307 research outputs found
The Holography Hypothesis and Pre-Big Bang Cosmology
The consequences of holography hypothesis are investigated for the
Pre-big-bang string cosmological models. The evolution equations are obtained
from the tree level string effective action. It is shown that is bounded
by a constant in each case, being the entropy within the volume bounded by
the horizon of area .Comment: 11 pages, revtex, 1 eps fil
Use of dopamine antagonists on induced spawning of Indian major carps
To test the efficacy of the technique of using dopamine-antagonists with pituitary extracts, experiments were conducted in July/August '93, at the CIFE Fresh water Fish Farm, Powerkheda. In all, 35 sets (1 female x 2 male in each set) were tried individually. 19 sets were treated with Domperidone (DOM) and Carp Pituitary Extract (CPE) and they constituted the experimental sets, while the rest 16 were treated with CPE and formed the control sets. The breeding, complete ovulation and hatching was 84.2%, 87.5% and 85.7%, respectively in the experimental sets whereas it was 93.7%, 60% and 72.7%, respectively in case of control sets. Experimental sets yielded 1.20 lakh spawn/kg body wt. (female) as compared to 0.83 lakh spawn kg body wt. (female) received from control sets on average basis. When DOM was used at 50-60% there was 100% breeding success but when increased to 70%, breeding rate fell to 66%. In mass breeding of Catla in the circular hatchery DOM mixed with CPE in 50:50 ratio gave excellent results
Stabilization of a Highly Concentrated Colloidal Suspension of Pristine Metallic Nanoparticles
A colloidal suspension containing a high concentration of metallic nanoparticles (NPs) finds potential applications in flexible electronic printing, nanofluids, healthcare, antifouling coating, and so on. Here, we demonstrate a generic, easily scalable, simple, and contamination-free cryogenic temperature grinding method, which can effectively be used to prepare pristine NPs that can be stabilized in polar liquids in high concentrations. These surfactant-free pristine NPs have been found to remain dispersed in different polar liquids (CH3OH, C2H5OH, glycol, etc.) for weeks. The long-term stability of the NPs in these liquids has been investigated using zeta potential, in situ Fourier transform infrared spectroscopy, indicating electrostatic stabilization for ultrapure, surfactant-free NPs. Furthermore, stabilization of the NPs has been probed with detailed calculations using the Derjaguin Landau Verwey Overbeek theory as well as atomistic molecular dynamics simulation (MD). Experimental measurements along with theoretical calculations categorically indicate that the electrostatic energy is helping these NPs to be stabilized in a polar liquid
Testing of newly developed glycophospholipid antigen for the detection of P. falciparum malaria by laser light immunoassay in endemic and non-endemic areas
A glycophospholipid (GPL) antigen isolated from Plasmodium falciparum culture supernatant hasbeen tested for its antigenicity. Detection of malaria positive known blood samples and unknown fieldsamples from endemic and non-endemic areas were compared. In this study laser light scattering immunoassay(LIA) was used for the detection of P. falciparum malaria. Test results of control (malaria negativesamples from Surat) were compared with known positive samples and unknown malaria positivefield samples. A positive correlation has been observed (97%) in falciparum positive samples from laboratoryand unknown samples from endemic area (Haldwani) by LIA method using GPL antigen. Fromthe results of the study it was found that GPL antigen has a better antigenic property and can detectalmost all the cases of Pf malaria by LIA method
Formation of complex Langmuir and Langmuir-Blodgett films of water soluble rosebengal
This communication reports the formation of complex Langmuir monolayer at the
air-water interface by charge transfer types of interaction with the water
soluble N- cetyl N, N, N trimethyl ammonium bromide (CTAB) molecules doped with
rosebengal (RB), with the stearic acid (SA) molecules of a preformed SA
Langmuir monolayer. The reaction kinetics of the formation of RB-CTAB-SA
complex monolayer was monitored by observing the increase in surface pressure
with time while the barrier was kept fixed. Completion of interaction kinetics
was confirmed by FTIR study. This complex Langmuir films at the air-water
interface was transferred onto solid substrates at a desired surface pressure
to form multilayered Langmuir-Blodgett films. Spectroscopic characterizations
reveal some molecular level interactions as well as formation of
microcrystalline aggregates depending upon the molar ratios of CTAB and RB
within the complex LB films. Presence of two types of species in the complex LB
films was confirmed by fluorescence spectroscopy.Comment: 13 pages, figures
Zeta Function Zeros, Powers of Primes, and Quantum Chaos
We present a numerical study of Riemann's formula for the oscillating part of
the density of the primes and their powers. The formula is comprised of an
infinite series of oscillatory terms, one for each zero of the zeta function on
the critical line and was derived by Riemann in his paper on primes assuming
the Riemann hypothesis. We show that high resolution spectral lines can be
generated by the truncated series at all powers of primes and demonstrate
explicitly that the relative line intensities are correct. We then derive a
Gaussian sum rule for Riemann's formula. This is used to analyze the numerical
convergence of the truncated series. The connections to quantum chaos and
semiclassical physics are discussed
Anomalous Cosmic Rays and their Ionization States
Ionization states of 16 individual anomalous cosmic ray events have been determined in the anuradha cosmic ray experiment conducted onboard Spacelab-3. The geomagnetic field was used as a rigidity filter for the energetic charged particles, and the upper limit on their ionization states is obtained by using the relation Z <= M.p.c/R/sub c/. Out of 16 events, 11 are found to be singly ionized and the other five events are consistent with their being in singly ionized states. The singly ionized nature of the anomalous cosmic ray particles suggests neutrals in the local interstellar space as their source
Complete solutions to the metric of spherically collapsing dust in an expanding spacetime with a cosmological constant
We present semi-analytical solutions to the background equations describing
the Lema\^itre-Tolman-Bondi (LTB) metric as well as the homogeneous Friedmann
equations, in the presence of dust, curvature and a cosmological constant
Lambda. For none of the presented solutions any numerical integration has to be
performed. All presented solutions are given for expanding and collapsing
phases, preserving continuity in time and radius. Hence, these solutions
describe the complete space time of a collapsing spherical object in an
expanding universe. In the appendix we present for completeness a solution of
the Friedmann equations in the additional presence of radiation, only valid for
the Robertson-Walker metric.Comment: 23 pages, one figure. Numerical module for evaluation of the
solutions released at
http://web.physik.rwth-aachen.de/download/valkenburg/ColLambda/ Matches
published version, published under Open Access. Note change of titl
Understanding Volumetric Water Storage in Monsoonal Wetlands of Northeastern Bangladesh
The volume of water stored in seasonal wetlands is a fundamental but difficult to measure variable for developing a physical understanding of wetland behavior. For seasonal wetlands that are a major source of water for rice and fish production, this physical understanding is key to planning for water-food security and ecosystem services. This study quantified variations in volumetric storage for the numerous seasonal wetlands of northeastern Bangladesh, locally known as “haors.” These haors receive transboundary runoff from densely vegetated and mountainous terrain in India and face persistent monsoonal cloud cover as they become full. We estimated volumetric storage for 13 haors by using extensive remote sensing data on water surface extent and elevation that was complemented with citizen-contributed gauge data. Assuming a trapezoidal bathymetry, an area-volume relationship was developed for selected haors. This relationship was assumed to be valid for extrapolating volumetric estimations over all the haors in the region. Results suggested that as haors get filled with the onset of monsoon rains, total estimated storage relative to the lowest observable level varied from 6.5 (±0.4) km3 in May to 30.9 (±2.0) km3 in July (peak of monsoon). Choosing a rectangular bathymetry can lead to 47% higher estimates compared to trapezoidal cross section. Estimating this intra-annual/interannual increase in storage is important for the region to plan water management policies that balance the human and ecosystem needs. Our analytical approach has potential for application to wetlands worldwide in light of the upcoming Surface Water and Ocean Topography (SWOT) mission
Dark energy as a mirage
Motivated by the observed cosmic matter distribution, we present the
following conjecture: due to the formation of voids and opaque structures, the
average matter density on the path of the light from the well-observed objects
changes from Omega_M ~ 1 in the homogeneous early universe to Omega_M ~ 0 in
the clumpy late universe, so that the average expansion rate increases along
our line of sight from EdS expansion Ht ~ 2/3 at high redshifts to free
expansion Ht ~ 1 at low redshifts. To calculate the modified observable
distance-redshift relations, we introduce a generalized Dyer-Roeder method that
allows for two crucial physical properties of the universe: inhomogeneities in
the expansion rate and the growth of the nonlinear structures. By treating the
transition redshift to the void-dominated era as a free parameter, we find a
phenomenological fit to the observations from the CMB anisotropy, the position
of the baryon oscillation peak, the magnitude-redshift relations of type Ia
supernovae, the local Hubble flow and the nucleosynthesis, resulting in a
concordant model of the universe with 90% dark matter, 10% baryons, no dark
energy, 15 Gyr as the age of the universe and a natural value for the
transition redshift z_0=0.35. Unlike a large local void, the model respects the
cosmological principle, further offering an explanation for the late onset of
the perceived acceleration as a consequence of the forming nonlinear
structures. Additional tests, such as quantitative predictions for angular
deviations due to an anisotropic void distribution and a theoretical derivation
of the model, can vindicate or falsify the interpretation that light
propagation in voids is responsible for the perceived acceleration.Comment: 33 pages, 2 figs; v2: minor clarifications, results unchanged; v3:
matches the version published in General Relativity and Gravitatio
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