2,665 research outputs found
Hawking Radiation of Black p-Branes from Gravitational Anomaly
We investigate the Hawking radiation of black -branes of superstring
theories using the method of anomaly cancelation, specially, we use the method
of [S. Iso, H. Umetsu and F. Wilczek, {\sl Phys. Rev. Lett.} {\bf 96}, 151302
(2006); {\sl Phys. Rev. D} {\bf 74}, 044017 (2006)]. The metrics of black
-branes are spherically symmetric, but not the Schwarzschild type. In order
to simplify the calculation, we first make a coordinate transformation to
transform the metric to the Schwarzschild type. Then we calculate its
energy-momentum flux from the method of anomaly cancelation of the above
mentioned references. The obtained energy-momentum flux is equal to a black
body radiation, the thermodynamic temperature of the radiation is equal to its
Hawking temperature. And we find that the results are not changed for the
original non-Schwarzschild type spherically symmetric metric.Comment: 19 pages Latex, some mistakes correcte
Some are more equal than others : the role of ‘keystone’ species in the degradation of recalcitrant substrates
Peer reviewedPublisher PD
Non-Markovian effect on the quantum discord
We study the non-Markovian effect on the dynamics of the quantum discord by
exactly solving a model consisting of two independent qubits subject to two
zero-temperature non-Markovian reservoirs, respectively. Considering the two
qubits initially prepared in Bell-like or extended Werner-like states, we show
that there is no occurrence of the sudden death, but only instantaneous
disappearance of the quantum discord at some time points, in comparison to the
entanglement sudden death in the same range of the parameters of interest. It
implies that the quantum discord is more useful than the entanglement to
describe quantum correlation involved in quantum systems.Comment: 5 pages, 5 figure
Constraints on holographic dark energy models using the differential ages of passively evolving galaxies
Using the absolute ages of passively evolving galaxies observed at different
redshifts, one can obtain the differential ages, the derivative of redshift
with respect to the cosmic time (i.e. ). Thus, the
Hubble parameter can be measured through the relation . By comparing the measured Hubble parameter at different
redshifts with the theoretical one containing free cosmological parameters, one
can constrain current cosmological models. In this paper, we use this method to
present the constraint on a spatially flat Friedman-Robert-Walker Universe with
a matter component and a holographic dark energy component, in which the
parameter plays a significant role in this dark energy model. Firstly we
consider three fixed values of =0.6, 1.0 and 1.4 in the fitting of data. If
we set free, the best fitting values are , ,
. It is shown that the holographic dark energy behaves like a
quintom-type at the level. This result is consistent with some other
independent cosmological constrains, which imply that is favored. We
also test the results derived from the differential ages using another
independent method based on the lookback time to galaxy clusters and the age of
the universe. It shows that our results are reliable.Comment: 18 pages including 7 figures and 1 tables. Final version for
publication in Modern Physics Letters A (MPLA)[minor revision to match the
appear version
China’s emerging tax regime: Devolution, fiscal federalism, or tax farming?
China like other transition economies needs to establish a tax regime compatible with a market economy. The paper singles out the general and China-specific features by which national legislation attempts to accompany economic transformation. Based on an empirical study in two provinces this paper shows that without including local government agencies and their budgets, China’s fiscal federalism cannot be analysed. This paper argues that China’s emerging tax regime depends on the institutional design that shapes the interaction between firms (as major tax payers at the local level), local government agencies, and the national tax administration
Fulvic acid affects pepper antioxidant activity and fruit quality
Fulvic acid has been considered as a valuable fertilizer for sustainable agriculture. The present investigation was undertaken to evaluate the effect of fulvic acid (FA) on antioxidant compounds and fruit quality of pepper under field conditions. Plants were grown in the Department of Horticulture Farm, Ferdowsi University of Mashhad, Iran (latitude 36‹ 17Œ N, longitude 59‹ 35Œ E and 985 m elevation). The experiment was designed in randomized block design with three replications. Treatments consisted of five levels of fulvic acid (0, 25, 100, 175 and 250 mg kg-1). The results indicate that fruit antioxidant activity, total phenolic, carbohydrate, capsaicin and carotenoids contents were influenced by fulvic acid, but total flavonoid and ascorbic acid contents were not affected significantly by fulvic acid treatments applications. FA applied at 25 mg kg-1 resulted in the highest carbohydrate content, lycopene and ƒÀ-carotene contents, while the lowest values were recorded in the control. Fulvic acid treatments positively affected fruit quality (total soluble solids and titratable acidity); total soluble solids and titratable acidity significantly increased in response to FA treatments. These results confirm that the use of fulvic acid have a positive effect on antioxidant activity and quality of hot pepper under field conditions.Key words: Fulvic acid, antioxidant activity, quality, pepper
(D* to D + gamma) and (B* to B + gamma) as derived from QCD Sum Rules
The method of QCD sum rules in the presence of the external electromagnetic
field is used to analyze radiative decays of charmed or bottomed
mesons such as and , with the
susceptibilities obtained previously from the study of baryon magnetic moments.
Our predictions on decays agree very well with the experimental
data. There are differences among the various theoretical predictions on
decays but the data are not yet available.Comment: 11 pages, Late
The influence of slope and peatland vegetation type on riverine dissolved organic carbon and water colour at different scales
Peatlands are important sources of fluvial carbon. Previous research has shown that riverine dissolved organic carbon (DOC) concentrations are largely controlled by soil type. However, there has been little work to establish the controls of riverine DOC within blanket peatlands that have not undergone major disturbance from drainage or burning. A total of 119 peatland catchments were sampled for riverine DOC and water colour across three drainage basins during six repeated sampling campaigns. The topographic characteristics of each catchment were determined from digital elevation models. The dominant vegetation cover was mapped using 0.5 m resolution colour infrared aerial images, with ground-truthed validation revealing 82 % accuracy. Forward and backward stepwise regression modelling showed that mean slope was a strong (and negative) determinant of DOC and water colour in blanket peatland river waters. There was a weak role for plant functional type in determining DOC and water colour. At the basin scale, there were major differences between the models depending on the basin. The dominance of topographic predictors of DOC found in our study, combined with a weaker role of vegetation type, paves the way for developing improved planning tools for water companies operating in peatland catchments. Using topographic data and aerial imagery it will be possible to predict which tributaries will typically yield lower DOC concentrations and which are therefore more suitable and cost-effective as raw water intakes
Anatomical Region-Specific In Vivo Wireless Communication Channel Characterization
In vivo wireless body area networks (WBANs) and their associated technologies are shaping the future of healthcare by providing continuous health monitoring and noninvasive surgical capabilities, in addition to remote diagnostic and treatment of diseases. To fully exploit the potential of such devices, it is necessary to characterize the communication channel which will help to build reliable and high-performance communication systems. This paper presents an in vivo wireless communication channel characterization for male torso both numerically and experimentally (on a human cadaver) considering various organs at 915 MHz and 2.4 GHz. A statistical path loss (PL) model is introduced, and the anatomical region-specific parameters are provided. It is found that the mean PL in dB scale exhibits a linear decaying characteristic rather than an exponential decaying profile inside the body, and the power decay rate is approximately twice at 2.4 GHz as compared to 915 MHz. Moreover, the variance of shadowing increases significantly as the in vivo antenna is placed deeper inside the body since the main scatterers are present in the vicinity of the antenna. Multipath propagation characteristics are also investigated to facilitate proper waveform designs in the future wireless healthcare systems, and a rootmean- square (RMS) delay spread of 2.76 ns is observed at 5 cm depth. Results show that the in vivo channel exhibit different characteristics than the classical communication channels, and location dependency is very critical for accurate, reliable, and energy-efficient link budget calculations
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