Dipolar Bose-Einstein condensate of Stationary-Light Dark-state Polaritons

We put forward and discuss in detail a scheme to achieve Bose-Einstein condensation of stationary-light dark-state polaritons with dipolar interaction. To this end we have introduced a diamond-like coupling scheme in a vapor of Rydberg atoms under the frozen gas approximation. To determine the system's dynamics we employ normal modes and identify the dark-state polariton corresponding to one of the modes. We show that in contrast to atomic dipolar ultra-cold vapors dark-state polariton Bose-Einstein condensates proposed here can be stable for a negative dipolar interaction constant.Comment: 5 pages, 1 figur

A comparison of two magnetic ultra-cold neutron trapping concepts using a Halbach-octupole array

This paper describes a new magnetic trap for ultra-cold neutrons (UCNs) made from a 1.2 m long Halbach-octupole array of permanent magnets with an inner bore radius of 47 mm combined with an assembly of superconducting end coils and bias field solenoid. The use of the trap in a vertical, magneto-gravitational and a horizontal setup are compared in terms of the effective volume and ability to control key systematic effects that need to be addressed in high precision neutron lifetime measurements

Effects of Warming and Nutrient Enrichment on How Grazing Pressure Affects Leaf Litter–Colonizing Bacteria

In view of current scenarios of global environmental change, we investigated the effects of warming and nutrient addition (N and P) on the impact of detritivores on density and community composition of leaf litter-colonizing bacteria in a freshwater environment. Within 10 d, detritivorous amphipods (Gammarus pulex) reduced bacterial numbers at 10 degrees C and to a lesser degree at 15 degrees C. However, the detritivore-induced decrease in bacterial numbers was compensated for by nutrient addition. After 31 d of incubation, amphipods reduced bacterial numbers only at 15 degrees C, and nutrient addition did not counteract detritivore effects. Similarly, changes in bacterial numbers in response to nutrient addition were more pronounced at low temperature within 10 d, whereas nutrient effects were stronger at high temperature after 31 d of incubation. Thus, warming without detritivores did not affect bacterial numbers under low-nutrient conditions (10 d). When detritivores were present, warming increased bacterial density significantly just under high-nutrient conditions (P < 0.05). After 31 d of incubation, warming did not affect bacterial density in detritivore-free controls in both nutrient conditions and did not affect bacterial density in both nutrient conditions in the presence of detritivores. Warming exhibited a significant effect on the composition of litter-associated bacterial communities irrespective of nutrient load (P < 0.05), whereas nutrients had less consistent effects. We conclude that warming, and to a lesser degree nutrient enrichment, may have influence on grazer-induced changes in bacterial biofilm composition, whereas nutrient enrichment may mostly interfere with those processes that depend on bacterial density

Determinants of old-age mortality in Taiwan

Journal ArticleRelationships among socio-demographic characteristics, general assessments of health, and old-age mortality are well established in developed countries. There is also an increasing focus on the connection between early-life experiences and late-life health. This paper tests these and other associations using representative survey data from Taiwan on the population aged 60 and older in 1989, 1993, and 1996 that have been linked to data on deaths between 1989 and 1999 from a national death registry. The study also explores the possible influence of Taiwan's Universal Health Insurance Program, instituted in 1995, and whether or not the survival of some groups of older people may have been differentially enhanced. Mortality is modeled using Gompertz regression. Multiple survey waves are employed to construct time-varying covariates. Some results verify findings of past studies; others are new. Effects of education are attenuated after the introduction of some health indicators. Functional and global assessments of health have stronger associations with mortality than do self-reports of health behaviors or particular chronic conditions such as diabetes. Mainlanders have higher survival than others. The survival of older adults with the greatest number and severity of functional limitations improved over the 1990s, suggesting a possible beneficial influence of the insurance program

Education of adult children and mortality of their elderly parents in Taiwan

Journal ArticleResearch shows an older adult's education is strongly associated with mortality. But in societies such as Taiwan, where families are highly integrated, the education of family members may be linked to survival. Such may be the case in settings where there are large gaps in levels of education across generations and high levels of resource transfers between family members. This study employs 14 years of longitudinal data from Taiwan to examine the combined effects of education of older adults and their adult children on mortality outcomes of older adults. Nested Gompertz hazard models are used to evaluate the importance of education of an older adult and their highest-educated child after controlling for socioeconomic, demographic, and health characteristics. To gain further insight, additional models stratify results by whether older adults report serious chronic health conditions. Results indicate that educational levels of both parent and child are associated with older adult mortality, but the child's education is more important when a) controlling for the health of the older adult, and b) when examining only those older adults who already report a serious chronic condition, suggesting different roles for education in onset versus progression of a health disorder that may lead to death

Changes in functional limitations and survival among the elderly in Taiwan: 1993, 1996, and 1999

Journal ArticleThis paper focuses on changes in the prevalence of functional limitations among nationally representative samples of adults aged 65 and older in Taiwan as measured in 1993, 1996, and 1999. Using data from the Survey of Health and Living Status of the Elderly in Taiwan, we investigate changes in difficulties walking and climbing stairs, two tasks that represent basic lower body movements that are less likely to be influenced by changes in living environments and social roles than are activities of daily living and instrumental activities of daily living. Results are shown for both unadjusted prevalence rates and rates adjusted for changes in population composition. Findings indicate that Taiwan does not appear to be experiencing the improvements in functioning that have been witnessed recently in the United States. The prevalence of functional limitation increased between 1993 and 1996 and between 1996 and 1999. One possible reason for the increase in limitation is the change in old-age survival in Taiwan, which appeared over the study period to have benefited those who have functional limitations, especially in a severe form. The country's Universal Health Insurance program, established in 1995, may have increased access to care and thus survival of those in poorest health

Qualification of a robotized Friction Stir Welding System

This paper presents an experimental methodology to determine a Friction Stir Welding (FSW) means of production based on the experimental study of the tool / material mechanical interactions generated during the welding operation. These two stages have been identified as being characteristic for the qualification of a FSW equipment. This paper presents the experimental results of the parametric study done on the plunging and welding phases. Ranges of forces and torques diagrams were established according to the processing parameters, in order to qualify a means of production and select the process parameters allowing the operation on the available FSW equipment

Methodology for qualifying a Friction Stir Welding equipment

The objective of this research work is the industrialization of the friction stir welding process in order to provide tools to industrials to select and qualify a machine for their FSW applications. This paper presents a methodology to determine the Friction Stir Welding equipment adequate to an application. The adequate equipment can be every machine that can perform friction stir welds. This paper presents a short review, based on literature survey, of the existing friction stir welding equipments. Then, the methodology developed is presented. It is based on the studying of the interactions between the tool and the workpiece

Determining the ability of a high payload robot to perform FSW applications

This paper presents an experimental methodology to determine a Friction Stir Welding (FSW) means of production based on the experimental study of the tool / material mechanical interactions generated during the welding operation. These two stages have been identified as being characteristic for the qualification of a FSW equipment. This paper presents the experimental results of the parametric study done on the plunging and welding phases. Ranges of forces and torques diagrams were established according to the processing parameters, in order to qualify a means of production and to select the processing parameters allowing the operation on the available FSW equipment

Predator avoidance in extremophile fish

Extreme habitats are often characterized by reduced predation pressures, thus representing refuges for the inhabiting species. The present study was designed to investigate predator avoidance of extremophile populations of Poecilia mexicana and P. sulphuraria that either live in hydrogen sulfide-rich (sulfidic) springs or cave habitats, both of which are known to have impoverished piscine predator regimes. Focal fishes that inhabited sulfidic springs showed slightly weaker avoidance reactions when presented with several naturally occurring predatory cichlids, but strongest differences to populations from non-sulfidic habitats were found in a decreased shoaling tendency with non-predatory swordtail (Xiphophorus hellerii) females. When comparing avoidance reactions between P. mexicana from a sulfidic cave (Cueva del Azufre) and the adjacent sulfidic surface creek (El Azufre), we found only slight differences in predator avoidance, but surface fish reacted much more strongly to the non-predatory cichlid Vieja bifasciata. Our third experiment was designed to disentangle learned from innate effects of predator recognition. We compared laboratory-reared (i.e., predator-naïve) and wild-caught (i.e., predator-experienced) individuals of P. mexicana from a non-sulfidic river and found no differences in their reaction towards the presented predators. Overall, our results indicate (1) that predator avoidance is still functional in extremophile Poecilia spp. and (2) that predator recognition and avoidance reactions have a strong genetic basis