12,716 research outputs found

    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

    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 < .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

    Exploring the effect of ADHD traits on the moment‐to‐moment interplay between provocation and aggression: Evidence from dynamic structural equation modeling

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    The relation between attention deficit hyperactivity disorder (ADHD) symptoms and aggression is well documented; however, the processes that account for higher levels of aggression associated with ADHD in the course of daily life are little understood. The current study used ecological momentary assessment to explore how ADHD traits relate to individual differences in perceiving provocation from others and the resultant aggressive behaviors; and the strengths of the links between provocation and aggression in the flow of daily life. A dynamic structural equation model was fit using data from a subpopulation of young adults involved in the longitudinal z‐proso study (n = 259, median‐age 20). Data on provocation and aggression was collected at four quasi‐random time periods per day over a 14‐day period. Individuals with higher ADHD trait levels reported higher instances of provocation and aggression, with ADHD traits significantly moderating aggression inertia such that those with higher levels of ADHD traits showed greater persistence of aggressive behavior over time. However, ADHD trait levels did not significantly moderate any of the observed cross‐lagged effects. Our findings suggest that individuals with higher levels of ADHD traits are at greater risk of exposure to interpersonal interactions involving interpersonal provocation, show higher levels of aggressive behavior in daily life, and find it more difficult to reduce their aggression once triggered. These findings support the importance of targeting factors such as social skills and emotion regulation that may underpin the increased difficulties in interpersonal interactions often experienced by individuals with high levels of ADHD symptoms

    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

    Long-Term Stability of Horseshoe Orbits

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    Unlike Trojans, horseshoe coorbitals are not generally considered to be long-term stable (Dermott and Murray, 1981; Murray and Dermott, 1999). As the lifetime of Earth's and Venus's horseshoe coorbitals is expected to be about a Gyr, we investigated the possible contribution of late-escaping inner planet coorbitals to the lunar Late Heavy Bombardment. Contrary to analytical estimates, we do not find many horseshoe objects escaping after first 100 Myr. In order to understand this behaviour, we ran a second set of simulations featuring idealized planets on circular orbits with a range of masses. We find that horseshoe coorbitals are generally long lived (and potentially stable) for systems with primary-to-secondary mass ratios larger than about 1200. This is consistent with results of Laughlin and Chambers (2002) for equal-mass pairs or coorbital planets and the instability of Jupiter's horseshoe companions (Stacey and Connors, 2008). Horseshoe orbits at smaller mass ratios are unstable because they must approach within 5 Hill radii of the secondary. In contrast, tadpole orbits are more robust and can remain stable even when approaching within 4 Hill radii of the secondary.Comment: Accepted for MNRA

    NICMOS Observations of the Transiting Hot Jupiter XO-1b

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    We refine the physical parameters of the transiting hot Jupiter planet XO-1b and its stellar host XO-1 using HST NICMOS observations. XO-1b has a radius Rp=1.21+/-0.03 RJup, and XO-1 has a radius Rs=0.94+/-0.02 RSun, where the uncertainty in the mass of XO-1 dominates the uncertainty of Rp and Rs. There are no significant differences in the XO-1 system properties between these broad-band NIR observations and previous determinations based upon ground-based optical observations. We measure two transit timings from these observations with 9 s and 15 s precision. As a residual to a linear ephemeris model, there is a 2.0 sigma timing difference between the two HST visits that are separated by 3 transit events (11.8 days). These two transit timings and additional timings from the literature are sufficient to rule out the presence of an Earth mass planet orbiting in 2:1 mean motion resonance coplanar with XO-1b. We identify and correct for poorly understood gain-like variations present in NICMOS time series data. This correction reduces the effective noise in time series photometry by a factor of two, for the case of XO-1.Comment: 13 pages, 8 figures, submitted to Ap

    The Mid-Infrared Properties of X-ray Sources

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    We combine the results of the Spitzer IRAC Shallow Survey and the Chandra XBootes Survey of the 8.5 square degrees Bootes field of the NOAO Deep Wide- Field Survey to produce the largest comparison of mid-IR and X-ray sources to date. The comparison is limited to sources with X-ray fluxes >8x10-15 erg cm-2s-1 in the 0.5-7.0 keV range and mid-IR sources with 3.6 um fluxes brighter than 18.4 mag (12.3 uJy). In this most sensitive IRAC band, 85% of the 3086 X-ray sources have mid-IR counterparts at an 80% confidence level based on a Bayesian matching technique. Only 2.5% of the sample have no IRAC counterpart at all based on visual inspection. Even for a smaller but a significantly deeper Chandra survey in the same field, the IRAC Shallow Survey recovers most of the X-ray sources. A majority (65%) of the Chandra sources detected in all four IRAC bands occupy a well-defined region of IRAC [3.6] - [4.5] vs [5.8] - [8.0] color-color space. These X-ray sources are likely infrared luminous, unobscured type I AGN with little mid-infrared flux contributed by the AGN host galaxy. Of the remaining Chandra sources, most are lower luminosity type I and type II AGN whose mid-IR emission is dominated by the host galaxy, while approximately 5% are either Galactic stars or very local galaxies.Comment: Accepted for publication in Ap

    Educating for Practical Wisdom: An Ideal and a Journey

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    This working paper details the work of the Habits of Inquiry and Reflection Practical Wisdom Fellows. It offers an understanding of the term, discusses opportunities for growing in practical wisdom, and connects it to learning across campus

    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
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