144 research outputs found
Low cost breeding and hatching techniques for the catfish (Heteropneustes fossilis) for small-scale farmers
The high demand for the stinging catfish (Heteropneustes fossilis) and declining wild stocks led the Centre for Aquaculture Research and Extension of India to look for methods for the culture of the species. This paper presents a low-cost, simple breeding technique developed and tested by the Centre that can be easily adopted by rural farmers
Addition of NOCl to cyclic vinylsilanes: An unexpected reversal of regiochemistry
NOCl adds to cyclic vinylsilanes in a syn manner with NO+ bonding to the β-carbon and Cl- to the α-carbon, which is a reversal of the regiochemistry expected from the β-silicon effect. The adducts dimerize to a single diastereomer containing enantiomeric pairs and/or give secondary products on further reaction. © 2001 Elsevier Science Ltd
J/psi Production at the LHC
We firstly examine hadroproduction of prompt J/psi's at the Fermilab Tevatron
in a Monte Carlo Framework by means of the event generator PYTHIA 5.7 in which
those colour-octet matrix elements processes relevant for charmonium production
have been implemented accordingly. We find that colour-octet matrix elements
presented in literature from p-pbar collider data are systematically
overestimated due to overlooking of the effective primordial transverse
momentum of partons (i.e. including higher-order QCD effects). We estimate the
size of these effects using different parton distribution functions. Finally,
after normalization to Tevatron data, we extrapolate up to LHC energies making
a prediction on the expected pt differential cross-section for charmonium.Comment: 4 pages, LaTex, 3 Figures included in the text, Contribution to the
2nd Int. Conference on Hyperons, charm and beauty hadrons (Montreal, Aug
27-30, 1996
Results from Bottomonia Production at the Tevatron and Prospects for the LHC
We extend our previous analysis on inclusive heavy quarkonia hadroproduction
to the whole Upsilon(nS) (n=1,2,3) resonance family. We use a Monte Carlo
framework with the colour-octet mechanism implemented in the PYTHIA event
generator. We include in our study higher order QCD effects such as
initial-state emission of gluons and Altarelli-Parisi evolution of final-state
gluons. We extract some NRQCD colour-octet matrix elements relevant for
Upsilon(nS) (n=1,2,3) hadroproduction from CDF data at the Fermilab Tevatron.
Then we extrapolate to LHC energies to predict prompt bottomonia production
rates. Finally, we examine the prospect to probe the gluon density in protons
from heavy quarkonia inclusive hadroproduction at high transverse momentum and
its feasibility in LHC general-purpose experiments.Comment: LaTeX, 30 pages, 30 EPS figure
Quantum mechanical analysis of the equilateral triangle billiard: periodic orbit theory and wave packet revivals
Using the fact that the energy eigenstates of the equilateral triangle
infinite well (or billiard) are available in closed form, we examine the
connections between the energy eigenvalue spectrum and the classical closed
paths in this geometry, using both periodic orbit theory and the short-term
semi-classical behavior of wave packets. We also discuss wave packet revivals
and show that there are exact revivals, for all wave packets, at times given by
where and are the length of one side
and the mass of the point particle respectively. We find additional cases of
exact revivals with shorter revival times for zero-momentum wave packets
initially located at special symmetry points inside the billiard. Finally, we
discuss simple variations on the equilateral
() triangle, such as the half equilateral
() triangle and other `foldings', which have
related energy spectra and revival structures.Comment: 34 pages, 9 embedded .eps figure
Scanning Fourier Spectroscopy: A microwave analog study to image transmission paths in quantum dots
We use a microwave cavity to investigate the influence of a movable absorbing
center on the wave function of an open quantum dot. Our study shows that the
absorber acts as a position-selective probe, which may be used to suppress
those wave function states that exhibit an enhancement of their probability
density near the region where the impurity is located. For an experimental
probe of this wave function selection, we develop a technique that we refer to
as scanning Fourier spectroscopy, which allows us to identify, and map out, the
structure of the classical trajectories that are important for transmission
through the cavity.Comment: 4 pages, 5 figure
The Fermi motion contribution to J/\psi production at the hadron colliders
We investigate the relativistic Fermi motion effect in the case of
production in various hadron colliders. A light-cone wave function is adopted
to represent the final state. The change in the confinement parameter
which sets a scale for the size of the final state, allows one to see the
effect in an explicit manner. While the effect has considerable influence on
the fragmentation probabilities and the differential cross sections, the total
cross sections are essentially left unchanged. such a feature is in agreement
with the momentum sum rule which the fragmentation functions should satisfy.Comment: 10 pages, 4 figures, to appear in Phys. Lett.
Charmonium Production at Tevatron, HERA and LHC
Charmonia hadro- and photo-production are analyzed in the framework of the
color-octet model taking into account higher-order effects induced by
initial-state radiation of gluons. We argue that color-octet matrix elements
obtained from Tevatron data might be reconciled with those extracted from HERA
data on inelastic photoproduction. Finally we estimate cross sections
for events with muons from prompt 's as a background for the B physics
programme at LHC experiments.Comment: LaTeX, 4 pages, 2 EPS figures, presented at III Int. Conf. Hyperons,
Charm and Beauty Hadrons, Genova (Italy), June 30 - July 3, 199
ChemInform Abstract: Addition of NOCl to Cyclic Vinylsilanes: An Unexpected Reversal of Regiochemistry.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option
Recent developments in the characterization of superconducting films by microwaves
We describe and analyze selected surface impedance data recently obtained by
different groups on cuprate, ruthenate and diboride superconducting films on
metallic and dielectric substrates for fundamental studies and microwave
applications. The discussion includes a first review of microwave data on MgB2,
the weak-link behaviour of RABiTS-type YBa2Cu3O7-d tapes, and the observation
of a strong anomalous power-dependence of the microwave losses in MgO at low
temperatures. We demonstrate how microwave measurements can be used to
investigate electronic, magnetic, and dielectric dissipation and relaxation in
the films and substrates. The impact of such studies reaches from the
extraction of microscopic information to the engineering of materials and
further on to applications in power systems and communication technology.Comment: Invited contribution to EUCAS2001, accepted for publication in
Physica C in its present for
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