4,373 research outputs found
Astrometric and photometric initial mass functions from the UKIDSS Galactic Clusters Survey - II. The Alpha Persei open cluster
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2012 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.We present the results of a deep (J = 19.1mag) infrared (ZYJHK) survey over the full α Per open cluster extracted from the Data Release 9 of the United Kingdom Infrared Telescope Infrared Deep Sky Survey Galactic Clusters Survey (UKIDSS). We have selected ∼700 cluster member candidates in ∼56 square degrees in α Per by combining photometry in five near-infrared passbands and proper motions derived from the multiple epochs provided by the UKIDSS Galactic Clusters Survey (GCS) Data Release 9 (DR9). We also provide revised membership for all previously published α Per low-mass stars and brown dwarfs recovered in GCS based on the new photometry and astrometry provided by DR9. We find no evidence of K-band variability in members of α Per with dispersion less than 0.06-0.09mag. We employed two independent but complementary methods to derive the cluster luminosity and mass functions: a probabilistic analysis and a more standard approach consisting of stricter astrometric and photometric cuts. We find that the resulting luminosity and mass functions obtained from both methods are consistent. We find that the shape of the α Per mass function is similar to that of the Pleiades although the characteristic mass may be higher after including higher mass data from earlier studies (the dispersion is comparable). We conclude that the mass functions of α Per, the Pleiades and Praesepe are best reproduced by a log-normal representation similar to the system field mass function although with some variation in the characteristic mass and dispersion values.Peer reviewe
Southern Infrared Proper Motion Survey I: Discovery of New High Proper Motion Stars From First Full Hemisphere Scan
We present the first results from the Southern Infrared Proper Motion Survey.
Using 2 Micron All Sky Survey data along with that of the SuperCOSMOS sky
survey we have been able to produce the first widefield infrared proper motion
survey. Having targeted the survey to identify nearby M, L and T dwarfs we have
discovered 72 such new objects with proper motions greater than 0.5''/yr with
10 of these having proper motions in excess of 1''/yr. The most interesting of
these objects is SIPS1259-4336 a late M dwarf. We have calculated a
trigonometric parallax for this object of milliarcseconds
yielding a distance of pc. We have also discovered a common proper
motion triple system and an object with a common proper motion with LHS 128.
The survey completeness is limited by the small epoch differences between many
2MASS and UKI observations. Hence we only recover 22% of Luyten objects with
favourable photometry. However the Luyten study is itself unquantifiably
incomplete. We discuss the prospect of enhancing the survey volume by reducing
the lower proper motion limit.Comment: 20 pages, 11 figures, accepted for publication in Astronomy and
Astrophysic
Equivalent Axleloads for Pavement Design
Proper structural design of highway pavements requires an evaluation of the destructive effects of the anticipated vehicular loading. The concept of load equivalency provides a means for expressing these destructive effects in terms of a single measure, the equivalent axleloads (EAL\u27s). The design EAL\u27s represents the equivalent number of applications of a standard or base axleload anticipated during the design life
Pap smear rates among Australian community-attached lesbian and bisexual women: some good news but disparities persist
Background: Research in the US and UK shows lesbian women are less likely than their heterosexual peers to attend for routine Pap smear tests. This study examined Pap smear test rates among community-attached lesbian, bisexual and queer (LBQ) women in New South Wales, to investigate if rates had changed between 2002 and 2012, compare rates to the general NSW population and identify predictive factors for Pap smear test attendance. Method: Data was taken from the Sydney Women and Sexual Health (SWASH) survey, a self-completed biennial questionnaire of LBQ women’s health and wellbeing. Results: Of the 4083 respondents, 83% had ever had a Pap smear test. Recent attendance rates were slightly higher than the general population. Significant predictors for ever having attended for a Pap smear test were older age, post-year 12 education, ever having had an STI test, being out about sexuality to a regular doctor and ever having had sex with men. Conclusions: Pap smear rates for LBQ women are encouraging when compared to rates in similar countries. A significant proportion of LBQ women are never receiving Pap smear tests. Predictive factors suggest a continued perception that women who have not had sex with men are not at risk of HPV, and highlight the importance of health providers providing a safe and welcoming environment for LBQ women to openly discuss their health.ACON (NSW’s largest community-based gay, lesbian, bisexual and transgender health and HIV/AIDS organisatio
Serendipitous Formation of a Cerium(IV)-Mercury(II) Separated Ion Coordination Polymer#
Trivalent cerium tris-tert-butoxide, "[Ce(OtBu)(3)]", was synthesised in situ and treated with excess HgCl2. After reaction, colourless crystals were identified amongst excess HgCl2. Analysis by X-ray crystallography revealed the formation of an unusual ion separated coordination polymer consisting of two [Ce-IV(OtBu)(3)(thf)(3)](+) ions and a di-anionic chloridomercurate(II) two dimensional sheet [Hg8Cl18](2-), giving the overall formula [{Ce(OtBu)(3)(thf)(3)}(2){Hg8Cl18}](infinity) (1)
Unexpected C-F activation during redox transmetallation with silver N,N '-bis(2,6-difluorophenyl)formamidinate
The trivalent lanthanoid formamidinates, [Yb-2(DFForm)(4)F-2(py)(2)]center dot CH3CN (1) (DFForm=N,N'-bis(2,6-difluorophenyl)formamidinate), and [La-6(DFForm)(8)F8O(CH3CN)(2)].6CH(3)CN (2) have been prepared from redox transmetallation (RT) reactions employing lanthanoid metals and silver formamidinate (AgDFForm) in CH3CN. C-F activation was observed in both reactions. The structure of 1 is a fluorine bridged dimer with two seven-coordinate ytterbium metal ions. Surprisingly the lanthanum complex is a trivalent cage with an unexpected central oxygen atom. [La-6(DFForm)(8)F8O(CH3CN)(2)].6CH(3)CN (2) formed a 15 membered ring cage of six La atoms, eight F and one O at the centre. There are three different La3+ ions in 2 with two different coordination numbers. All the La atoms are coordinated by four bridging fluorides and the central oxygen
Characteristics of Outdoor Recreational Travel
The purpose of this investigation was to examine the characteristics of travel to outdoor recreational areas in Kentucky. Data were obtained by means of a license-plate, origin-destination survey at 160 sites within 42 recreational areas and by means of a continuous vehicle counting program at eight of these sites. A computer algorithm was developed for error detection and subsequent adjustment of the volume data as necessitated by occasional malfunction of the traffic recorders and vandalism. Vehicle occupancy was found to depend of the type of recreational area, distance traveled, and vehicle type. Occupancy increased with increasing distance and was greatest for those vehicles pulling camping trailers. Percentages of the various vehicle types were also influenced by the type of recreational area and the distance traveled. The proportion of camping units in the traffic stream increased with increasing distance of travel. In general, trip lengths were quite short as evidenced by the fact that 60 percent of all vehicles traveled less than 50 miles. However, trip-length distribution was highly dependent of the type and location of the recreational area. Analysis of the distribution of traffic over time verified that recreational travel is much more highly peaked than other forms of highway travel and, with the exception of holidays, is concentrated on Sundays during the spring and summer months. This time period appears most appropriate for the design of highways and parking facilities to serve recreational areas. It is highly recommended that future data collection programs be concentrated on the average summer Sunday to enable collection of the maximum amount of usable traffic data with a minimum of effort. Much of the data reported herein can be used in initial efforts to characterize travel to similar types of recreational areas outside of Kentucky
Identification of Hazardous Rural Highway Locations
An effective procedure was determined for identifying hazardous rural highway locations based on accident statistics. Multiple indicators of accident experience that are necessary include the number of fatal accidents, the total number of accidents, the number of effective-property-damage-only accidents, and the accident rate. Critical levels of these four indicators should vary from state to state depending on the nature of the local safety improvement program as well as local traffic and roadway conditions and prevailing attitudes toward highway safety. Specific recommendations are given for use in Kentucky. Critical accident rates are established using quality control procedures.
To identify hazardous highway locations, it is necessary to distinguish between short highway segments (spots) and large segments (sections) and to further classify spots as intersection and non-intersection locations. Intersection spots should include a distance of 0.15 mile (0.24 km) along all approaches; non-intersection spots should be 0.3-mile (0.48-km), floating segments; and sections should be 3-mile (4.8-km), floating segments. Both spots and sections should be classified by highway type and location. The use of dual time intervals of 1 and 2 years for accumulating and evaluating accident statistics was found to be desirable
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