8,634 research outputs found
The political dimension of seasonal allocations: Developing a seasonal allocation strategy in a water-short system in Sri Lanka
Water allocation, Irrigation programs, Reservoirs, Participatory management, Farmer participation, Water rights, Irrigated farming, Rice, Water shortage, Farmers' attitudes, Farmer-agency interactions, Sri Lanka
Late-Type Stars in M31. I.: A Photometric Study of AGB Stars and Metallicity Gradients.
We have imaged five 7\arcmin \x 7\arcmin\ fields in M31 spanning
galactocentric radii from 4 to 32 kpc along the SW-major axis. The fields were
observed through two broad-band (\V\ and \I) and two narrow-band (\CN\ and
\TiO) filters. The broad-band data were used to construct \IvsVI\
color-magnitude diagrams (CMDs) and, in some of our fields, we found
significant numbers of stars in the Cepheid instability strip. A distance
modulus for the Cepheids in the middle field was found that agreed well with
other values in the literature values. The width of the giant branch (GB) in
the \IvsVI\ CMD of all 5 fields was investigated, and we show that in four of
the fields a likely explanation for the GB width is a combination of {\it both}
metallicity and mass variations. Using the broad-band data, the asymptotic
giant branch (AGB) luminosity functions (LFs) were measured in the five fields,
and we show that differences exist between these LFs. We speculate on how the
different star forming histories in the fields may lead to the observed AGB LFs
and GB widths. Using the narrow-band data along with the broad-band data we
separated the AGB stars into carbon-rich (C) and oxygen-rich (M) types. The
carbon stars LFs were used to obtain an estimate for the distance modulus of
M31 which agrees with the value derived from Cepheids. The ratio of C- to
M-stars (C/M) is believed to be an indicator of gaseous chemical abundance at
the time of formation of these stars. We show that the C/M ratio increases
smoothly with galactocentric distance, suggesting an inverse correlation with
metallicity. This is the first demonstration of this effect within a single
extragalactic system. We find that differences in the width of the GB and the
AGB LFs do not significantly affect the C/M ratio. We consider the effect of
the increasing C/M ratio on the ISM in M31, and cite evidence in favor of a
model where the grain composition in M31 is a function of galactocentric
distance.Comment: UUencoded compressed postscript, 3 Figs. available on request.
(Contact [email protected]
Thermodynamically consistent equilibrium properties of normal-liquid Helium-3
The high-precision data for the specific heat C_{V}(T,V) of normal-liquid
Helium-3 obtained by Greywall, taken together with the molar volume V(T_0,P) at
one temperature T_0, are shown to contain the complete thermodynamic
information about this phase in zero magnetic field. This enables us to
calculate the T and P dependence of all equilibrium properties of normal-liquid
Helium-3 in a thermodynamically consistent way for a wide range of parameters.
The results for the entropy S(T,P), specific heat at constant pressure
C_P(T,P), molar volume V(T,P), compressibility kappa(T,P), and thermal
expansion coefficient alpha(T,P) are collected in the form of figures and
tables. This provides the first complete set of thermodynamically consistent
values of the equilibrium quantities of normal-liquid Helium-3. We find, for
example, that alpha(T,P) has a surprisingly intricate pressure dependence at
low temperatures, and that the curves alpha(T,P) vs T do not cross at one
single temperature for all pressures, in contrast to the curves presented in
the comprehensive survey of helium by Wilks.
Corrected in cond-mat/9906222v3: The sign of the coefficient d_0 was
misprinted in Table I of cond-mat/9906222v1 and v2. It now correctly reads
d_0=-7.1613436. All results in the paper were obtained with the correct value
of d_0. (We would like to thank for E. Collin, H. Godfrin, and Y. Bunkov for
finding this misprint.)Comment: 19 pages, 19 figures, 9 tables; published version; note added in
proof; v3: misprint correcte
Zero-temperature generalized phase diagram of the 4d transition metals under pressure
We use an accurate implementation of density functional theory (DFT) to
calculate the zero-temperature generalized phase diagram of the 4 series of
transition metals from Y to Pd as a function of pressure and atomic number
. The implementation used is full-potential linearized augmented plane waves
(FP-LAPW), and we employ the exchange-correlation functional recently developed
by Wu and Cohen. For each element, we obtain the ground-state energy for
several crystal structures over a range of volumes, the energy being converged
with respect to all technical parameters to within meV/atom. The
calculated transition pressures for all the elements and all transitions we
have found are compared with experiment wherever possible, and we discuss the
origin of the significant discrepancies. Agreement with experiment for the
zero-temperature equation of state is generally excellent. The generalized
phase diagram of the 4 series shows that the major boundaries slope towards
lower with increasing for the early elements, as expected from the
pressure induced transfer of electrons from states to states, but are
almost independent of for the later elements. Our results for Mo indicate a
transition from bcc to fcc, rather than the bcc-hcp transition expected from
- transfer.Comment: 28 pages and 10 figures. Submitted to Phys. Rev.
Individual differences in working memory capacity predict benefits to memory from intention offloading
Research suggests that individuals with lower working memory have difficulty remembering to fulfil delayed intentions. The current study examined whether the ability to offload intentions onto the environment mitigated these deficits. Participants (N = 268) completed three versions of a delayed intention task with and without the use of reminders, along with three measures of working memory capacity. Results showed that individuals with higher working memory fulfilled more intentions when having to rely on their own memory, but this difference was eliminated when offloading was permitted. Individuals with lower working memory chose to offload more often, suggesting that they were less willing to engage in effortful maintenance of internal representations when given the option. Working memory was not associated with metacognitive confidence or optimal offloading choices based on point value. These findings suggest offloading may help circumvent capacity limitations associated with maintaining and remembering delayed intentions
Carbon Stars and other Luminous Stellar Populations in M33
The M33 galaxy is a nearby, relatively metal-poor, late-type spiral. Its
proximity and almost face-on inclination means that it projects over a large
area on the sky, making it an ideal candidate for wide-field CCD mosaic
imaging. Photometry was obtained for more than 10^6 stars covering a 74' x 56'
field centered on M33. Main sequence (MS), supergiant branch (SGB), red giant
branch (RGB) and asymptotic giant branch (AGB) populations are identified and
classified based on broad-band V and I photometry. Narrow-band filters are used
to measure spectral features allowing the AGB population to be further divided
into C and M-star types. The galactic structure of M33 is examined using star
counts, colour-colour and colour-magnitude selected stellar populations. We use
the C to M-star ratio to investigate the metallicity gradient in the disk of
M33. The C/M-star ratio is found to increase and then flatten with increasing
galactocentric radius in agreement with viscous disk formation models. The
C-star luminosity function is found to be similar to M31 and the SMC,
suggesting that C-stars should be useful distance indicators. The ``spectacular
arcs of carbon stars'' in M33 postulated recently by Block et al. (2004) are
found in our work to be simply an extension of M33's disk.Comment: 20 pages, 20 figures. Accepted for publication in The Astronomical
Journa
Palaeontology, stratigraphy and sedimentology of Woodeaton Quarry (Oxfordshire) and a new microvertebrate site from the White Limestone Formation (Bathonian, Jurassic)
Woodeaton Quarry in Oxfordshire has previously yielded a number of large sauropod vertebrae and other (unpublished) dinosaur remains from a horizon in the Rutland Formation. No review of the wider terrestrial fauna from Woodeaton has been published to date. Here we present an overview of new material recovered from a microvertebrate site at the top of the White Limestone Formation (Middle Jurassic, Bathonian, Great Oolite Group, Retrocostatum Zone) and review the stratigraphy to provide a comprehensive local stratigraphic framework and place the quarry in the correct regional context. The terrestrial fauna is similar to that found from other UK Bathonian microvertebrate sites and includes probable dromaeosaurid theropods, ornithischians, tritylodontids and mammaliaforms such as amphitheriids, docodonts, ‘eutriconodonts’, ‘haramyids’ and multituberculates. Placement of the White Limestone Formation boundaries are clarified with respect to the Rutland and Forest Marble Formations. This indicates that the microvertebrate bed from Woodeaton is slightly older than that of the well-known mammal bed from nearby Kirtlington Quarry
Narrative, identity, and recovery from serious mental illness: A life history of a runner
In recent years, researchers have investigated the psychological effects of exercise for people with mental health problems, often by focusing on how exercise may alleviate symptoms of mental illness. In this article I take a different tack to explore the ways in which exercise contributed a sense of meaning, purpose, and identity to the life of one individual named Ben, a runner diagnosed with schizophrenia. Drawing on life history data, I conducted an analysis of narrative to explore the narrative types that underlie Ben's stories of mental illness and exercise. For Ben, serious mental illness profoundly disrupted a pre-existing athletic identity removing agency, continuity, and coherence from his life story. By returning to exercise several years later, Ben reclaimed his athletic identity and reinstated some degree of narrative agency, continuity, and coherence. While the relationships between narrative, identity, and mental health are undoubtedly complex, Ben's story suggests that exercise can contribute to recovery by being a personally meaningful activity which reinforces identity and sense of self
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Laser-Induced Spall Of Aluminum And Aluminum Alloys At High Strain Rates
We conducted laser-induced spall experiments aimed at studying how a material's microstructure affects the tensile fracture characteristics at high strain rates (> 10(6) s(-1)). We used the Z-Beamlet Laser at Sandia National Laboratory to drive shocks and to measure the spall strength of aluminum targets with various microstructures. The targets were recrystallized, high-purity aluminum (Al-HP RX), recrystallized aluminum + 3 wt.% magnesium (Al-3Mg RX), and cold-worked aluminum + 3 wt.% magnesium (Al-3Mg CW). The Al-3Mg RX and Al-3Mg CW are used to explore the roles that solid-solution alloying and cold-work strengthening play in the spall process. Using a line-VISAR (Velocity Interferometer System for Any Reflector) and analysis of recovered samples, we were able to measure spall strength and determine failure morphology in these targets. We find that the spall strength is highest for Al-HP RX. Analysis reveals that material grain size plays a vital role in the fracture morphology and spall strength results.Mechanical Engineerin
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