10,600 research outputs found
Spectroscopy and Photometry of Cataclysmic Variable Candidates from the Catalina Real Time Survey
The Catalina Real Time Survey (CRTS) has found over 500 cataclysmic variable
(CV) candidates, most of which were previously unknown. We report here on
followup spectroscopy of 36 of the brighter objects. Nearly all the spectra are
typical of CVs at minimum light. One object appears to be a flare star, while
another has a spectrum consistent with a CV but lies, intriguingly, at the
center of a small nebulosity. We measured orbital periods for eight of the CVs,
and estimated distances for two based on the spectra of their secondary stars.
In addition to the spectra, we obtained direct imaging for an overlapping
sample of 37 objects, for which we give magnitudes and colors. Most of our new
orbital periods are shortward of the so-called period gap from roughly 2 to 3
hours. By considering the cross-identifications between the Catalina objects
and other catalogs such as the Sloan Digital Sky Survey, we argue that a large
number of cataclysmic variables remain uncatalogued. By comparing the CRTS
sample to lists of previously-known CVs that CRTS does not recover, we find
that the CRTS is biased toward large outburst amplitudes (and hence shorter
orbital periods). We speculate that this is a consequence of the survey
cadence.Comment: Accepted for publication in The Astronomical Journal. 35 pages,
including 7 figure
Towards developing understanding of the drivers, constraints from the consumption values underpinning participation in physical activity.
Overall participation rates in physical activity across the UK have remained relatively static since the mid 1980s, with attendant causes for concern about the inequality of participation rates amongst various target groups that may be worthy of specific investigation. Behaviour change models from the fields of leisure studies, consumer behaviour and social psychology offer conceptualisation of a notion of exchange underpinning the expectancy-value process, noting that, in order to facilitate a voluntary exchange there needs to be a value proposition that induces action and/or motivates effort from the consumer. It is therefore reasonable to assume that such value expectations will also influence health behaviour intentions.
This paper therefore aims to offer a more developing understanding of the drivers, constraints and experiential consumption values underpinning participation in physical activity. Results suggest that, rather than focusing on the social and altruistic values of behavioural changes, and given that the functional value of participation is already well-known (if not always acted upon) through social marketing campaignsâ educational efforts and through the media, it may be worth policymakers and leisure service providers focusing more on highlighting the emotional benefits to be gained, especially when targeting women to increase their participation in physical activit
Why donât people do whatâs good for them? : an examination of the value(s) which affect physical activity.
One of the 21st Centuryâs major public health issues is physical inactivity. Therefore one of the greatest public policy challenges is to find new ways of conferring to an inactive population the health related benefits that arise from being physically active in a way that not only leads to knowledge acquisition, but which also leads to increased levels of participation in physical activity. Participation rates in physical activity across the UK have remained stubbornly static since the midâ 1980s and retain a range of gender, age, socialâeconomic and ethnic participation inequalities.
Research has indicated that, when compared to men, women are more likely to: lead sedentary lifestyles (Hausenblas and SymonsâDowns, 2005), experience poor health (Bertakis et al., 2000), and feel more uncomfortable about their body image (Liechty et al., 2006), factors which impact on and/or result in lower participation levels, suggesting that social marketing campaigns to date have been largely ineffective. A central tenet of social marketing is to achieve a voluntary, not forced or coerced behaviour change by emphasising a value proposition that induces action from the consumer. Set in the context of publicly funded leisure facilities this paper offers empirical insights regarding the drivers, constraints and consumption values underpinning womenâs participation in physical activity. Our results suggest that value perceptions regarding the costs, benefits and enjoyment of exercise do not differ with gender. However, statistically significant differences exist between the genders regarding: the physical environment within which exercise occurs; the quality of service experience; and intrinsic factors such as social and altruistic value.
Insights gained from this research may be able to inform policymakers and leisure services providers regarding more effective methods of engaging âhardâtoâreachâ groups, such as women. Specifically, our findings suggest that exercise adoption is likely to be increased with targeted social marketing campaigns which focus on emphasising the experiential aspects of consuming physical activity viewed from the perspective of valueâinâuse rather than from the traditional priceâbased perspective that tends to focus on the trade off of costs against benefits
Passive instrumentation and stimuli generation for Saturn IB equipment checkout. Volume I - Summary technical report Final technical report, 26 Jun. 1965 - 31 May 1966
Passive instrumentation and stimuli generation for Saturn IB equipment checkout - nondestructive testin
Cataclysmic Variables in the SUPERBLINK Proper Motion Survey
We have discovered a new high proper motion cataclysmic variable (CV) in the
SUPERBLINK proper motion survey, which is sensitive to stars with proper
motions greater than 40 mas/yr. This CV was selected for follow-up observations
as part of a larger search for CVs selected based on proper motions and their
NUV-V and V-K colors. We present spectroscopic observations from the 2.4m
Hiltner Telescope at MDM Observatory. The new CV's orbital period is near 96
minutes, its spectrum shows the double-peaked Balmer emission lines
characteristic of quiescent dwarf novae, and its V magnitude is near 18.2.
Additionally, we present a full list of known CVs in the SUPERBLINK catalog.Comment: Accepted for publication in The Astronomical Journal, 22 pages, 6
figure
Implementations guidelines, airborne evaluation equipment, advanced system checkout design, phase B Final report, 29 Jun. 1965 - 29 Jul. 1966
Airborne checkout equipment functions and implementation for Saturn IVB stage and instrument uni
Optical Studies of Twenty Longer-Period Cataclysmic Binaries
We obtained time-series radial velocity spectroscopy of twenty cataclysmic
variable stars, with the aim of determining orbital periods P_orb. All of the
stars reported here prove to have P_orb > 3.5 h. For sixteen of the stars,
these are the first available period determinations, and for the remaining four
(V709 Cas, AF Cam, V1062 Tau, and RX J2133+51) we use new observations to
improve the accuracy of previously-published periods. Most of the targets are
dwarf novae, without notable idiosyncracies. Of the remainder, three (V709 Cas,
V1062 Tau, and RX J2133+51) are intermediate polars (DQ Her stars); one (IPHAS
0345) is a secondary-dominated system without known outbursts, similar to LY
UMa; one (V1059 Sgr) is an old nova; and two others (V478 Her and V1082 Sgr)
are long-period novalike variables. The stars with new periods are IPHAS 0345
(0.314 d); V344 Ori (0.234 d); VZ Sex (0.149 d); NSVS 1057+09 (0.376 d); V478
Her (0.629 d); V1059 Sgr (0.286 d); V1082 Sgr (0.868 d); FO Aql (0.217 d); V587
Lyr (0.275 d); V792 Cyg (0.297 d); V795 Cyg (0.181 d); V811 Cyg (0.157 d); V542
Cyg (0.182 d); PQ Aql (0.247 d); V516 Cyg (0.171 d); and VZ Aqr(0.161 d).
Noteworthy results on individual stars are as follows. We see no indication of
the underlying white dwarf star in V709 Cas, as has been previously claimed;
based on the non-detection of the secondary star, we argue that the system is
farther away that had been thought and the white dwarf contribution is probably
negligible. V478 Her had been classified as an SU UMa-type dwarf nova, but this
is incompatible with the long orbital period we find. We report the first
secondary-star velocity curve for V1062 Tau. In V542 Cyg, we find a late-type
contribution that remains stationary in radial velocity, yet the system is
unresolved in a direct image, suggesting that it is a hierarchical triple
system.Comment: P.A.S.P., in press. 34 pages and 8 figure
Optimizing Filter-Probe Diffusion Weighting in the Rat Spinal Cord for Human Translation
Diffusion tensor imaging (DTI) is a promising biomarker of spinal cord injury (SCI). In the acute aftermath, DTI in SCI animal models consistently demonstrates high sensitivity and prognostic performance, yet translation of DTI to acute human SCI has been limited. In addition to technical challenges, interpretation of the resulting metrics is ambiguous, with contributions in the acute setting from both axonal injury and edema. Novel diffusion MRI acquisition strategies such as double diffusion encoding (DDE) have recently enabled detection of features not available with DTI or similar methods. In this work, we perform a systematic optimization of DDE using simulations and an in vivo rat model of SCI and subsequently implement the protocol to the healthy human spinal cord. First, two complementary DDE approaches were evaluated using an orientationally invariant or a filter-probe diffusion encoding approach. While the two methods were similar in their ability to detect acute SCI, the filter-probe DDE approach had greater predictive power for functional outcomes. Next, the filter-probe DDE was compared to an analogous single diffusion encoding (SDE) approach, with the results indicating that in the spinal cord, SDE provides similar contrast with improved signal to noise. In the SCI rat model, the filter-probe SDE scheme was coupled with a reduced field of view (rFOV) excitation, and the results demonstrate high quality maps of the spinal cord without contamination from edema and cerebrospinal fluid, thereby providing high sensitivity to injury severity. The optimized protocol was demonstrated in the healthy human spinal cord using the commercially-available diffusion MRI sequence with modifications only to the diffusion encoding directions. Maps of axial diffusivity devoid of CSF partial volume effects were obtained in a clinically feasible imaging time with a straightforward analysis and variability comparable to axial diffusivity derived from DTI. Overall, the results and optimizations describe a protocol that mitigates several difficulties with DTI of the spinal cord. Detection of acute axonal damage in the injured or diseased spinal cord will benefit the optimized filter-probe diffusion MRI protocol outlined here
Spacelab 3 vapor crystal growth experiment
The Space Shuttle Challenger, with Spacelab 3 as its payload, was launched into orbit April 29, 1985. The mission, number 51-B, emphasized materials processing in space, although a wide variety of experiments in other disciplines were also carried onboard. One of the materials processing experiments on this flight is described, specifically the growth of single crystals of mercuric iodide by physical vapor transport
Boundary regularity of conformally compact Einstein metrics
We show that C^2 conformally compact Riemannian Einstein metrics have
conformal compactifications that are smooth up to the boundary in dimension 3
and all even dimensions, and polyhomogeneous in odd dimensions greater than 3.Comment: Latex2e, 25 pages. This is the final version accepted for publication
in the Journal of Differential Geometr
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