1,446 research outputs found

    Families and Flexibility: Building the 21st Century Workplace

    Get PDF
    This report details the findings of a survey of working New Yorkers -- conducted by the Comptroller's Office, in partnership with A Better Balance -- designed to provide policymakers with insight into how flexible work arrangements are, or are not, being used by individuals and businesses throughout the city. It is intended to gauge the need for workplace reforms, including but not limited to, legislation establishing the "right to request" FWA's, paid family leave, and advance notification of schedules. The survey, while non-scientific, yielded over 1,100 responses from residents of all five boroughs working in a range of industries, from professional services and education, to health care, retail, and construction between June and August 2015. The results suggest that New Yorkers from all walks of life face an untenable tension between their professional and personal responsibilities, and that a new model of work is needed to ensure that parents can remain in the workforce, families have the flexibility to care for loved ones of all ages, and workers of every stripe have the opportunity to succeed

    Cryptic female choice favours sperm from major histocompatibility complex-dissimilar males

    Get PDF
    Cryptic female choice may enable polyandrous females to avoid inbreeding or bias offspring variability at key loci after mating. However, the role of these genetic benefits in cryptic female choice remains poorly understood. Female red junglefowl, Gallus gallus, bias sperm use in favour of unrelated males. Here, we experimentally investigate whether this bias is driven by relatedness per se, or by similarity at the major histocompatibility complex (MHC), genes central to vertebrate acquired immunity, where polymorphism is critical to an individual's ability to combat pathogens. Through experimentally controlled natural matings, we confirm that selection against related males' sperm occurs within the female reproductive tract but demonstrate that this is more accurately predicted by MHC similarity: controlling for relatedness per se, more sperm reached the eggs when partners were MHC-dissimilar. Importantly, this effect appeared largely owing to similarity at a single MHC locus (class I minor). Further, the effect of MHC similarity was lost following artificial insemination, suggesting that male phenotypic cues might be required for females to select sperm differentially. These results indicate that postmating mechanisms that reduce inbreeding may do so as a consequence of more specific strategies of cryptic female choice promoting MHC diversity in offspring

    Differential sperm storage by female zebra finches Taeniopygia guttata

    Get PDF
    When females mate promiscuously, female sperm storage provides scope to bias the fertilization success towards particular males via the non-random acceptance and utilization of sperm. The difficulties observing postcopulatory processes within the female reproductive tract mean that the mechanisms underlying cryptic female choice remain poorly understood. Here, we use zebra finches Taeniopygia guttata, selected for divergent sperm lengths, combined with a novel technique for isolating and extracting sperm from avian sperm storage tubules (SSTs), to test the hypothesis that sperm from separate ejaculates are stored differentially by female birds. We show that sperm from different inseminations enter different SSTs in the female reproductive tract, resulting in almost complete segregation of the sperm of competing males. We propose that non-random acceptance of sperm into SSTs, reflected in this case by sperm phenotype, provides a mechanism by which long sperm enjoy enhanced fertilization success in zebra finches

    Intra-ejaculate sperm selection in female zebra finches

    Get PDF
    Among internal fertilizers, typically fewer than 1% sperm survive the journey through the oviduct. Several studies suggest that the sperm reaching the ovum-the 'fertilizing set'-comprise a non-random sub-population, but the characteristics of this group remain unclear. We tested whether oviductal selection in birds results in a morphologically distinct subset of sperm, by exploiting the fact that the fertilizing set are trapped by the perivitelline layer of the ovum. We show that these sperm have remarkably low morphological variation, as well as smaller head size and greater tail length, compared with those inseminated. Our study shows that the morphological composition of sperm-rather than length alone-influences success in reaching the ovum

    BMQ

    Full text link
    BMQ: Boston Medical Quarterly was published from 1950-1966 by the Boston University School of Medicine and the Massachusetts Memorial Hospitals

    Structure of the avian oviduct with emphasis on sperm storage in poultry

    Get PDF

    Turkey hen fertility and egg production after artificial insemination and multiple oviduct eversion during the pre-laying period

    Get PDF
    The onset of egg production (mean 18 · 3 days after the onset of photostimulation) and the rate of egg production (flock averaged 4 · 9 eggs per bird per week for the first 8 weeks of egg production) were not affected by 5 days of twice daily oviduct eversion (\u27venting\u27) in the pre-laying period when compared to unvented controls. After the onset of photostimulation, pre-laying hens were inseminated twice daily on Days 12 to 16 with 3 μl semen containing 15 × 106 spermatozoa, and compared with groups of hens inseminated once daily on Days 15 and 16 with 15 μl semen containing 75 × 106 spermatozoa or 41 μl semen containing 200 × 106 spermatozoa. Fertility remained high for the first 5 weeks ofegg production. However, by Week 6 the fertility of the hens receiving frequent low doses of semen dropped significantly below that of the others, which suggests that multiple inseminations with a low semen volume containing relatively low numbers of spermatozoa does not lead to an increase in the efficacy of sperm transport and storage in the oviduct

    Effects of point defects and microstructure on the pseudo-elasticity of ThCr2Si2-type crystals, The

    Get PDF
    2018 Fall.Includes bibliographical references.Ternary intermetallic compounds with the ThCr2Si2-type structure, which are known for their high-temperature superconductivity, have recently garnered interest due to the discovery of a pseudo-elastic mechanical response to compression along the c-axis. However, the effects of point defects and doping on this response remain unknown. In this work, these effects are investigated with density functional theory (DFT) in conjunction with continuum-scale models. DFT simulations of hydrostatic and uniaxial compression of pure ThCr2Si2-type crystals were conducted. The magnetic phase transition of CaFe2As2 was reproduced, while LaRu2P2 exhibited a continuous transition into its collapsed tetragonal phase. The two-phase DFT data was used to build a continuum-scale, thermodynamically-driven composite model which predicts the pseudo-elastic response of a large sample under displacement control and load control scenarios. Strain along the c-axis was shown to be the critical parameter in predicting crystal collapse. Then, DFT simulations of defected or doped unit cells were conducted to investigate their energetics and mechanical responses to compression. In some cases, the addition of vacancies effectively suppressed the pseudo-elastic response of the crystals. Simulations of crystals doped with varying concentrations revealed alterations of the mechanical properties as well. Tunable variability of the phase change with respect to dopant concentration was predicted in disordered doped structures, while multiple phase changes were predicted in ordered doped structures. Composite models were then built with the DFT data to predict the response of a sample comprised of multiple microstructures. The models predict a wide range of variability in the mechanical behavior and provide insight into how impurities and defects can be used to tune the response of these materials
    corecore