167 research outputs found
A Different Approach to Horse Handling, Based on the Jeffery Method
A method of horse training is discussed which is based on an old technique known in Australia as the Jeffery method. It makes use of several behavioral principles, including understanding of horse behavior, reinforcement for desired behavior, and use of flight distance principles
A Different Approach to Horse Handling, Based on the Jeffery Method
A method of horse training is discussed, which is based on an old technique known in Australia as the Jeffery method. It uses several behavioral principles, including understanding horse behavior, reinforcement for desired behavior, and flight distance principles
Combination interventions for Hepatitis C and Cirrhosis reduction among people who inject drugs: An agent-based, networked population simulation experiment
Hepatitis C virus (HCV) infection is endemic in people who inject drugs
(PWID), with prevalence estimates above 60 percent for PWID in the United
States. Previous modeling studies suggest that direct acting antiviral (DAA)
treatment can lower overall prevalence in this population, but treatment is
often delayed until the onset of advanced liver disease (fibrosis stage 3 or
later) due to cost. Lower cost interventions featuring syringe access (SA) and
medically assisted treatment (MAT) for addiction are known to be less costly,
but have shown mixed results in lowering HCV rates below current levels. Little
is known about the potential synergistic effects of combining DAA and MAT
treatment, and large-scale tests of combined interventions are rare. While
simulation experiments can reveal likely long-term effects, most prior
simulations have been performed on closed populations of model agents--a
scenario quite different from the open, mobile populations known to most health
agencies. This paper uses data from the Centers for Disease Control's National
HIV Behavioral Surveillance project, IDU round 3, collected in New York City in
2012 by the New York City Department of Health and Mental Hygiene to
parameterize simulations of open populations. Our results show that, in an open
population, SA/MAT by itself has only small effects on HCV prevalence, while
DAA treatment by itself can significantly lower both HCV and HCV-related
advanced liver disease prevalence. More importantly, the simulation experiments
suggest that cost effective synergistic combinations of the two strategies can
dramatically reduce HCV incidence. We conclude that adopting SA/MAT
implementations alongside DAA interventions can play a critical role in
reducing the long-term consequences of ongoing infection
Near-UV transit photometry of HAT-P-32 b with the LBT: Silicate aerosols in the planetary atmosphere
Broad-band exoplanet transit photometry can characterize the planetary
atmosphere when observed at multiple selected filters. This observing technique
can reveal gradients in the spectra of extrasolar planets, for example the
slope of decreasing opacity from short to long optical wavelengths caused by
aerosol scattering. In this work we observed a transit of the hot Jupiter
HAT-P-32 b in the shortest wavelength possible from the ground using the Large
Binocular Telescope (LBT). The data comprise the best-quality ground-based
U-band taken so far of an exoplanet transit. Compared to broad-band
observations of intermediate and long optical wavelength published previously,
a clear scattering slope in the planetary transmission spectrum is revealed.
Most likely, the scattering particles are magnesium silicate aerosols larger
than 0.1 micrometer. We define a spectral index to compare this scattering
feature of HAT-P-32 b to published results of other exoplanets. It turns out to
be very typical in amplitude within the comparison sample. Furthermore, we
searched for correlation in this sample of the spectral index with planetary
equilibrium temperature, surface acceleration and stellar activity indicator,
but could not reveal any.Comment: accepted for publication in Astronomical Notes (AN). Version2,
several typos correcte
The XUV environments of exoplanets from Jupiter-size to super-Earth
Planets that reside close-in to their host star are subject to intense high-energy irradiation. Extreme-ultraviolet (EUV) and X-ray radiation (together, XUV) is thought to drive mass-loss from planets with volatile envelopes. We present XMM–Newton observations of six nearby stars hosting transiting planets in tight orbits (with orbital period, Porb < 10 d), wherein we characterize the XUV emission from the stars and subsequent irradiation levels at the planets. In order to reconstruct the unobservable EUV emission, we derive a new set of relations from Solar TIMED/SEE data that are applicable to the standard bands of the current generation of X-ray instruments. From our sample, WASP-80b and HD 149026b experience the highest irradiation level, but HAT-P-11b is probably the best candidate for Ly α evaporation investigations because of the system’s proximity to the Solar system. The four smallest planets have likely lost a greater percentage of their mass over their lives than their larger counterparts. We also detect the transit of WASP-80b in the near-ultraviolet with the optical monitor on XMM–Newton
Excitonic Instability in the Transition from the Black Phase to the Golden Phase of SmS under Pressure Investigated by Infrared Spectroscopy
We report the pressure-dependent optical reflectivity spectra of a strongly
correlated insulator, samarium monosulfide (SmS), in the far- and
middle-infrared regions to investigate the origin of the pressure-induced phase
transition from the black phase to the golden phase. The energy gap becomes
narrow with increasing pressure in the black phase. A valence transition from
Sm2+ in the black phase to mainly Sm3+ in the golden phase accompanied by
spectral change from insulator to metal were observed at the transition
pressure of 0.65 GPa. The black-to-golden phase transition occurs when the
energy gap size of black SmS becomes the same as the binding energy of the
exciton at the indirect energy gap before the gap closes. This result indicates
that the valence transition originates from an excitonic instability.Comment: 5 pages, 4 figures. To be published in J. Phys. Soc. Jpn. Vol. 77,
No. 1
Family and healthcare professionals’ perceptions of a pilot hospice at home programme for children: a qualitative study
Density split statistics: Joint model of counts and lensing in cells
© 2018 American Physical Society. We present density split statistics, a framework that studies lensing and counts-in-cells as a function of foreground galaxy density, thereby providing a large-scale measurement of both 2-point and 3-point statistics. Our method extends our earlier work on trough lensing and is summarized as follows: given a foreground (low redshift) population of galaxies, we divide the sky into subareas of equal size but distinct galaxy density. We then measure lensing around uniformly spaced points separately in each of these subareas, as well as counts-in-cells statistics (CiC). The lensing signals trace the matter density contrast around regions of fixed galaxy density. Through the CiC measurements this can be related to the density profile around regions of fixed matter density. Together, these measurements constitute a powerful probe of cosmology, the skewness of the density field and the connection of galaxies and matter. In this paper we show how to model both the density split lensing signal and CiC from basic ingredients: a non-linear power spectrum, clustering hierarchy coefficients from perturbation theory and a parametric model for galaxy bias and shot-noise. Using N-body simulations, we demonstrate that this model is sufficiently accurate for a cosmological analysis on year 1 data from the Dark Energy Survey
Dark Energy Survey Year 1 results: measurement of the galaxy angular power spectrum
We use data from the first-year observations of the DES collaboration to measure the galaxy angular power spectrum (APS), and search for its BAO feature. We test our methodology in a sample of 1800 DES Y1-like mock catalogues. We use the pseudo-C method to estimate the APS and the mock catalogues to estimate its covariance matrix. We use templates to model the measured spectra and estimate template parameters firstly from the C’s of the mocks using two different methods, a maximum likelihood estimator and a Markov Chain Monte Carlo, finding consistent results with a good reduced χ2. Robustness tests are performed to estimate the impact of different choices of settings used in our analysis. Finally, we apply our method to a galaxy sample constructed from DES Y1 data specifically for LSS studies. This catalogue comprises galaxies within an effective area of 1318 deg2 and 0.6 < z < 1.0. We find that the DES Y1 data favour a model with BAO at the 2.6σ C.L. However, the goodness of fit is somewhat poor, with χ2/(d.o.f.) = 1.49. We identify a possible cause showing that using a theoretical covariance matrix obtained from C ’s that are better adjusted to data results in an improved value of χ2/(dof) = 1.36 which is similar to the value obtained with the real-space analysis. Our results correspond to a distance measurement of DA (zeff = 0.81)/rd = 10.65 ± 0.49, consistent with the main DES BAO findings. This is a companion paper to the main DES BAO article showing the details of the harmonic space analysis
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