Tunneling of a Quantized Vortex: Roles of Pinning and Dissipation

We have performed a theoretical study of the effects of pinning potential and dissipation on vortex tunneling in superconductors. Analytical results are obtained in various limits relevant to experiment. In general we have found that pinning and dissipation tend to suppress the effect of the vortex velocity dependent part of the Magnus force on vortex tunneling.Comment: Latex, 12 page

Response of Growing Pigs to Diet Physical Form and Allzyme® SSF Supplementation in a Palm Kernel Meal-Based Diet

. The increasing cost of conventional feeds calls for the unconventional ones. The effect of Allzyme®SSF and diet physical form on performance, haematological and serum biochemical indices of growing pigs fed with palm kernel meal-based diet was determined. Twenty four growing pigs comprising of twelve male and twelve female weighing 8.95±1.01Kg were assigned into four dietary treatment groups involving dry mash diet, wet mash diet, dry mash diet+ Allzyme®SSF and wet mash diet+ Allzyme®SSF in a completely randomized design. After feeding experiment for six weeks, haematological and serum biochemical parameters were determined. Growth performance was observed on a weekly basis for six consecutive weeks. The results showed that the diet physical form and Allzyme®SSF supplementation in a palm kernel meal-based diet did not significantly affect the haematological and serum biochemical parameters; however weight gain and feed conversion ratio were significantly influenced by the diet physical form and Allzyme®SSF supplementation, thus making dry mash diet + Allzyme®SSF the best dietary treatment. The experiment showed that the diet physical form and Allzyme®SSF supplementation in a palm kernel meal-based diet did not have any negative effect on the growing pigs and growth performance was not hindered; therefore palm kernel meal-based diet in wet or dry mash form with or without Allzyme® SSF supplementation could be fed to growing pigs

Berry's Phase in the Presence of a Stochastically Evolving Environment: A Geometric Mechanism for Energy-Level Broadening

The generic Berry phase scenario in which a two-level system is coupled to a second system whose dynamical coordinate is slowly-varying is generalized to allow for stochastic evolution of the slow system. The stochastic behavior is produced by coupling the slow system to a heat resevoir which is modeled by a bath of harmonic oscillators initially in equilibrium at temperature T, and whose spectral density has a bandwidth which is small compared to the energy-level spacing of the fast system. The well-known energy-level shifts produced by Berry's phase in the fast system, in conjunction with the stochastic motion of the slow system, leads to a broadening of the fast system energy-levels. In the limit of strong damping and sufficiently low temperature, we determine the degree of level-broadening analytically, and show that the slow system dynamics satisfies a Langevin equation in which Lorentz-like and electric-like forces appear as a consequence of geometrical effects. We also determine the average energy-level shift produced in the fast system by this mechanism.Comment: 29 pages, RevTex, submitted to Phys. Rev.

Advances and Limitations of Atmospheric Boundary Layer Observations with GPS Occultation over Southeast Pacific Ocean

The typical atmospheric boundary layer (ABL) over the southeast (SE) Pacific Ocean is featured with a strong temperature inversion and a sharp moisture gradient across the ABL top. The strong moisture and temperature gradients result in a sharp refractivity gradient that can be precisely detected by the Global Positioning System (GPS) radio occultation (RO) measurements. In this paper, the Constellation Observing System for Meteorology, Ionosphere & Climate (COSMIC) GPS RO soundings, radiosondes and the high-resolution ECMWF analysis over the SE Pacific are analyzed. COSMIC RO is able to detect a wide range of ABL height variations (1-2 kilometer) as observed from the radiosondes. However, the ECMWF analysis systematically underestimates the ABL heights. The sharp refractivity gradient at the ABL top frequently exceeds the critical refraction (e.g., 157 N-unit per kilometer) and becomes the so-called ducting condition, which results in a systematic RO refractivity bias (or called N-bias) inside the ABL. Simulation study based on radiosonde profiles reveals the magnitudes of the N-biases are vertical resolution dependent. The N-bias is also the primary cause of the systematically smaller refractivity gradient (rarely exceeding 110 N-unit per kilometer) at the ABL top from RO measurement. However, the N-bias seems not affect the ABL height detection. Instead, the very large RO bending angle and the sharp refractivity gradient due to ducting allow reliable detection of the ABL height from GPS RO. The seasonal mean climatology of ABL heights derived from a nine-month composite of COSMIC RO soundings over the SE Pacific reveals significant differences from the ECMWF analysis. Both show an increase of ABL height from the shallow stratocumulus near the coast to a much higher trade wind inversion further off the coast. However, COSMIC RO shows an overall deeper ABL and reveals different locations of the minimum and maximum ABL heights as compared to the ECMWF analysis. At low latitudes, despite the decreasing number of COSMIC RO soundings and the lower percentage of soundings that penetrate into the lowest 500-m above the mean-sea-level, there are small sampling errors in the mean ABL height climatology. The difference of ABL height climatology between COSMIC RO and ECMWF analysis over SE Pacific is significant and requires further studies

Randomization of two dosing regimens of vaginal misoprostol for cervical ripening and labor induction in a low resource setting

Objectives: To compare the effectiveness of two dosing regimens of vaginal misoprostol for cervical ripening and induction of labour.Materials and Methods: Pregnant women with singleton low risk pregnancy at term scheduled for elective induction of labour were randomized to  receive either 25 µg or 50 µg of vaginal misoprostol for pre.labour  cervical ripening. All the patients received antenatal care and delivered at the University College Hospital (UCH) from January 1st to May 31st 2006. A total of 128 patients were randomized; 65 patients received 25 µg and 63 patients received 50 µg of vaginal misoprostol.Results: Significantly higher number of patients in the 50 µg group   progressed to active labour as compared with the 25 µg group (95.2% versus 84.6%, P < 0.05). The need for oxytocin augmentation of labour was higher among the 25 µg as compared with 50 µg (39.7% versus 16.4%, P = 0.007). There was higher proportion of patients in the 50 µg group delivering vaginally within 24 hours as compared with the 25 µg group (98.2% versus 90.0%, P = 0.063). However, the mean interval between the first dose of misoprostol and vaginal delivery was not  statistically different in the two groups (754 } 362 minutes and 885 } 582 minutes, P = 0.152). The incidence of caesarean section was similar in the two groups (7.7% versus 11%, P = 0.580). Labour complications, such as precipitate labour, tachysystole and abnormal fetal heart rate patterns were greater in the 50 µg group.Conclusion: Twenty.five microgram of misoprostol appears to be as  effective as 50 µg for pre.induction cervical ripening and labour induction. Though 50 µg of vaginal misoprostol resulted in relatively faster delivery and less need for oxytocin augmentation, it was associated with more  labour complications as compared with 25 µg of misoprostol.Key words: Cervical ripening, labour induction, misoprosto

Rotation of electromagnetic fields and the nature of optical angular momentum

The association of spin and orbital angular momenta of light with its polarization and helical phase fronts is now well established. The problems in linking this with electromagnetic theory, as expressed in Maxwell's equations, are rather less well known. We present a simple analysis of the problems involved in defining spin and orbital angular momenta for electromagnetic fields and discuss some of the remaining challenges. Crucial to our investigation is the duplex symmetry between the electric and magnetic fields

Binary Bose-Einstein Condensate Mixtures in Weakly and Strongly Segregated Phases

We perform a mean-field study of the binary Bose-Einstein condensate mixtures as a function of the mutual repulsive interaction strength. In the phase segregated regime, we find that there are two distinct phases: the weakly segregated phase characterized by a `penetration depth' and the strongly segregated phase characterized by a healing length. In the weakly segregated phase the symmetry of the shape of each condensate will not take that of the trap because of the finite surface tension, but its total density profile still does. In the strongly segregated phase even the total density profile takes a different symmetry from that of the trap because of the mutual exclusion of the condensates. The lower critical condensate-atom number to observe the complete phase segregation is discussed. A comparison to recent experimental data suggests that the weakly segregated phase has been observed.Comment: minor change

Microscopic theory of vortex dynamics in homogeneous superconductors

Vortex dynamics in fermionic superfluids is carefully considered from the microscopic point of view. Finite temperatures, as well as impurities, are explicitly incorporated. To enable readers understand the physical implications, macroscopic demonstrations based on thermodynamics and fluctuations- dissipation theorems are constructed. For the first time a clear summary and a critical review of previous results are given.Comment: Presentations are made more straightforward. A detailed presentation that why the vortex friction is finite when the geometric phase exists, as required by referees, though I think it is obviou

Zero-temperature phase diagram of binary boson-fermion mixtures

We calculate the phase diagram for dilute mixtures of bosons and fermions at zero temperature. The linear stability conditions are derived and related to the effective boson-induced interaction between the fermions. We show that in equilibrium there are three possibilities: a) a single uniform phase, b) a purely fermionic phase coexisting with a purely bosonic one and c) a purely fermionic phase coexisting with a mixed phase.Comment: 8 pages, revtex, 3 postscript figures; NORDITA-1999/71 C