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Phytoplankton is responsible for most primary production in Antarctica, but the short timescale dynamics of its size structure and composition are poorly described and understood. The abundance and composition of phytoplankton in Fildes Bay, western Antarctic Peninsula, was followed for 12 days during the summer using a range of methods, including size fractionation of chlorophyll, microscopy, flow cytometry and terminal-restriction fragment length polymorphism (T-RFLP) of the plastid 16S rRNA gene. A rapid increase in biomass and cell abundance occurred in response to a vertical mixing event. This increase also resulted in a shift in composition from diatoms to Prymnesiophyceae, and then back to diatoms as the water column re-stratified. Our results show a strong dominance of nanophytoplankton represented by Thalassiosira and Phaeocystis. The rapid response of the phytoplankton suggests that it is well adapted to short-term environmental changes.
In an effort to reduce uncertainties in the theoretical radiative opacities a new code has been developed at LLNL which removes several of the approximation present in past calculations. Results from the new code with comparisons to other available opacity calculations are presented as well as experiments.
Recent ROSAT and EUVE detections of spin-powered neutron stars suggest that many emit ‘thermal’ radiation, peaking in the EUV/soft X-ray band. These data constrain the neutron stars’ thermal history, but interpretation requires comparison with model atmosphere computations, since emergent spectra depend strongly on the surface composition and magnetic field. As recent opacity computations show substantial change to absorption cross sections at neutron star photospheric conditions, we report here on new model atmosphere computations employing such data. The results are compared with magnetic atmosphere models and applied to PSR J0437−4715, a low field neutron star.
Classical Atriopulmonary Fontan connections tend to fail in the long term due to progressive anastomotic site obstruction, right atrial enlargement, and refractory atrial arrhythmias. Conversion to total cavopulmonary connection with concomitant arrhythmia surgery is a promising treatment but optimal timing of the procedure remains controversial.
Between the years 2002 and 2009, 15 patients with a median age of 26.2 (12–43) years underwent Fontan conversion operation with concomitant arrhythmia surgery. All were symptomatic and 14 out of the 15 patients had refractory arrhythmias. The duration of pre-operative arrhythmia and the outcome of surgery were correlated to study the impact of delay in surgical intervention on post-operative survival and arrhythmia control.
There were two patients who died in the early post-operative period (13.3%). At the mid-term follow-up, 53 (20–86) months, late atrial arrhythmias had recurred in two of the 13 surviving patients (15.30%) and one patient developed late sinus node dysfunction. The need for anti-arrhythmic drugs decreased considerably from 93.5% to 15.3% on mid-term follow-up. There was no late death or need for cardiac transplantation. The duration of arrhythmia before surgery was prolonged for more than 10 years in patients who died as well as in those who had complications like late recurrence of arrhythmias, dependence on anti-arrhythmic medications, and worsening of ventricular dysfunction.
Fontan conversion is a well-established treatment option for salvaging the failing atriopulmonary connections. Concomitant arrhythmia surgery effectively resolves the refractory atrial arrhythmias and improves survival, but we need to optimise the timing of Fontan conversion to improve the long-term outcome.
The objectives of this study were to determine the influence of various sociodemographic variables and estimate the impact of additional psychological factors (aggressive personality traits and the sexual double standard) on rape-supportive attitudes. A sample of 700 men and 800 women from El Salvador aged between 18 and 40 years completed the Social Desirability Scale, the Double Standard Scale, the Aggression Questionnaire, the State-Trait Anger Expression Inventory-2 and the Rape-Supportive Attitude Scale. Results show gender-based and age-based differences in rape-supportive attitudes, as well as an interaction between gender and age. They also highlight the importance of the sexual double standard and aggressive personality traits in explaining such attitudes.
In a recent study Tsytovich et al. [J. Plasma
Phys. 56, 127 (1996)] claimed to
obtain new expressions for electron–ion bremsstrahlung in plasmas.
It is shown,
however, that they interpreted earlier work incorrectly and simply reproduced
The infrared complex permittivity function of pseudo-cubic, disordered, spinel-type variety of alumina, η–Al2O3, obtained by spray pyrolysis, has been determined from its IR reflectance spectra, measured at near to normal incidence on pressed powder pellets. The optical constants obtained therefrom have been verified by using them in the simulation of the corresponding absorption spectra for KBr-diluted pellets of this material, and these are in excellent agreement with the experimental spectra. All calculations are based on a procedure for the estimation of the effective dielectric function of a mixture incorporating percolation features, which has been recently developed by the authors.
Commercial cassava production from true cassava seeds (TCS) appears to be a promising option for reducing or eliminating several of the production constraints associated with vegetative propagation. The most important contribution of TCS would be to reduce virus build-up in vegetative material and to resolve the problems of stake storage, low multiplication rate and the long growth cycle. Preliminary results suggest that the root yield potential of TCS is comparable with that of traditional vegetative propagation. Improvements in the capacity of true seed progenies to germinate and establish in the field can be achieved either genetically or through pre-planting seed treatments such as coating the seed with rock phosphate. Development of a successful TCS technology will require a multidisciplinary approach, involving basic studies in cassava breeding, physiology, agronomy, socio-economics and other fields.
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