17 research outputs found
SU(4) Chiral Quark Model with Configuration Mixing
Chiral quark model with configuration mixing and broken SU(3)\times U(1)
symmetry has been extended to include the contribution from c\bar c
fluctuations by considering broken SU(4) instead of SU(3). The implications of
such a model have been studied for quark flavor and spin distribution functions
corresponding to E866 and the NMC data. The predicted parameters regarding the
charm spin distribution functions, for example, \Delta c, \frac{\Delta
c}{{\Delta \Sigma}}, \frac{\Delta c}{c} as well as the charm quark distribution
functions, for example, \bar c, \frac{2\bar c}{(\bar u+\bar d)}, \frac{2 \bar
c}{(u+d)} and \frac{(c+ \bar c)}{\sum (q+\bar q)} are in agreement with other
similar calculations. Specifically, we find \Delta c=-0.009, \frac{\Delta
c}{{\Delta \Sigma}}=-0.02, \bar c=0.03 and \frac{(c+ \bar c)}{\sum (q+\bar
q)}=0.02 for the \chiQM parameters a=0.1, \alpha=0.4, \beta=0.7,
\zeta_{E866}=-1-2 \beta, \zeta_{NMC}=-2-2 \beta and \gamma=0.3, the latter
appears due to the extension of SU(3) to SU(4).Comment: 10 RevTeX pages. Accepted for publication in Phys. Rev.
Pancreatic involvement in fatal human leptospirosis: clinical and histopathological features
dependence of the quark distribution functions in the CQM
Chiral constituent quark model with configuration mixing (\chiCQM_{{\rm
config}}) is known to provide a satisfactory explanation of the ``proton spin
problem'' and related issues. In order to enlarge the scope of \chiCQM_{{\rm
config}}, we have attempted to phenomenologically incorporate x-dependence in
the quark distribution functions. In particular, apart from calculating valence
and sea quark distributions q_{{\rm val}}(x) and \bar q(x), we have carried out
a detailed analysis to estimate the sea quark asymmetries \bar d(x)-\bar u(x),
\bar d(x)/\bar u(x) and \frac{\bar d(x)-\bar u(x)}{u(x)-d(x)} as well as spin
independent structure functions F_2^p(x)-F_2^n(x) and as
functions of . We are able to achieve a satisfactory fit for all the above
mentioned quantities simultaneously. The inclusion of effects due to
configuration mixing have also been examined in the case F_2^p(x)-F_2^n(x) and
F_2^n(x)/F_2^p(x) where the valence quark distributions dominate and it is
found that it leads to considerable improvement in the results. Further, the
valence quark structure has also be tested by extrapolating the predictions of
our model in the limit x \to 1 where data is not available.Comment: 20 pages, 7 figures. To appear in Eur. Phys. J.
GWAS of thyroid stimulating hormone highlights pleiotropic effects and inverse association with thyroid cancer
Thyroid stimulating hormone (TSH) is critical for normal development and metabolism. To better understand the genetic contribution to TSH levels, we conduct a GWAS meta-analysis at 22.4 million genetic markers in up to 119,715 individuals and identify 74 genome-wide significant loci for TSH, of which 28 are previously unreported. Functional experiments show that the thyroglobulin protein-altering variants P118L and G67S impact thyroglobulin secretion. Phenome-wide association analysis in the UK Biobank demonstrates the pleiotropic effects of TSH-associated variants and a polygenic score for higher TSH levels is associated with a reduced risk of thyroid cancer in the UK Biobank and three other independent studies. Two-sample Mendelian randomization using TSH index variants as instrumental variables suggests a protective effect of higher TSH levels (indicating lower thyroid function) on risk of thyroid cancer and goiter. Our findings highlight the pleiotropic effects of TSH-associated variants on thyroid function and growth of malignant and benign thyroid tumors
PRESSURE DROP IN FIXED, EXPANDED AND FLUIDIZED BEDS, PACKED COLUMNS AND STATIC MIXERS - A UNIFIED APPROACH
Competing asymmetric fusion-fission and quasifission in neutron-deficient sub-lead nuclei
International audienceTo disentangle the role of shell effects and dynamics, fission fragment mass distributions of 191 Au, a nucleus in the newly identified island of mass asymmetric fission in the sub-lead region, have been measured down to excitation energy of ≈20 MeV above the fission barrier via two different entrance channels, viz. 16 O+ 175 Lu and 37 Cl+ 154 Sm reactions. Apart from having signature of the shell effects in both the cases, clear experimental evidence of quasifission has been observed in the mass distributions of the Cl induced reaction, that has also been substantiated by the theoretical calculations. This crucial evidence along with a systematic analysis of the available experimental data has revealed that the dynamics in the entrance channel has significant influence on most of the reactions used earlier to explore the persistence of recently discovered mass asymmetry in β -delayed fission at low energy in this mass region, ignoring which might lead to ambiguity in interpreting the heavy-ion data
Conclusive evidence of quasifission in heavy-ion induced reactions in neutron-deficient sub-lead nuclei exhibiting asymmetric fission
Fission fragment mass distributions of 191Au, a nucleus in the newly identified island of mass asymmetric fission in the sub-lead region, have been measured down to excitation energy of ~ 20 MeV above the fission barrier via two different entrance channels, viz. 16O+ 175Lu and 37Cl+ 154Sm reactions. Apart from having signature of the shell effects in both the cases, clear evidence of quasi-fission has been observed in the mass distributions of the Cl induced reaction. A systematic analysis of available experimental data reveals that the dynamics in the entrance channel has significant influence on most of the reactions used to study asymmetric fission in this region, ignoring which might lead to ambiguity