77 research outputs found

    Accreting Protoplanets in the LkCa 15 Transition Disk

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    Exoplanet detections have revolutionized astronomy, offering new insights into solar system architecture and planet demographics. While nearly 1900 exoplanets have now been discovered and confirmed, none are still in the process of formation. Transition discs, protoplanetary disks with inner clearings best explained by the influence of accreting planets, are natural laboratories for the study of planet formation. Some transition discs show evidence for the presence of young planets in the form of disc asymmetries or infrared sources detected within their clearings, as in the case of LkCa 15. Attempts to observe directly signatures of accretion onto protoplanets have hitherto proven unsuccessful. Here we report adaptive optics observations of LkCa 15 that probe within the disc clearing. With accurate source positions over multiple epochs spanning 2009 - 2015, we infer the presence of multiple companions on Keplerian orbits. We directly detect H{\alpha} emission from the innermost companion, LkCa 15 b, evincing hot (~10,000 K) gas falling deep into the potential well of an accreting protoplanet.Comment: 35 pages, 3 figures, 1 table, 9 extended data item

    Product and process innovation in manufacturing firms: a 30-year bibliometric analysis

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    Built upon a thirty-year dataset collected from the Web of Science database, the present research aims to offer a comprehensive overview of papers, authors, streams of research, and the most influential journals that discuss product and process innovation in the manufacturing environment. The dataset is composed of 418 papers from more than 150 journals from the period between 1985 and 2015. Homogeneity analysis by means of alternating least squares (HOMALS) and Social Network Analysis (SNA) are used to accomplish the objectives listed above through the keywords given by authors. Initially, the paper highlights and discusses the similarity between the topics debated by the main journals in this field. Subsequently, a wide-range map of topics is presented highlighting five main areas of interests; namely, performance, patent, small firm, product development, and organization. A SNA is also performed in order to validate the results that emerged from HOMALS. Finally, several insights about future research avenues in the manufacturing field are provided

    Dietary patterns and risk of breast cancer

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    Background: Evidence is emerging that prudent/healthy dietary patterns might be associated with a reduced risk of breast cancer. Methods: Using data from the prospective Melbourne Collaborative Cohort Study, we applied principal factor analysis to 124 foods and beverages to identify dietary patterns and estimated their association with breast cancer risk overall and by tumour characteristics using Cox regression. Results: During an average of 14.1 years of follow-up of 20 967 women participants, 815 invasive breast cancers were diagnosed. Among the four dietary factors that we identified, only that characterised by high consumption of fruit and salad was associated with a reduced risk, with stronger associations observed for tumours not expressing oestrogen (ER) and progesterone receptors (PR). Compared with women in the lowest quintile of the factor score, the hazard ratio for women in the highest quintile was 0.92 (95% confidence interval (CI)=0.70-1.21; test for trend, P=0.5) for ER-positive or PR-positive tumours and 0.48 (95% CI=0.26-0.86; test for trend, P=0.002) for ER-negative and PR-negative tumours (test for homogeneity, P=0.01). Conclusion: Our study provides additional support for the hypothesis that a dietary pattern rich in fruit and salad might protect against invasive breast cancer and that the effect might be stronger for ER- and PR-negative tumours. © 2011 Cancer Research UK All rights reserved

    Paneth Cells in Intestinal Homeostasis and Tissue Injury

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    Adult stem cell niches are often co-inhabited by cycling and quiescent stem cells. In the intestine, lineage tracing has identified Lgr5+ cells as frequently cycling stem cells, whereas Bmi1+, mTert+, Hopx+ and Lrig1+ cells appear to be more quiescent. Here, we have applied a non-mutagenic and cell cycle independent approach to isolate and characterize small intestinal label-retaining cells (LRCs) persisting in the lower third of the crypt of Lieberkühn for up to 100 days. LRCs do not express markers of proliferation and of enterocyte, goblet or enteroendocrine differentiation, but are positive for Paneth cell markers. While during homeostasis, LR/Paneth cells appear to play a supportive role for Lgr5+ stem cells as previously shown, upon tissue injury they switch to a proliferating state and in the process activate Bmi1 expression while silencing Paneth-specific genes. Hence, they are likely to contribute to the regenerative process following tissue insults such as chronic inflammation

    mTORC1-mediated translational elongation limits intestinal tumour initiation and growth.

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    Inactivation of APC is a strongly predisposing event in the development of colorectal cancer, prompting the search for vulnerabilities specific to cells that have lost APC function. Signalling through the mTOR pathway is known to be required for epithelial cell proliferation and tumour growth, and the current paradigm suggests that a critical function of mTOR activity is to upregulate translational initiation through phosphorylation of 4EBP1 (refs 6, 7). This model predicts that the mTOR inhibitor rapamycin, which does not efficiently inhibit 4EBP1 (ref. 8), would be ineffective in limiting cancer progression in APC-deficient lesions. Here we show in mice that mTOR complex 1 (mTORC1) activity is absolutely required for the proliferation of Apc-deficient (but not wild-type) enterocytes, revealing an unexpected opportunity for therapeutic intervention. Although APC-deficient cells show the expected increases in protein synthesis, our study reveals that it is translation elongation, and not initiation, which is the rate-limiting component. Mechanistically, mTORC1-mediated inhibition of eEF2 kinase is required for the proliferation of APC-deficient cells. Importantly, treatment of established APC-deficient adenomas with rapamycin (which can target eEF2 through the mTORC1-S6K-eEF2K axis) causes tumour cells to undergo growth arrest and differentiation. Taken together, our data suggest that inhibition of translation elongation using existing, clinically approved drugs, such as the rapalogs, would provide clear therapeutic benefit for patients at high risk of developing colorectal cancer

    Interferometric Observations of Rapidly Rotating Stars

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    Optical interferometry provides us with a unique opportunity to improve our understanding of stellar structure and evolution. Through direct observation of rotationally distorted photospheres at sub-milliarcsecond scales, we are now able to characterize latitude dependencies of stellar radius, temperature structure, and even energy transport. These detailed new views of stars are leading to revised thinking in a broad array of associated topics, such as spectroscopy, stellar evolution, and exoplanet detection. As newly advanced techniques and instrumentation mature, this topic in astronomy is poised to greatly expand in depth and influence.Comment: Accepted for publication in A&AR

    The Magpie Trial follow up study: outcome after discharge from hospital for women and children recruited to a trial comparing magnesium sulphate with placebo for pre-eclampsia

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    Contributing member: Caroline Crowther is listed as a member of the Magpie Trial Follow Up Study Collaborative GroupBACKGROUND: The Magpie Trial compared magnesium sulphate with placebo for women with pre-eclampsia. 10,141 women were recruited, 8804 before delivery. Overall, 9024 children were included in the analysis of outcome at discharge from hospital. Magnesium sulphate more than halved the risk of eclampsia, and probably reduced the risk of maternal death. There did not appear to be any substantive harmful effects on the baby, in the short term. It is now important to assess whether these benefits persist, and to provide adequate reassurance about longer term safety. The main objective of the Magpie Trial Follow Up Study is to assess whether in utero exposure to magnesium sulphate has a clinically important effect on the child's chance of surviving without major neurosensory disability. Other objectives are to assess long term outcome for the mother, and to develop and assess appropriate strategies for following up large numbers of children in perinatal trials. STUDY DESIGN: Follow up is only feasible in selected centres. We therefore anticipate contacting 2800–3350 families, for 2435–2915 of whom the woman was randomised before delivery. A further 280–335 children would have been eligible for follow up if they had survived. The total sample size for the children is therefore 3080–3685, 2680–3210 of whom will have been born to women randomised before delivery. Families eligible for the follow up will be contacted, and surviving children screened using the Ages and Stages Questionnaires. Children who screen positive, and a sample of those who screen negative, will whenever possible have a paediatric and neurodevelopmental assessment. When women are contacted to ask how their child is, they will also be asked about their own health. The primary outcome is a composite measure of death or neurosensory disability for the child at 18 months. DISCUSSION: The Follow Up Study began in 2002, and now involves collaborators in 19 countries. Data collection will close at the end of 2003

    Pooled analysis of who surgical safety checklist use and mortality after emergency laparotomy

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    Background: The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods: In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results: Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89⋅6 per cent) compared with that in countries with a middle (753 of 1242, 60⋅6 per cent; odds ratio (OR) 0⋅17, 95 per cent c.i. 0⋅14 to 0⋅21, P < 0⋅001) or low (363 of 860, 42⋅2 percent; OR 0⋅08, 0⋅07 to 0⋅10, P < 0⋅001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference −9⋅4 (95 per cent c.i. −11⋅9 to −6⋅9) per cent; P < 0⋅001), but the relationship was reversed in low-HDI countries (+12⋅1 (+7⋅0 to +17⋅3) per cent; P < 0⋅001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0⋅60, 0⋅50 to 0⋅73; P < 0⋅001). The greatest absolute benefit was seen for emergency surgery in low-and middle-HDI countries. Conclusion: Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries

    Global variation in anastomosis and end colostomy formation following left-sided colorectal resection

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    Background End colostomy rates following colorectal resection vary across institutions in high-income settings, being influenced by patient, disease, surgeon and system factors. This study aimed to assess global variation in end colostomy rates after left-sided colorectal resection. Methods This study comprised an analysis of GlobalSurg-1 and -2 international, prospective, observational cohort studies (2014, 2016), including consecutive adult patients undergoing elective or emergency left-sided colorectal resection within discrete 2-week windows. Countries were grouped into high-, middle- and low-income tertiles according to the United Nations Human Development Index (HDI). Factors associated with colostomy formation versus primary anastomosis were explored using a multilevel, multivariable logistic regression model. Results In total, 1635 patients from 242 hospitals in 57 countries undergoing left-sided colorectal resection were included: 113 (6·9 per cent) from low-HDI, 254 (15·5 per cent) from middle-HDI and 1268 (77·6 per cent) from high-HDI countries. There was a higher proportion of patients with perforated disease (57·5, 40·9 and 35·4 per cent; P < 0·001) and subsequent use of end colostomy (52·2, 24·8 and 18·9 per cent; P < 0·001) in low- compared with middle- and high-HDI settings. The association with colostomy use in low-HDI settings persisted (odds ratio (OR) 3·20, 95 per cent c.i. 1·35 to 7·57; P = 0·008) after risk adjustment for malignant disease (OR 2·34, 1·65 to 3·32; P < 0·001), emergency surgery (OR 4·08, 2·73 to 6·10; P < 0·001), time to operation at least 48 h (OR 1·99, 1·28 to 3·09; P = 0·002) and disease perforation (OR 4·00, 2·81 to 5·69; P < 0·001). Conclusion Global differences existed in the proportion of patients receiving end stomas after left-sided colorectal resection based on income, which went beyond case mix alone

    Self-efficacy, medication beliefs and adherence to antiretroviral therapy by patients attending a health facility in Pretoria

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    Background: Self-efficacy and medication beliefs are known factors that influence adherence to treatment in chronic medical conditions. We carried out a cross-sectional study on human immunodeficiency virus (HIV) -infected patients with the aim of determining the predictive relationship between these two variables and adherence to antiretroviral therapy (ART) at a health facility in Pretoria.Method: Participants’ medication beliefs were assessed using the Beliefs about Medicines Questionnaire. Self-efficacy was evaluated using the HIV Adherence Self-Efficacy Scale, and adherence to ART determined using the AIDS Clinical Trial Group questionnaire.Results: The mean age of the 232 participants was 40 years (standard deviation 15.6). Seventy per cent were females. Most had been on ART for over two years (87%), and 81.5% were adherent to at least 95% of the prescribed antiretroviral drugs. Nonadherence was highest in those on ART for more than three years (63%). The mean HIV Adherence Self-Efficacy score was 6.45 out of a possible 10. Beliefs held by the participants about the importance of (necessity) and concerns about ART in the management of HIV infection were generally positive. There was a mean score of 4.05 out of 5, indicating a strong belief in the use of ART. There was a strong association between adherence self-efficacy and ART adherence (p 0.001) in the nonadherent participants. Regression analysis showed significance for adherence self-efficacy on ART nonadherence (p 0.041), with adherence self-efficacy explaining 9.8% of the variance.Conclusion: Patients’ adherence self-efficacy explained a significant portion of variation in the nonadherence to ART, which suggests that low adherence self-efficacy is influential in ART nonadherence. Interventions aimed at improving adherence to ART should address adherence self-efficacy
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