215 research outputs found
Early observations of the Afterglow of GRB000301c
We report multiband observations of the Optical Transient (OT) associated
with GRB000301c carried out between 2--4 March 2000 using the 2.34-m Vainu
Bappu Telescope (VBT) at Kavalur, India. When combined with other reported
data, the initial decline in the R-band magnitude with log (), the time
since the burst is fit with a slope = -0.70 0.07 which
steepens after about 6.0 days to a slope of = -2.44 0.29.
This change in slope does not occur smoothly but there is an indication for a
bimodal distribution. The available measurements of the evolution of (B--R)
color do not show any discernible evolution in the first 12 days.Comment: 14 pages, 2 postscript figures, Accepted for Publication in ApJ
Letter
Narrow band photometry of selected asteroids
The CCD photometry of selected asteroids was carried out to check for possible cometary activity in them. To distinguish the asteroids with possible cometary activity from those of the main belt, each object of interest was observed in two filters; one centered on the C2 emission band at 5140A (90A bandpass) and the other centered on the nearby continuum at 4845A (65A bandpass). None of the observed asteroids appear to have any C2 emission
Variational Monte Carlo and Configurational Interaction Studies of and its Fragments
The molecule and its fragments are studied using Configuration
Interaction (CI) and Variational Monte Carlo (VMC) techniques, within the
Hubbard model. Using benzene as a test case, we compare the results of the
approximate calculations with exact calculations. The fragments of
studied are pyracylene, fluoranthene and corannulene. The energies, bond
orders, spin-spin and charge-correlation functions of these systems are
obtained for various values of the Hubbard parameter, . The analysis of bond
orders and correlation functions of these individual molecules allow us to
visualise pyracylene as a naphthalene unit with two ethylenic moieties and
fluoranthene as weakly bridged benzene and naphthalene units. Corannulene is
the largest fragment of that we have studied. The hexagon-hexagon(h-h)
bond orders are slightly larger than those of the hexagon-pentagon bonds(h-p),
a feature also found in other fragments. We also find bonds between two
co-ordinated carbon sites to be stronger than bonds involving three coordinated
carbon sites. In , the h-h bonds are stronger than in corannulene and
the h-p bonds weaker than in corannulene for all correlation strengths.
Introducing bond alternation in the buckyball enhances this difference.Comment: 42 pages, 5 figures available on request, to appear in J. Phys. Che
On the Clustering of GRBs on the Sky
The two-point correlation of the 4th (current) BATSE catalog (2494 objects)
is calculated. It is shown to be consistent with zero at nearly all angular
scales of interest. Assuming that GRBs trace the large scale structure in the
universe we calculate the angular correlation function for the standard CDM
(sCDM) model. It is shown to be at if the
BATSE catalog is assumed to be a volume-limited sample up to .
Combined with the error analysis on the BATSE catalog this suggests that nearly
GRBs will be needed to make a positive detection of the two-point
angular correlation function at this angular scale.Comment: 5 pages, Latex with aipproc.sty, incl. 1 ps-Fig., Proc. of the 5th
Huntsville Gamma Ray Burst Symposium, Oct. 1999, ed. R.M. Kippen, AI
Luminosity Function of GRBs
We attempt to constrain the luminosity function of Gamma Ray Bursts (GRBs) from the observed number count--flux relation and the afterglow redshift data. We assume three classes of luminosity functions for our analysis: (a) Log-normal distribution, (b) Schechter distribution, and (c) Scale-free distribution. We assume several models of the evolution of the GRB population for each luminosity function. Our analysis shows that: (a) log-normal is the only luminosity function that is compatible with both the observations. This result is independent of the GRB evolution model, (b) for log-normal function, the average photon luminosity and the width of the luminosity function that are compatible with both the observations fall in the range: 10^{55} sec^{-1} \la L_0 \la 10^{56} sec^{-1} and 2 \la \sigma \la 3, (c) the agreement of observations with other luminosity functions requires the GRB population to evolve more strongly than the evolution of the star-formation rate of the universe
A statistical analysis of corpus based approach on learning sentence patterns
This research paper examines the adverse effect of theoretical explanation of the grammatical rules among the learners. Exploration of the methods and materials taught inductively or deductively is the panacea to achieve the required goal. The study throws light on the pedagogical implication of adopting appropriate methods and materials for building the learners’ grammar and language. It primarily intends to explore a new teaching method using language corpora that can be employed in the English grammar classes in colleges at the undergraduate level. It strives to evaluate the effectiveness of teaching sentence patterns through corpus based activities comparing with the traditional based teaching. Thus the methodology aims to encourage students to become independent corpus users
Complete Genome Sequence of Soil Fungus Aspergillus terreus (KM017963), a Potent Lovastatin Producer
We report the complete genome of Aspergillus terreus (KM017963), a tropical soil isolate. The genome sequence is 29 Mb, with a G+C content of 51.12%. The genome sequence of A. terreus shows the presence of the complete gene cluster responsible for lovastatin (an anti-cholesterol drug) production in a single scaffold (1.16)
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