2,308 research outputs found
Characterizing Intermittency of 4-Hz Quasi-periodic Oscillation in XTE J1550-564 using Hilbert-Huang Transform
We present the time-frequency analysis results based on the Hilbert-Huang
transform (HHT) for the evolution of a 4-Hz low-frequency quasi-periodic
oscillation (LFQPO) around the black hole X-ray binary XTE J1550-564. The
origin of LFQPOs is still debated. To understand the cause of the peak
broadening, we utilized a recently developed time-frequency analysis, HHT, for
tracking the evolution of the 4-Hz LFQPO from XTE J1550 564. By adaptively
decomposing the ~4-Hz oscillatory component from the light curve and acquiring
its instantaneous frequency, the Hilbert spectrum illustrates that the LFQPO is
composed of a series of intermittent oscillations appearing occasionally
between 3 Hz and 5 Hz. We further characterized this intermittency by computing
the confidence limits of the instantaneous amplitudes of the intermittent
oscillations, and constructed both the distributions of the QPO's high and low
amplitude durations, which are the time intervals with and without significant
~4-Hz oscillations, respectively. The mean high amplitude duration is 1.45 s
and 90% of the oscillation segments have lifetimes below 3.1 s. The mean low
amplitude duration is 0.42 s and 90% of these segments are shorter than 0.73 s.
In addition, these intermittent oscillations exhibit a correlation between the
oscillation's rms amplitude and mean count rate. This correlation could be
analogous to the linear rms-flux relation found in the 4-Hz LFQPO through
Fourier analysis. We conclude that the LFQPO peak in the power spectrum is
broadened owing to intermittent oscillations with varying frequencies, which
could be explained by using the Lense-Thirring precession model.Comment: 27 pages, 9 figures, accepted for publication in The Astrophysical
Journa
Atividade de celulase de Termoactinomicetos e Bacillus spp. isolados de resÃduos derivados de compostos de Brassica
ResÃduos vegetais apresentam alta concentração de celulose, que é um material orgânico ideal para preparação de composto. Cinco linhagens de termófilos foram isoladas de resÃduos processados de Brassica e a atividade hidrolÃtica em vários substratos contendo celulose e seus padrões de temperatura foram determinados. O seqüenciamento de rRNA 16S permitiu a identificação dessas isolados como Thermoactinomyces e Bacillus spp. A atividade máxima de celulase foi determinada como de 2,3 U mL-1 de enzima. O uso dessas linhagens em resÃduos de Brassica rapa resultou em um aumento total do conteúdo de nitrogênio. TA-3, uma linhagem de Thermoactinomycetes sp., apresentou melhor desempenho entre os inoculantes, aumentando o conteúdo de nitrogênio de 0,74 para 0,91%, e diminuindo o conteúdo de carbono de 15,4 para 12,2%, mostrando sua alta eficiência e bioatividade durante a compostagem.Plant wastes present a high cellulose content, which is an ideal organic material for composting. Five strains of thermophiles from processed Brassica waste were isolated, and the hydrolytic activity on various cellulosic biomass substrata and their temperature profiles were determined. 16S rRNA sequencing identified these strains as Thermoactinomyces and Bacillus spp. Maximal cellulase activity corresponded to 2.3 U mL-1 of enzyme. The application of these strains on Brassica rapa residues demonstrates increased total nitrogen content). TA-3, a Thermoactinomycetes sp. strain, performs best among all inoculants, increasing the nitrogen content from 0.74 to 0.91%, and decreasing the carbon content from 15.4 to 12.2%, showing its high efficiency and bioactivity during compositing
Effects of natto extract on endothelial injury in a rat model
Vascular endothelial damage has been found to be associated with thrombus formation, which is considered to be a risk factor for cardiovascular disease. A diet of natto leads to a low prevalence of cardiovascular disease. The aim of the present study was to investigate the effects of natto extract on vascular endothelia damage with exposure to laser irradiation. Endothelial damage both in vitro and in vivo was induced by irradiation of rose bengal using a DPSS green laser. Cell viability was determined by MTS assay, and the intimal thickening was verified by a histological approach. The antioxidant content of natto extract was determined for the free radical scavenging activity. Endothelial cells were injured in the presence of rose bengal irradiated in a dose-dependent manner. Natto extract exhibits high levels of antioxidant activity compared with purified natto kinase. Apoptosis of laser-injured endothelial cells was significantly reduced in the presence of natto extract. Both the natto extract and natto kinase suppressed intimal thickening in rats with endothelial injury. The present findings suggest that natto extract suppresses vessel thickening as a synergic effect attributed to its antioxidant and anti-apoptosis properties
General properties of fidelity in non-Hermitian quantum systems with PT symmetry
The fidelity susceptibility is a tool for studying quantum phase transitions
in the Hermitian condensed matter systems. Recently, it has been generalized
with the biorthogonal basis for the non-Hermitian quantum systems. From the
general perturbation description with the constrain of parity-time (PT)
symmetry, we show that the fidelity is always real for the
PT-symmetric states. For the PT-broken states, the real part of the fidelity
susceptibility equals to one half of the sum of the fidelity susceptibility of
the PT-broken and the PT-partner states, . The negative infinity of the
fidelity susceptibility is explored by the perturbation theory when the
parameter approaches the exceptional point (EP). Moreover, at the second-order
EP where two eigenstates and eigenenergies coalesce, we prove that the real
part of the fidelity between PT-symmetric and PT-broken states is
. We demonstrate these general properties
for non-interacting and interacting systems by two examples: the two-legged
non-Hermitian Su-Schrieffer-Heeger (SSH) model and the non-Hermitian XXZ spin
chain.Comment: 14 pages, 8 figure
Dynamic Finite Element Analysis on Underlay Microstructure of Cu/low-k Wafer during Wirebonding
The aim of present research is to investigate dynamic stress analysis for microstructure of Cu/Low-K wafer subjected to wirebonding predicted by finite element software ANSYS/LS-DYNA. Two major analyses are conducted in the present research. In the first, the characteristic of heat affected zone (HAZ) and free air ball (FAB) on ultra thin Au wire have been carefully experimental measured. Secondary, the dynamic response on Al pad/beneath the pad of Cu/low-K wafer during wirebonding process has been successfully predicted by finite element analysis (FEA). Tensile mechanical properties of ultra thin wire before/after electric flame-off (EFO) process have been investigated by self-design pull test fixture. The experimental obtained hardening value has significantly influence on localize stressed area on Al pad. This would result in Al pad squeezing around the smashed FAB during impact stage and the consequent thermosonic vibration stage. Microstructure of FAB and HAZ are also carefully measured by micro/nano indentation instruments. All the measured data serves as material inputs for the FEA explicit software ANSYS/LS-DYNA. Because the crack of low-k layer and delamination of copper via are observed, dynamic transient analysis is performed to inspect the overall stress/strain distributions on the microstructure of Cu/low-k wafer. Special emphasizes are focused on the copper via layout and optimal design of Cu/low-k microstructure. It is also shown that the Al pad can be replaced by Al-Cu alloy pad or Cu pad to avoid large deformation on pad and cracking beneath the surface. A series of comprehensive experimental works and FEA predictions have been performed to increase bondability and reliability in this study
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