66,424 research outputs found
Modified algesimeter provides accurate depth measurements
Algesimeter which incorporates a standard sensory needle with a sensitive micrometer, measures needle point depth penetration in pain tolerance research. This algesimeter provides an inexpensive, precise instrument with assured validity of recordings in those biomedical areas with a requirement for repeated pain detection or ascertaining pain sensitivity
On the Form of the Spitzer Leavitt Law and its Dependence on Metallicity
The form and metallicity-dependence of Spitzer mid-infrared Cepheid relations
are a source of debate. Consequently, Spitzer 3.6 and 4.5 um period-magnitude
and period-color diagrams were re-examined via robust routines, thus providing
the reader an alternative interpretation to consider. The relations (nearly
mean-magnitude) appear non-linear over an extensive baseline (0.45< logPo
<2.0), particularly the period-color trend, which to first-order follows
constant (3.6-4.5) color for shorter-period Cepheids and may transition into a
bluer convex trough at longer-periods. The period-magnitude functions can be
described by polynomials (e.g., [3.6 um]=Ko-(3.071+-0.059)
logPo-(0.120+-0.032)logPo^2), and Cepheid distances computed using 3.6 and 4.5
um relations agree and the latter provides a first-order consistency check (CO
sampled at 4.5 um does not seriously compromise those distances). The
period-magnitude relations appear relatively insensitive to metallicity
variations ([Fe/H]~0 to -0.75), a conclusion inferred partly from comparing
galaxy distances established from those relations and NED-D (n>700), yet a
solid conclusion awaits comprehensive mid-infrared observations for metal-poor
Cepheids in IC 1613 ([Fe/H] -1). The Cepheid-based distances were corrected for
dust obscuration using a new ratio (i.e., A(3.6)/E(B-V)=0.18+-0.06) deduced
from GLIMPSE (Spitzer) data.Comment: To appear in Ap
Visibility graphs and landscape visibility analysis
Visibility analysis based on viewsheds is one of the most frequently used GIS analysis tools. In this paper we present an approach to visibility analysis based on the visibility graph. A visibility graph records the pattern of mutual visibility relations in a landscape, and provides a convenient way of storing and further analysing the results of multiple viewshed analyses for a particular landscape region. We describe how a visibility graph may be calculated for a landscape. We then give examples, which include the interactive exploration ofa landscape, and the calculation of new measures of a landscape?s visual properties based on graph metrics ? in particular, neighbourhood clustering coefficient and path length analysis. These analyses suggest that measures derived from the visibility graph may be of particular relevance to the growing interest in quantifying the perceptual characteristics of landscapes
Graduate perceptions of a UK university based coach education programme, and impacts on development and employability
This investigation explored graduatesā perceptions and experiences of a Higher Education (HE) coach education programme. It aimed to identify if this formal learning source had impacted upon attendeesā development and employability, while uncovering information to potentially inform future provision. 10 graduate coaches who had completed coaching modules at a United Kingdom (UK) HE institution participated in in-depth semi-structured interviews. Graduate coaches highlighted a positive educational experience that developed critical analytical skills, assisted in their perceived accelerated development, and enhanced employability. Using Carl Rogersā work as a framework to analyse the data, it is demonstrated that the findings collectively offer implicit support for the adoption of a person-centred educational philosophy. Further research and debate is identified as necessary to ascertain whether the person-centred approach offers a legitimate and effective alternative form of coach education.Peer reviewe
Alessi 95 and the short period Cepheid SU Cassiopeiae
The parameters for the newly-discovered open cluster Alessi 95 are
established on the basis of available photometric and spectroscopic data, in
conjunction with new observations. Colour excesses for
spectroscopically-observed B and A-type stars near SU Cas follow a reddening
relation described by E(U-B)/E(B-V)=0.83+0.02*E(B-V), implying a value of
R=Av/E(B-V)~2.8 for the associated dust. Alessi 95 has a mean reddening of
E(B-V)_(B0)=0.35+-0.02 s.e., an intrinsic distance modulus of Vo-Mv=8.16+-0.04
s.e. (+-0.21 s.d.), d=429+-8 pc, and an estimated age of 10^8.2 yr from ZAMS
fitting of available UBV, CCD BV, NOMAD, and 2MASS JHKs observations of cluster
stars. SU Cas is a likely cluster member, with an inferred space reddening of
E(B-V)=0.33+-0.02 and a luminosity of =-3.15+-0.07 s.e., consistent with
overtone pulsation (P_FM=2.75 d), as also implied by the Cepheid's light curve
parameters, rate of period increase, and Hipparcos parallaxes for cluster
stars. There is excellent agreement of the distance estimates for SU Cas
inferred from cluster ZAMS fitting, its pulsation parallax derived from the
infrared surface brightness technique, and Hipparcos parallaxes, which all
agree to within a few percent.Comment: Accepted for Publication (MNRAS
Identifying Contaminated K-band Globular Cluster RR Lyrae Photometry
Acquiring near-infrared K-band (2.2 um) photometry for RR Lyrae variables in
globular clusters and nearby galaxies is advantageous since the resulting
distances are less impacted by reddening and metallicity. However, K-band
photometry for RR Lyrae variables in M5, Reticulum, M92, omega Cen, and M15
display clustercentric trends. HST ACS data imply that multiple stars in close
proximity to RR Lyrae variables located near the cluster core, where the
stellar density increases markedly, are generally unresolved in ground-based
images. RR Lyrae variables near the cluster cores appear to suffer from
photometric contamination, thereby yielding underestimated cluster distances
and biased ages. The impact is particularly pernicious since the contamination
propagates a systematic uncertainty into the distance scale, and hinders the
quest for precision cosmology. The clustercentric trends are probably
unassociated with variations in chemical composition since an empirical K-band
period-magnitude relation inferred from Araucaria/VLT data for RR Lyrae
variables in the Sculptor dSph exhibits a negligible metallicity dependence:
(0.059+-0.095)[Fe/H], a finding that supports prior observational results. A
future multi-epoch high-resolution near-infrared survey, analogous to the
optical HST ACS Galactic Globular Cluster Survey, may be employed to establish
K-band photometry for the contaminating stars discussed here.Comment: To appear in PAS
Anisotropic magnetohydrodynamic turbulence in a strong external magnetic field
A strong external dc magnetic field introduces a basic anisotropy into incompressible magnetohydrodynamic turbulence. The modifications that this is likely to produce in the properties of the turbulence are explored for the high Reynolds number case. The conclusion is reached that the turbulent spectrum splits into two parts: an essentially two dimensional spectrum with both the velocity field and magnetic fluctuations perpendicular to the dc magnetic field, and a generally weaker and more nearly isotropic spectrum of Alfven waves. A minimal characterization of the spectral density tensors is given. Similarities to measurements from the Culham-Harwell Zeta pinch device and the UCLA Macrotor Tokamak are remarked upon, as are certain implications for the Belcher and Davis measurements of magnetohydrodynamic turbulence in the solar wind
- ā¦