23,402 research outputs found
Absorption cross section and Hawking radiation in two-dimensional AdS black hole
We calculate the absorption coefficient of scalar field on the background of
the two-dimensional AdS black hole, which is of relevance to Hawking radiation.
For the massless scalar field, we find that there does not exist any massless
radiation.Comment: 6 pages, revtex, no figure
Electromagnetic Radiation Hardness of Diamond Detectors
The behavior of artificially grown CVD diamond films under intense
electromagnetic radiation has been studied. The properties of irradiated
diamond samples have been investigated using the method of thermally stimulated
current and by studying their charge collection properties. Diamonds have been
found to remain unaffected after doses of 6.8 MGy of 10 keV photons and 10 MGy
of MeV-range photons. This observation makes diamond an attractive detector
material for a calorimeter in the very forward region of the proposed TESLA
detector.Comment: 19 pages, 9 figure
Hyperons analogous to the \Lambda(1405)
The low mass of the hyperon with , which is
higher than the ground state mass by 290 MeV, is difficult to
understand in quark models. We analyze the hyperon spectrum in the bound state
approach of the Skyrme model that successfully describes both the
and the . This model predicts that several
hyperon resonances of the same spin but with opposite parity form parity
doublets that have a mass difference of around 300 MeV, which is indeed
realized in the observed hyperon spectrum. Furthermore, the existence of the
and the of is predicted by this model.
Comments on the baryons and heavy quark baryons are made as well.Comment: 4 pages, talk presented at the Fifth Asia-Pacific Conference on
Few-Body Problems in Physics 2011 (APFB2011), Aug. 22-26, 2011, Seoul, Kore
A Hard Look at NGC 5347: Revealing a Nearby Compton-thick AGN
Current measurements show that the observed fraction of Compton-thick (CT) active galactic nuclei (AGN) is smaller than the expected values needed to explain the cosmic X-ray background. Prior fits to the X-ray spectrum of the nearby Seyfert-2 galaxy NGC 5347 (z = 0.00792, D = 35.5 Mpc ) have alternately suggested a CT and Compton-thin source. Combining archival data from Suzaku, Chandra, and—most importantly—new data from NuSTAR, ... See full text for complete abstrac
Fabrication of n-type carbon nanotube field-effect transistors by Al doping
We report the effect of an Al layer, covering the central part of the nanotube channel, on the electrical transport properties of carbon nanotube field-effect transistors (CNFETs). The CNFETs, consisting of single-walled carbon nanotube or double-walled carbon nanotube between two Pd electrodes on top of Si O2 layer, which showed p -type or ambipolar transport behaviors, exhibit clear n -type characteristics after the Al deposition. We ascribe such conversions into n -type behaviors to the electron doping in the Al-covered nanotube region, which results in the bending of the nanotube bands nearby the edges of the Al layer. This technique, Al deposition under a high vacuum, may give rise to a practical fabrication method for the n -type CNFET, which may enable us to develop complementary logic nanotube electronic devices.open151
Characterization and Modeling of Non-Uniform Charge Collection in CVD Diamond Pixel Detectors
A pixel detector with a CVD diamond sensor has been studied in a 180 GeV/c
pion beam. The charge collection properties of the diamond sensor were studied
as a function of the track position, which was measured with a silicon
microstrip telescope. Non-uniformities were observed on a length scale
comparable to the diamond crystallites size. In some regions of the sensor, the
charge drift appears to have a component parallel to the sensor surface (i.e.,
normal to the applied electric field) resulting in systematic residuals between
the track position and the hits position as large as 40 m. A numerical
simulation of the charge drift in polycrystalline diamond was developed to
compute the signal induced on the electrodes by the electrons and holes
released by the passing particles. The simulation takes into account the
crystallite structure, non-uniform trapping across the sensor, diffusion and
polarization effects. It is in qualitative agreement with the data. Additional
lateral electric field components result from the non-uniform trapping of
charges in the bulk. These provide a good explanation for the large residuals
observed.Comment: Accepted by Nucl. Instr. and Met
Microalgae for municipal wastewater nutrient remediation: mechanisms, reactors and outlook for tertiary treatment
This review explores the use of microalgae for nutrient removal in municipal wastewater treatment, considering recent improvements in the understanding of removal mechanisms and developments of both suspended and non-suspended systems. Nutrient removal is associated to both direct and indirect uptake, with the former associated to the biomass concentration and growth environment (reactor). Importantly, direct uptake is influenced by the Nitrogen:Phosphorus content in both the cells and the surrounding wastewater, with opposite trends observed for N and P. Comparison of suspended and non-suspended systems revealed that whilst all were capable of achieving high levels of nutrient removal, only non-suspended immobilized systems could do so with reduced hydraulic retention times of less than 1 day. As microalgae are photosynthetic organisms, the metabolic processes associated with nutrient assimilation are driven by light. Optimization of light delivery remains a key area of development with examples of improved mixing in suspended systems and the use of pulsating lights to enhance light utilization and reduce costs. Recent data provide increased confidence in the use of microalgae for nutrient removal in municipal wastewater treatment, enabling effluent discharges below 1 mg L−1 to be met whilst generating added value in terms of bioproducts for energy production or nutrient recovery. Ultimately, the review suggests that future research should focus on non-suspended systems and the determination of the added value potential. In so doing, it is predicted that microalgae systems will be significant in the delivery of the circular economy
Effects of soybean lipid infusion on triglyceride and unbound free fatty acid levels in preterm infants
© 2018 Informa UK Limited, trading as Taylor & Francis Group Objective: To determine the plasma triglyceride (TG) and unbound free fatty acid (FFAu) levels in infants treated with increasing dosages of soybean lipid, intralipid (IL), infusion. Study design: TG and FFAu levels were measured in 78 preterm infants (BW 500–2000 g; GA 23–34 weeks) using the fluorescent probe ADIFAB2 and enzymatic method. Results: The infants’ BW was 1266.2 ± 440.7 g and GA 28.8 ± 3.1 weeks. TG levels were 77.4 ± 50 mg/dL, 140.2 ± 188 mg/dL (p \u3c .04 compared to levels during low dose IL infusion) and 135.6 ± 118 mg/dL (p \u3c .004), respectively during increased IL rates. FFAu levels were 17.7 ± 13 nM, 47.3 ± 102.8 nM (p = .07) and 98 ± 234 nM (p = .03). TG levels correlated with IL dose, the rate of IL administration, and FFAu levels. TG and FFAu levels were higher in infants below 28 weeks’ gestation Conclusions: Increasing dosage of IL is associated with increasing levels of TG and FFAu, especially in infants below 29 weeks of gestation. The increased level of FFAu suggests inefficient cellular utilization
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