1,184 research outputs found
Mass and Angular Momentum Transfer in the Massive Algol Binary RY Persei
We present an investigation of H-alpha emission line variations observed in
the massive Algol binary, RY Per. We give new radial velocity data for the
secondary based upon our optical spectra and for the primary based upon high
dispersion UV spectra. We present revised orbital elements and an estimate of
the primary's projected rotational velocity (which indicates that the primary
is rotating 7 times faster than synchronous). We use a Doppler tomography
algorithm to reconstruct the individual primary and secondary spectra in the
region of H-alpha, and we subtract the latter from each of our observations to
obtain profiles of the primary and its disk alone. Our H-alpha observations of
RY Per show that the mass gaining primary is surrounded by a persistent but
time variable accretion disk. The profile that is observed outside-of-eclipse
has weak, double-peaked emission flanking a deep central absorption, and we
find that these properties can be reproduced by a disk model that includes the
absorption of photospheric light by the band of the disk seen in projection
against the face of the star. We developed a new method to reconstruct the disk
surface density distribution from the ensemble of H-alpha profiles observed
around the orbit, and this method accounts for the effects of disk occultation
by the stellar components, the obscuration of the primary by the disk, and flux
contributions from optically thick disk elements. The resulting surface density
distribution is elongated along the axis joining the stars, in the same way as
seen in hydrodynamical simulations of gas flows that strike the mass gainer
near trailing edge of the star. This type of gas stream configuration is
optimal for the transfer of angular momentum, and we show that rapid rotation
is found in other Algols that have passed through a similar stage.Comment: 39 pages, 12 figures, ApJ in press, 2004 June 20 issu
Paradox in the pursuit of a critical theorization of the development of self in family relationships
This article starts with my dissatisfaction with the post-structuralist treatment of the production of subjectivity within regulatory discourses and practices due to its neglect of psychological processes. Taking starting points from within the history set out in the previous article, it highlights the paradox for critical psychologists like myself involved in both applying a post-structuralist critique to 'psy' discourses and trying to theorize subjectivity in a way that goes beyond the dualism of individual and society, of psychology and sociology. The relational, or intersubjective, approach to self that originates in object relations psychoanalysis as it emerged in the mid-20th-century UK is central to both of these activities; object of the former and resource for the latter. I explore the paradox that this creates for critical psychology, both epistemological and ontological. In aiming to provide a psycho-social account of self in family relationships, I deploy the radical conceptualisation of intersubjectivity initiated in British object relations theory as a way of going beyond both the individualized self and the neglect of psychological processes in constructionist theorizing subjectivity
The coalition for conservation genetics: working across organizations to build capacity and achieve change in policy and practice
The Coalition for Conservation Genetics (CCG) brings together four eminentorganizations with the shared goal of improving the integration of geneticinformation into conservation policy and practice. We provide a historicalcontext of conservation genetics as a field and reflect on current barriers toconserving genetic diversity, highlighting the need for collaboration acrosstraditional divides, international partnerships, and coordinated advocacy. Wethen introduce the CCG and illustrate through examples how a coalitionapproach can leverage complementary expertise and improve the organiza-tional impact at multiple levels. The CCG has proven particularly successfulat implementing large synthesis-type projects, training early-career scientists,and advising policy makers. Achievements to date highlight the potential forthe CCG to make effective contributions to practical conservation policy andmanagement that no one“parent”organization could achieve on its own.Finally, we reflect on the lessons learned through forming the CCG, and ourvision for the futur
Alcohol and marijuana use while driving-an unexpected crash risk in Pakistani commercial drivers: a cross-sectional survey
Background:A significant proportion of road traffic crashes are attributable to alcohol and marijuana use while driving globally. Sale and use of both substances is illegal in Pakistan and is not considered a threat for road traffic injuries. However literature hints that this may not be the case. We did this study to assess usage of alcohol and marijuana in Pakistani commercial drivers.Methods:A sample of 857 commercial bus and truck drivers was interviewed in October 2008 at the largest commercial vehicle station in Rawalpindi and Islamabad, Pakistan. Time location cluster sampling was used to select the subjects and a structured questionnaire was used to assess the basic demographic profile, substance abuse habits of the drivers while on the road, and reasons for usage of illicit substances while driving were recorded. Self reported information was collected after obtaining informed consent. Chi square and fisher exact tests were used to assess differences between groups and logistic regression was used to identify significant associations between driver characteristics and alcohol and marijuana use.Results:Almost 10% of truck drivers use alcohol while driving on Pakistani roads. Marijuana use is almost 30% in some groups. Statistically different patterns of usage are seen between population subgroups based on age, ethnicity, education, and marital status. Regression analysis shows association of alcohol and marijuana use with road rage and error behaviours, and also with an increased risk of being involved in road crashes. The reported reasons for using alcohol or marijuana show a general lack of awareness of the hazardous nature of this practice among the commercial driver population.Conclusion:Alcohol and marijuana use is highly prevalent in Pakistani commercial drivers. The issue needs to be recognized by concerned authorities and methods such as random breath tests and sobriety check points need to be employed for proper law enforcement
The effectiveness of extra corporeal shock wave therapy for plantar heel pain: a systematic review and meta-analysis
BACKGROUND: There is considerable controversy regarding the effectiveness of extracorporeal shock wave therapy in the management of plantar heel pain. Our aim was to conduct a systematic review of randomised controlled trials to investigate the effectiveness of extracorporeal shock wave therapy and to produce a precise estimate of the likely benefits of this therapy. METHODS: We conducted a systematic review of all randomised controlled trials (RCTs) identified from the Cochrane Controlled trials register, MEDLINE, EMBASE and CINAHL from 1966 until September 2004. We included randomised trials which evaluated extracorporeal shock wave therapy used to treat plantar heel pain. Trials comparing extra corporeal shock wave therapy with placebo or different doses of extra corporeal shock wave therapy were considered for inclusion in the review. We independently applied the inclusion and exclusion criteria to each identified randomised controlled trial, extracted data and assessed the methodological quality of each trial. RESULTS: Six RCTs (n = 897) permitted a pooled estimate of effectiveness based on pain scores collected using 10 cm visual analogue scales for morning pain. The estimated weighted mean difference was 0.42 (95% confidence interval 0.02 to 0.83) representing less than 0.5 cm on a visual analogue scale. There was no evidence of heterogeneity and a fixed effects model was used. CONCLUSION: A meta-analysis of data from six randomised-controlled trials that included a total of 897 patients was statistically significant in favour of extracorporeal shock wave therapy for the treatment of plantar heel pain but the effect size was very small. A sensitivity analysis including only high quality trials did not detect a statistically significant effect
One-pot Selective Formylation and Claisen Rearrangement on Calix[4]arenes
A versatile synthon with formyl and allyl groups at the upper rim of calix[4]arene has been synthesized in two steps. Selective formylation of 25,27-diallyloxy-26,28-dihydroxycalix[4]arene, along with the Claisen rearrangement of the allyl groups, was achieved by reaction with hexamethylenetetraamine (hexamine) in glacial acetic acid. A control reaction of the dipropyl analogue shows that the selective formylation takes place independently of the Claisen rearrangement. The crystal structure of the dimethylacetal derivative of 5,17-diformyl-11,23-diallylcalix[4]arene is reported
Mirror Mirror on the Wall, Which Is the Most Convincing of Them All? Exploring Anti-Domestic Violence Posters.
Although domestic abuse of women by men has received significant media, police, and research attention, domestic violence directed toward men has been marginalized across the board and is still rarely treated seriously. The purpose of this research, then, is to examine and compare different anti-domestic violence messages in which the abuser's gender is not always clear. In Study 1, 200 U.K. participants (100 females and 100 males, aged 18-67, M = 28.98, SD = 9.613) evaluated posters that varied across three levels; in that the subject (male or female) was depicted as being silenced, bruised, or experiencing live abuse. The results showed that the posters featuring female victims were all rated as more effective than posters showing male victims. In Study 2, 140 different U.K. participants (95 females; 45 males) aged 18 to 59 (M = 27.27, SD = 10.662) evaluated the cartoon facial images of Disney characters who had been altered to look like victims of violence and real-life corresponding photos of human models. The results showed that the realistic posters were found to be more believable, emotional, and effective than the cartoons. The implications of such perceptions are discussed
Engineering bacteria to solve the Burnt Pancake Problem
<p>Abstract</p> <p>Background</p> <p>We investigated the possibility of executing DNA-based computation in living cells by engineering <it>Escherichia coli </it>to address a classic mathematical puzzle called the Burnt Pancake Problem (BPP). The BPP is solved by sorting a stack of distinct objects (pancakes) into proper order and orientation using the minimum number of manipulations. Each manipulation reverses the order and orientation of one or more adjacent objects in the stack. We have designed a system that uses site-specific DNA recombination to mediate inversions of genetic elements that represent pancakes within plasmid DNA.</p> <p>Results</p> <p>Inversions (or "flips") of the DNA fragment pancakes are driven by the <it>Salmonella typhimurium </it>Hin/<it>hix </it>DNA recombinase system that we reconstituted as a collection of modular genetic elements for use in <it>E. coli</it>. Our system sorts DNA segments by inversions to produce different permutations of a promoter and a tetracycline resistance coding region; <it>E. coli </it>cells become antibiotic resistant when the segments are properly sorted. Hin recombinase can mediate all possible inversion operations on adjacent flippable DNA fragments. Mathematical modeling predicts that the system reaches equilibrium after very few flips, where equal numbers of permutations are randomly sorted and unsorted. Semiquantitative PCR analysis of <it>in vivo </it>flipping suggests that inversion products accumulate on a time scale of hours or days rather than minutes.</p> <p>Conclusion</p> <p>The Hin/<it>hix </it>system is a proof-of-concept demonstration of <it>in vivo </it>computation with the potential to be scaled up to accommodate larger and more challenging problems. Hin/<it>hix </it>may provide a flexible new tool for manipulating transgenic DNA <it>in vivo</it>.</p
The First VERITAS Telescope
The first atmospheric Cherenkov telescope of VERITAS (the Very Energetic
Radiation Imaging Telescope Array System) has been in operation since February
2005. We present here a technical description of the instrument and a summary
of its performance. The calibration methods are described, along with the
results of Monte Carlo simulations of the telescope and comparisons between
real and simulated data. The analysis of TeV -ray observations of the
Crab Nebula, including the reconstructed energy spectrum, is shown to give
results consistent with earlier measurements. The telescope is operating as
expected and has met or exceeded all design specifications.Comment: Accepted by Astroparticle Physic
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