588 research outputs found
Metacarpophalangeal pattern profile analysis of a sample drawn from a North Wales population
This is tha author's PDF version of an article published in Annals of human biology© 2001. The definitive version is available at http://www.tandf.co.uk/journalsSexual dimorphism and population differences were investigated using metacarpophalangeal pattern profile (MCPP) analysis. Although it is an anthropmetric technique, MCPP analysis is more frequently used in genetic syndrome analysis and has been under-used in the study of human groups. The present analysis used a series of hand radiographics from Gwynedd, North Wales, to make comparisons, first, between the sexes within the sample and then with previously reported data from Japan. The Welsh sexes showed MCPP analyses that indicated size and shape differences but certain similarities in shape were also evident. Differences with the Japanese data were more marked. MCPP anlysis is a potentially useful anthropmetric technique but requires further statistical development
Investigation of planetary ionospheres
Feasibility of using radio sounding techniques to investigate ionospheric properties of planet
The Rate of Type Ia Supernovae at z~0.2 from SDSS-I Overlapping Fields
In the course of the Sloan Digital Sky Survey (SDSS-I), a large fraction of
the surveyed area was observed more than once due to field tiling overlap,
usually at different epochs. We utilize some of these data to perform a
supernova (SN) survey at a mean redshift of z=0.2. Our archival search, in ~ 5%
of the SDSS-I overlap area, produces 29 SN candidates clearly associated with
host galaxies. Using the Bayesian photometric classification algorithm of
Poznanski et al., and correcting for classification bias, we find 17 of the 29
candidates are likely Type Ia SNe. Accounting for the detection efficiency of
the survey and for host extinction, this implies a Type Ia SN rate of
R=14.0+(2.5,1.4}-(2.5,1.1}+/-2.5 10^-14 h(70)^2 yr^-1 L_sun^-1, where the
errors are Poisson error, systematic detection efficiency error, and systematic
classification error, respectively. The volumetric rate is
R=1.89+(0.42,0.18)-(0.34,0.15)+/-0.42 10^-5 yr^-1 h(70)^3 Mpc^-3. Our
measurement is consistent with other rate measurements at low redshift. An
order of magnitude increase in the number of SNe is possible by analyzing the
full SDSS-I database.Comment: 11 pages, 7 figures, Accepted by MNRA
Supernovae in Low-Redshift Galaxy Clusters: Observations by the Wise Observatory Optical Transient Search (WOOTS)
We describe the Wise Observatory Optical Transient Search (WOOTS), a survey
for supernovae (SNe) and other variable and transient objects in the fields of
redshift 0.06-0.2 Abell galaxy clusters. We present the survey design and
data-analysis procedures, and our object detection and follow-up strategies. We
have obtained follow-up spectroscopy for all viable SN candidates, and present
the resulting SN sample here. Out of the 12 SNe we have discovered, seven are
associated with our target clusters while five are foreground or background
field events. All but one of the SNe (a foreground field event) are Type Ia
SNe. Our non-cluster SN sample is uniquely complete, since all SN candidates
have been either spectroscopically confirmed or ruled out. This allows us to
estimate that flux-limited surveys similar to WOOTS would be dominated (~80%)
by SNe Ia. Our spectroscopic follow-up observations also elucidate the
difficulty in distinguishing active galactic nuclei from SNe. In separate
papers we use the WOOTS sample to derive the SN rate in clusters for this
redshift range, and to measure the fraction of intergalactic cluster SNe. We
also briefly report here on some quasars and asteroids discovered by WOOTS.Comment: Submitted to ApJ. Comments welcom
The Massive Progenitor of the Possible Type II-Linear Supernova 2009hd in Messier 66
We present observations of SN2009hd in the nearby galaxy M66. This SN is one
of the closest to us in recent years but heavily obscured by dust, rendering it
unusually faint in the optical, given its proximity. We find that the observed
properties of SN2009hd support its classification as a possible Type II-L SN, a
relatively rare subclass of CC-SNe. High-precision relative astrometry has been
employed to attempt to identify a SN progenitor candidate, based on a
pixel-by-pixel comparison between HST F555W and F814W images of the SN site
prior to explosion and at late times. A progenitor candidate is identified in
the F814W images only; this object is undetected in F555W. Significant
uncertainty exists in the astrometry, such that we cannot definitively identify
this object as the SN progenitor. Via insertion of artificial stars into the
pre-SN HST images, we are able to constrain the progenitor's properties to
those of a possible supergiant, with M(F555W)0>-7.6 mag and (V-I) 0>0.99 mag.
The magnitude and color limits are consistent with a luminous RSG; however,
they also allow for the possibility that the star could have been more yellow
than red. From a comparison with theoretical massive-star evolutionary tracks,
which include rotation and pulsationally enhanced mass loss, we can place a
conservative upper limit on the initial mass for the progenitor of <20 M_sun.
If the actual mass of the progenitor is near the upper range allowed by our
derived mass limit, then it would be consistent with that for the identified
progenitors of the SNII-L 2009kr and the high-luminosity SNII-P 2008cn. The
progenitors of these three SNe may possibly bridge the gap between lower-mass
RSG that explode as SNeII-P and LBV, or more extreme RSG, from which the more
exotic SNeII-n may arise. Very late-time imaging of the SN2009hd site may
provide us with more clues regarding the true nature of its progenitor.Comment: 19 pages, 9 figures, 3 tables, accepted for publication in Ap
Role of transport performance on neuron cell morphology
The compartmental model is a basic tool for studying signal propagation in
neurons, and, if the model parameters are adequately defined, it can also be of
help in the study of electrical or fluid transport. Here we show that the input
resistance, in different networks which simulate the passive properties of
neurons, is the result of an interplay between the relevant conductances,
morphology and size. These results suggest that neurons must grow in such a way
that facilitates the current flow. We propose that power consumption is an
important factor by which neurons attain their final morphological appearance.Comment: 9 pages with 3 figures, submitted to Neuroscience Letter
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