3,969 research outputs found
Resilience amongst Australian Aboriginal youth: an ecological analysis of factors associated with psychosocial functioning in high and low family risk contexts
Abstract: We investigate whether the profile of factors protecting psychosocial functioning of high risk exposed Australian Aboriginal youth are the same as those promoting psychosocial functioning in low risk exposed youth. Data on 1,021 youth aged 12–17 years were drawn from the Western Australian Aboriginal Child Health Survey, a population representative survey of the health and well-being of Aboriginal children, their families and community contexts. A person-centered approach was used to define four groups of youth cross-classified according to level of risk exposure (high/low) and psychosocial functioning (good/poor). Multivariate logistic regression was used to model the influence of individual, family, cultural and community factors on psychosocial outcomes separately for youth in high and low family-risk contexts. Results showed that in high family risk contexts, prosocial friendship and low area-level socioeconomic status uniquely protected psychosocial functioning. However, in low family risk contexts the perception of racism increased the likelihood of poor psychosocial functioning. For youth in both high and low risk contexts, higher self-esteem and self-regulation were associated with good psychosocial functioning although the relationship was non-linear. These findings demonstrate that an empirical resilience framework of analysis can identify potent protective processes operating uniquely in contexts of high risk and is the first to describe distinct profiles of risk, protective and promotive factors within high and low risk exposed Australian Aboriginal youth
Mycoplasma genitalium: An Emerging Cause of Pelvic Inflammatory Disease
Mycoplasma genitalium is a sexually transmitted pathogen that is increasingly identified among women with pelvic inflammatory disease (PID). Although Chlamydia trachomatis and Neisseria gonorrhoeae frequently cause PID, up to 70% of cases have an unidentified etiology. This paper summarizes evidence linking M. genitalium to PID and its long-term reproductive sequelae. Several PCR studies have demonstrated that M. genitalium is associated with PID, independent of gonococcal and chlamydial infection. Most have been cross-sectional, although one prospective investigation suggested that M. genitalium was associated with over a thirteenfold risk of endometritis. Further, a nested case-control posttermination study demonstrated a sixfold increased risk of PID among M. genitalium positive patients. Whether or not M. genitalium upper genital tract infection results in long-term reproductive morbidity is unclear, although tubal factor infertility patients have been found to have elevated M. genitalium antibodies. Several lines of evidence suggest that M. genitalium is likely resistant to many frequently used PID treatment regimens. Correspondingly, M. genitalium has been associated with treatment failure following cefoxitin and doxycycline treatment for clinically suspected PID. Collectively, strong evidence suggests that M. genitalium is associated with PID. Further study of M. genitalium upper genital tract infection diagnosis, treatment and long-term sequelae is warranted
Management of Chlamydia trachomatis genital tract infection: screening and treatment challenges
Chlamydia trachomatis is a prevalent sexually transmitted infection that can lead to serious reproductive morbidity. Management and control of C. trachomatis is a challenge, largely due to its asymptomatic nature and our incomplete understanding of its natural history. Although chlamydia screening programs have been implemented worldwide, several countries have observed increasing rates of reported chlamydia cases. We reviewed the literature relating to the long-term complications of C. trachomatis, as well as screening strategies, treatment, and prevention strategies for reducing chlamydia in the population. Articles from 1950–2010 were identified through a Medline search using the keyword “Chlamydia trachomatis” combined with “screening”, “pelvic inflammatory disease”, “endometritis”, “salpingitis”, “infertility”, “ectopic pregnancy”, “urethritis”, “epididymitis”, “proctitis”, “prostatitis”, “reinfection”, “cost-effectiveness”, “treatment”, “vaccines”, or “prevention”. Progression of C. trachomatis varies, and recurrent infections are common. Currently, there is limited evidence on the effectiveness of chlamydia screening. Higher quality studies are needed to determine the efficacy of more frequent screening, on a broader range of sequelae, including infertility and ectopic pregnancy, in addition to pelvic inflammatory disease. Studies should focus on delineating the natural history of recurrent infections, paying particular attention to treatment failures. Furthermore, alternatives to screening, such as vaccines, should continue to be explored
Contrasting hybridization rates between sympatric three-spined sticklebacks highlight the fragility of reproductive barriers between evolutionarily young species.
Three-spined sticklebacks (Gasterosteus aculeatus) are a powerful evolutionary model system due to the rapid and repeated phenotypic divergence of freshwater forms from a marine ancestor throughout the Northern Hemisphere. Many of these recently derived populations are found in overlapping habitats, yet are reproductively isolated from each other. This scenario provides excellent opportunities to investigate the mechanisms driving speciation in natural populations. Genetically distinguishing between such recently derived species, however, can create difficulties in exploring the ecological and genetic factors defining species boundaries, an essential component to our understanding of speciation. We overcame these limitations and increased the power of analyses by selecting highly discriminatory markers from the battery of genetic markers now available. Using species diagnostic molecular profiles, we quantified levels of hybridization and introgression within three sympatric species pairs of three-spined stickleback. Sticklebacks within Priest and Paxton lakes exhibit a low level of natural hybridization and provide support for the role of reinforcement in maintaining distinct species in sympatry. In contrast, our study provides further evidence for a continued breakdown of the Enos Lake species pair into a hybrid swarm, with biased introgression of the 'limnetic' species into that of the 'benthic'; a situation that highlights the delicate balance between persistence and breakdown of reproductive barriers between young species. A similar strategy utilizing the stickleback microsatellite resource can also be applied to answer an array of biological questions in other species' pair systems in this geographically widespread and phenotypically diverse model organism
Ecological selection against hybrids in natural populations of sympatric threespine sticklebacks.
Experimental work has provided evidence for extrinsic post-zygotic isolation, a phenomenon unique to ecological speciation. The role that ecological components to reduced hybrid fitness play in promoting speciation and maintaining species integrity in the wild, however, is not as well understood. We addressed this problem by testing for selection against naturally occurring hybrids in two sympatric species pairs of benthic and limnetic threespine sticklebacks (Gasterosteus aculeatus). If post-zygotic isolation is a significant reproductive barrier, the relative frequency of hybrids within a population should decline significantly across the life-cycle. Such a trend in a natural population would give independent support to experimental evidence for extrinsic, rather than intrinsic, post-zygotic isolation in this system. Indeed, tracing mean individual hybridity (genetic intermediateness) across three life-history stages spanning four generations revealed just such a decline. This provides compelling evidence that extrinsic selection plays an important role in maintaining species divergence and supports a role for ecological speciation in sticklebacks
Compton scattering in strong magnetic fields: Spin-dependent influences at the cyclotron resonance
The quantum electrodynamical (QED) process of Compton scattering in strong
magnetic fields is commonly invoked in atmospheric and inner magnetospheric
models of x-ray and soft gamma-ray emission in high-field pulsars and
magnetars. A major influence of the field is to introduce resonances at the
cyclotron frequency and its harmonics, where the incoming photon accesses
thresholds for the creation of virtual electrons or positrons in intermediate
states with excited Landau levels. At these resonances, the effective cross
section typically exceeds the classical Thomson value by over 2 orders of
magnitude. Near and above the quantum critical magnetic field of 44.13
TeraGauss, relativistic corrections must be incorporated when computing this
cross section. This paper presents formalism for the QED magnetic Compton
differential cross section valid for both subcritical and supercritical fields,
yet restricted to scattered photons that are below pair creation threshold.
Calculations are developed for the particular case of photons initially
propagating along the field, mathematically simple specializations that are
germane to interactions involving relativistic electrons frequently found in
neutron star magnetospheres. This exposition of relativistic, quantum, magnetic
Compton cross sections treats electron spin dependence fully, since this is a
critical feature for describing the finite decay lifetimes of the intermediate
states. The formalism employs both the Johnson and Lippmann (JL) wave functions
and the Sokolov and Ternov (ST) electron eigenfunctions of the magnetic Dirac
equation. The ST states are formally correct for self-consistently treating
spin-dependent effects that are so important in the resonances. Relatively
compact analytic forms for the cross sections are presented that will prove
useful for astrophysical modelers.Comment: 45 pages, 10 figures, accepted for publication in Phys. Rev.
A research-inspired laboratory sequence investigating acquired drug resistance
Here, we present a six-session laboratory exercise designed to introduce students to standard biochemical techniques in the context of investigating a high impact research topic, acquired resistance to the cancer drug Gleevec. Students express a Gleevec-resistant mutant of the Abelson tyrosine kinase domain, the active domain of an oncogenic protein implicated in chronic myelogenous leukemia, and investigate the kinase activity of wild type and mutant enzyme in the presence of two cancer drugs. Techniques covered include protein expression, purification, and gel analysis, kinase activity assays, and protein structure viewing. The exercises provide students with a hands-on understanding of the impact of biochemistry on human health, and demonstrate their potential as the next generation of investigators.Howard Hughes Medical Institut
Night-time on a postnatal ward: experiences of mothers, infants, and staff
This chapter illustrates an alternative approach to video ethnography, in which video case studies are described alongside semi-structured interview responses to detail night-time challenges of mothers, newborns, and hospital staff on a postnatal ward. Data from three original, inter-related research projects were combined. We uncovered five themes: maternal need for support, response to infant cues, negative experiences, bedsharing as a way of coping, and insufficient staffing. In detailing these issues, we draw attention to previously unknown or unacknowledged obstacles for new mothers and their infants, as well as the constraints on the staff involved in their care
The pervasive effects of timing of parental mental health disorders on adolescent deliberate self-harm risk
Children whose parents have mental health disorders are at increased risk for deliberate self-harm (DSH). However, the effect of timing of parental mental health disorders on adolescent DSH risk remains under-researched. The aim of this study was to investigate how parental hospital admissions for mental health disorders and/or DSH in different developmental periods impact on the child’s DSH risk in adolescence. A nested case-control sample was compiled from a total population cohort sample drawn from administrative health records in Western Australia. The sample comprised 7,151 adolescents who had a DSH-related hospital admission (cases), and 143,020 matched controls who hadn’t had a DSH-related hospital admission. The occurrence of parental hospital admissions related to mental health disorders and/or DSH behaviours was then analysed for the cases and controls. The timing of the parental hospital admissions was partitioned into four stages in the child’s life course: (1) pre-pregnancy, (2) pregnancy and infancy, (3) childhood, and (4) adolescence. We found that adolescents of a parent with mental health and/or DSH-related hospital admissions in all developmental periods except pregnancy and infancy were significantly more likely than controls to have a DSH-related hospital admission. Compared to parental hospital admissions that occurred during childhood and adolescence, those that occurred before pregnancy conferred a higher risk for adolescent DSH: adjusted odds ratio (aOR) = 1.25 for having only one parent hospitalised and 1.66 for having both parents hospitalised for mental health disorders; aOR = 1.97 for having any parent hospitalised for DSH, all being significant at the level of p < .001. This study shows that timing is important for understanding intergenerational transmission of DSH risk. The pre-pregnancy period is as critical as period after childbirth for effective intervention targeting adult mental health disorders and DSH, highlighting the important role of adult mental health services in preventing DSH risk in future generations
Perspectives: Entrepreneurship Training Can Empower Students Being Left Behind
Entrepreneurial self-employment, however, would hold great promise for business-minded students, if they learn entrepreneurship in high school and can test out their innovative business plans on consumers in their own neighborhoods and beyond — especially Internet start-up ideas. The social and community networking success of MySpace opens a wide door for anyone to market a new idea or product to a myriad of potential customers instantly
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