Kinetic Theory of Collective Modes in Atomic Clouds above the Bose-Einstein Transition Temperature

We calculate frequencies and damping rates of the lowest collective modes of a dilute Bose gas confined in an anisotropic trapping potential above the Bose-Einstein transition temperature. From the Boltzmann equation with a simplified collision integral we derive a general dispersion relation that interpolates between the collisionless and hydrodynamic regimes. In the case of axially symmetric traps we obtain explicit expressions for the frequencies and damping rates of the lowest modes in terms of a phenomenological collision time. Our results are compared with microscopic calculations and experiments.Comment: Nordita preprint NORDITA-1999/46 C

Wet chemical etching mechanism of silicon

We review what can be said on wet chemical etching of single crystals from the viewpoint of the science of crystal growth. Starting point is that there are smooth and rough crystal surfaces. The kinetics of smooth faces is controlled by a nucleation barrier that is absent on rough faces. The latter therefore etch faster by orders of magnitude. The analysis of the diamond crystal structure reveals that the {111} face is the only smooth face in this lattice-other faces might be smooth only because of surface reconstruction. In this way we explain the minimum of the etch rate in KOH:H2O in the <001> direction. Two critical predictions concerning the shape of the minimum of the etch rate close to <001> and the transition from isotropic to anisotropic etching in HF:HNO3 based solutions are tested experimentally. The results are in-agreement with the theor

Avian embryonic development in hyperdynamic environments

Embryos which developed for 24 hours in the oviduct of hens maintained at 2 G and which were subsequently incubated at Earth gravity had a 14% reduction in hatchability. Increased mortality during the first 4 days, and an increase in embryonic abnormalities were of the types usually found during the first mortality peak (2-3 days). Embryos in eggs that were produced at Earth gravity and continued their development on the centrifuge at fields of 2 G or less did not appear to be greatly affected by the treatment. At 4 G, 91% of the embryos died, mostly on the first and second days of incubation. Abnormalities prominent in the centrifuged eggs include: (a) a failure of the primitive streak to develop; (b) interference with the development of the axial skeleton; (c) multiple hemorrhages, mostly petechial which is consistent with capillary fragility; and (d) retardation of embryo growth, possibly caused by an interference with gaseous diffusion, the result of an acceleration-induced increase in gas density in the centrifuging incubator

Protection of pigs against challenge with virulent <i>Streptococcus suis</i> serotype 2 strains by a muramidase-released protein and extracellular factor vaccine

The efficacy of a muramidase-released protein (MRP) and extracellular factor (EF) vaccine in preventing infection and disease in pigs challenged either with a homologous or a heterologous Streptococcus suis serotype 2 strain (MRP EF ) was compared with the efficacy of a vaccine containing formalin-killed bacterin of S suis serotype 2 (MRP EF ). The enhancement of the immune response by different adjuvants (a water-in-oil emulsion [wo] and an aluminium hydroxide-based adjuvant [AH]) and their side effects were also studied. The MRP and EF were purified by affinity chromatography. Pigs were vaccinated twice at three weeks and six weeks of age and challenged intravenously with virulent S suis serotype 2 strains (MRP EF ) at eight weeks of age. At challenge, the pigs vaccinated with MRP EF/WO had high anti-MRP and anti-EF titres and were protected as effectively as pigs vaccinated with wo-formulated vaccines with bacterin. Eight of the nine pigs survived the challenge and almost no clinical signs of disease were observed. The titres obtained with the MRP EF/AH vaccine were low and only two of the five pigs were protected. Pigs vaccinated with either MRP or EF were less well protected; three of the four pigs died after challenge but the clinical signs of disease were significantly less severe than those observed in the placebo-vaccinated pigs. The protective capacity of the bacterin/AH vaccine was very low, and the mortality among these pigs was as high as in the placebo-vaccinated pigs (80 per cent). Postmortem histological examination revealed meningitis, polyserositis and arthritis in the clinically affected pigs. The results demonstrate that a subunit vaccine containing both MRP and EF, formulated with the wo adjuvant, protected pigs against challenge with virulent S suis type 2 strains

The Impact of Treatment of Organic Manures on Future Soil Carbon Sequestration Under Different Tillage Systems in Pakistan

Funds provided by Higher Education Commission (HEC) of Pakistan for carrying out this Ph.D. research work under “Indigenous 5000 Fellowship Program” and “International Research Support Initiative Program” are highly acknowledged.Peer reviewedPublisher PD

Effect of individual-level and socioeconomic factors on long-term survival after cataract surgery over a 30-year period

Purpose: To evaluate survival and the risk for mortality after cataract surgery in relation to individual-level and socioeconomic factors in Scotland over 3 decades. Setting: Linked healthcare data, United Kingdom. Design: Representative population-based study. Methods: A 5% random sample of Scottish decedents linked to hospital records (1981 to 2012) was assessed. Survival time, survival probability, and determinants of mortality were evaluated after the first and second recorded hospital episodes for cataract surgery. Cox proportional-hazards regression models were used to assess the effect of individual-level and socioeconomic factors including age, geographic location, socioeconomic status, and comorbidity on mortality. Results: The study evaluated linked administrative healthcare data from 9228 deceased patients who had cataract surgery. The mean survival time was 2383 days ± 1853 (SD). The survival probability decreased from 98% 90 days after surgery to 22% at 10 years, 2% at 20 years, and 0% after 30 years. The mean age was 77 ± 9 years. Age (hazard ratio [HR] 3.66; 95% confidence interval [CI], 2.97-3.80; P &#60; .001) and severe comorbidity (HR 1.68; 95% CI, 1.47-1.91; P &#60; .001) were associated with an increased risk for mortality; women had a 20% lower risk than men (HR 0.80; 95% CI, 0.76-0.83; P &#60; .001). Socioeconomic status and rural geographic locations were not linked to mortality. Conclusions: Long-term survival after cataract surgery was determined by individual-level characteristics reflecting the mortality patterns of aging populations. The mortality risk was independent of socioeconomic and geographic factors per se

Household energy and recycling of nutrients and carbon to the soil in integrated crop-livestock farming systems : a case study in Kumbursa village, Central Highlands of Ethiopia

Acknowledgements We are grateful to the farmers of Kumbursa village for their wholehearted cooperation in providing genuine responses to interview questions during the household survey. We are also thankful to the Development Agent of Kumbursa village, Mr Dinku Chala, for facilitating our relations with farmers of the study area and for participating in data collection. We are indebted to Addis Ababa University and AUC funded Afri-Flame project (Adaptation of small-scale biogas digesters for use in rural households in Sub-Saharan Africa) for their joint financial support. Our heartfelt gratitude also goes to the staff of Debre Zeit Agricultural Research Center for their cooperation in nutrient content analysis of crop residues and dung cakes. Finally, we owe our heartfelt indebtedness to the two anonymous reviewers for their constructive comments which greatly contributed to the improvement and final refinement of this paperPeer reviewedPublisher PD

Star Formation and the Interstellar Medium In Nearby Tidal Streams (SAINTS): Spitzer Mid-infrared Spectroscopy and Imaging of Intergalactic Star-forming Objects

A spectroscopic analysis of 10 intergalactic star forming objects (ISFOs) and a photometric analysis of 67 ISFOs in a sample of 14 interacting systems is presented. The majority of the ISFOs have relative polycyclic aromatic hydrocarbon (PAH) band strengths similar to those of nearby spiral and starburst galaxies. In contrast to what is observed in blue compact dwarfs (BCDs) and local giant HII regions in the Milky Way (NGC 3603) and the Magellanic Clouds (30 Doradus and N 66), the relative PAH band strengths in ISFOs correspond to models with a significant PAH ion fraction (<50%) and bright emission from large PAHs (~100 carbon atoms). The [NeIII]/[NeII] and [SIV]/[SIII] line flux ratios indicate moderate levels of excitation with an interstellar radiation field that is harder than the majority of the Spitzer Infrared Nearby Galaxies Survey and starburst galaxies, but softer than BCDs and local giant HII regions. The ISFO neon line flux ratios are consistent with a burst of star formation < 6 million years ago. Most of the ISFOs have ~million solar masses of warm molecular hydrogen with a likely origin in photo-dissociation regions (PDRs). Infrared Array Camera photometry shows the ISFOs to be bright at 8 um, with one third having [4.5] - [8.0] > 3.7, i.e., enhanced non-stellar emission, most likely due to PAHs, relative to normal spirals, dwarf irregulars and BCD galaxies. The relative strength of the 8 um emission compared to that at 3.6 um or 24 um separates ISFOs from dwarf galaxies in Spitzer two color diagrams. The infrared power in two thirds of the ISFOs is dominated by emission from grains in a diffuse interstellar medium. One in six ISFOs have significant emission from PDRs, contributing ~30 % - 60 % of the total power. ISFOs are young knots of intense star formation.Comment: Accepted in ApJ. 49 pages 9 figure

Nasal Drug Delivery Systems: An Overview

Since ancient times, drugs have been administered via the nasal route for therapeutic and recreational purposes. The interest in, and importance, of the systemic effects of drugs administered through the nasal route, have expanded over recent decades. Intra-nasal administration of drugs offers an interesting alternative for achieving systemic therapeutic effects of drugs that are comparable to the parenteral route, which can be inconvenient at times or oral administration, which can result in unacceptably low drug bioavailability. So, it is important to understand the potential and limitations of various nasal drug delivery systems. Therefore, the aim of this review article is to discuss the various pharmaceutical dosage forms that have the potential to be utilised for local or systemic drug administration. It is intuitively expected that this review will help to understand and further to develop suitable intra-nasal formulations to achieve specific therapeutic objectives