Internal structure of preformed Cooper pairs

In order to obtain information about the internal structure of the preformed pairs in the pseudogap state of high $T_c$ superconductors, we calculate the propagator of a singlet pair with center of mass coordinate $\mathbf{r}$, and relative distance $\pmb{\rho}$, by solving the Bethe-Salpeter equation, representing the sum over repeated two-particle scattering events due to a distance dependent attraction. We define then a ``pair structure function'' $g_{P}(\mathbf{P},\pmb{\rho})$ that depends on the internal distance $\pmb{\rho}$ between the partners and on the momentum $\mathbf{P}$ of the pair. We calculate this function both for a local potential and $s-$wave symmetry of the order parameter and for a separable potential and $d-$wave symmetry of the order parameter. The influence of the center of mass momentum, strenght of the interaction, temperature, density of particles and of the pseudogap in the one-electron spectrum is studied for both cases.Comment: 12 pages, REVTeX4, 8 EPS figure

Dynamical Phase Transitions In Driven Integrate-And-Fire Neurons

We explore the dynamics of an integrate-and-fire neuron with an oscillatory stimulus. The frustration due to the competition between the neuron's natural firing period and that of the oscillatory rhythm, leads to a rich structure of asymptotic phase locking patterns and ordering dynamics. The phase transitions between these states can be classified as either tangent or discontinuous bifurcations, each with its own characteristic scaling laws. The discontinuous bifurcations exhibit a new kind of phase transition that may be viewed as intermediate between continuous and first order, while tangent bifurcations behave like continuous transitions with a diverging coherence scale.Comment: 4 pages, 5 figure

Church Attendance and Religious Experience : Differential Associations to Well-Being for Norwegian Women and Men?

Previous studies have shown that gender may moderate the relationship between religiousness and mental health in most countries, but few studies have been conducted in Norway and Denmark. This study examined gender differences in religious experiences and church attendance as predictors of existential well-being among 295 women and 233 men from the general Norwegian population. Analyses showed that the structural equation models for women and men did not differ significantly on the global level. The models for women and men, however, showed different patterns. Among men, church attendance and negative religious experiences predicted existential well-being; among women, positive and negative religious experiences were related to existential well-being, but church attendance was not. The present findings suggest that men may benefit more from active religiousness, whereas women may benefit more from affective religiousness. Comparing these results with research in other cultural contexts, we find that different operationalizations of church attendance yield the same types of patterns across cultural contexts. Consequently, the benefits of religiousness may be similar for women and men irrespective of cultural context.© The Author(s) 2015 This article is distributed under the terms of the Creative Commons Attribution 3.0 License (http://www.creativecommons.org/licenses/by/3.0/) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (https://us.sagepub.com/en-us/nam/open-access-at-sage)

Sodium reduction regulations in South Africa – the consumer perspective

The prevalence of adult hypertension has increased at an alarming rate in recent years in South Africa. Salt reduction legislation is considered a cost-effective way to reduce this burden, as salt is a driver of hypertension. This cross-sectional, descriptive study aimed to determine consumers’ awareness of, and perceptions towards, the salt legislation, and their salt consumption habits. An interviewer-administered survey was used to gather data from literate adult consumers (N=583) at four randomly selected shopping malls in the Tygerberg Health sub-district, City of Cape Town. More than half (56.9%) of all participants tried to consume less salt because they thought it was healthier (38.3%) yet processed foods were a major source of salt in their diets (50.4%). Only 16.5% of participants were aware of the national salt legislation. Almost half of participants (47.9%) thought the legislation would affect the taste of food negatively, yet 80.9% have not noticed a change after implementation of the first phase of the legislation. To conclude, regulating manufacturers of food products could facilitate a reduction in population salt intake. An integrative strategy and collaboration between all stakeholders with regards to legislation, labelling and health education is needed in order to achieve health targets for population salt reduction

Widths of Isobaric Analog Resonances: a microscopic approach

A self-consistent particle-phonon coupling model is used to investigate the properties of the isobaric analog resonance in $^{208}$Bi. It is shown that quantitative agreement with experimental data for the energy and the width can be obtained if the effects of isospin-breaking nuclear forces are included, in addition to the Coulomb force effects. A connection between microscopic model predictions and doorway state approaches which make use of the isovector monopole resonance, is established via a phenomenological ansatz for the optical potential.Comment: 18 pages, 1 figure. To appear on Phys. Rev. C (tentatively scheduled for June 1998

Determining the minimum mass and cost of a magnetic refrigerator

An expression is determined for the mass of the magnet and magnetocaloric material needed for a magnetic refrigerator and these are determined using numerical modeling for both parallel plate and packed sphere bed regenerators as function of temperature span and cooling power. As magnetocaloric material Gd or a model material with a constant adiabatic temperature change, representing a infinitely linearly graded refrigeration device, is used. For the magnet a maximum figure of merit magnet or a Halbach cylinder is used. For a cost of \$40 and \$20 per kg for the magnet and magnetocaloric material, respectively, the cheapest 100 W parallel plate refrigerator with a temperature span of 20 K using Gd and a Halbach magnet has 0.8 kg of magnet, 0.3 kg of Gd and a cost of \$35. Using the constant material reduces this cost to \$25. A packed sphere bed refrigerator with the constant material costs \$7. It is also shown that increasing the operation frequency reduces the cost. Finally, the lowest cost is also found as a function of the cost of the magnet and magnetocaloric material.Comment: 12 pages, 10 figure

Two new pulsating hot subdwarf stars from the Edinburgh-Cape survey

We report the discovery of very rapid pulsations in two hot subdwarf stars from the Edinburgh- Cape blue object survey. The short periods, small amplitudes and multiperiodicity establish these stars as members of the class of rapidly-pulsating sdB stars. The spectrograms of both stars, however, show relatively strong He II 4686 and they are therefore more properly classified as sdOB. The light curve of EC 01541?1409 is dominated by two strong (?1 per cent) variations with frequencies near 7114 and 7870 ?Hz (periods near 140.6 and 127.1 s), though at least five frequencies are present with amplitudes above about 0.002 mag. The light curve of EC 22221?3152 appears to be generated by at least 10 frequencies in the range 5670-11850 ?Hz (about 175-85 s) with amplitudes between about 0.01 and 0.001 mag, including the first overtone of the strongest variation. Somewhat surprisingly, this number of frequencies is detectable in observing runs as short as 3 h, probably due to the fact that the detected frequencies are well-separated.IS