304 research outputs found
Active Seismic frame synchronization
This ATM determines the probability of sync, false sync, and the probability of loosing sync for an 11 bit and 6 bit frame sync code. The number of bits/frame range from 1344 to 4032. The amount of data lost during loss of sync is also determined.prepared by H. Lanning
Proper Motions of Faint UV-Bright Sources in the Sandage Two-color Survey of the Galactic Plane
Proper motions with values >10 mas/yr or <-10 mas/yr have been extracted from
the USNO-B1.0 and Tycho II catalogues for all Lanning UV-bright sources
identified in the Sandage Two-color Survey of the Galactic Plane and presented
in Papers I-VI. Of the 572 sources examined, we find at least 213 which exhibit
a significantly large proper motion. Based on the location of the sources in a
reduced proper motion diagram, we demonstrate that about two thirds of the high
proper motion sources are likely or very likely to be heretofore unidentified
white dwarfs.Comment: 15 pages, to appear in Publications of the Astronomical Society of
the Pacifi
Cool Customers in the Stellar Graveyard II: Limits to Substellar Objects Around Nearby DAZ White Dwarfs
Results from a concerted Hubble Space Telescope (HST) survey of nearby white
dwarfs for substellar objects is presented. A total of 7 DAZ white dwarfs with
distances of 50 pc had high contrast and high spatial resolution NICMOS
coronagraphic images taken to search for candidate substellar objects at
separations \ltorder10\arcsec away. Limits to unresolved companions are
derived through analysis of 2MASS photometry of the white dwarfs compared to
expected fluxes based on the WDs effective temperature, distance, and gravity.
From our survey with HST we find several candidate companions, which have
been or will be followed up with second epoch observations. We find that for
four of the white dwarfs we are sensitive to planetary companions \gtorder10
M, and sensitive to companions 18 M for all of the targets.
The lack of significant near infrared excesses for our targets limits any kind
of unresolved companions present to be substellar. In light of these results we
make several comments on the possibility of determining the origin of white
dwarfs with metals in their atmospheres.Comment: 11 pages, 7 figures, emulateapj, revisions to figures and text, to
appear in September A
Immunolocalization of KATP channel subunits in mouse and rat cardiac myocytes and the coronary vasculature.
BACKGROUND: Electrophysiological data suggest that cardiac KATP channels consist of Kir6.2 and SUR2A subunits, but the distribution of these (and other KATP channel subunits) is poorly defined. We examined the localization of each of the KATP channel subunits in the mouse and rat heart. RESULTS: Immunohistochemistry of cardiac cryosections demonstrate Kir6.1 protein to be expressed in ventricular myocytes, as well as in the smooth muscle and endothelial cells of coronary resistance vessels. Endothelial capillaries also stained positive for Kir6.1 protein. Kir6.2 protein expression was found predominantly in ventricular myocytes and also in endothelial cells, but not in smooth muscle cells. SUR1 subunits are strongly expressed at the sarcolemmal surface of ventricular myocytes (but not in the coronary vasculature), whereas SUR2 protein was found to be localized predominantly in cardiac myocytes and coronary vessels (mostly in smaller vessels). Immunocytochemistry of isolated ventricular myocytes shows co-localization of Kir6.2 and SUR2 proteins in a striated sarcomeric pattern, suggesting t-tubular expression of these proteins. Both Kir6.1 and SUR1 subunits were found to express strongly at the sarcolemma. The role(s) of these subunits in cardiomyocytes remain to be defined and may require a reassessment of the molecular nature of ventricular KATP channels. CONCLUSIONS: Collectively, our data demonstrate unique cellular and subcellular KATP channel subunit expression patterns in the heart. These results suggest distinct roles for KATP channel subunits in diverse cardiac structures
Paging Materials to Maintain Quality Library Service During a Two-Year Renovation
Beginning in July 2002, the Health Sciences Library at the University of North Carolina at Chapel Hill underwent an 11 million dollar renovation. During three phases of the renovation, parts of the collection were inaccessible to patrons. In order to continue to make the library’s collection available, library staff created a paging system. Patrons submitted requests for needed library materials using paper and electronic forms and library staff retrieved the requested items. The paging service was modified three times based on prior experience. Patrons were generally satisfied with the service. The renovation ended in December 2004
Optimal static pricing for a tree network
We study the static pricing problem for a network service provider in a loss system with a tree structure. In the network, multiple classes share a common inbound link and then have dedicated outbound links. The motivation is from a company that sells phone cards and needs to price calls to different destinations. We characterize the optimal static prices in order to maximize the steady-state revenue. We report new structural findings as well as alternative proofs for some known results. We compare the optimal static prices versus prices that are asymptotically optimal, and through a set of illustrative numerical examples we show that in certain cases the loss in revenue can be significant. Finally, we show that static prices obtained using the reduced load approximation of the blocking probabilities can be easily obtained and have near-optimal performance, which makes them more attractive for applications.Massachusetts Institute of Technology. Center for Digital BusinessUnited States. Office of Naval Research (Contract N00014-95-1-0232)United States. Office of Naval Research (Contract N00014-01-1-0146)National Science Foundation (U.S.) (Contract DMI-9732795)National Science Foundation (U.S.) (Contract DMI-0085683)National Science Foundation (U.S.) (Contract DMI-0245352
Scattered-Light Echoes from the Historical Galactic Supernovae Cassiopeia A and Tycho (SN 1572)
We report the discovery of an extensive system of scattered light echo
arclets associated with the recent supernovae in the local neighbourhood of the
Milky Way: Tycho (SN 1572) and Cassiopeia A. Existing work suggests that the
Tycho SN was a thermonuclear explosion while the Cas A supernova was a core
collapse explosion. Precise classifications according to modern nomenclature
require spectra of the outburst light. In the case of ancient SNe, this can
only be done with spectroscopy of their light echo, where the discovery of the
light echoes from the outburst light is the first step. Adjacent light echo
positions suggest that Cas A and Tycho may share common scattering dust
structures. If so, it is possible to measure precise distances between
historical Galactic supernovae. On-going surveys that alert on the development
of bright scattered-light echo features have the potential to reveal detailed
spectroscopic information for many recent Galactic supernovae, both directly
visible and obscured by dust in the Galactic plane.Comment: 4 pages, 4 color figures, accepted for publication in ApJ
Recovered memories, satanic abuse, Dissociative Identity Disorder and false memories in the UK: a survey of Clinical Psychologists and Hypnotherapists
An online survey was conducted to examine psychological therapists’ experiences of, and beliefs about, cases of recovered memory, satanic / ritualistic abuse, Multiple Personality Disorder / Dissociative Identity Disorder, and false memory. Chartered Clinical Psychologists (n=183) and Hypnotherapists (n=119) responded. In terms of their experiences, Chartered Clinical Psychologists reported seeing more cases of satanic / ritualistic abuse compared to Hypnotherapists who, in turn, reported encountering more cases of childhood sexual abuse recovered for the first time in therapy, and more cases of suspected false memory. Chartered Clinical Psychologists were more likely to rate the essential accuracy of reports of satanic / ritualistic abuse as higher than Hypnotherapists. Belief in the accuracy of satanic / ritualistic abuse and Multiple Personality Disorder / Dissociative Identity Disorder reports correlated negatively with the belief that false memories were possible
I-SceI-Mediated Double-Strand Break Does Not Increase the Frequency of Homologous Recombination at the Dct Locus in Mouse Embryonic Stem Cells
Targeted induction of double-strand breaks (DSBs) at natural endogenous loci was shown to increase the rate of gene replacement by homologous recombination in mouse embryonic stem cells. The gene encoding dopachrome tautomerase (Dct) is specifically expressed in melanocytes and their precursors. To construct a genetic tool allowing the replacement of Dct gene by any gene of interest, we generated an embryonic stem cell line carrying the recognition site for the yeast I-SceI meganuclease embedded in the Dct genomic segment. The embryonic stem cell line was electroporated with an I-SceI expression plasmid, and a template for the DSB-repair process that carried sequence homologies to the Dct target. The I-SceI meganuclease was indeed able to introduce a DSB at the Dct locus in live embryonic stem cells. However, the level of gene targeting was not improved by the DSB induction, indicating a limited capacity of I-SceI to mediate homologous recombination at the Dct locus. These data suggest that homologous recombination by meganuclease-induced DSB may be locus dependent in mammalian cells
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