4,334 research outputs found
Pressure Treated Wood
Discusses chemical treatments to increase wood's fire resistance and protect it from rot and termites
Attitudes to telecare among older people, professional care workers and informal carers: a preventative strategy or crisis management?
This paper reports findings from an attitudinal survey towards telecare that emerged from twenty-two focus groups comprising ninety-two older people, fifty-five professional stakeholders and thirty-nine carers. These were convened in three different regions of England as a precursor to telecare service development. The results from this study suggest that informants’ views were shaped by prior knowledge of conventional health and social care delivery in their locality and the implication is that expectations and requirements in respect of telecare services in general are likely to be informed by wider perceptions about the extent to which community care should operate as a preventative strategy or as a mechanism for crisis management
Damped Lyman alpha systems and disk galaxies: number density, column density distribution and gas density
We present a comparison between the observed properties of damped Lyman alpha
systems (DLAs) and the predictions of simple models for the evolution of
present day disk galaxies, including both low and high surface brightness
galaxies. We focus in particular on the number density, column density
distribution and gas density of DLAs, which have now been measured in
relatively large samples of absorbers. From the comparison we estimate the
contribution of present day disk galaxies to the population of DLAs, and how it
varies with redshift. Based on the differences between the models and the
observations, we also speculate on the nature of the fraction of DLAs which
apparently do not arise in disk galaxies.Comment: 11 pages, 10 figures, accepted in MNRA
Sea turtle nesting in the Ten Thousand Islands of Florida
Loggerhead sea turtles (Caretta caretta) nest in numerous substrate and beach
types within the Ten Thousand Islands (TTl) of southwest Florida. Nesting beach
selection was analyzed on 12 islands within this archipelago. Numerous physical
characteristics were recorded to identify the relatedness of these variables and determine
their importance for nesting beach selection in C. caretta. These variables were chosen
after evaluating the islands, conducting literature searches and soliciting personal
communications. Along transects, data were collected, on the following: height of
canopy, beach width, overall slope (beach slope and slope of offshore approach) and sand
samples analyzed for pH, percentage of water, percentage of organic content, percentage
of carbonate and particle size (8 size classes). Data on ordinal aspect of beaches and
beach length were also recorded and included in the analysis. All of the variables were
analyzed by tree regression, incorporating the nesting data into the analysis. In the TTl,
loggerheads appear to prefer wider beaches (p< 0.001; R2
= 0.56) that inherently have less
slope, and secondarily, wider beaches that have low amounts of carbonate (p< O.00 1). In
addition, C. caretta favors nest sites within or in close proximity to the supra-littoral
vegetation zone of beaches in the TTl (p< 0.001). (86 page document
Carbureting conditions characteristics of aircraft engines
Tests were conducted at the altitude laboratory erected at the Bureau of Standards for the National Advisory Committee for Aeronautics to determine the changes in engine performance with changes in atmospheric temperature and pressure at various levels above the earth's surface, with special reference to (a) the variables affecting the functioning of the carburetor and (b) the changes in performance resulting from variables in the carburetor itself. This report constitutes a concise statement of the difficulties to be encountered in this branch of carburetion
Survival and Growth of American Alligator (Alligator mississippiensis) hatchlings after artificial incubation and repatriation
Hatchling American Alligators (Alligator mississippiensis) produced from artificially incubated
wild eggs were returned to their natal areas (repatriated). We compared artificially incubated and
repatriated hatchlings released within and outside the maternal alligator’s home range with naturally
incubated hatchlings captured and released within the maternal alligator’s home range on Lake Apopka,
Lake Griffin, and Orange Lake in Florida. We used probability of recapture and total length at approximately
nine months after hatching as indices of survival and growth rates. Artificially incubated hatchlings released
outside of the maternal alligator’s home range had lower recapture probabilities than either naturally
incubated hatchlings or artificially incubated hatchlings released near the original nest site. Recapture
probabilities of other treatments did not differ significantly. Artificially incubated hatchlings were
approximately 6% shorter than naturally incubated hatchlings at approximately nine months after hatching.
We concluded that repatriation of hatchlings probably would not have long-term effects on populations
because of the resiliency of alligator populations to alterations of early age-class survival and growth rates of
the magnitude that we observed. Repatriation of hatchlings may be an economical alternative to repatriation
of older juveniles for population restoration. However, the location of release may affect subsequent survival
and growth
Sewing sound quantum flesh onto classical bones
Semiclassical transformation theory implies an integral representation for
stationary-state wave functions in terms of angle-action variables
(). It is a particular solution of Schr\"{o}dinger's time-independent
equation when terms of order and higher are omitted, but the
pre-exponential factor in the integrand of this integral
representation does not possess the correct dependence on . The origin of
the problem is identified: the standard unitarity condition invoked in
semiclassical transformation theory does not fix adequately in a
factor which is a function of the action written in terms of and
. A prescription for an improved choice of this factor, based on
succesfully reproducing the leading behaviour of wave functions in the vicinity
of potential minima, is outlined. Exact evaluation of the modified integral
representation via the Residue Theorem is possible. It yields wave functions
which are not, in general, orthogonal. However, closed-form results obtained
after Gram-Schmidt orthogonalization bear a striking resemblance to the exact
analytical expressions for the stationary-state wave functions of the various
potential models considered (namely, a P\"{o}schl-Teller oscillator and the
Morse oscillator).Comment: RevTeX4, 6 page
Formation of Dark Matter Haloes in a Homogeneous Dark Energy Universe
Several independent cosmological tests have shown evidences that the energy
density of the Universe is dominated by a dark energy component, which cause
the present accelerated expansion. The large scale structure formation can be
used to probe dark energy models, and the mass function of dark matter haloes
is one of the best statistical tools to perform this study. We present here a
statistical analysis of mass functions of galaxies under a homogeneous dark
energy model, proposed in the work of Percival (2005), using an observational
flux-limited X-ray cluster survey, and CMB data from WMAP. We compare, in our
analysis, the standard Press-Schechter (PS) approach (where a Gaussian
distribution is used to describe the primordial density fluctuation field of
the mass function), and the PL (Power Law) mass function (where we apply a
nonextensive q-statistical distribution to the primordial density field). We
conclude that the PS mass function cannot explain at the same time the X-ray
and the CMB data (even at 99% confidence level), and the PS best fit dark
energy equation of state parameter is , which is distant from the
cosmological constant case. The PL mass function provides better fits to the
HIFLUGCS X-ray galaxy data and the CMB data; we also note that the
parameter is very sensible to modifications in the PL free parameter, ,
suggesting that the PL mass function could be a powerful tool to constrain dark
energy models.Comment: 4 pages, 2 figures, Latex. Accepted for publication in the
International Journal of Modern Physics D (IJMPD)
From Heisenberg matrix mechanics to EBK quantization: theory and first applications
Despite the seminal connection between classical multiply-periodic motion and
Heisenberg matrix mechanics and the massive amount of work done on the
associated problem of semiclassical (EBK) quantization of bound states, we show
that there are, nevertheless, a number of previously unexploited aspects of
this relationship that bear on the quantum-classical correspondence. In
particular, we emphasize a quantum variational principle that implies the
classical variational principle for invariant tori. We also expose the more
indirect connection between commutation relations and quantization of action
variables. With the help of several standard models with one or two degrees of
freedom, we then illustrate how the methods of Heisenberg matrix mechanics
described in this paper may be used to obtain quantum solutions with a modest
increase in effort compared to semiclassical calculations. We also describe and
apply a method for obtaining leading quantum corrections to EBK results.
Finally, we suggest several new or modified applications of EBK quantization.Comment: 37 pages including 3 poscript figures, submitted to Phys. Rev.
Constraints on supernova progenitors from spatial correlations with H-alpha emission
We have attempted to constrain the progenitors of all supernova types,
through correlations of the positions of historical supernovae with recent star
formation, as traced by H-alpha emission. Through pixel statistics we have
found that a large fraction of the SNII population do not show any association
with current star formation, which we put down to a 'runaway' fraction of these
progenitors. The SNIb/c population accurately traces the H-alpha emission, with
some suggestion that the SNIc progenitors show a higher degree of correlation
than the SNIb, suggesting higher mass progenitors for the former. Overall the
SNIa population only show a weak correlation to the positions of HII regions,
but as many as a half may be associated with a young stellar population.Comment: To appear in conference proceedings: "Supernova 1987A: 20 Years After
-- Supernovae & Gamma-Ray Bursters", held in Aspen, February 200
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