3,121 research outputs found
Tourists’ willingness to pay for entry to the Annapurna Conservation Area, Nepal
This study seeks to determine international tourists’ willingness to pay (WTP) for entry fees in the Annapurna Conservation Area (ACA), Nepal. Data were collected in the ACA from May to June of 2011where 101 international tourists participated in a contingent valuation survey. A modified New Environmental Paradigm scale, with both attitudinal and behavioural statements, was utilized to assess the influence of environmental commitment on WTP. The analysis suggests that the rating of trekking as the most important motive for entering the ACA was the only variable with a potentially important influence on WTP for the entrance fee into the ACA. A majority of participants were willing to pay considerably more than the current entry fee of USD 27. Environmental commitment was not found to have a significant effect on WTP. The mean and median WTP values were found to be USD 71.63 and USD 60, respectively. There is some evidence that this study may have been subjected to starting point bias. As such, the WTP values may be inflated
Monoclonal Antibody Identification of Subpopulations of Cerebral Cortical Neurons Affected in Alzheimer disease
Neuronal degeneration is one of the hallmarks of Alzheimer disease (AD). Given the paucity of molecular markers available for the identification of neuronal subtypes, the specificity of neuronal loss within the cerebral cortex has been difficult to evaluate. With a panel of four monoclonal antibodies (mAbs) applied to central nervous system tissues from AD patients, we have immunocytochemically identified a population of vulnerable cortical neurons; a subpopulation of pyramidal neurons is recognized by mAbs 3F12 and 44.1 in the hippocampus and neocortex, and clusters of multipolar neurons in the entorhinal cortex reactive with mAb 44.1 show selective degeneration. Closely adjacent stellate-like neurons in these regions, identified by mAb 6A2, show striking preservation in AD. The neurons recognized by mAbs 3F12 and 44.1, to the best of our knowledge, do not comprise a single known neurotransmitter system. mAb 3A4 identifies a phosphorylated antigen that is undetectable in normal brain but accumulates early in the course of AD in somas of vulnerable neurons. Antigen 3A4 is distinct from material reactive with thioflavin S or antibody generated against paired helical filaments. Initially, antigen 3A4 is localized to neurons in the entorhinal cortex and subiculum, later in the association neocortex, and, ultimately in cases of long duration, in primary sensory cortical regions. mAb 3F12 recognizes multiple bands on immunoblots of homogenates of normal and Ad cortical tissues, whereas mAb 3A4 does not bind to immunoblots containing neurofilament proteins or brain homogenates from AD patients. Ultrastructurally, antigen 3A4 is localized to paired-helical filaments. Using these mAbs, further molecular characterization of the affected cortical neurons is now possible
Theory of agent-based market models with controlled levels of greed and anxiety
We use generating functional analysis to study minority-game type market
models with generalized strategy valuation updates that control the psychology
of agents' actions. The agents' choice between trend following and contrarian
trading, and their vigor in each, depends on the overall state of the market.
Even in `fake history' models, the theory now involves an effective overall bid
process (coupled to the effective agent process) which can exhibit profound
remanence effects and new phase transitions. For some models the bid process
can be solved directly, others require Maxwell-construction type
approximations.Comment: 30 pages, 10 figure
A Morse-theoretical analysis of gravitational lensing by a Kerr-Newman black hole
Consider, in the domain of outer communication of a Kerr-Newman black hole, a
point (observation event) and a timelike curve (worldline of light source).
Assume that the worldline of the source (i) has no past end-point, (ii) does
not intersect the caustic of the past light-cone of the observation event, and
(iii) goes neither to the horizon nor to infinity in the past. We prove that
then for infinitely many positive integers k there is a past-pointing lightlike
geodesic of (Morse) index k from the observation event to the worldline of the
source, hence an observer at the observation event sees infinitely many images
of the source. Moreover, we demonstrate that all lightlike geodesics from an
event to a timelike curve in the domain of outer communication are confined to
a certain spherical shell. Our characterization of this spherical shell shows
that in the Kerr-Newman spacetime the occurrence of infinitely many images is
intimately related to the occurrence of centrifugal-plus-Coriolis force
reversal.Comment: 14 pages, 2 figures; REVTEX; submitted to J. Math. Phy
The first direct detection of a gravitational micro-lens toward the Galactic bulge
We present a direct detection of the gravitational lens that caused the
microlensing event MACHO-95-BLG-37. This is the first fully resolved
microlensing system involving a source in the Galactic bulge, and the second
such system in general. The lens and source are clearly resolved in images
taken with the High Resolution Channel of the Advanced Camera for Surveys on
board the Hubble Space Telescope (HST) ~9 years after the microlensing event.
The presently available data are not sufficient for the final, unambiguous
identification of the gravitational lens and the microlensed source. While the
light curve models combined with the high resolution photometry for individual
objects indicate that the source is red and the lens is blue, the
color-magnitude diagram for the line of sight and the observed proper motions
strongly support the opposite case. The first scenario points to a metal-poor
lens with mass M = ~0.6 M_Sun at the distance D_l = ~4 kpc. In the second
scenario the lens could be a main-sequence star with M = 0.8 - 0.9 M_Sun about
half-way to the Galactic bulge or in the foreground disk, depending on the
extinction.Comment: Accepted for publication in Ap
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Ignoring Puff Counts: Another Shortcoming of the Federal Trade Commission Cigarette Testing Programme
OBJECTIVES; To examine reasons behind the failure of the Federal Trade Commission (FTC) to preserve puff count information from standard cigarette testing and to elucidate the importance of puff count to overall tar yields.METHODS; We reviewed industry documents on origins of the FTC test and data sets provided by the Tobacco Institute Testing Laboratory to the tobacco industry and FTC for reporting purposes.RESULTS; The majority of the tobacco industry argued for "dual reporting" of tar yields-both per cigarette and per puff. Despite a request from the Tobacco Institute in 1967 that puff count information be preserved, documents and recent communications with the FTC indicate that puff number data have not been maintained by the government. In contrast, for the cigarette industry, puff count data are a fundamental and routine part of testing and important to cigarette design. A sample of puff counts for cigarettes tested in 1996 (n = 471) shows that on average 100 mm cigarettes have 18% more puffs taken on them than do 85 mm cigarettes in standard tests (7.66 vs 9.03; p<0.01). The 10th percentile puff count is 6.8 and the 90th percentile is 8.8 for king size; the 10th percentile puff count is 8.2 and the 90th percentile is 10.0 for 100 mm cigarettes, indicating that puff counts can vary substantially among brands.CONCLUSIONS; The FTC has failed to seek or preserve puff count information that the industry finds important. Any standard test of tar and nicotine yields should at minimum preserve puff count information
Mid-infrared Variability from the Spitzer Deep Wide-field Survey
We use the multi-epoch, mid-infrared Spitzer Deep Wide-Field Survey to investigate the variability of objects in 8.1 deg^2 of the NOAO Deep Wide Field Survey Boötes field. We perform a Difference Image Analysis of the four available epochs between 2004 and 2008, focusing on the deeper 3.6 and 4.5 μm bands. Out of 474, 179 analyzed sources, 1.1% meet our standard variability selection criteria that the two light curves are strongly correlated (r > 0.8) and that their joint variance (σ_(12)) exceeds that for all sources with the same magnitude by 2σ. We then examine the mid-IR colors of the variable sources and match them with X-ray sources from the XBoötes survey, radio catalogs, 24 μm selected active galactic nucleus (AGN) candidates, and spectroscopically identified AGNs from the AGN and Galaxy Evolution Survey (AGES). Based on their mid-IR colors, most of the variable sources are AGNs (76%), with smaller contributions from stars (11%), galaxies (6%), and unclassified objects, although most of the stellar, galaxy, and unclassified sources are false positives. For our standard selection criteria, 11%-12% of the mid-IR counterparts to X-ray sources, 24 μm AGN candidates, and spectroscopically identified AGNs show variability. The exact fractions depend on both the search depth and the selection criteria. For example, 12% of the 1131 known z>1 AGNs in the field and 14%-17% of the known AGNs with well-measured fluxes in all four Infrared Array Camera bands meet our standard selection criteria. The mid-IR AGN variability can be well described by a single power-law structure function with an index of γ ≈ 0.5 at both 3.6 and 4.5 μm, and an amplitude of S _0 ≃ 0.1 mag on rest-frame timescales of 2 yr. The variability amplitude is higher for shorter rest-frame wavelengths and lower luminosities
Generalized pseudo-Newtonian potential for studying accretion disk dynamics in off-equatorial planes around rotating black holes: Description of a vector potential
We prescribe a pseudo-Newtonian vector potential for studying accretion disks
around Kerr black holes. The potential is useful to study the inner properties
of disk not confined to the equatorial plane where general relativistic effect
is indispensable. Therefore, we incorporate the essential properties of the
metric at the inner radii through the pseudo-Newtonian potential derived from
the general Kerr spacetime. The potential, reproducing most of the salient
features of the general-relativity, is valid for entire regime of Kerr
parameter. It reproduces the last stable circular orbit exactly as that in the
Kerr geometry. It also reproduces last bound orbit and energy at last stable
circular orbit with a maximum error ~7% and ~15% respectively upto an orbital
inclination 30 degree.Comment: 22 AASTeX pages including 5 postscript figures; Accepted for
publication in The Astrophysical Journa
Can Life develop in the expanded habitable zones around Red Giant Stars?
We present some new ideas about the possibility of life developing around
sub-giant and red giant stars. Our study concerns the temporal evolution of the
habitable zone. The distance between the star and the habitable zone, as well
as its width, increases with time as a consequence of stellar evolution. The
habitable zone moves outward after the star leaves the main sequence, sweeping
a wider range of distances from the star until the star reaches the tip of the
asymptotic giant branch. If life could form and evolve over time intervals from
to years, then there could be habitable planets with
life around red giant stars. For a 1 M star at the first stages of
its post main-sequence evolution, the temporal transit of the habitable zone is
estimated to be of several 10 years at 2 AU and around 10 years at 9
AU. Under these circumstances life could develop at distances in the range 2-9
AU in the environment of sub-giant or giant stars and in the far distant future
in the environment of our own Solar System. After a star completes its first
ascent along the Red Giant Branch and the He flash takes place, there is an
additional stable period of quiescent He core burning during which there is
another opportunity for life to develop. For a 1 M star there is an
additional years with a stable habitable zone in the region from 7 to 22
AU. Space astronomy missions, such as proposed for the Terrestrial Planet
Finder (TPF) and Darwin should also consider the environments of sub-giants and
red giant stars as potentially interesting sites for understanding the
development of life
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