5,685 research outputs found
Improved method and apparatus for waste collection and storage
A method and apparatus for the collection of fecal matter are designed to operate efficiently in a zero gravity environment. The system comprises a waste collection area within a body having a seat opening. Low pressure within the waste collection area directs fecal matter away from the user's buttocks and prevents the escape of undesirable gases. The user actuates a piston covered with an absorbent pad that sweeps through the waste collection area to collect fecal matter, scrub the waste collection area, press the matter against an end of the waste collection area and retracts, leaving the used pad. Multiple pads are provided on the piston to accommodate multiple uses of the system. Also a valve allows air to be drawn through the body, which valve will not be plugged with fecal matter. A sheet feeder feeds fresh sheets of absorbent pad to a face of the piston with each actuation
DichroMatch: a website for similarity searching of circular dichroism spectra
Circular dichroism (CD) spectroscopy is a widely used method for examining the structure, folding and conformational changes of proteins. A new online CD analysis server (DichroMatch) has been developed for identifying proteins with similar spectral characteristics by detecting possible structurally and functionally related proteins and homologues. DichroMatch includes six different methods for determining the spectral nearest neighbours to a query protein spectrum and provides metrics of how similar these spectra are and, if corresponding crystal structures are available for the closest matched proteins, information on their secondary structures and fold classifications. By default, DichroMatch uses all the entries in the Protein Circular Dichroism Data Bank (PCDDB) for its comparison set, providing the broadest range of publicly available protein spectra to match with the unknown protein. Alternatively, users can download or create their own specialized data sets, thereby enabling comparisons between the structures of related proteins such as wild-type versus mutants or homologues or a series of spectra of the same protein under different conditions. The DichroMatch server is freely available at http://dichromatch.cryst.bbk.ac.uk
A constraint on a varying proton--electron mass ratio 1.5 billion years after the Big Bang
A molecular hydrogen absorber at a lookback time of 12.4 billion years,
corresponding to 10 of the age of the universe today, is analyzed to put a
constraint on a varying proton--electron mass ratio, . A high resolution
spectrum of the J14432724 quasar, which was observed with the Very Large
Telescope, is used to create an accurate model of 89 Lyman and Werner band
transitions whose relative frequencies are sensitive to , yielding a limit
on the relative deviation from the current laboratory value of
.Comment: Accepted for publication in PRL. Includes supplemental materia
Evaluation of parameter estimation and field application of transgenerational genetic mark-recapture
Use of a genetic-based analogue of the traditional mark-recapture method (transgenerational genetic mark-recapture, tGMR) is rapidly expanding as a means to estimate total escapement of Pacific salmon. The tGMR approach is similar to the simple Lincoln-Peterson mark-recapture method. In tGMR, adults returning to fresh water to spawn are collected in the first sampling occasion and their juvenile offspring that are migrating out to sea are collected during the second sampling occasion. Recaptures are determined by the number of parent-offspring pairs identified through genetic parentage analysis of the adult and juvenile collections. Two versions of tGMR are currently in use, referred to as the âwith replacementâ and the âwithout replacementâ models. For each version, parentage analysis is used to estimate model parameters. I evaluated accuracy of tGMR parameters estimated by genetic parentage analysis by conducting a series of simulations that mimicked application of the approach for estimating escapement of a small northern California coho salmon population. Accuracy was evaluated by comparing known values of the parameters taken from the simulated pedigrees to estimated values based upon parentage analysis of SNP genotypes using the software COLONY. All parentage-based parameter estimates were biased, (ranging from -0.40 to 0.23) indicating improvements in parentage analysis are needed for applications of tGMR. To further evaluate tGMR, I applied this method to coho salmon in two northern California streams resulting in total escapement estimates using the âwith replacementâ and âwithout replacementâ models of 576 and 444 (Mill Creek, 2011-2012), 131 and 193 (Mill Creek, 2012-2013), and 430 and 468 (Freshwater Creek, 2012-2013). The tGMR approach shows promise for highly fecund species because the number of individuals captured during the second sampling occasion can greatly exceed the adult population size. This can possibly lead to lower variance in tGMR estimates in comparison to traditional mark-recapture estimators, but improvements in genetic parentage analysis are needed to reduce or eliminate bias from parentage analysis that results in biased estimates of total escapement using tGMR
ValiDichro: a website for validating and quality control of protein circular dichroism spectra
Circular dichroism (CD) spectroscopy is widely used in structural biology as a technique for examining the structure, folding and conformational changes of proteins. A new server, ValiDichro, has been developed for checking the quality and validity of CD spectral data and metadata, both as an aid to data collection and processing and as a validation procedure for spectra to be included in publications. ValiDichro currently includes 25 tests for data completeness, consistency and quality. For each test that is done, not only is a validation report produced, but the user is also provided with suggestions for correcting or improving the data. The ValiDichro server is freely available at http://valispec.cryst.bbk.ac.uk/circularDichroism/ValiDichro/upload.html
The Luminosity Functions of Old and Intermediate-Age Globular Clusters in NGC 3610
The WFPC2 Camera on board HST has been used to obtain high-resolution images
of NGC 3610, a dynamically young elliptical galaxy. These observations
supersede shorter, undithered HST observations where an intermediate-age
population of globular clusters was first discovered. The new observations show
the bimodal color distribution of globular clusters more clearly, with peaks at
(V-I)o = 0.95 and 1.17. The luminosity function (LF) of the blue, metal-poor
population of clusters in NGC 3610 turns over, consistent with a Gaussian
distribution with a peak Mv ~= -7.0, similar to old globular-cluster
populations in ellipticals. The red, metal-rich population of clusters has a LF
that is more extended toward both the bright and faint ends, as expected for a
cluster population of inter-mediate age. It is well fit by a power law with an
exponent of alpha = -1.78 +-0.05, or -1.90+-0.07 when corrected for
observational scatter. A Kolmogorov-Smirnov test confirms the significant
difference between the LFs of the red and blue clusters, with a probability of
less than 0.1% that they come from the same population. A comparison with the
Fall & Zhang cluster disruption models shows marginal agreement with the
observed LF, although there are differences in detail. In particular, there is
no clear evidence of the predicted turnover at the faint end. A by-product of
the analysis is the demonstration that, at any given metallicity, the peak of
the LF should remain nearly constant from 1.5 Gyr to 12 Gyr, since the effect
of the disruption of faint clusters is almost perfectly balanced by the fading
of the clusters. This may help explain the apparent universality of the peak of
the globular cluster luminosity function. (Abridged)Comment: 32 pages, LaTeX, 13 PS figures, 1 table; to appear in AJ (July 2002
First Starbursts at high redshift: Formation of globular clusters
Numerical simulations of a Milky Way-size galaxy demonstrate that globular
clusters with the properties similar to observed can form naturally at z > 3 in
the concordance Lambda-CDM cosmology. The clusters in our model form in the
strongly baryon-dominated cores of supergiant molecular clouds. The first
clusters form at z = 12, while the peak formation appears to be at z = 3-5. The
zero-age mass function of globular clusters can be approximated by a power-law
dN/dM ~ M^-2, in agreement with observations of young massive star clusters.Comment: 4 pages, proceedings of the "Multi-Wavelength Cosmology" meeting,
June 200
The Infrared Massive Stellar Content of M83
We present an analysis of archival Spitzer images and new ground-based and
Hubble Space Telescope (HST) near-infrared (IR) and optical images of the field
of M83 with the goal of identifying rare, dusty, evolved massive stars. We
present point source catalogs consisting of 3778 objects from
Infrared Array Camera (IRAC) Band 1 (3.6 m) and Band 2 (4.5 m), and
975 objects identified in Magellan 6.5m FourStar near-IR and
images. A combined catalog of coordinate matched near- and mid-IR point sources
yields 221 objects in the field of M83. Using this photometry we identify 185
massive evolved stellar candidates based on their location in color-magnitude
and color-color diagrams. We estimate the background contamination to our
stellar candidate lists and further classify candidates based on their
appearance in Wide Field Camera 3 (WFC3) observations of M83. We find 49
strong candidates for massive stars which are very promising objects for
spectroscopic follow-up. Based on their location in a versus
diagram, we expect at least 24, or roughly 50%, to be confirmed as red
supergiants.Comment: 32 pages, 23 figures, accepted for publication in A&
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