13,891 research outputs found
Nuclei Near and Far From β-Stability Line
Proton to neutron ratio around β-stability line presents an open challenge to the nuclear physicists. The prominent milestone in this regard is the discovery of the super heavy elements, nuclear halos in the lightest neutron-rich nuclei, experimental mapping of the nuclear shell structure near and far from stability. In this present paper, the behavior of the p- and n- halo nuclei near the β-stability line are discussed considering the variation of radius with respect to the mass number and N~Z for different nuclei. Our aim is to study the nuclear properties through neutron and proton skin. The isospin symmetry breaking is for heavy halo nuclei of strong interest
Near real-time determination of earthquake source parameters for tsunami early warning from geodetic observations
Exemplifying the tsunami source immediately after an earthquake is the most critical component of tsunami early warning, as not every earthquake generates a tsunami. After a major under sea earthquake, it is very important to determine whether or not it has actually triggered the deadly wave. The near real-time observations from near field networks such as strong motion and Global Positioning System (GPS) allows rapid determination of fault geometry. Here we present a complete processing chain of Indian Tsunami Early Warning System (ITEWS), starting from acquisition of geodetic raw data, processing, inversion and simulating the situation as it would be at warning center during any major earthquake. We determine the earthquake moment magnitude and generate the centroid moment tensor solution using a novel approach which are the key elements for tsunami early warning. Though the well established seismic monitoring network, numerical modeling and dissemination system are currently capable to provide tsunami warnings to most of the countries in and around the Indian Ocean, the study highlights the critical role of geodetic observations in determination of tsunami source for high-quality forecasting
Color Octet Contribution to High p_T J/\Psi Production in pp Collisions at \sqrt s = 500 and 200 GeV at RHIC
We compute \frac{d\sigma}{dp_T} of the J/\psi production in pp collisions at
RHIC at \sqrt s = 500 and 200 GeV by using both the color octet and singlet
models in the framework of non-relativistic QCD. The J/\psi we compute here
includes the direct J/\psi from the partonic fusion processes and the J/\psi
coming from the radiative decays of \chi_J's both in the color octet and
singlet channel. The high p_T J/\psi production cross section is computed
within the PHENIX detector acceptance ranges: -0.35 < \eta < 0.35 and 1.2 <
\|\eta| < 2.4, the central electron and forward muon arms. It is found that the
color octet contribution to J/\psi production is dominant at RHIC energy in
comparison to the color singlet contributions. We compare our results with the
recent preliminary data obtained by PHENIX detector for the high p_T J/\psi
measurements. While the color singlet model fails to explain the data
completely the color octet model is in agreement with the single data point
above 2 GeV transverse momentum. A measurement of J/\psi production at RHIC in
the next run with better statistics will allow us to determine the validity of
the color octet model of J/\psi production at RHIC energies. This is very
important because it is necessary to know the exact mechanism for J/\psi
production in pp collisions at RHIC if one is to make predictions of J/\psi
suppression as a signature of quark-gluon plasma. These mechanisms also play an
important role in determining the polarized spin structure function of the
proton at RHIC.Comment: 16 pages latex, 6 figure
Separation energies of light nuclei with atomic number from 1 to 20
The 1n and 1p halo nuclei from atomic number 1 to 20 are discussed here to calculate the variation of separation energy with mass defect and binding energy. Semi-empirical mass formula and shell model are the methods applied here. The appearances of p- and r-branches satisfying the selection rules for different isotopes of nuclides are discussed
General Form of the Color Potential Produced by Color Charges of the Quark
Constant electric charge satisfies the continuity equation where is the current density of the electron.
However, the Yang-Mills color current density of the quark
satisfies the equation which is not a continuity
equation () which implies that a color charge
of the quark is not constant but it is time dependent where
are color indices. In this paper we derive general form of color
potential produced by color charges of the quark. We find that the general form
of the color potential produced by the color charges of the quark at rest is
given by \Phi^a(x) =A_0^a(t,{\bf x}) =\frac{q^b(t-\frac{r}{c})}{r}\[\frac{{\rm
exp}[g\int dr \frac{Q(t-\frac{r}{c})}{r}] -1}{g \int dr
\frac{Q(t-\frac{r}{c})}{r}}\]_{ab} where integration is an indefinite
integration, ~~ , ~~, ~~ is the retarded time, ~~ is the speed
of light, ~~ is the position of the quark at the retarded
time and the repeated color indices (=1,2,...8) are summed. For constant
color charge we reproduce the Coulomb-like potential
which is consistent with the Maxwell theory where
constant electric charge produces the Coulomb potential
.Comment: Final version, two more sections added, 45 pages latex, accepted for
publication in JHE
Gyroscopic Precession and Inertial Forces in Axially Symmetric Stationary Spacetimes
We study the phenomenon of gyroscopic precession and the analogues of
inertial forces within the framework of general relativity. Covariant
connections between the two are established for circular orbits in stationary
spacetimes with axial symmetry. Specializing to static spacetimes, we prove
that gyroscopic precession and centrifugal force both reverse at the photon
orbits. Simultaneous non-reversal of these in the case of stationary spacetimes
is discussed. Further insight is gained in the case of static spacetime by
considering the phenomena in a spacetime conformal to the original one.
Gravi-electric and gravi-magnetic fields are studied and their relation to
inertial forces is established.Comment: 21 pages, latex, no figures, http://202.41.67.76/~nayak/gpifass.te
First determination of the content of and updated determination of the contents of and
Quantum-correlated decays collected by the CLEO-c
experiment are used to perform a first measurement of , the
fractional -even content of the self-conjugate decay , obtaining a value of . An important
input to the measurement comes from the use of
and decays to tag the signal mode. This same
technique is applied to the channels and , yielding and
, where the first uncertainty is
statistical and the second systematic. These measurements are consistent with
those of an earlier analysis, based on -eigenstate tags, and can be
combined to give values of and
. The results will enable the three modes to
be included in a model-independent manner in measurements of the unitarity
triangle angle using decays, and in time-dependent
studies of violation and mixing in the system.Comment: Minor revisions following journal acceptanc
Analysis of cytology of germ cell tumors with histopathological and serum tumor marker correlation: a tertiary care centre experience
Background: Germ cell tumors are found primarily in children and young adults usually arising from gonads and rarely from extragonadal sites like mediastinum, retroperitoneum, pineal gland and sacrococcygeal region. Involvement of lymphnodes or bodycavities (pleural/peritoneal cavity) is usually associated with metastatic disease.Methods: This is a retrospective analysis of 96 cases of germ cell tumor for which a primary diagnosis of germ cell tumor was given by cytology from primary and metastatic sites. The study period is from January 1993- December 2013. Pap stained and Romanowsky stained smears and cell block sections (10cases) were studied. Serum tumor markers (LDH, BetaHCG and AFP) were correlated in all cases along with histopathology in available cases.Results: Among 96 cases 34 were diagnosed as seminoma/dysgerminoma,10 as embryonal carcinoma,9 as yolk sac tumor,6 as teratoma and 2 as mixed germ ell tumor. In 25 cases the cytology report was suggestive of germ cell tumor and in 10 cases malignant cells favouring germ cell tumor. Among the 10 cases the serum markers were high in six of the cases and the clinician after discussing with the pathologist treated them as germ cell tumors. 47 cases had histopathology and it correlated with cytology except in 14 cases which showed no residual neoplasm after chemotherapy. 15 cases expired immediately after the diagnosis or during the course of treatment 12cases were lost to follow up. Rest of the cases have completed the treatment. In our study the serum tumor markers showed a sensitivity of 92.75% and positive predictive value was 71.11%.Conclusions: The study highlights the importance of picking up the diagnosis of germ cell tumors by fine needle aspiration cytology so that patient can get an early diagnosis, effective treatment and a multidisciplinary approach is essential in diagnosing a difficult case of germ cell tumor. Previous history, radiology, clinical features and serum tumor markers all aid in the cytological diagnosis of germ cell tumor
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