized silver phosphate particles embedded in the Ca-P matrix; and via a two-step method (Ag/Ca-P(2)) where silver is deposited as metallic silver nanoparticle on the Ca-P coating. The Ag/Ca-P(1) coating displays a bacterial reduction of 76.1 +/- 8.3% via Ag-ion leaching. The Ag/Ca-P(2) coating displays a bacterial reduction of 83.7 +/- 4.5% via contact killing. Interestingly, by preincubation in phosphate-buffered saline solution, bacterial reduction improves to 97.6 +/- 2.7 and 99.7 +/- 0.4% for Ag/Ca-P(1) and Ag/Ca-P(2) coatings, respectively, due to leaching of formed AgClx(x-1)- species. The biocompatibility evaluation indicates that the Ag/Ca-P(1) coating is cytotoxic towards osteoblasts while the Ag/Ca-P(2) coating shows excellent compatibility. The electrochemical deposition of highly bactericidal coatings with excellent biocompatibility will enable us to coat future bone implants even with complex or porous structures
15-epi-lipoxin A(4)-mediated induction of nitric oxide explains how aspirin inhibits acute inflammation
Random Resonators and Prelocalized Modes in Disordered Dielectric Films
Areal density of disorder-induced resonators with a high quality factor,
, in a film with fluctuating refraction index is calculated
theoretically. We demonstrate that for a given , where is the light
wave vector, and is the transport mean free path, when {\em on average} the
light propagation is diffusive, the likelihood for finding a random resonator
increases dramatically with increasing the correlation radius of the disorder.
Parameters of {\em most probable} resonators as functions of and are
found.Comment: 6 pages including 2 figure
Cutting the chorda tympani: not just a matter of taste
Abstract Introduction: Chorda tympani injury as a complication of middle-ear surgery has been extensively studied with regard to its effects upon taste. However, the chorda tympani also carries parasympathetic fibres to the salivary glands of the oral cavity. To date, little has been reported about the effect of chorda tympani section upon salivary function. Setting: Tertiary care centre. Material and methods: We report a case series of three patients with bilateral chorda tympani lesions. Chorda tympani function was assessed using ‘taste strips' and unstimulated sialometry. A careful history of oral symptoms was taken. Results: All patients showed transient or permanent bilateral ageusia of the anterior two-thirds of the tongue, and a decreased resting salivary flow rate. In addition, all patients suffered from transient or persistent, distressing xerostomia. Conclusion: Taste disorders may occur after middle-ear surgery but they are mostly transient, even when the chorda tympani nerves are sectioned bilaterally. In contrast, bilateral chorda tympani lesions may lead to severe, persistent and distressing xerostomia. Based on this neglected aspect of chorda tympani function, we emphasise the importance of preserving the chorda tympani whenever possibl
Sifting for Sapphires: Systematic Selection of Tidal Disruption Events in iPTF
We present results from a systematic selection of tidal disruption events
(TDEs) in a wide-area (4800~deg), band, Intermediate Palomar
Transient Factory (iPTF) experiment. Our selection targets typical
optically-selected TDEs: bright (60\% flux increase) and blue transients
residing in the center of red galaxies. Using photometric selection criteria to
down-select from a total of 493 nuclear transients to a sample of 26 sources,
we then use follow-up UV imaging with the Neil Gehrels Swift Telescope,
ground-based optical spectroscopy, and light curve fitting to classify them as
14 Type Ia supernovae (SNe Ia), 9 highly variable active galactic nuclei
(AGNs), 2 confirmed TDEs, and 1 potential core-collapse supernova. We find it
possible to filter AGNs by employing a more stringent transient color cut ( 0.2 mag); further, UV imaging is the best discriminator for filtering
SNe, since SNe Ia can appear as blue, optically, as TDEs in their early phases.
However, when UV-optical color is unavailable, higher precision astrometry can
also effectively reduce SNe contamination in the optical. Our most stringent
optical photometric selection criteria yields a 4.5:1 contamination rate,
allowing for a manageable number of TDE candidates for complete spectroscopic
follow-up and real-time classification in the ZTF era. We measure a TDE per
galaxy rate of 1.7 10 gal yr (90\%
CL in Poisson statistics). This does not account for TDEs outside our selection
criteria, thus may not reflect the total TDE population, which is yet to be
fully mapped.Comment: 24 pages, 21 figures. Accepted for publication in the Astrophysical
Journal Supplement Serie
Assessment of Antioxidant Activities, Total Phenolics, and Flavonoids of Different Extracts of Strobilanthes Schomburgkii Leaves
The main purpose of this work was to assess the antioxidant activities of the n-hexane, ethyl acetate and methanol extracts of Strobilanthes schomburgkii leaves collected in Laocai province, Vietnam. Total phenolic and flavonoid contents were determined. The DPPH, H2O2 radical scavenging activity, and total antioxidant activity via phosphomolybdenum method were investigated. The results showed that the methanol extract concluded a high concentration of phenolics and flavonoids which were 65.42 mg/g and 52.05 mg/g, respectively. There was a significant correlation between total phenolic and flavonoid concentrations and EC50 values of different antioxidant assays. The antioxidant properties of the different extracts from Strobilanthes schomburgkii leaves were reported for the first time
Plasma heat shock protein 27 is associated with coronary artery disease, abdominal aortic aneurysm and peripheral artery disease
Low protein levels of Hsp27 have been reported in atherosclerotic plaques. In addition, human studies have indicated that circulating Hsp27 levels are lower in coronary artery disease patients compared with controls. It remains, however, unclear whether this applies to other forms of atherosclerotic disease. Plasma Hsp27 from 280 subjects was examined by ELISA. The cohort included 80 coronary artery disease (CAD), 40 peripheral artery disease (PAD) and 80 abdominal aortic aneurysm (AAA) patients. Eighty elderly subjects, without any clinical history of vascular diseases, were used as a control group. Receiver operating curve (ROC) and logistic regression model analysis were performed to evaluate the potential value of Hsp27 as a circulating biomarker. Patients with atherosclerotic vascular diseases had significantly lower levels of Hsp27 than control subjects (p < 0.001). Moreover, Hsp27 was significantly lower in CAD patients than other atherosclerotic vascular disease groups (p < 0.001). There was no difference in Hsp27 levels between the AAA and PAD groups. Using the ROC-generated optimal cut-off values for Hsp27, logistic regression modeling indicated that low plasma Hsp27 was independently associated with the presence of multiple forms of atherosclerotic disease. In conclusion, circulating Hsp27 is significantly lower in patients with multiple forms of atherosclerotic arterial disease
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