1,715 research outputs found

    Spatial and temporal patterns of nest distribution influence sexual selection in a marine fish

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    In many species, the natural distribution of material resources important for reproduction can profoundly impact reproductive success among individuals and, hence, the opportunity and intensity of sexual selection. Here, we report on a field-based experiment investigating the effects of nest aggregation on sexual selection in a fish, the sand goby Pomatoschistus minutus. We found that the distribution of potential nests (sparse versus aggregated nest treatments) affected patterns of nest colonization and reproductive success. Specifically, in the treatment with aggregated nesting resources, a greater proportion of nests remained unoccupied by sand goby males. Although the size of nesting males did not differ between treatments, eggs accumulated more rapidly when nests were sparsely distributed. We found that the opportunity for selection decreased over time with the accumulation of eggs in the nests in both the aggregated and sparse treatments. Moreover, the effect of male size on reproductive success was influenced by an interaction between nest distribution and time, with the selection gradient being highest right after nest colonization when nests were aggregated, while the opposite pattern was observed in the sparse nest treatment. Such findings highlight the vital role that environmental and social factors can play in determining the importance of male phenotypic traits (in this case, male size). More broadly, our results also underscore how the natural distribution of resources, both in space and time, can impact the strength of sexual selection acting on wild animal populations.Peer reviewe

    The First Brown Dwarf Discovered by the Backyard Worlds: Planet 9 Citizen Science Project

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    The Wide-field Infrared Survey Explorer (WISE) is a powerful tool for finding nearby brown dwarfs and searching for new planets in the outer solar system, especially with the incorporation of NEOWISE and NEOWISE-Reactivation data. So far, searches for brown dwarfs in WISE data have yet to take advantage of the full depth of the WISE images. To efficiently search this unexplored space via visual inspection, we have launched a new citizen science project, called "Backyard Worlds: Planet 9," which asks volunteers to examine short animations composed of difference images constructed from time-resolved WISE coadds. We report the discovery of the first new substellar object found by this project, WISEA J110125.95+540052.8, a T5.5 brown dwarf located approximately 34 pc from the Sun with a total proper motion of ∌\sim0.7 as yr−1^{-1}. WISEA J110125.95+540052.8 has a WISE W2W2 magnitude of W2=15.37±0.09W2=15.37 \pm 0.09, this discovery demonstrates the ability of citizen scientists to identify moving objects via visual inspection that are 0.9 magnitudes fainter than the W2W2 single-exposure sensitivity, a threshold that has limited prior motion-based brown dwarf searches with WISE.Comment: 9 pages, 4 figures, 1 table. Accepted for publication in the Astrophysical Journal Letter

    The Randall-Sundrum Scenario with an Extra Warped Dimension

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    We investigate a scenario with two four-branes embedded in six dimensions. When the metric is periodic and compact in one of the dimensions parallel to the branes, the value of the effective cosmological constant for the remaining five dimensions can assume a variety of values, determined by the dependence of the metric on the sixth dimension. The picture that emerges resembles the Randall-Sundrum model but with an extra warped dimension that allows the usual brane-bulk fine tuning to be satisfied without finely tuning any of the parameters in the underlying six dimensional theory. Although the action contains terms with four derivatives of the metric, we show that when the branes have a finite, natural thickness, such terms have only a small effect on the Randall-Sundrum structure. The presence of these four derivative terms also allows a configuration that resembles that produced by a domain wall but which results from gravity alone.Comment: 12 pages, 3 figures, requires harvmac and picte

    B fields in OB stars (BOB): Detection of a magnetic field in the He-strong star CPD-57{\deg} 3509

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    We report the detection of a magnetic field in the helium-strong star CPD-57 3509 (B2 IV), a member of the Galactic open cluster NGC3293, and characterise the star's atmospheric and fundamental parameters. Spectropolarimetric observations with FORS2 and HARPSpol are analysed using two independent approaches to quantify the magnetic field strength. A high-S/N FLAMES/GIRAFFE spectrum is analysed using a hybrid non-LTE model atmosphere technique. Comparison with stellar evolution models constrains the fundamental parameters of the star. We obtain a firm detection of a surface averaged longitudinal magnetic field with a maximum amplitude of about 1 kG. Assuming a dipolar configuration of the magnetic field, this implies a dipolar field strength larger than 3.3 kG. Moreover, the large amplitude and fast variation (within about 1 day) of the longitudinal magnetic field implies that CPD-57 3509 is spinning very fast despite its apparently slow projected rotational velocity. The star should be able to support a centrifugal magnetosphere, yet the spectrum shows no sign of magnetically confined material; in particular, emission in H{\alpha} is not observed. Apparently, the wind is either not strong enough for enough material to accumulate in the magnetosphere to become observable or, alternatively, some leakage process leads to loss of material from the magnetosphere. The quantitative spectroscopic analysis of the star yields an effective temperature and a logarithmic surface gravity of 23750+-250 K and 4.05+-0.10, respectively, and a surface helium fraction of 0.28+-0.02 by number. The surface abundances of C, N, O, Ne, S, and Ar are compatible with the cosmic abundance standard, whereas Mg, Al, Si, and Fe are depleted by about a factor of 2. This abundance pattern can be understood as the consequence of a fractionated stellar wind. CPD-57 3509 is one of the most evolved He-strong stars known.Comment: 15 pages, 11 figures. Accepted for publication in A&

    CD20 and CD40 mediated mitogenic responses in B-lineage acute lymphoblastic leukaemia

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    Activation of CD20, a cross-membrane ion channel, induces cell cycle progression from G0 to G1 in B lymphocytes. Subsequent activation of CD40, a membrane receptor of the nerve growth factor receptor superfamily, transits the B cells to the S phase. CD40 may also act synergistically in combination with IL-4 (B lymphocytes) or IL-3/IL-7 (B-cell precursors). We investigated the proliferative responses of B-lineage acute lymphoblastic leukaemia (ALL) cells to CD20/CD40 activation. In 18/56 ALL cases, CD20 activation resulted in significant increases in DNA synthesis. Similar, although more moderate, effects were seen of activation of CD40 in 10/44 cases. Responses to CD20 or CD40 activation were independent of co-stimulation with IL-3, IL-4 or IL-7, and various cocktails of the different growth stimuli did not act synergistically

    Alkali metal-refractory metal biphase electrode for AMTEC

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    An electrode having increased output with slower degradation is formed of a film applied to a beta-alumina solid electrolyte (BASE). The film comprises a refractory first metal M.sup.1 such as a platinum group metal, suitably platinum or rhodium, capable of forming a liquid or a strong surface adsorption phase with sodium at the operating temperature of an alkali metal thermoelectric converter (AMTEC) and a second refractory metal insoluble in sodium or the NaM.sup.1 liquid phase such as a Group IVB, VB or VIB metal, suitably tungsten, molybdenum, tantalum or niobium. The liquid phase or surface film provides fast transport through the electrode while the insoluble refractory metal provides a structural matrix for the electrode during operation. A trilayer structure that is stable and not subject to deadhesion comprises a first, thin layer of tungsten, an intermediate co-deposited layer of tungsten-platinum and a thin surface layer of platinum

    Fit and Tipsy? The Interrelationship between Cardiorespiratory Fitness and Alcohol Consumption and Dependence

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    Purpose To examine whether higher levels of cardiorespiratory fitness are related to increased alcohol consumption and dependence among a large sample of adults attending a preventive medicine clinic.Methods A cross-sectional study of 38,653 apparently healthy patients who visited the Cooper Clinic (Dallas, TX) for preventive medical examinations (1988–2019) and enrolled in the Cooper Center Longitudinal Study. The primary independent variable was cardiorespiratory fitness, based on a maximal treadmill test, and the dependent variables were alcohol consumption and dependence (self-reported). The relations between fitness category (low, moderate, high) and alcohol consumption (low, moderate, heavy) and suggested alcohol dependence (Cut down, Annoyed, Guilty, Eye opener score ≄2) among women and men were estimated via multivariable regression while adjusting for covariates (e.g., age, birth year cohort, marital status, and body mass index).Results Women within the moderate and high fitness categories had 1.58 (95% confidence interval [CI], 1.32–1.91) and 2.14 (95% CI, 1.77–2.58) greater odds of moderate/heavy alcohol consumption, respectively, in comparison to their low fitness counterparts. Similarly, moderate and high fit men had 1.42 (95% CI, 1.30–1.55) and 1.63 (95% CI, 1.49–1.80) times greater odds of moderate-to-heavy alcohol consumption, respectively, in comparison to the low fitness group. In addition, among men who were heavy drinkers (but not women), higher fitness levels were related to lower rates of suggested alcohol dependence. Specifically, these men had 45.7%, 41.7%, and 34.9% proportions of clinically relevant alcohol problems across low, moderate, and high fitness categories (adjusted P for trend &lt;0.001).Conclusions Higher fitness levels are significantly related to greater alcohol consumption among a large cohort of adult patients. Interventions focusing on increasing fitness (via physical activity promotion) might consider concurrently aiming to reduce alcohol consumption.<br/

    Long-Term Weight Loss Success and the Health Behaviors of Adults in the United States:Findings from a Nationally Representative Cross-sectional Study

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    Objective To describe the relationship between long-term weight loss (LTWL) success and lifestyle behaviours among US adults.Design Serial cross-sectional data from National Health and Nutrition Examination Survey cycles 2007–2014.Setting and participants Population-based nationally representative sample. The analytic sample included 3040 adults aged 20–64 years who tried to lose weight in the past year.Measures Participants were grouped into five LTWL categories (&lt;5%, 5%–9.9%, 10%–14.9%, 15%–19.9% and ≄20%). Lifestyle-related behaviours included the following: alcohol intake, physical activity, smoking, fast-food consumption, dietary quality (Healthy Eating Index (HEI)) and caloric intake. Multivariable regression was employed adjusting for age, sex, race/ethnicity, marital status, education, household income and size, current body mass index and self-reported health status.Results Individuals in the 15%–19.9% LTWL group differed significantly from the reference group (&lt;5% LTWL) in their physical activity and dietary quality (HEI) but not caloric intake. Specifically, they had a higher HEI score (ÎČ=3.19; 95% CI 0.39 to 5.99) and were more likely to meet physical activity guidelines (OR=1.99; 95% CI 1.11 to 3.55). In comparison, the ≄20% LTWL group was significantly more likely to smoke (OR=1.63; 95% CI 1.03 to 2.57) and to consume lower daily calories (ÎČ=−202.91; 95% CI –345.57 to –60.25) than the reference group; however, dietary quality and physical activity did not significantly differ.Conclusion Among a national sample of adults, a higher level of LTWL success does not necessarily equate to healthy weight loss behaviours. Future research should attempt to design interventions aimed at facilitating weight loss success while encouraging healthy lifestyle behaviours

    Scaling tests of the improved Kogut-Susskind quark action

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    Improved lattice actions for Kogut-Susskind quarks have been shown to improve rotational symmetry and flavor symmetry. In this work we find improved scaling behavior of the rho and nucleon masses expressed in units of a length scale obtained from the static quark potential, and better behavior of the Dirac operator in instanton backgrounds.Comment: 4 pages, 4 figures, Revte

    The endocrine disruptor 17 beta-trenbolone alters the relationship between pre- and post-copulatory sexual traits in male mosquitofish (Gambusia holbrooki)

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    It is now well-established that reproduction in wildlife can be disrupted by anthropogenic environmental changes, such as chemical pollution. However, very little is known about how these pollutants might affect the interplay between pre-and post-copulatory mechanisms of sexual selection. Here, we investigated the impacts of 21-day exposure of male eastern mosquitofish (Gambusia holbrooki) to a field-realistic level (average measured concentration: 11 ng/L) of the endocrine-disrupting chemical 17S-trenbolone (17S-TB) on pre-and post-copulatory reproductive traits. We examined male reproductive behaviour by testing the time spent near a female behind a partition, as well as the number of copulation attempts made, and the time spent chasing a female in a free-swimming context. Sperm traits were also assayed for all males. We found that exposure of male fish to 17S-TB altered the relationship between key pre-and post-copulatory reproductive traits. Furthermore, 17S-TB-exposed males had, on average, a higher percentage of motile sperm, and performed fewer copulation attempts than unexposed males. However, there was no overall effect of 17S-TB exposure on either the time males spent associating with or chasing females. Taken together, our findings demonstrate the potential for chemical pollutants to affect both pre-and post-copulatory sexual traits, and the interplay between these mechanisms of sexual selection in contaminated wildlife. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/)
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