Evidence for a dynamical ground state in the frustrated pyrohafnate Tb2Hf2O7

We report the physical properties of Tb2Hf2O7 based on ac magnetic susceptibility \chi_ac(T), dc magnetic susceptibility \chi(T), isothermal magnetization M(H), and heat capacity C_p(T) measurements combined with muon spin relaxation (\muSR) and neutron powder diffraction measurements. No evidence for long-range magnetic order is found down to 0.1 K. However, \chi_ac(T) data present a frequency-dependent broad peak (near 0.9 K at 16 Hz) indicating slow spin dynamics. The slow spin dynamics is further evidenced from the \muSR data (characterized by a stretched exponential behavior) which show persistent spin fluctuations down to 0.3 K. The neutron powder diffraction data collected at 0.1 K show a broad peak of magnetic origin (diffuse scattering) but no magnetic Bragg peaks. The analysis of the diffuse scattering data reveals a dominant antiferromagnetic interaction in agreement with the negative Weiss temperature. The absence of long-range magnetic order and the presence of slow spin dynamics and persistent spin fluctuations together reflect a dynamical ground state in Tb2Hf2O7.Comment: 11 pages and 8 figure

Influence of Josephson current second harmonic on stability of magnetic flux in long junctions

We study the long Josephson junction (LJJ) model which takes into account the second harmonic of the Fourier expansion of Josephson current. The dependence of the static magnetic flux distributions on parameters of the model are investigated numerically. Stability of the static solutions is checked by the sign of the smallest eigenvalue of the associated Sturm-Liouville problem. New solutions which do not exist in the traditional model, have been found. Investigation of the influence of second harmonic on the stability of magnetic flux distributions for main solutions is performed.Comment: 4 pages, 6 figures, to be published in Proc. of Dubna-Nano2010, July 5-10, 2010, Russi

Characterization of the size-segregated water-soluble inorganic ions at eight Canadian rural sites

Size-segregated water-soluble inorganic ions, including particulate sulphate (SO<sub>4</sub><sup>2-</sup>), nitrate (NO<sub>3</sub><sup>-</sup>), ammonium (NH<sub>4</sub><sup>+</sup>), chloride (Cl<sup>-</sup>), and base cations (K<sup>+</sup>, Na<sup>+</sup>, Mg<sup>2+</sup>, Ca<sup>2+</sup>), were measured using a Micro-Orifice Uniform Deposit Impactor (MOUDI) during fourteen short-term field campaigns at eight locations in both polluted and remote regions of eastern and central Canada. The size distributions of SO<sub>4</sub><sup>2-</sup> and NH<sub>4</sub><sup>+</sup> were unimodal, peaking at 0.3–0.6 µm in diameter, during most of the campaigns, although a bimodal distribution was found during one campaign and a trimodal distribution was found during another campaign made at a coastal site. SO<sub>4</sub><sup>2-</sup> peaked at slightly larger sizes in the cold seasons (0.5–0.6 µm) compared to the hot seasons (0.3–0.4 µm) due to the higher relative humidity in the cold seasons. The size distributions of NO<sub>3</sub><sup>-</sup> were unimodal, peaking at 4.0–7.0 µm during the warm-season campaigns, and bimodal, with one peak at 0.3–0.6 µm and another at 4–7 µm during the cold-season campaigns. A unimodal size distribution, peaking at 4–6 µm, was found for Cl<sup>-</sup>, Na<sup>+</sup>, Mg<sup>2+</sup>, and Ca<sup>2+</sup> during approximately half of the campaigns and a bimodal distribution, with one peak at 2 µm and the other at 6 µm, was found during the rest of the campaigns. For K<sup>+</sup>, a bimodal distribution, with one peak at 0.3 µm and the other at 4 µm, was observed during most of the campaigns. Seasonal contrasts in the size-distribution profiles suggest that emission sources and air mass origins were the major factors controlling the size distributions of the primary aerosols while meteorological conditions were more important for the secondary aerosols. <br><br> The dependence of the particle acidity on the particle size from the nucleation mode to the accumulation mode was not consistent from site to site or from season to season. Particles in the accumulation mode were more acidic than those in the nucleation mode when submicron particles were in the state of strong acidity; however, when submicron particles were neutral or weakly acidic, particles in the nucleation mode could sometimes be more acidic. The inconsistency of the dependence of the particle acidity on the particle size should have been caused by the different emission sources of all the related species and the different meteorological conditions during the different campaigns. The results presented here at least partially explain the controversial phenomenon found in previous studies on this topic

Dynamic compartmentalization of bacteria: accurate division in E. coli

Positioning of the midcell division plane within the bacterium E. coli is controlled by the min system of proteins: MinC, MinD and MinE. These proteins coherently oscillate from end to end of the bacterium. We present a reaction--diffusion model describing the diffusion of min proteins along the bacterium and their transfer between the cytoplasmic membrane and cytoplasm. Our model spontaneously generates protein oscillations in good agreement with experiments. We explore the oscillation stability, frequency and wavelength as a function of protein concentration and bacterial length.Comment: 4 pages, 4 figures, Latex2e, Revtex

Occurrence of Eimeria species parasites on small-scale commercial chicken farms in Africa and indication of economic profitability.

Small-scale commercial poultry production is emerging as an important form of livestock production in Africa, providing sources of income and animal protein to many poor households, yet the occurrence and impact of coccidiosis on this relatively new production system remains unknown. The primary objective of this study was to examine Eimeria parasite occurrence on small-scale commercial poultry farms in Ghana, Tanzania and Zambia. Additionally, farm economic viability was measured by calculating the farm gross margin and enterprise budget. Using these economic measures as global assessments of farm productivity, encompassing the diversity present in regional husbandry systems with a measure of fundamental local relevance, we investigated the detection of specific Eimeria species as indicators of farm profitability. Faecal samples and data on production parameters were collected from small-scale (less than 2,000 birds per batch) intensive broiler and layer farms in peri-urban Ghana, Tanzania and Zambia. All seven Eimeria species recognised to infect the chicken were detected in each country. Furthermore, two of the three genetic variants (operational taxonomic units) identified previously in Australia have been described outside of Australia for the first time. Detection of the most pathogenic Eimeria species associated with decreased farm profitability and may be considered as an indicator of likely farm performance. While a causal link remains to be demonstrated, the presence of highly pathogenic enteric parasites may pose a threat to profitable, sustainable small-scale poultry enterprises in Africa

The effectiveness of critical time intervention for abused women leaving women’s shelters: a randomized controlled trial

Objectives: To examine the effectiveness of critical time intervention (CTI)—an evidence-based intervention—for abused women transitioning from women’s shelters to community living. Methods A randomized controlled trial was conducted in nine women’s shelters across the Netherlands. 136 women were assigned to CTI (n = 70) or care-as-usual (n = 66). Data were analyzed using intention-to-treat three-level mixed-effects models. Results: Women in the CTI group had significant fewer symptoms of post-traumatic stress (secondary outcome) (adjusted mean difference - 7.27, 95% CI - 14.31 to - 0.22) and a significant fourfold reduction in unmet care needs (intermediate outcome) (95% CI 0.06–0.94) compared to women in the care-as-usual group. No differences were found for quality of life (primary outcome), re-abuse, symptoms of depression, psychological distress, self-esteem (secondary outcomes), family support, and social support (intermediate outcomes). Conclusions: This study shows that CTI is effective in a population of abused women in terms of a reduction of posttraumatic stress symptoms and unmet care needs. Because follow-up ended after the prescribed intervention period, further research is needed to determine the full long-term effects of CTI in this population

Effectiveness and moderators of individual cognitive behavioral therapy versus treatment as usual in clinically depressed adolescents:A randomized controlled trial

We examined if manualized cognitive behavioral therapy (CBT) was more effective than Treatment As Usual (TAU) for clinically depressed adolescents within routine care. This multisite Randomized controlled trail included 88 clinically depressed adolescents (aged 12-21 years) randomly assigned to CBT or TAU. Multiple assessments (pre-, post treatment and six-month follow-up) were done using semi-structured interviews, questionnaires and ratings and multiple informants. The primary outcome was depressive or dysthymic disorder based on the KSADS. Completers, CBT (n = 19) and TAU (n = 26), showed a significant reduction of affective diagnoses at post treatment (76% versus 76%) and after six months (90% versus 79%). Intention-to-treat analyses on depressive symptoms showed that 41.6% within CBT and 31.8% within the TAU condition was below clinical cut-off at post treatment and after six-months, respectively 61.4% and 47.7%. No significant differences in self-reported depressive symptoms between CBT and TAU were found. No prediction or moderation effects were found for age, gender, child/parent educational level, suicidal criteria, comorbidity, and severity of depression. We conclude that CBT did not outperform TAU in clinical practice in the Netherlands. Both treatments were found to be suitable to treat clinically referred depressed adolescents. CBT needs further improvement to decrease symptom levels below the clinical cut-off at post treatment

A questionnaire to identify patellofemoral pain in the community: an exploration of measurement properties

Background Community-based studies of patellofemoral pain (PFP) need a questionnaire tool that discriminates between those with and those without the condition. To overcome these issues, we have designed a self-report questionnaire which aims to identify people with PFP in the community. Methods Study designs: comparative study and cross-sectional study. Study population: comparative study: PFP patients, soft-tissue injury patients and adults without knee problems. Cross-sectional study: adults attending a science festival. Intervention: comparative study participants completed the questionnaire at baseline and two weeks later. Cross-sectional study participants completed the questionnaire once. The optimal scoring system and threshold was explored using receiver operating characteristic curves, test-retest reliability using Cohen’s kappa and measurement error using Bland-Altman plots and standard error of measurement. Known-group validity was explored by comparing PFP prevalence between genders and age groups. Results Eighty-four participants were recruited to the comparative study. The receiver operating characteristic curves suggested limiting the questionnaire to the clinical features and knee pain map sections (AUC 0.97 95 % CI 0.94 to 1.00). This combination had high sensitivity and specificity (over 90 %). Measurement error was less than the mean difference between the groups. Test–retest reliability estimates suggest good agreement (N = 51, k = 0.74, 95 % CI 0.52–0.91). The cross-sectional study (N = 110) showed expected differences between genders and age groups but these were not statistically significant. Conclusion A shortened version of the questionnaire, based on clinical features and a knee pain map, has good measurement properties. Further work is needed to validate the questionnaire in community samples