3,188 research outputs found
The spectral variability of FSRQs
The optical variability of 29 flat spectrum radio quasars in SDSS Stripe 82
region are investigated by using DR7 released multi-epoch data. All FSRQs show
variations with overall amplitude ranging from 0.24 mag to 3.46 mag in
different sources. About half of FSRQs show a bluer-when-brighter trend, which
is commonly observed for blazars. However, only one source shows a
redder-when-brighter trend, which implies it is rare in FSRQs. In this source,
the thermal emission may likely be responsible for the spectral behavior.Comment: 4 pages, 1 figure, to be published in Journal of Astrophysics and
Astronomy, as a proceeding paper of the conference "Multiwavelength
Variability of Blazars", Guangzhou, China, September 22-24, 201
High-energy scale revival and giant kink in the dispersion of a cuprate superconductor
In the present photoemission study of a cuprate superconductor
Bi1.74Pb0.38Sr1.88CuO6+delta, we discovered a large scale dispersion of the
lowest band, which unexpectedly follows the band structure calculation very
well. The incoherent nature of the spectra suggests that the hopping-dominated
dispersion occurs possibly with the assistance of local spin correlations. A
giant kink in the dispersion is observed, and the complete self-energy
containing all interaction information is extracted for a doped cuprate in the
low energy region. These results recovered significant missing pieces in our
current understanding of the electronic structure of cuprates.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Lett. on May 21, 200
Variability of the Spectral Energy Distribution of the Blazar S5 0716+714
The emission from blazars is known to be variable at all wavelengths. The
flux variability is often accompanied by spectral changes. Spectral energy
distribution (SED) changes must be associated with changes in the spectra of
emitting electrons and/or the physical parameters of the jet. Meaningful
modeling of blazar broadband spectra is required to understand the extreme
conditions within the emission region. Not only is the broadband SED crucial,
but also information about its variability is needed to understand how the
highest states of emission occur and how they differ from the low states. This
may help in discriminating between models. Here we present the results of our
SED modeling of the blazar S5 0716+714 during various phases of its activity.
The SEDs are classified into different bins depending on the optical brightness
state of the source.Comment: 4 pages, 3 figures, contributed talk presented at the conference
Multifrequency Variability of Blazars, Guangzhou, China, September 22-24,
2010. To appear in Journal of Astrophysics and Astronomy (JAA
High-transition-temperature superconductivity in the absence of the magnetic-resonance mode
The fundamental mechanism that gives rise to high-transition-temperature
(high-Tc) superconductivity in the copper oxide materials has been debated
since the discovery of the phenomenon. Recent work has focussed on a sharp
'kink' in the kinetic energy spectra of the electrons as a possible signature
of the force that creates the superconducting state. The kink has been related
to a magnetic resonance and also to phonons. Here we report that infrared
spectra of Bi2Sr2CaCu2O(8+d), (Bi-2212) show that this sharp feature can be
separated from a broad background and, interestingly, weakens with doping
before disappearing completely at a critical doping level of 0.23 holes per
copper atom. Superconductivity is still strong in terms of the transition
temperature (Tc approx 55 K), so our results rule out both the magnetic
resonance peak and phonons as the principal cause of high-Tc superconductivity.
The broad background, on the other hand, is a universal property of the copper
oxygen plane and a good candidate for the 'glue' that binds the electrons.Comment: 4 pages, 3 figure
Nonlinear Localization in Metamaterials
Metamaterials, i.e., artificially structured ("synthetic") media comprising
weakly coupled discrete elements, exhibit extraordinary properties and they
hold a great promise for novel applications including super-resolution imaging,
cloaking, hyperlensing, and optical transformation. Nonlinearity adds a new
degree of freedom for metamaterial design that allows for tuneability and
multistability, properties that may offer altogether new functionalities and
electromagnetic characteristics. The combination of discreteness and
nonlinearity may lead to intrinsic localization of the type of discrete
breather in metallic, SQUID-based, and symmetric metamaterials. We
review recent results demonstrating the generic appearance of breather
excitations in these systems resulting from power-balance between intrinsic
losses and input power, either by proper initialization or by purely dynamical
procedures. Breather properties peculiar to each particular system are
identified and discussed. Recent progress in the fabrication of low-loss,
active and superconducting metamaterials, makes the experimental observation of
breathers in principle possible with the proposed dynamical procedures.Comment: 19 pages, 14 figures, Invited (Review) Chapte
KIAA0101 (OEACT-1), an expressionally down-regulated and growth-inhibitory gene in human hepatocellular carcinoma
BACKGROUND: Our previous cDNA array results indicated KIAA0101 as one of the differentially expressed genes in human hepatocellular carcinoma (HCC) as compared with non-cancerous liver. However, it is necessary to study its expression at protein level in HCC and its biological function for HCC cell growth. METHOD: Western blot and tissue array were performed to compare KIAA0101 protein expression level in paired human HCC and non-cancerous liver tissues from the same patients. Investigation of its subcellular localization was done by using dual fluorescence image examination and enriched mitochondrial protein Western blot analysis. The in vitro cell growth curve was used for examing the effect of over-expression of KIAA0101 in HCC cells. FACS was used to analyze the cell cycle pattern in KIAA0101 expression positive (+) and negative (-) cell populations isolated by the pMACSKK(II )system after KIAA0101 cDNA transfection. RESULTS: Western blot showed KIAA0101 protein expression was down-regulated in HCC tissues as compared with their counterpart non-cancerous liver tissues in 25 out of 30 cases. Tissue array also demonstrated the same pattern in 161 paired samples. KIAA0101 was predominantly localized in mitochondria and partially in nuclei. KIAA0101 cDNA transfection could inhibit the HCC cell growth in vitro. In cell cycle analysis, it could arrest cells at the G(1 )to S phase transition. CONCLUSION: KIAA0101 protein expression was down-regulated in HCC. This gene could inhibit the HCC cell growth in vitro and presumably by its blocking effect on cell cycle
Towards universal quantum computation through relativistic motion
We show how to use relativistic motion to generate continuous variable Gaussian cluster states within cavity modes. Our results can be demonstrated experimentally using superconducting circuits where tuneable boundary conditions correspond to mirrors moving with velocities close to the speed of light. In particular, we propose the generation of a quadripartite square cluster state as a first example that can be readily implemented in the laboratory. Since cluster states are universal resources for universal one-way quantum computation, our results pave the way for relativistic quantum computation schemes
Blood pressure, body mass index and risk of cardiovascular disease in Chinese men and women
<p>Abstract</p> <p>Background</p> <p>It is still uncertain whether increased blood pressure (BP) has a stronger effect on the risk of cardiovascular disease (CVD) in lean persons than in obese persons. We tested it using a data set collected from a large cohort of Chinese adults.</p> <p>Methods</p> <p>Systolic and diastolic BP, body mass index (BMI) and other variables were measured in 169,871 Chinese men and women ≥ 40 years of age in 1991 using standard protocols. Follow-up evaluation was conducted in 1999-2000, with a response rate of 93.4%. Data were analyzed with Cox proportional hazards models.</p> <p>Results</p> <p>After adjusted for age, sex, cigarette smoking, alcohol consumption, high school education, physical inactivity, geographic region, and urbanization, we found that the effects of systolic or diastolic BP on risk of CVD generally increased with the increasing BMI levels (underweight, normal, overweight, and obese). For example, hazard ratios (HRs) and 95% confidence interval (CI) per 1- standard deviation (SD) increase in systolic BP within corresponding BMI levels were 1.27(1.21-1.33), 1.45(1.41-1.48), 1.52 (1.45-1.59) and 1.63 (1.51-1.76), respectively. Statistically significant interactions (P < 0.0001) were observed between systolic BP, diastolic BP and BMI in relation to CVD. In baseline hypertensive participants we found both obese men and women had higher risk of CVD than normal-weight persons. The multivariate-adjusted HRs(95%CI) were 1.23(1.03-1.47) and 1.20(1.02-1.40), respectively.</p> <p>Conclusion</p> <p>Our study suggests that the magnitude of the association between BP and CVD generally increase with increasing BMI. Hypertension should not be regarded as a less serious risk factor in obese than in lean or normal-weight persons in Chinese adults.</p
A First Generation Microsatellite- and SNP-Based Linkage Map of Jatropha
Jatropha curcas is a potential plant species for biodiesel production. However, its seed yield is too low for profitable production of biodiesel. To improve the productivity, genetic improvement through breeding is essential. A linkage map is an important component in molecular breeding. We established a first-generation linkage map using a mapping panel containing two backcross populations with 93 progeny. We mapped 506 markers (216 microsatellites and 290 SNPs from ESTs) onto 11 linkage groups. The total length of the map was 1440.9 cM with an average marker space of 2.8 cM. Blasting of 222 Jatropha ESTs containing polymorphic SSR or SNP markers against EST-databases revealed that 91.0%, 86.5% and 79.2% of Jatropha ESTs were homologous to counterparts in castor bean, poplar and Arabidopsis respectively. Mapping 192 orthologous markers to the assembled whole genome sequence of Arabidopsis thaliana identified 38 syntenic blocks and revealed that small linkage blocks were well conserved, but often shuffled. The first generation linkage map and the data of comparative mapping could lay a solid foundation for QTL mapping of agronomic traits, marker-assisted breeding and cloning genes responsible for phenotypic variation
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