633 research outputs found
Atomic Parity Non-Conservation, Neutron Radii, and Effective Field Theories of Nuclei
Accurately calibrated effective field theories are used to compute atomic
parity non-conserving (APNC) observables. Although accurately calibrated, these
effective field theories predict a large spread in the neutron skin of heavy
nuclei. While the neutron skin is strongly correlated to a large number of
physical observables, in this contribution we focus on its impact on new
physics through APNC observables. The addition of an isoscalar-isovector
coupling constant to the effective Lagrangian generates a wide range of values
for the neutron skin of heavy nuclei without compromising the success of the
model in reproducing well constrained nuclear observables. Earlier studies have
suggested that the use of isotopic ratios of APNC observables may eliminate
their sensitivity to atomic structure. This leaves nuclear structure
uncertainties as the main impediment for identifying physics beyond the
standard model. We establish that uncertainties in the neutron skin of heavy
nuclei are at present too large to measure isotopic ratios to better than the
0.1% accuracy required to test the standard model. However, we argue that such
uncertainties will be significantly reduced by the upcoming measurement of the
neutron radius in 208Pb at the Jefferson Laboratory.Comment: 24 pages, 6 figures, revtex4; one figure adde
Superheavy nuclei in relativistic effective Lagrangian model
Isotopic and isotonic chains of superheavy nuclei are analyzed to search for
spherical double shell closures beyond Z=82 and N=126 within the new effective
field theory model of Furnstahl, Serot, and Tang for the relativistic nuclear
many-body problem. We take into account several indicators to identify the
occurrence of possible shell closures, such as two-nucleon separation energies,
two-nucleon shell gaps, average pairing gaps, and the shell correction energy.
The effective Lagrangian model predicts N=172 and Z=120 and N=258 and Z=120 as
spherical doubly magic superheavy nuclei, whereas N=184 and Z=114 show some
magic character depending on the parameter set. The magicity of a particular
neutron (proton) number in the analyzed mass region is found to depend on the
number of protons (neutrons) present in the nucleus.Comment: 26 pages, REVTeX, 10 ps figures; changed conten
Superheavy nuclei in relativistic effective Lagrangian model
Isotopic and isotonic chains of superheavy nuclei are analyzed to search for
spherical double shell closures beyond Z=82 and N=126 within the new effective
field theory model of Furnstahl, Serot, and Tang for the relativistic nuclear
many-body problem. We take into account several indicators to identify the
occurrence of possible shell closures, such as two-nucleon separation energies,
two-nucleon shell gaps, average pairing gaps, and the shell correction energy.
The effective Lagrangian model predicts N=172 and Z=120 and N=258 and Z=120 as
spherical doubly magic superheavy nuclei, whereas N=184 and Z=114 show some
magic character depending on the parameter set. The magicity of a particular
neutron (proton) number in the analyzed mass region is found to depend on the
number of protons (neutrons) present in the nucleus.Comment: 26 pages, REVTeX, 10 ps figures; changed conten
Energy dissipation in wave propagation in general relativistic plasma
Based on a recent communication by the present authors the question of energy
dissipation in magneto hydrodynamical waves in an inflating background in
general relativity is examined. It is found that the expanding background
introduces a sort of dragging force on the propagating wave such that unlike
the Newtonnian case energy gets dissipated as it progresses. This loss in
energy having no special relativistic analogue is, however, not mechanical in
nature as in elastic wave. It is also found that the energy loss is model
dependent and also depends on the number of dimensions.Comment: 12 page
Topical delivery of niacinamide: influence of neat solvents
Niacinamide (NIA) has been widely used in cosmetic and personal care formulations for several skin conditions. Permeation of topical NIA has been confirmed in a number of studies under infinite dose conditions. However, there is limited information in the literature regarding permeation of NIA following application of topical formulations in amounts that reflect the real-life use of such products by consumers. The aim of the present work was therefore to investigate skin delivery of NIA from single solvent systems in porcine skin under finite dose conditions. A secondary aim was to probe the processes underlying the previously reported low recovery of NIA following in vitro permeation and mass balance studies. The solubility and stability of NIA in various single solvent systems was examined. The solvents investigated included Transcutol® P (TC), propylene glycol (PG), 1-2 hexanediol (HEX), 1-2 pentanediol (1-2P), 1-5 pentanediol (1-5P), 1-3 butanediol (1-3B), glycerol (GLY) and dimethyl isosorbide (DMI). Skin permeation and deposition of the molecule was investigated in full thickness porcine skin in vitro finite dose Franz-type diffusion experiments followed by mass balance studies. Stability of NIA for 72 h in the solvents was confirmed. The solubility of NIA in the solvents ranged from 82.9 ± 0.8 to 311.9 ± 4.5 mg/mL. TC delivered the highest percentage permeation of NIA at 24 h, 32.6 ± 12.1 % of the applied dose. Low total recovery of NIA after mass balance studies was observed for some vehicles, with values ranging from 55.2 ± 12.8 % to 106.3 ± 2.3 %. This reflected the formation of a number of NIA degradation by-products in the receptor phase during the permeation studies. Identification of other vehicles for synergistic enhancement of NIA skin delivery will be the subject of future work
On the role of a new type of correlated disorder in extended electronic states in the Thue-Morse lattice
A new type of correlated disorder is shown to be responsible for the
appearance of extended electronic states in one-dimensional aperiodic systems
like the Thue-Morse lattice. Our analysis leads to an understanding of the
underlying reason for the extended states in this system, for which only
numerical evidence is available in the literature so far. The present work also
sheds light on the restrictive conditions under which the extended states are
supported by this lattice.Comment: 11 pages, LaTeX V2.09, 1 figure (available on request), to appear in
Physical Review Letter
Sistema reprodutivo do cupuaçuzeiro (Theobroma grandiflorum) - alguns aspectos da morfologia floral.
Nuclei in Strongly Magnetised Neutron Star Crusts
We discuss the ground state properties of matter in outer and inner crusts of
neutron stars under the influence of strong magnetic fields. In particular, we
demonstrate the effects of Landau quantization of electrons on compositions of
neutron star crusts. First we revisit the sequence of nuclei and the equation
of state of the outer crust adopting the Baym, Pethick and Sutherland (BPS)
model in the presence of strong magnetic fields and most recent versions of the
theoretical and experimental nuclear mass tables. Next we deal with nuclei in
the inner crust. Nuclei which are arranged in a lattice, are immersed in a
nucleonic gas as well as a uniform background of electrons in the inner crust.
The Wigner-Seitz approximation is adopted in this calculation and each lattice
volume is replaced by a spherical cell. The coexistence of two phases of
nuclear matter - liquid and gas, is considered in this case. We obtain the
equilibrium nucleus corresponding to each baryon density by minimizing the free
energy of the cell. We perform this calculation using Skyrme nucleon-nucleon
interaction with different parameter sets. We find nuclei with larger mass and
charge numbers in the inner crust in the presence of strong magnetic fields
than those of the zero field case for all nucleon-nucleon interactions
considered here. However, SLy4 interaction has dramatic effects on the proton
fraction as well as masses and charges of nuclei. This may be attributed to the
behaviour of symmetry energy with density in the sub-saturation density regime.
Further we discuss the implications of our results to shear mode oscillations
of magnetars.Comment: presented in "Exciting Physics Symposium" held in Makutsi, South
Africa in November, 2011 and to be published in a book by Springer Verla
Pentoxifylline Plus Prednisolone versus Pentoxifylline Only for Severe Alcoholic Hepatitis: A Randomized Controlled Clinical Trial
Background: Prednisolone and pentoxifylline (PTX) have been shown to be individually useful in severe alcoholic hepatitis with Maddrey discriminant function (MDF) score .32. Previous report suggests that PTX is probably superior to prednisolone alone. However the efficacy of PTX and prednisolone combination over PTX alone in the management of acute alcoholic hepatitis (MDF score ≥32) is yet unrevealed.Aim: The present study was initiated to find out the efficacy of combined pentoxifylline and prednisolone versus PTX alone in acute alcoholic hepatitis in respect of short and intermediate term outcomes.Subjects and Methods: A total of 124 patients with severe alcoholic hepatitis (MDF score ≥32) initially were evaluated. 62 patients who fulfilled the inclusion and exclusion criteria were randomized and divided into 2 groups. Group 1 received PTX only, whereas Group 2 received PTX plus Prednisolone. The total duration of follow-up was 12 months. Studentfs t-test, Chi-square test, the Kaplan-Meier methods were used forstatistical analysis. Results: A total of 60 patients, 30 in each group were available for finalanalysis. In Group-1, 6 patients expired at the end of 1 year (5 within 3 months and another after 3 months). In Group 2, 10 patients expired at the end of 1 year (9 within 3 months and another after 3 months). Though survival probability is higher among Group 1 patients but the difference is not statistically significant.Conclusion: The combination of PTX plus Prednisolone yields no additional benefit in terms of mortality and morbidity from that of PTX monotherapy.Keywords: Alcoholic hepatitis, Maddrey discriminant function score, Pentoxifylline, Prednisolon
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