724 research outputs found
Non-equilibrium two-phase coexistence in a confined granular layer
We report the observation of the homogenous nucleation of crystals in a dense
layer of steel spheres confined between two horizontal plates vibrated
vertically. Above a critical vibration amplitude, two-layer crystals with
square symmetry were found to coexist in steady state with a surrounding
granular liquid. By analogy to equilibrium hard sphere systems, the phase
behavior can be explained through entropy maximization. However, dramatic
non-equilibrium effects are present, including a significant difference in the
granular temperatures of the two phases.Comment: 4 pages, 3 figures, RevTex4 forma
Level densities and -strength functions in Sm
The level densities and -strength functions of the weakly deformed
Sm and Sm nuclei have been extracted. The temperature versus
excitation energy curve, derived within the framework of the micro canonical
ensemble, shows structures, which we associate with the break up of Cooper
pairs. The nuclear heat capacity is deduced within the framework of both the
micro canonical and the canonical ensemble. We observe negative heat capacity
in the micro canonical ensemble whereas the canonical heat capacity exhibits an
S-shape as function of temperature, both signals of a phase transition. The
structures in the -strength functions are discussed in terms of the
pygmy resonance and the scissors mode built on exited states. The samarium
results are compared with data for the well deformed Dy,
Er and Yb isotopes and with data from
(n,)-experiments and giant dipole resonance studies.Comment: 12 figure
The dynamics of thin vibrated granular layers
We describe a series of experiments and computer simulations on vibrated
granular media in a geometry chosen to eliminate gravitationally induced
settling. The system consists of a collection of identical spherical particles
on a horizontal plate vibrating vertically, with or without a confining lid.
Previously reported results are reviewed, including the observation of
homogeneous, disordered liquid-like states, an instability to a `collapse' of
motionless spheres on a perfect hexagonal lattice, and a fluctuating,
hexagonally ordered state. In the presence of a confining lid we see a variety
of solid phases at high densities and relatively high vibration amplitudes,
several of which are reported for the first time in this article. The phase
behavior of the system is closely related to that observed in confined
hard-sphere colloidal suspensions in equilibrium, but with modifications due to
the effects of the forcing and dissipation. We also review measurements of
velocity distributions, which range from Maxwellian to strongly non-Maxwellian
depending on the experimental parameter values. We describe measurements of
spatial velocity correlations that show a clear dependence on the mechanism of
energy injection. We also report new measurements of the velocity
autocorrelation function in the granular layer and show that increased
inelasticity leads to enhanced particle self-diffusion.Comment: 11 pages, 7 figure
Level density and thermal properties in rare earth nuclei
A convergent method to extract the nuclear level density and the gamma-ray
strength function from primary gamma-ray spectra has been established.
Thermodynamical quantities have been obtained within the microcanonical and
canonical ensemble theory. Structures in the caloric curve and in the heat
capacity curve are interpreted as fingerprints of breaking of Cooper pairs and
quenching of pairing correlations. The strength function can be described using
models and common parameterizations for the E1, M1 and pygmy resonance
strength. However, a significant decrease of the pygmy resonance strength at
finite temperatures has been observed.Comment: 15 pages including 8 figures. Proceedings article for the conference
Nuclear Structure and Related Topics, Dubna, Russia, June 6-10, 200
The encounter with the unknown: Nurses lived experiences of their responsibility for the care of the patient in the Swedish ambulance service
Registered nurses (RNs) have, according to the Swedish National Board of Health and Welfare, the overall responsibility for the medical care in the ambulance care setting. Bringing RNs into the ambulance service are judged, according to earlier studies, to lead to a degree of professionalism with a higher quality of medical care. Implicitly in earlier studies, the work in the ambulance service involves interpersonal skills. The aim of this study was to describe RNs' experiences of being responsible for the care of the patient in the Swedish ambulance service. A reflective lifeworld approach within the perspective of caring science was used. Five RNs with at least five years experience from care in the ambulance care setting were interviewed. The findings show that the essence of the phenomenon is to prepare and create conditions for care and to accomplish care close to the patient. Three meaning constituents emerged in the descriptions: prepare and create conditions for the nursing care, to be there for the patient and significant others and create comfort for the patient and significant others. The responsibility is a complex phenomenon, with a caring perspective, emerging from the encounter with the unique human being
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Home learning environments and children’s language and literacy skills: A meta-analytic review of studies conducted in low- and middle-income countries
A robust finding from research in high-income countries is that children living in resource-poor homes are vulnerable to difficulties with language and literacy but less is known about this association in low- and middle-income (LMI) countries. We present a meta-analysis of 6,678 correlations from studies in 43 LMI countries. Overall, the results indicate a small but significant association (r = .08) between home language and literacy environment and children's language and literacy skills. After examining a range of moderators, adult literacy practices and books-at-home had a significantly larger association with children's language and literacy skills than did home tutoring. Studies using customized measures demonstrated a more marked association between home attributes and children's outcomes (r = .14) than studies using a common measure across multiple sites (r = .06). Published studies showed significantly larger associations than unpublished studies, and countries with greater income inequality showed a larger association than relatively egalitarian societies. We conclude that the small overall association should not be taken as support for the absence of, or a vanishingly small relationship between the home learning environment and children's language and literacy skills in LMI countries. Rather, an important factor in detecting this relationship is that assessments must better reflect the nature of homes in different cultures to capture true variation in the population. Such contextually situated measurement would lead to an inclusive conceptualization of home learning environments and can better inform intervention programs to enhance children's educational success, a critical target for many LMI countries. (PsycInfo Database Record (c) 2024 APA, all rights reserved)
Non-relativistic metrics from back-reacting fermions
It has recently been pointed out that under certain circumstances the
back-reaction of charged, massive Dirac fermions causes important modifications
to AdS_2 spacetimes arising as the near horizon geometry of extremal black
holes. In a WKB approximation, the modified geometry becomes a non-relativistic
Lifshitz spacetime. In three dimensions, it is known that integrating out
charged, massive fermions gives rise to gravitational and Maxwell Chern-Simons
terms. We show that Schrodinger (warped AdS_3) spacetimes exist as solutions to
a gravitational and Maxwell Chern-Simons theory with a cosmological constant.
Motivated by this, we look for warped AdS_3 or Schrodinger metrics as exact
solutions to a fully back-reacted theory containing Dirac fermions in three and
four dimensions. We work out the dynamical exponent in terms of the fermion
mass and generalize this result to arbitrary dimensions.Comment: 26 pages, v2: typos corrected, references added, minor change
Effect of Galactose Ingestion Before and During Exercise on Substrate Oxidation, Postexercise Satiety, and Subsequent Energy Intake in Females.
OBJECTIVE: To examine the effects of consuming a galactose carbohydrate (CHO) drink on substrate oxidation, postexercise satiety, and subsequent energy intake. METHODS: Nine recreationally active eumenorrheic females undertook 3 trials, each consisting of running for 60 minutes at 65% VO2peak followed immediately by a 90-minute rest period. Prior to (300 ml) and at 15-minute intervals during exercise (150 ml), participants consumed either a glucose (GLU: GI 89) or galactose (GAL: GI 20) drink, each of which contained 45 g of CHO, or an artificially sweetened placebo (PLA). Following the rest period, participants were provided with an ad libitum test lunch and asked to record food intake for the remainder of the day. RESULTS: Plasma glucose was significantly greater throughout exercise and rest following the GLU trial compared with the GAL and PLA trials (P < 0.05); however there were no differences in CHO oxidation. Hunger was significantly lower (P < 0.05) throughout the GAL compared to the GLU and PLA trials. There were no significant differences between trials for energy intake during the postexercise meal. Overall net energy balance for the 24 hours was negative in both the GAL (-162 ± 115 kcal; P < 0.05 vs GLU) and PLA trials (-49 ± 160 kcal). CONCLUSIONS: Results demonstrate that ingesting a solution containing GAL before and during exercise can positively impact postexercise satiety and energy balance throughout the day, compared to a more readily available and widely consumed form of CHO. Despite this, there appears to be no apparent benefit in consuming a CHO beverage on fuel utilization for this moderate exercise intensity and duration
Relationship between psychological and biological factors and physical activity and exercise behaviour in Filipino students
The aim of the present study was threefold. Firstly, it investigated whether a general measure or specific measure of motivational orientation was better in describing the relationship between motivation and exercise behaviour. Secondly, it examined the relationship between the four most popular indirect methods of body composition assessment and physical activity and exercise patterns. Thirdly, the interaction between motivation and body composition on physical activity and exercise behaviour was explored in a sample of 275 Filipino male and female students. Males were found to have higher levels of exercise whereas females had higher levels of physical activity. Furthermore, general self-motivation together with body weight and percentage body fat were found to be the best predictor of exercise behaviour whereas the tension/pressure subscale of the ‘Intrinsic Motivation Inventory’ (IMI) was the best predictor of levels of physical activity. However, significant gender differences were observed. That is, for the males only self-motivation and for the females only body weight and BMI predicted exercise behaviour. Also, tension/pressure predicted physical activity levels for the females but not the males. No inverse relationship was found between the four body composition measures and exercise and physical activity behaviour. The results support the notion that the psychobiological approach might be particularly relevant for high intensity exercise situations but also highlights some important gender differences. Finally, the results of this study emphasise the need for more cross-cultural research
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