273 research outputs found

    Testes asymmetry, condition and sexual selection in birds: an experimental test

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    The functional significance of the marked directional asymmetry in testes size observed in many bird species is obscure. Møller suggested that (i) the smaller of the two testes serves a compensatory role and increases in size (and hence reduces asymmetry) when the larger one is defective in some way, and (ii) as a consequence, the degree of directional asymmetry in testes size reflects male quality and covaries positively with the expression of secondary sexual traits.We conducted an experimental test of these two hypotheses in the zebra finch,Taeniopygia guttata. Neither hypothesis was supported. First, there was no significant relationship between the size of the left testis and relative testes asymmetry. Second, we obtained no support for the hypothesis that the degree of directional asymmetry in testes mass covaried with condition. On the contrary, directional asymmetry in testes mass was signifcantly greater in birds whose condition was experimentally reduced, compared with control birds. Moreover, we found no significant relationships between testes asymmetry and secondary sexual traits. We conclude that directional asymmetry in testes size does not reflect male condition in the zebra finch

    A spatio-temporal description of the abrupt changes in the photospheric magnetic and Lorentz-force vectors during the 2011 February 15 X2.2 flare

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    The active region NOAA 11158 produced the first X-class flare of Solar Cycle 24, an X2.2 flare at 01:44 UT on 2011 February 15. Here we analyze SDO/HMI magnetograms covering a 12-hour interval centered at the time of this flare. We describe the spatial distributions of the photospheric magnetic changes associated with this flare, including the abrupt changes in the field vector, vertical electric current and Lorentz force vector. We also trace these parameters' temporal evolution. The abrupt magnetic changes were concentrated near the neutral line and in two neighboring sunspots. Near the neutral line, the field vectors became stronger and more horizontal during the flare and the shear increased. This was due to an increase in strength of the horizontal field components near the neutral line, most significant in the horizontal component parallel to the neutral line but the perpendicular component also increased in strength. The vertical component did not show a significant, permanent overall change at the neutral line. The increase in total flux at the neutral line was accompanied by a compensating flux decrease in the surrounding volume. In the two sunspots near the neutral line the azimuthal flux abruptly decreased during the flare but this change was permanent in only one of the spots. There was a large, abrupt, downward vertical Lorentz force change during the flare, consistent with results of past analyses and recent theoretical work. The horizontal Lorentz force acted in opposite directions along each side of neutral line, with the two sunspots at each end subject to abrupt torsional forces. The shearing forces were consistent with field contraction and decrease of shear near the neutral line, whereas the field itself became more sheared as a result of the flux collapsing towards the neutral line from the surrounding volume.Comment: DOI 10.1007/s11207-012-0071-0. Accepted for publication in Solar Physics SDO3 Topical Issue. Some graphics missing due to 15MB limi

    Prospects for asteroseismology

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    The observational basis for asteroseismology is being dramatically strengthened, through more than two years of data from the CoRoT satellite, the flood of data coming from the Kepler mission and, in the slightly longer term, from dedicated ground-based facilities. Our ability to utilize these data depends on further development of techniques for basic data analysis, as well as on an improved understanding of the relation between the observed frequencies and the underlying properties of the stars. Also, stellar modelling must be further developed, to match the increasing diagnostic potential of the data. Here we discuss some aspects of data interpretation and modelling, focussing on the important case of stars with solar-like oscillations.Comment: Proc. HELAS Workshop on 'Synergies between solar and stellar modelling', eds M. Marconi, D. Cardini & M. P. Di Mauro, Astrophys. Space Sci., in the press Revision: correcting abscissa labels on Figs 1 and

    Male phenotype and ejaculate quality in the zebra finch Taeniopygia guttata

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    We tested the idea that female preference for relatively attractive extra-pair males arises because the morphological and behavioural features that females find attractive covary with ejaculate features: Sheldon's (Proc. R. Soc. Lond. B 257 25-30 (1994)) phenotype-linked fertility insurance hypothesis. Two phenotypic traits that female zebra finches find attractive in males are song rate and symmetry of chest band plumage, but we found neither of these to be significantly related to any of the following ejaculate features. number of sperm, percentage of live sperm, absolute number of sperm, sperm length or sperm swimming velocity. Furthermore, and surprisingly, we did not find the predicted negative relationship between male song rate and fluctuating asymmetry of chest band plumage. Because most ejaculate features (except sperm numbers in rested males) show low levels of repeatability, it is unlikely that female zebra finches could reliably obtain a better quality ejaculate by choosing to copulate with a more attractive male. There was thus no evidence for the phenotype-linked fertility insurance hypothesis. Nor did we obtain evidence for the more general fertility insurance hypothesis: we found that female zebra finches paired to a vasectomized male, and hence receiving no sperm, were no more likely to seek an extra-pair copulation than females paired to an intact male

    Transient Magnetic and Doppler Features Related to the White-light Flares in NOAA 10486

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    Rapidly moving transient features have been detected in magnetic and Doppler images of super-active region NOAA 10486 during the X17/4B flare of 28 October 2003 and the X10/2B flare of 29 October 2003. Both these flares were extremely energetic white-light events. The transient features appeared during impulsive phases of the flares and moved with speeds ranging from 30 to 50 km s1^{-1}. These features were located near the previously reported compact acoustic \cite{Donea05} and seismic sources \cite{Zharkova07}. We examine the origin of these features and their relationship with various aspects of the flares, {\it viz.}, hard X-ray emission sources and flare kernels observed at different layers - (i) photosphere (white-light continuum), (ii) chromosphere (Hα\alpha 6563\AA), (iii) temperature minimum region (UV 1600\AA), and (iv) transition region (UV 284\AA).Comment: 26 pages, 13 figures, 2 tables, accepted for publication in Solar Physic

    Antisense oligonucleotides targeting angiogenic factors as potential cancer therapeutics

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    Cancer is one of the leading causes of death worldwide and conventional cancer therapies such as surgery, chemotherapy and radiotherapy do not address the underlying molecular pathologies, leading to inadequate treatment and tumour recurrence. Angiogenic factors, such as EGF, PDGF, bFGF, TGF-β, TGF-α, VEGF, Endoglin and Angiopoietins play important roles in regulating tumour development and metastasis, and serve as potential targets for developing cancer therapeutics. Nucleic acid-based therapeutic strategies have received significant attention in the last two decades, and antisense oligonucleotide-mediated intervention is a prominent therapeutic approach for targeted manipulation of gene expression. Clinical benefits of antisense oligonucleotides have been recognised by the US Food and Drug Administration, with full or conditional approval of Vitravene, Kynamro, Exondys51 and Spinraza. Herein, we review the scope of antisense oligonucleotides that target angiogenic factors towards tackling solid cancers

    Magnetic Fields in the Milky Way

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    This chapter presents a review of observational studies to determine the magnetic field in the Milky Way, both in the disk and in the halo, focused on recent developments and on magnetic fields in the diffuse interstellar medium. I discuss some terminology which is confusingly or inconsistently used and try to summarize current status of our knowledge on magnetic field configurations and strengths in the Milky Way. Although many open questions still exist, more and more conclusions can be drawn on the large-scale and small-scale components of the Galactic magnetic field. The chapter is concluded with a brief outlook to observational projects in the near future.Comment: 22 pages, 5 figures, to appear in "Magnetic Fields in Diffuse Media", eds. E.M. de Gouveia Dal Pino and A. Lazaria

    The extent of eating disorders and comorbid psychopathology among adolescent school pupils

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    Objective Limited literature exists on the extent of eating concerns among adolescents. This study examines the extent of eating disorder pathology and psychosocial correlates among 11- to 18-year-olds. Method School pupils (N = 382; 52% female; 72.8% Caucasian) provided demographic information and completed measures of eating disorder pathology (using a cut-off of > 3.64 on the seven-item Eating Disorders Examination-Questionnaire), psychosocial impairment, body shape dissatisfaction and mood. Levels of comorbid problems were compared across adolescents with low- and high-risk for eating disorders, using Mann-Whitney tests and Chi-squared tests and an alpha of 0.001 (to account for exploratory analyses). Results A fifth (20.7%) of pupils exhibited clinical levels of eating disorder pathology, and they scored significantly worse on the other measures of psychopathology than those without such eating concerns. The majority (89.9%) of pupils with eating disorder pathology scores were above the clinical threshold in one or more comorbid areas. Eating disorder pathology and measures of comorbidity were all significantly intercorrelated. Discussion A fifth of pupils were at-risk of eating disorder pathology, and almost all demonstrated substantial comorbidity. Contrary to the ‘white female’ eating disorder stereotype, many of those with eating concerns were non-white and over a third did not identify as female. These findings require further work on the screening technology, but highlight the pressing need for access to eating disorder prevention and treatment for a diverse population of such adolescents

    Fecal Immunochemical Test Screening and Risk of Colorectal Cancer Death.

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    The fecal immunochemical test (FIT) is widely used for colorectal cancer (CRC) screening, but evidence of its effectiveness is limited. To evaluate whether FIT screening is associated with a lower risk of dying from CRC overall, according to cancer location, and within demographic groups. This nested case-control study in a cohort of screening-eligible people was conducted in 2 large, integrated health systems of racially, ethnically, and socioeconomically diverse members with long-term programs of mailed FIT screening outreach. Eligible participants included people aged 52 to 85 years who died from colorectal adenocarcinoma between 2011 and 2017 (cases); cases were matched in a 1:8 ratio based on age, sex, health-plan membership duration, and geographic area to randomly selected persons who were alive and CRC-free on case's diagnosis date (controls). Data analysis was conducted from January 2002 to December 2017. Completing 1 or more FIT screenings in the 5-year period prior to the CRC diagnosis date among cases or the corresponding date among controls; in secondary analyses, 2- to 10-year intervals were evaluated. The primary study outcome was CRC death overall and by tumor location. Secondary analyses were performed to assess CRC death by race and ethnicity. From a cohort of 2 127 128 people, a total of 10 711 participants (3529 aged 60-69 years [32.9%]; 5587 male [52.1%] and 5124 female [47.8%]; 1254 non-Hispanic Asian [11.7%]; 973 non-Hispanic Black [9.1%]; 1929 Hispanic or Latino [18.0%]; 6345 non-Hispanic White [59.2%]) was identified, including 1103 cases and 9608 controls. Among controls during the 10-year period prior to the reference date, 6101 (63.5%) completed 1 or more FITs with a cumulative 12.6% positivity rate (768 controls), of whom 610 (79.4%) had a colonoscopy within 1 year. During the 5-year period, 494 cases (44.8%) and 5345 controls (55.6%) completed 1 or more FITs. In regression analysis, completing 1 or more FIT screening was associated with a 33% lower risk of death from CRC (adjusted odds ratio [aOR], 0.67; 95% CI, 0.59-0.76) and 42% lower risk in the left colon and rectum (aOR, 0.58; 95% CI, 0.48-0.71). There was no association with right colon cancers (aOR, 0.83; 95% CI, 0.69-1.01) but the difference in the estimates between the right colon and left colon or rectum was statistically significant (P = .01). FIT screening was associated with lower CRC mortality risk among non-Hispanic Asian (aOR, 0.37; 95% CI, 0.23-0.59), non-Hispanic Black (aOR, 0.58; 95% CI, 0.39-0.85) and non-Hispanic White individuals (aOR, 0.70; 95% CI, 0.57-0.86) (P for homogeneity = .04 for homogeneity). In this nested case-control study, completing FIT was associated with a lower risk of overall death from CRC, particularly in the left colon, and the associations were observed across racial and ethnic groups. These findings support the use of FIT in population-based screening strategies

    A preliminary qualitative exploration of pupils, parents and school staff perspectives on a brief, school-based intervention for eating disorders

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    Background: While around one-fifth of UK secondary school pupils exhibit clinically significant eating pathology, in-school mental health provision does not include interventions to address such eating pathology. Aims: This preliminary qualitative study aimed to explore the views of staff, parents and pupils, on the idea of introducing a school-based brief cognitive behavioural therapy programme for non-underweight eating disorders. Method: 31 pupils, 22 parents and 27 staff participated in 12 focus groups across four schools. The semi-structured interview guide covered topics around the practicalities of a potential eating disorders treatment programme, the acceptability of the intervention, and likelihood of future uptake. Results: Five over-arching themes and 12 subthemes emerged, reflecting the scale of eating and body image concerns, management limitations, and the importance of prioritising mental health over education. Advantages, challenges, considerations, and solutions were proposed for an in-school eating disorders treatment programme. Conclusions: These qualitative data show that there is support for an appropriately implemented in-school delivery of brief, evidence-based treatment, demonstrating the potential scope of such an approach to support children and adolescents to receive early help with their eating problems and body image concerns
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