14 research outputs found
The 21 cm Signature of Shock Heated and Diffuse Cosmic String Wakes
The analysis of the 21 cm signature of cosmic string wakes is extended in
several ways. First we consider the constraints on from the absorption
signal of shock heated wakes laid down much later than matter radiation
equality. Secondly we analyze the signal of diffuse wake, that is those wakes
in which there is a baryon overdensity but which have not shock heated. Finally
we compare the size of these signals compared to the expected thermal noise per
pixel which dominates over the background cosmic gas brightness temperature and
find that the cosmic string signal will exceed the thermal noise of an
individual pixel in the Square Kilometre Array for string tensions .Comment: 10 pages, 4 figures, Appendix added, version published in JCA
Computation of the Heavy-Light Decay Constant using Non-relativistic Lattice QCD
We report results on a lattice calculation of the heavy-light meson decay
constant employing the non-relativistic QCD approach for heavy quark and Wilson
action for light quark. Simulations are carried out at on a
lattice. Signal to noise ratio for the ground state is
significantly improved compared to simulations in the static approximation,
enabling us to extract the decay constant reliably. We compute the heavy-light
decay constant for several values of heavy quark mass and estimate the
magnitude of the deviation from the heavy mass scaling law . For the meson we find MeV, while
an extrapolation to the static limit yields = MeV.Comment: 34 pages in LaTeX including 10 figures using epsf.sty,
uuencoded-gziped-shar format, HUPD-940
Local wind speed forecasting based on WRF-HDWind coupling
Wind speed forecasts obtained by Numerical Weather Prediction models are limited for fine interpretation in heterogeneous terrain, in which different roughnesses and orographies occur. This limitation is derived from the use of low-resolution and grid-box averaged data. In this paper a dynamical downscaling method is presented to increase the local accuracy of wind speed forecasts. The proposed method divides the wind speed forecasting into two steps. In the first one, the mesoscale model WRF (Weather Research and Forecasting) is used for getting wind speed forecasts at specific points of the study domain. On a second stage, these values are used for feeding the HDWind microscale model. HDWind is a local model that provides both a high-resolution wind field that covers the entire study domain and values of wind speed and direction at very located points. As an example of use of the proposed method, we calculate a high-resolution wind field in an urban-interface area from Badajoz, a South-West Spanish city located near the Portugal border. The results obtained are compared with the values read by a weathervane tower of the Spanish State Meteorological Agency (AEMET) in order to prove that the microscale model improves the forecasts obtained by the mesoscale model
Local wind speed forecasting based on WRF-HDWind coupling
[EN] Wind speed forecasts obtained by Numerical Weather Prediction models are limited for fine interpretation in
heterogeneous terrain, in which different roughnesses and orographies occur. This limitation is derived from the
use of low-resolution and grid-box averaged data. In this paper a dynamical downscaling method is presented to
increase the local accuracy of wind speed forecasts. The proposed method divides the wind speed forecasting
into two steps. In the first one, the mesoscale model WRF (Weather Research and Forecasting) is used for getting
wind speed forecasts at specific points of the study domain. On a second stage, these values are used for feeding
the HDWind microscale model. HDWind is a local model that provides both a high-resolution wind field that
covers the entire study domain and values of wind speed and direction at very located points. As an example of
use of the proposed method, we calculate a high-resolution wind field in an urban-interface area from Badajoz, a
South-West Spanish city located near the Portugal border. The results obtained are compared with the values
read by a weathervane tower of the Spanish State Meteorological Agency (AEMET) in order to prove that the
microscale model improves the forecasts obtained by the mesoscale model
Probing the imprints of generalized interacting dark energy on the growth of perturbations
We extensively study the evolution and distinct signatures of cosmological models, in which dark energy interacts directly with dark matter. We first focus on the imprints of these coupled models on the cosmic microwave background temperature power spectrum, in which we discuss the multipole peak separation together with the integrated Sachs-Wolfe effect. We also address the growth of matter perturbations, and disentangle the interacting dark energy models using the expansion history together with the growth history. We find that a disformal coupling between dark matter and dark energy induces intermediate-scales and time-dependent damped oscillatory features in the matter growth rate function, a unique characteristic of this coupling. Apart from the disformal coupling, we also consider conformally coupled models, together with models which simultaneously make use of both couplings
Comparative plant growth promoting traits and distribution of rhizobacteria associated with heavy metals in contaminated soils
The heavy metals at high concentration are generally toxic to the
plants for their metabolism and growth; therefore, interactions among
metals, rhizosphere microbes and plants have attracted attention
because of the biotechnological potential of microorganisms for metal
removal directly from contaminated soils or the possible transference
of them to the plants. The aim of this study was to compare the
relationships between the physiological in vitro characteristics of
rhizobacteria isolated from plant metal accumulators and their
distribution relating with the heavy metals content in contaminated
soils. The results of this study showed that the heavy metals present
in the rhizosphere of the plant species analyzed, decrease the
microbial biomass and content of heavy metals caused a different
distribution of rhizobacteria found. Gram negative rhizobacteria (90%)
and gram positive rhizobacteria (10%) were isolated; all of them are
metal-resistant rhizobacteria and 50% of the isolated rhizobacteria
possess both traits: higher indol acetic acid and siderophore
producers. The inoculation with these rhizosphere microorganisms that
possess metal-tolerating ability and plant growth promoting activities,
can be recommended with a practical importance for both
metal-contaminated environment and plant growth promotion