Microanalysis of dissolved iron and phosphate in pore waters of hypersaline sediment

Diurnal fluctuations of reduced iron concentrations, expected to occur in reduced sediments in the photic zone, were studied. Iron concentration was compared to O2-H2S, a microcanalysis of sulfate reduction was performed, as well as an examination of diurnal concentration of dissolved phosphate and changes in interstitial CO2. The iron profiles suggest a strong correlation between iron remobilization and processes occurring in the light. Phosphate profiles suggest the removal of phosphate is strongly correlated with precipitation of oxidized iron in the upper 2 mm to 5 mm of the sediments. Pore water CO2 concentrations and carbon isotope ratios are presented. These data are from the analyses of minisediment cores collected from the 42 per mil salt pond and incubated in the laboratory under light and dark conditions

Critical behavior of an Ising model with aperiodic interactions

We write exact renormalization-group recursion relations for a ferromagnetic Ising model on the diamond hierarchical lattice with an aperiodic distribution of exchange interactions according to a class of generalized two-letter Fibonacci sequences. For small geometric fluctuations, the critical behavior is unchanged with respect to the uniform case. For large fluctuations, the uniform fixed point in the parameter space becomes fully unstable. We analyze some limiting cases, and propose a heuristic criterion to check the relevance of the fluctuations.Comment: latex file, 5 figures, accepted by Braz. Jour. Phy

Role of the cooling rate in the stability of the superconducting phase of (TMTSF)_2ClO_4

The noncentrosymmetric ClO$_4$ anions of the organic superconductor (TMTSF)$_2$ClO$_4$ order below 24K. The size of domains where the anions are ordered is substantially dependent on the cooling rate which is a key parameter for the stability of the low temperature electronic ground states. We study the effect of the cooling rate on the SC phase within a self consistent approach in the framework of the time dependent Ginzburg-Landau theory taking into account the superconducting fluctuations. We derive the superconducting transition temperature which is found to decrease with increasing cooling rate in agreement with recent experimental data.Comment: 5 pages including one figure. Published online in Europhysics Letter

Agricultural research and poverty reduction:

International agricultural research has contributed enormously to increasing world food supplies to their current state of plenty. Yet poverty remains a major problem and the challenge for agricultural research now lies in developing strategies that more explicitly address the needs of the poor. This paper, based on the study commissioned by the Technical Advisory Committee (TAC) of the CGIAR system, addresses this issue. Based on an analysis of the links between agricultural research and poverty alleviation in different types of countries and rural regions, Peter Hazell and Lawrence Haddad identify six key priorities for a pro-poor agricultural research agenda and discuss strategies for achieving each of these goals with the least trade-off in national agricultural growth. (Excerpted from Forward by Per Pinstrup-Andersen and Emil Javier)agricultural research, poverty, food supply,

Association between pruritus and serum concentrations of parathormone, calcium and phosphorus in hemodialysis patients.

Chronic renal disorders have a progressive course in most cases, and finally result in end-stage renal disease (ESRD). Hemodialysis (HD) is one of the mainstays in the treatment of these patients. Disturbance in calcium (Ca) and phosphorus (P) metabolism and alteration of serum levels of parathormone (PTH) are observed in these patients. One of the most common cutaneous manifestations in patients on HD is pruritus. The aim of this study is to evaluate the association between pruritus and serum concentrations of Ca, P and PTH in patients with chronic renal disease. This analytic, descriptive, cross-sectional study was performed on 120 patients on HD at the Fifth-Azar Hospital in Gorgan, Iran, in 2010. Information related to the patients, including age, gender, pruritus, time of pruritus and duration on dialysis, was extracted from questionnaires. Serum concentrations of intact PTH, Ca and P were measured. Data were analyzed by the chi-square test and SPSS-16 software. A P-value less than 0.05 was considered statistically significant. Among the 120 study patients, 50% were male and the mean age (±SD) was 49 ± 12.3 years. Sixty percent of the patients had pruritus, of whom 33.3% had PTH levels above the normal range. Among the 40% of the patients who did not have pruritus, 39.6% had PTH levels higher than the normal levels. The mean serum Ca and P levels were 8.44 ± 1.65 mg/dL and 5.48 ± 1.81 mg/dL, respectively. The mean (±SD) Ca-P product was 55.46 ± 47.16 and the mean PTH concentration was 274.34 ± 286.53 pg/mL. No significant association was found between pruritus and age, sex, serum PTH and P levels as well as Ca-P product. However, the association between serum Ca levels and pruritus was significant (P = 0.03). Our study showed that most patients with pruritus had serum Ca levels in the abnormal range (lower or higher), and there was no significant correlation between serum iPTH level and pruritis. Thus, good control of serum Ca levels is important to reduce pruritus in these patients

Are women overrepresented among the poor?

This paper presents new evidence on the proportion of women in poverty in ten developing countries. It compares poverty measures for males and females and male- and female-headed households, and investigates the sensitivity of these measures to the use of per-capita and per-adult equivalent units and different definitions of the poverty line.Gender issues ,Developing countries ,Poverty ,

Microwave and millimeter-wave power generation in silicon carbide (SiC) IMPATT devices

There are two points that should be noted. First, in the thermal resistance calculations it is assumed that the device is operating at 773 K while the results of the room temperature simulations are used. This was done because there is not enough information to correctly predict the material parameters at 773 K. Since, in general, device performance degrades with increasing temperature, the cw results are perhaps a bit optimistic. Second, the electric field in these structures gets extremely high and there might be some possibility of tunneling. This was not incorporated into the simulation. Again, this could result in different device operating conditions

Gender and poverty

This paper presents new evidence on the association between gender and poverty based on an empirical analysis of 11 data sets from 10 developing countries. The paper computes income- and expenditure-based poverty measures and investigates their sensitivity to the use of per capita and per adult equivalent units. It also tests for differences in poverty incidence between individuals in male- and female-headed households using stochastic dominance analysis. Stochastic dominance analysis reveals that differences between male- and female-headed households among the very poor are not sufficiently large that one can conclude that one is unambiguously worse- or better-off, except for a few exceptions. When we use the method of endogenous bounds, persons in female-headed households in rural Ghana and Bangladesh are consistently worse-off, using two stochastic dominance criteria. These results suggest that, among the very poor, persons in male- and female-headed households may not differ significantly. The consistent and significant exceptions, rural Ghana and Bangladesh, suggest that cultural and institutional factors may be responsible for higher poverty among women in these countries. Our results point to the need to analyze determinants of household income and consumption using multivariate methods, and to give greater attention to the processes underlying female headship.Gender ,Household resource allocation ,Poverty ,rural population ,Developing countries ,