2,653 research outputs found
The finite-temperature thermodynamics of a trapped unitary Fermi gas within fractional exclusion statistics
We utilize a fractional exclusion statistics of Haldane and Wu hypothesis to
study the thermodynamics of a unitary Fermi gas trapped in a harmonic
oscillator potential at ultra-low finite temperature. The entropy per particle
as a function of the energy per particle and energy per particle versus
rescaled temperature are numerically compared with the experimental data. The
study shows that, except the chemical potential behavior, there exists a
reasonable consistency between the experimental measurement and theoretical
attempt for the entropy and energy per particle. In the fractional exclusion
statistics formalism, the behavior of the isochore heat capacity for a trapped
unitary Fermi gas is also analyzed.Comment: 6 pages, 6 figure
Haldane Exclusion Statistics and the Boltzmann Equation
We generalize the collision term in the one-dimensional Boltzmann-Nordheim
transport equation for quasiparticles that obey the Haldane exclusion
statistics. For the equilibrium situation, this leads to the ``golden rule''
factor for quantum transitions. As an application of this, we calculate the
density response function of a one-dimensional electron gas in a periodic
potential, assuming that the particle-hole excitations are quasiparticles
obeying the new statistics. We also calculate the relaxation time of a nuclear
spin in a metal using the modified golden rule.Comment: version accepted for publication in J. of Stat. Phy
UDP-glucose 4-epimerase from saccharomyces fragilis. Presence of an essential arginine residue at the substrate-binding site of the enzyme
UDP-glucose 4-epimerase from Saccharomyces fragilis was inactivated by the arginine-specific reagents phenylglyoxal, 1,2-cyclohexanedione, and 2,3-butanedione following pseudo first order reaction kinetics. The reaction order with respect to phenylglyoxal was 1.8 and that with respect to the other two diones was close to unity. Protection afforded by substrate and competitive inhibitors against inactivation by phenylglyoxal and the reduced interaction of 1-anilinonaphthalene 8-sulfonic acid, a fluorescent probe for the substrate-binding region after phenylglyoxal modification, suggested the presence of an essential arginine residue at the substrate-binding region. Experiments with [7-14C]phenylglyoxal in the presence of UMP, a ligand known to interact at the substrate-binding region, showed that only the arginine residue at the active site could be modified by phenylglyoxal. The characteristic coenzyme fluorescence of the yeast enzyme was found to be enhanced three times in phenylglyoxal-inactivated enzyme suggesting the incorporation of the phenyl ring near the pyridine moiety of NAD
Chiral symmetry breaking and stability of quark droplets
We discuss the stability of strangelets -- quark droplets with strangeness --
in the Nambu--Jona-Lasinio model supplemented by a boundary condition for quark
confinement. Effects of dynamical chiral symmetry breaking are considered
properly inside quark droplets of arbitrary baryon number. We obtain the energy
per baryon number of quark droplets with baryon number from one to thousands.
It is shown that strangelets are not the ground states as compared with nuclei,
though they can be locally stable
Collapse/Flattening of Nucleonic Bags in Ultra-Strong Magnetic Field
It is shown explicitly using MIT bag model that in presence of ultra-strong
magnetic fields, a nucleon either flattens or collapses in the direction
transverse to the external magnetic field in the classical or quantum
mechanical picture respectively. Which gives rise to some kind of mechanical
instability. Alternatively, it is argued that the bag model of confinement may
not be applicable in this strange situation.Comment: 8 pages, REVTEX, 3 figures .eps files (included
‘Zero-error’ versus ‘good-enough’: towards a ‘frugality’ narrative for defence procurement policy
The procurement decision-making process for complex military product systems (CoPS) has significant implications for military end-users, suppliers, and exchequers. This study examines the usefulness of adopting a fast and frugal decision-making approach for the acquisition of military CoPS. Defence procurement environment is complex. On the one hand, there are uncertainties and severe resource constraints due to regularly changing threat perceptions, limited flow of information about new technologies, and the growing demand to reduce defence related expenses. On the other hand, several stakeholders remain pre-occupied with the demand for ‘zero-error’ technologies. In such a setting, recurrent cost overruns and delays in supply are common in defence procurement programmes, across countries. Taking the illustrative examples of the missile system, fighter jet, and radar system acquisitions in India, we elucidate on ‘optimising’ versus ‘satisficing’ dynamics in the procurement decisions. The paper argues that a fast and frugal decision-making process by relying on judgement, experiential knowledge, and intuitive learning might make procurement processes, adaptively, more efficient. Such an approach would enable a ‘good enough’ technology to be inducted, and improved upon, through regular feedback from the actual environment. The study has implications for policy scholarships on innovation policy instruments under uncertainty
- …