Fluctuation Effects And Order Parameter Symmetry In The Cuprate Superconductors

Effect of phase fluctuations on superconducting states with anisotropic order parameters is studied in a BCS like lattice model of cuprate superconductors. The degradation of the mean field transition temperature due to phase fluctuations is estimated within a Kosterlitz-Thouless scenario. Values of the interaction parameters for optimal doping, corresponding to a stable superconducting state of $S_{xy}$ symmetry, which fit the nodal structure of the superconducting order parameter in the Bi2212 compound, are obtained. The angular position of the node is found to be insensitive to the dopant concentration.Comment: Latex file, 8 output pages, 5 figures (available from Authors on request), to appear in Europhysics Letter

Relationship between Social Capital and Livelihood Enhancing Capitals among Smallholder Farmers in Uganda

Social capital is an important characteristic of a community and is one of the components of the asset pentagon of the sustainable livelihood framework. The study aimed at assessing the levels and dimensions of social capital and how social capital influences other livelihood capitals. A Cross-sectional survey of a random sample of 208 households was conducted in Masindi and Hoima Districts in Uganda to assess the current livelihood conditions and strategies for improving rural livelihoods. An Index of social capital was generated using density of group membership and three levels of social capital where generated i.e. high, medium and low. Two dimensions of social capital (bonding and bridging) were considered. Results showed that households with high and medium social capital had enhanced skills to solve problems, do research and bargain with middle men. Social capital empowered more women to participate in decision making, fostered asset base creation and use of natural resource management technologies. There was a significant difference between level of social capital and participation in collective farming. Households with high social capital rated highly the community level of trust, reciprocity, and women’s confidence. However, there was no significant effect of social capital on household income. In conclusion, there was a positive relationship between level and dimension of social capital and access to livelihood assets implying that strengthening social capital is a powerful way to improve communities and requires consistent and effective approaches to build and reinforce the social and human capital.Relationship, Social Capital, Livelihood Capitals, Smallholder Farmers, Agricultural Finance, Consumer/Household Economics, Environmental Economics and Policy, Farm Management, Food Consumption/Nutrition/Food Safety, Health Economics and Policy, Labor and Human Capital, Marketing, Production Economics, Research and Development/Tech Change/Emerging Technologies,

Superconductivity and incommensurate spin fluctuations in a generalized t-J model for the cuprates

We consider the slave-fermion Schwinger-boson decomposition of an effective model obtained through a systematic low-energy reduction of the three-band Hubbard Hamiltonian. The model includes a three-site term t'' similar to that obtained in the large-U limit of the Hubbard model but of opposite sign for realistic or large O-O hopping. For parameters close to the most realistic ones for the cuprates, the mean-field solution exhibits d+s superconductivity (predominantly d_{x^2-y^2}) with a dependence on doping x very similar to the experimentally observed. We also obtained incommensurate peaks at wave vectors near $\pi (1,1 +(-) 2x)$ in the spin structure factor, which also agree with experiment.Comment: 9 pages, latex, 2 figures, to appear in Europhys. Let

Physical activity stimulation program for children with cerebral palsy did not improve physical activity: a randomised trial

AbstractQuestion: In children with cerebral palsy, does a 6-month physical activity stimulation program improve physical activity, mobility capacity, fitness, fatigue and attitude towards sports more than usual paediatric physiotherapy? Design: Multicentre randomised controlled trial with concealed allocation, blinded assessments and intention-to-treat analysis. Participants: Forty-nine walking children (28 males) aged 7–13 years with spastic cerebral palsy and severity of the disability classified as Gross Motor Function Classification System level I–III. Intervention: The intervention group followed a 6-month physical activity stimulation program involving counselling through motivational interviewing, home-based physiotherapy, and 4 months of fitness training. The control group continued their usual paediatric physiotherapy. Outcome measures: Primary outcomes were walking activity (assessed objectively with an activity monitor) and parent-reported physical activity (Activity Questionnaire for Adults and Adolescents). Secondary outcomes were: mobility capacity, consisting of Gross Motor Function Measure-66 (GMFM-66), walking capacity and functional strength, fitness (aerobic and anaerobic capacity, muscle strength), self-reported fatigue, and attitude towards sport (child and parent). Assessments were performed at baseline, 4 months, 6 months and 12 months. Results: There were no significant intervention effects for physical activity or secondary outcomes at any assessment time. Positive trends were found for parent-reported time at moderate-to-vigorous intensity (between-group change ratio=2.2, 95% CI 1.1 to 4.4) and GMFM-66 (mean between-group difference=2.8 points, 95% CI 0.2 to 5.4) at 6 months, but not at 12 months. There was a trend for a small, but clinically irrelevant, improvement in the children's attitudes towards the disadvantages of sports at 6 months, and towards the advantages of sports at 12 months. Conclusions: This physical activity stimulation program, that combined fitness training, counselling and home-based therapy, was not effective in children with cerebral palsy. Further research should examine the potential of each component of the intervention for improving physical activity in this population. Trial registration: NTR2099. [Van Wely L, Balemans ACJ, Becher JG, Dallmeijer AJ (2014) Physical activity stimulation program for children with cerebral palsy did not improve physical activity: a randomised trial. Journal of Physiotherapy 60: 40–49

Are EEP Events Important for the Tertiary Ozone Maximum?

Energetic particle precipitation (EPP) increases the production of odd hydrogen (HOX ) species in the mesosphere, which catalytically destroy ozone (O3) in sunlight. Hence, the EPP‐HOX impact on the tertiary O3 maximum (TOM) depends on a complex geometry of a geographic‐oriented TOM, geomagnetic‐oriented auroral zone, producing short‐lived HOX species, and a destruction process depending on the solar zenith angle (SZA). Particle observations from the Medium Energy Proton and Electron Detectors telescopes aboard the Polar Orbiting Environmental Satellites, and hydroxyl (OH) and O3 mixing ratios from Aura microwave limb sounder (MLS) are used to investigate the potential limitations of using the MLS observations to study EPP‐OH impact on the TOM in the Northern Hemisphere. Our results show limited overlap between the auroral zone and the TOM at twilight conditions. A composite analysis indicates O3 mixing ratio decrease over the auroral zone lagged by ∼1 day compared to the maximum energetic electron precipitation (EEP)‐OH impact. Hence, MLS is predominantly observing a lagged and lower estimate of the response of O3 to EEP‐OH at SZA > 95°. The EEP impact region within the TOM is smaller than the overlap region, strongly modulated by the background atmospheric dynamics. The results, although limited by the satellites viewing conditions, imply that the importance of EEP upon O3 mixing ratio is strongly influenced by the background atmosphere, both in terms of chemistry and dynamics. Multisatellite observations at different solar local times are required to separate the direct from the lagged EEP‐OH impact on O3.publishedVersio