14,600 research outputs found

    Digging supplementary buried channels: investigating the notch architecture within the CCD pixels on ESA's Gaia satellite

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    The European Space Agency (ESA) Gaia satellite has 106 CCD image sensors which will suffer from increased charge transfer inefficiency (CTI) as a result of radiation damage. To aid the mitigation at low signal levels, the CCD design includes Supplementary Buried Channels (SBCs, otherwise known as `notches') within each CCD column. We present the largest published sample of Gaia CCD SBC Full Well Capacity (FWC) laboratory measurements and simulations based on 13 devices. We find that Gaia CCDs manufactured post-2004 have SBCs with FWCs in the upper half of each CCD that are systematically smaller by two orders of magnitude (<50 electrons) compared to those manufactured pre-2004 (thousands of electrons). Gaia's faint star (13 < G < 20 mag) astrometric performance predictions by Prod'homme et al. and Holl et al. use pre-2004 SBC FWCs as inputs to their simulations. However, all the CCDs already integrated onto the satellite for the 2013 launch are post-2004. SBC FWC measurements are not available for one of our five post-2004 CCDs but the fact it meets Gaia's image location requirements suggests it has SBC FWCs similar to pre-2004. It is too late to measure the SBC FWCs onboard the satellite and it is not possible to theoretically predict them. Gaia's faint star astrometric performance predictions depend on knowledge of the onboard SBC FWCs but as these are currently unavailable, it is not known how representative of the whole focal plane the current predictions are. Therefore, we suggest Gaia's initial in-orbit calibrations should include measurement of the onboard SBC FWCs. We present a potential method to do this. Faint star astrometric performance predictions based on onboard SBC FWCs at the start of the mission would allow satellite operating conditions or CTI software mitigation to be further optimised to improve the scientific return of Gaia.Comment: Accepted for publication in MNRAS, 16 pages, 19 figure

    Candida albicans colonization and dissemination from the murine gastrointestinal tract : the influence of morphology and Th17 immunity

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    This article is protected by copyright. All rights reserved. This work was supported by the Wellcome Trust (086558, 080088, 102705), a Wellcome Trust Strategic Award (097377) and a studentship from the University of Aberdeen. D.K. was supported by grant 5R01AI083344 from the National Institute of Allergy and Infectious Diseases and by a Voelcker Young Investigator Award from the Max and Minnie Tomerlin Voelcker Fund.Peer reviewedPublisher PD

    Population growth of Mexican free-tailed bats \u3cem\u3e(Tadarida brasiliensis mexicana)\u3c/em\u3e predates human agricultural activity

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    Background Human activities, such as agriculture, hunting, and habitat modification, exert a significant effect on native species. Although many species have suffered population declines, increased population fragmentation, or even extinction in connection with these human impacts, others seem to have benefitted from human modification of their habitat. Here we examine whether population growth in an insectivorous bat (Tadarida brasiliensis mexicana) can be attributed to the widespread expansion of agriculture in North America following European settlement. Colonies of T. b. mexicana are extremely large (~106 individuals) and, in the modern era, major agricultural insect pests form an important component of their food resource. It is thus hypothesized that the growth of these insectivorous bat populations was coupled to the expansion of agricultural land use in North America over the last few centuries. Results We sequenced one haploid and one autosomal locus to determine the rate and time of onset of population growth in T. b. mexicana. Using an approximate Maximum Likelihood method, we have determined that T. b. mexicana populations began to grow ~220 kya from a relatively small ancestral effective population size before reaching the large effective population size observed today. Conclusions Our analyses reject the hypothesis that T. b. mexicana populations grew in connection with the expansion of human agriculture in North America, and instead suggest that this growth commenced long before the arrival of humans. As T. brasiliensis is a subtropical species, we hypothesize that the observed signals of population growth may instead reflect range expansions of ancestral bat populations from southern glacial refugia during the tail end of the Pleistocene

    The effect of alcohol marketing on people with, or at risk of, an alcohol problem: A rapid literature review

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    There is a comprehensive evidence base demonstrating the relationship between alcohol marketing and underage drinking. Far less is known about the impact of alcohol marketing on other potentially vulnerable populations, such as people with, or at risk of, an alcohol problem. For the purposes of this review, this includes people with an alcohol use disorder, in recovery from an alcohol use disorder, and hazardous and harmful drinkers. This report presents findings from a rapid review that aimed to answer the following research questions: • What is the effect of alcohol marketing on drinking behaviour in adults with, or at risk of, an alcohol problem? • What are the psychological and neurological effects of alcohol marketing in adults with, or at risk of, an alcohol problem? A rapid review of primary studies was conducted with the aim of exploring the effect or potential effect of alcohol marketing on people with, or at risk of an alcohol problem, as defined above. Studies were eligible for inclusion in this review if their populations were defined within the paper as being with, or at risk of an alcohol problem, taking into account the possibility of different definitions in different settings. Studies were only included if results or outcomes were presented separately for at least one of the populations of interest. Binge drinkers were not included as a population of interest in this review. Studies covering different aspects of the ‘marketing mix’ (the four Ps of promotion, place, product, and price) were included, with the exception of alcohol outlet density, labelling and non-branded alcohol cues. Children and adolescents were excluded from the review. Quantitative and qualitative study designs were eligible for inclusion. Outcomes related to alcohol use were included, as well as psychological indicators such as awareness of or noticing marketing, appeal or perception of alcohol advertisements, alcohol craving, intentions to consume alcohol, symptoms of alcohol dependence and alcohol-related emotions and cognitions. Searches for relevant literature were conducted through three peer-reviewed electronic literature databases (from inception to November 2021), reference list scanning and citation tracking of included studies, grey literature searching of relevant websites, and enquiries through expert networks. We undertook a narrative synthesis of included papers, grouping studies together by population (participants with harmful or hazardous consumption levels of alcohol and those recovering from an alcohol use disorder) and by type of study (quantitative; qualitative). The review included 11 studies, which focused on participants recovering from an alcohol use disorder (AUD, 6 studies) and those with hazardous or harmful consumption levels of alcohol (5 studies). Seven studies used a quantitative design and four used a qualitative design. Of the quantitative studies, three were crosssectional studies and four were experimental studies. A limited number of studies have investigated the effect of alcohol advertising in harmful/hazardous drinkers. In experimental studies, one included study found no effect of adverts on actual alcohol consumption, but found that alcohol advertising could influence positive alcohol-related emotions and cognitions among heavy drinkers. Another found that individuals who exhibit greater risky alcohol use are more likely to express intentions to consume alcohol upon exposure to beer than water ads. Finally, one study found shorter reaction times in problem drinkers relative to non-problem drinkers when exposed to non-branded alcohol images in a study where participants were instructed to respond as quickly as possible to ‘go’ stimuli whilst refraining from responding to ‘no-go’ stimuli with branded and unbranded alcohol pictures as stimuli. Two cross-sectional studies highlighted the potential risks of alcohol advertising for heavy drinkers: one found that drinkers reporting symptoms of alcohol problems were more likely to notice alcohol brands in magazines and newspapers, while another found that among students, heavy drinkers perceived alcohol adverts as more appealing; however, due to the observational designs used, neither of these studies were able to make causal inferences about the effect of alcohol advertising. Similarly, a small number of quantitative studies have investigated the effects of advertising on drinkers in recovery. Only two studies were found, both of which suggest a relatively small effect of alcohol advertising in this population. One crosssectional study reported that more than three quarters of participants (77%) recalled seeing alcohol marketing in the last six months, with 24% reporting that alcohol marketing was influential. The most influential factors affecting the purchase of a specific alcohol product included price, accessibility, the brand and alcohol percent. Using an experimental design, a further study reported increased craving after exposure to alcohol advertisements and this measure showed a positive association with the number of alcohol-dependence symptoms. In absolute terms, however, craving was relatively low. In three interview studies, respondents indicated that alcohol advertisements triggered a desire to drink, particularly those which contained the participants’ preferred drink and even where the advertisements were perceived negatively. Some reported that they viewed advertisements as being responsible for their relapse. Television was cited as being a particularly powerful medium, with feelings that television intruded into their own home. One study further reported that music and party scenes were particularly troubling in terms of creating an association with good times. Participants in both studies reported negative emotions associated with viewing alcohol advertisements, including loss, lack of belonging, anger, sadness, guilt and exclusion from the norm. Participants in these studies reported needing to use strategies to avoid alcohol advertising, either through turning off and avoiding adverts or recalling the negative aspects of alcohol use. The retail environment was also identified in one further qualitative study as being challenging for drinkers in recovery. High visibility of alcohol, especially in small shops where it is harder to avoid alcohol products, and in-store advertising were identified as risks to recovery. • Taken together, the findings of the studies included in this review suggest that an effect of alcohol marketing in people with, or at risk of, an alcohol problem is likely. • Several studies report effects of alcohol marketing such as influences on positive alcohol-related emotions and cognitions and alcohol craving, which may translate into effects on alcohol consumption. There is also evidence that alcohol marketing is perceived to act as a trigger by people in recovery from alcohol problems and pose a risk to recovery. • This review demonstrates that the impact of alcohol marketing on people with or at risk of an alcohol problem should be a concern for marketing regulators and a focus for future research. • Future research should include longitudinal and experimental studies to determine whether alcohol advertisement has a causal effect on alcohol use in people with or at risk of an alcohol problems, including the differential effects between these groups and of different types of marketing

    Referral for menstrual problems:cross sectional survey of symptoms, reasons for referral, and management

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    OBJECTIVES: To describe the menstrual experience of women referred for menstrual problems, in particular menorrhagia (excessive menstrual loss), and to assess associations with reasons for referral given by their general practitioners, the women's understanding of the reasons for their attendance at the hospital clinics, and clinic outcome. DESIGN: Questionnaire survey, with partial review of case notes after 8 months. SETTING: Three hospital gynaecology clinics in Glasgow and Edinburgh. PARTICIPANTS: 952 women completed the questionnaire, and the first 665 were reviewed. OUTCOME MEASURES: Reason for referral, women's reported menstrual problems and reason for clinic attendance, diagnosis, and treatment. RESULTS: Only 38% (95% confidence interval 34% to 41%) of women reported excessive menstrual loss as a severe problem. However 60% (57-63%) gave it as reason for attending a clinic, and 76% (73-79%) of general practitioners gave it as reason for referral. Reason for referral was significantly biased towards bleeding (McNemar odds ratio 4.01, 3.0 to 5.3, P<0.001) and against pain (0.54, 0.4 to 0.7, P<0.001). Dysfunctional uterine bleeding was diagnosed in 37% (31-42%) of the 259 women who gave as reason for attendance something other than bleeding. Women who were economically disadvantaged differed in prevalence of the main diagnoses and were more likely to fail to reattend. Hysterectomy was associated with referral for bleeding (relative risk 4.9, 1.6 to 15.6, P<0.001) but not with the patient stating bleeding as the reason for clinic attendance. CONCLUSIONS: Intolerance of the volume of their bleeding is not a key feature among women attending clinics for bleeding problems. Broad menstrual complaint tends to be reframed as excessive bleeding at referral and during management. This may result in women receiving inappropriate care. Conceptualisation and assessment of menorrhagia requires reconsideration

    Effect of live yeast culture supplementation on fibrolytic and saccharolytic bacterial populations in the faeces of horses fed a high-fibre or high-starch diet

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    The objective of this study was to assess the effect of live yeast (Saccharomyces cerevisiae) supplementation on the populations of specific cellulolytic (Fibrobacter succinogenes and Ruminococcus flavefaciens) and saccharolytic (Streptococcus equinus and Streptococcus bovis) bacteria in the feces of horses fed high-starch and high-fiber diets. Four horses were each fed diets consisting of high fiber with no yeast (HF), high fiber with yeast (HFY), high starch with no yeast (HS), and high starch with yeast (HSY) in a 4 × 4 Latin-square design study. Fresh fecal samples were collected on the last 3 days of each 31-day experimental period and were then assessed, using semiquantitative real-time PCR, for total bacterial load and levels of target bacterial species, relative to the total bacterial load. The most abundant of the target species was F. succinogenes, and the HSY diet resulted in a significant (P = .045) reduction in relative levels of this bacterium. No significant effect (P = .224) of diet was observed in relation to abundance of R. flavefaciens. Results show that diet did not have a significant (P = .068) effect on relative quantities of S. equinus, although there appeared to be a trend for increased levels of this bacterium during feeding of high-starch diets. Numbers of S. bovis were higher (P &lt; .001) when horses were fed HS and HSY diets than when fed the HF and HFY diets. Significant variation in levels of S. equinus (P = .024) and S. bovis (P = .049) was observed between individual horses

    A long-lived horseshoe companion to the Earth

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    We present a dynamical investigation of a newly found asteroid, 2010 SO16, and the discovery that it is a horseshoe companion of the Earth. The object's absolute magnitude (H=20.7) makes this the largest object of its type known to-date. By carrying out numerical integrations of dynamical clones, we find that (a) its status as a horseshoe is secure given the current accuracy of its ephemeris, and (b) the time spent in horseshoe libration with the Earth is several times 10^5 yr, two orders of magnitude longer than determined for other horseshoe asteroids of the Earth. Further, using a model based on Hill's approximation to the three-body problem, we show that, apart from the low eccentricity which prevents close encounters with other planets or the Earth itself, its stability can be attributed to the value of its Jacobi constant far from the regime that allows transitions into other coorbital modes or escape from the resonance altogether. We provide evidence that the eventual escape of the asteroid from horseshoe libration is caused by the action of planetary secular perturbations and the stochastic evolution of the eccentricity. The questions of its origin and the existence of as-yet-undiscovered co-orbital companions of the Earth are discussed.Comment: Accepted in MNRAS; 6 pages, 3 figures, 2 table

    Hypervelocity Planets and Transits Around Hypervelocity Stars

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    The disruption of a binary star system by the massive black hole at the Galactic Centre, SgrA*, can lead to the capture of one star around SgrA* and the ejection of its companion as a hypervelocity star (HVS). We consider the possibility that these stars may have planets and study the dynamics of these planets. Using a direct NN-body integration code, we simulated a large number of different binary orbits around SgrA*. For some orbital parameters, a planet is ejected at a high speed. In other instances, a HVS is ejected with one or more planets orbiting around it. In these cases, it may be possible to observe the planet as it transits the face of the star. A planet may also collide with its host star. In such cases the atmosphere of the star will be enriched with metals. In other cases, a planet is tidally disrupted by SgrA*, leading to a bright flare.Comment: 8 pages, 5 figures, 2 tables, accepted for publication in MNRA

    The Cluster and Field Galaxy AGN Fraction at z = 1 to 1.5: Evidence for a Reversal of the Local Anticorrelation Between Environment and AGN Fraction

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    The fraction of cluster galaxies that host luminous AGN is an important probe of AGN fueling processes, the cold ISM at the centers of galaxies, and how tightly black holes and galaxies co-evolve. We present a new measurement of the AGN fraction in a sample of 13 clusters of galaxies (M >= 10^{14} Msun) at 1<z<1.5 selected from the Spitzer/IRAC Shallow Cluster Survey, as well as the field fraction in the immediate vicinity of these clusters, and combine these data with measurements from the literature to quantify the relative evolution of cluster and field AGN from the present to z~3. We estimate that the cluster AGN fraction at 1<z<1.5 is f_A = 3.0^{+2.4}_{-1.4}% for AGN with a rest-frame, hard X-ray luminosity greater than L_{X,H} >= 10^{44} erg/s. This fraction is measured relative to all cluster galaxies more luminous than M*_{3.6}(z)+1, where M*_{3.6}(z) is the absolute magnitude of the break in the galaxy luminosity function at the cluster redshift in the IRAC 3.6um bandpass. The cluster AGN fraction is 30 times greater than the 3sigma upper limit on the value for AGN of similar luminosity at z~0.25, as well as more than an order of magnitude greater than the AGN fraction at z~0.75. AGN with L_{X,H} >= 10^{43} erg/s exhibit similarly pronounced evolution with redshift. In contrast with the local universe, where the luminous AGN fraction is higher in the field than in clusters, the X-ray and MIR-selected AGN fractions in the field and clusters are consistent at 1<z<1.5. This is evidence that the cluster AGN population has evolved more rapidly than the field population from z~1.5 to the present. This environment-dependent AGN evolution mimics the more rapid evolution of star-forming galaxies in clusters relative to the field.Comment: ApJ Accepted. 16 pages, 8 figures in emulateapj forma

    Neptune on tiptoes: dynamical histories that preserve the cold classical Kuiper belt

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    The current dynamical structure of the Kuiper belt was shaped by the orbital evolution of the giant planets, especially Neptune, during the era following planet formation, when the giant planets may have undergone planet-planet scattering and/or planetesimal-driven migration. Numerical simulations of this process, while reproducing many properties of the belt, fail to generate the high inclinations and eccentricities observed for some objects while maintaining the observed dynamically "cold" population. We present the first of a three-part parameter study of how different dynamical histories of Neptune sculpt the planetesimal disk. Here we identify which dynamical histories allow an in situ planetesimal disk to remain dynamically cold, becoming today's cold Kuiper belt population. We find that if Neptune undergoes a period of elevated eccentricity and/or inclination, it secularly excites the eccentricities and inclinations of the planetesimal disk. We demonstrate that there are several well-defined regimes for this secular excitation, depending on the relative timescales of Neptune's migration, the damping of Neptune's orbital inclination and/or eccentricity, and the secular evolution of the planetesimals. We model this secular excitation analytically in each regime, allowing for a thorough exploration of parameter space. Neptune's eccentricity and inclination can remain high for a limited amount of time without disrupting the cold classical belt. In the regime of slow damping and slow migration, if Neptune is located (for example) at 20 AU, then its eccentricity must stay below 0.18 and its inclination below 6{\deg}.Comment: Accepted to ApJ. Update: Fixed typos in text and Appendix equations. Published as ApJ, 746, 17
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