52 research outputs found
Star Formation History and Chemical Evolution of the Sextans Dwarf Spheroidal Galaxy
We present the star formation history and chemical evolution of the Sextans
dSph dwarf galaxy as a function of galactocentric distance. We derive these
from the photometry of stars in the field using the SMART
model developed by Yuk & Lee (2007, ApJ, 668, 876) and adopting a closed-box
model for chemical evolution. For the adopted age of Sextans 15 Gyr, we find
that 84% of the stars formed prior to 11 Gyr ago, significant star formation
extends from 15 to 11 Gyr ago ( 65% of the stars formed 13 to 15 Gyr ago
while 25% formed 11 to 13 Gyr ago), detectable star formation continued
to at least 8 Gyr ago, the star formation history is more extended in the
central regions than the outskirts, and the difference in star formation rates
between the central and outer regions is most marked 11 to 13 Gyr ago. Whether
blue straggler stars are interpreted as intermediate age main sequence stars
affects conclusions regarding the star formation history for times 4 to 8 Gyr
ago, but this is at most only a trace population. We find that the metallicity
of the stars increased rapidly up to [Fe/H]=--1.6 in the central region and to
[Fe/H]=--1.8 in the outer region within the first Gyr, and has varied slowly
since then. The abundance ratios of several elements derived in this study are
in good agreement with the observational data based on the high resolution
spectroscopy in the literature. We conclude that the primary driver for the
radial gradient of the stellar population in this galaxy is the star formation
history, which self-consistently drives the chemical enrichment history.Comment: 36 pages, 14 figures, To appear in the ApJ, 200
Attachment anxiety predicts depression and anxiety symptoms following coronary artery bypass graft surgery.
OBJECTIVE: Depression and anxiety are associated with poor recovery in coronary artery bypass graft (CABG) patients, but little is known about predictors of depression and anxiety symptoms. DESIGN: We tested the prospective association between attachment orientation, and symptoms of depression and anxiety in CABG patients, 6-8Â weeks, and 12Â months following surgery. METHOD: One hundred and fifty-five patients who were undergoing planned CABG surgery were recruited. Patients completed questionnaires measuring attachment, depression, and anxiety prior to surgery, then 6-8Â weeks, and 12Â months after surgery. RESULTS: Attachment anxiety predicted symptoms of depression and anxiety at both follow-up time points, whereas attachment avoidance was not associated with depression or anxiety symptoms. The findings remained significant when controlling for baseline mood scores, social support, demographic, and clinical risk factors. CONCLUSION: These results suggest that attachment anxiety is associated with short-term and long-term depression and anxiety symptoms following CABG surgery. These results may offer important insight into understanding the recovery process in CABG surgery. Statement of contribution What is already known on this subject? Depression and anxiety symptoms are twice more likely to occur in coronary artery bypass graft (CABG) populations than in any other medical group. Depression and anxiety are associated with poor recovery following cardiac surgery. Predictors of depression and anxiety in CABG patients have been underexplored. What does this study add? This study highlights the importance of close interpersonal relationships on health. Attachment anxiety was prospectively associated with higher levels of depression and anxiety. These results add to understanding mechanisms linked to recovery following CABG
Hydrogen ion dynamics and the Na+/H+ exchanger in cancer angiogenesis and antiangiogenesis
Tumour angiogenesis and cellular pH regulation, mainly represented by Na+/H+ antiporter exchange, have been heretofore considered unrelated subfields of cancer research. In this short review, the available experimental evidence relating these areas of modern cancer research is introduced. This perspective also helps to design a new approach that facilitates the opening and development of novel research lines oriented towards a rational incorporation of anticancer drugs into more selective and less toxic therapeutic protocols. The final aim of these efforts is to control cancer progression and dissemination through the control of tumour angiogenesis. Finally, different antiangiogenic drugs that can already be clinically used to this effect are briefly presented
Early-life predictors of resilience and related outcomes up to 66Â years later in the 6-day sample of the 1947 Scottish mental survey.
PURPOSE: Psychological resilience, the ability to manage and quickly recover from stress and trauma, is associated with a range of health and wellbeing outcomes. Resilience is known to relate to personality, self-esteem and positive affect, and may also depend upon childhood experience and stress. In this study, we investigated the role of early-life contributors to resilience and related factors in later life. METHODS: We used data from the 6-day sample of the Scottish mental survey 1947, an initially representative sample of Scottish children born in 1936. They were assessed on a range of factors between the ages of 11 and 27Â years, and resilience and other outcomes at 77Â years. RESULTS: Higher adolescent dependability unexpectedly predicted lower resilience in older-age, as did childhood illnesses, while a count of specific stressors experienced throughout early life significantly predicted higher later-life resilience. We also observed significant cross-sectional correlations between resilience and measures of physical health, mental health, wellbeing and loneliness. Some of the associations between early-life predictors and later-life outcomes were significantly mediated by resilience. CONCLUSIONS: Our results support the hypothesis that stress throughout early life may help to build resilience in later-life, and demonstrate the importance of resilience as a mediator of other influences on health and wellbeing in older age. We suggest that the mechanisms determining how early-life stress leads to higher resilience are worthy of further investigation, and that psychological resilience should be a focus of research and a target for therapeutic interventions aiming to improve older-age health and wellbeing
Phytotherapy for Polycystic Ovarian Syndrome: A review of the literature and evaluation of practitioners’ experiences
Background: Polycystic Ovarian Syndrome (PCOS) is a common, complex,
endocrine condition with potential long-term cardiovascular, endocrine and metabolic
health implications. Currently, there exists no medical treatment that addresses all
clinical presentations. Herbal practitioners often treat women with PCOS; yet, there
is a lack of research investigating PCOS and herbal treatment. This study aimed to
examine the current scientific literature on PCOS and phytotherapy, explore
practitioners’ experiences treating women with the syndrome and evaluate whether
there is a role for phytotherapy in the treatment of PCOS.
Methods: A literature search was conducted using the terms; ‘Polycystic Ovarian
Syndrome’ / ‘PCOS’ and ‘phytotherapy’/‘herbal medicine’ / ‘herbs’. The published
research identified by these terms was then reviewed. A brief questionnaire with a
mix of eleven open and closed questions was sent to herbal practitioners on the
National Institute of Medical Herbalists (NIMH) 2012 register.
Results: The literature review found promising results for the use of Mentha spicata,
Cinnamomum verum and berberine containing herbs. There was a weaker evidence
base for the use of Glycyrrhiza glabra and Paeonia lactiflora. The questionnaire was
completed by 72 practitioners, 71 % had treated women with PCOS. The majority
(38%, n=50) felt herbal medicine was ‘quite successful’ in treating PCOS. The
average time until herbal treatment started to be successful was 3.2 months. The
most frequently used herbs were Paeonia lactiflora, Glycyrrhiza glabra and Vitex
agnus castus. Dietary and lifestyle advice emerged as frequently identified
therapeutic interventions.
Conclusions: This exploratory study suggests that there is a role for phytotherapy in
the treatment of PCOS. Further investigation, consisting of well-designed clinical
trials and monitoring the successful use of herbal medicine by practitioners, is clearly
necessary. This future research would serve to substantiate positive empirical
evidence, constructing a more robust evidence base for the effective use of
phytotherapy as a therapeutic option for women with PCOS
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