481 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

    Contextual factors in shared decision making: a randomised controlled trial in women with a strong suspicion of breast cancer

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    Decision aids in North American breast cancer outpatients have been shown to assist with treatment decision making and reduce decisional conflict. To date, appropriate delivery formats to effectively increase patient participation in newly diagnosed breast cancer inpatients have not been investigated in the context of German health care provision. The impact of a decision aid intervention was studied in patients (n=111) with a strong suspicion of breast cancer in a randomised controlled trial. The primary outcome variable was decisional conflict. Participants were followed up 1 week post-intervention with a retention rate of 92%. Analyses revealed that the intervention group felt better informed (ηp2=0.06) but did not experience an overall reduction in decisional conflict as compared with the control group. The intervention had no effect on uptake rates of treatment options, length of consultation with the surgeon, time point of treatment decision making, perceived involvement in decision making, neither decision related nor general patient satisfaction. Patients who received the decision aid intervention experienced a small benefit with regards to how informed they felt about advantages and disadvantages of relevant treatment options. Results are discussed in terms of contextual factors and individual differences as moderators of treatment decision aid effectiveness

    SPECULOOS exoplanet search and its prototype on TRAPPIST

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    One of the most significant goals of modern science is establishing whether life exists around other suns. The most direct path towards its achievement is the detection and atmospheric characterization of terrestrial exoplanets with potentially habitable surface conditions. The nearest ultracool dwarfs (UCDs), i.e. very-low-mass stars and brown dwarfs with effective temperatures lower than 2700 K, represent a unique opportunity to reach this goal within the next decade. The potential of the transit method for detecting potentially habitable Earth-sized planets around these objects is drastically increased compared to Earth-Sun analogs. Furthermore, only a terrestrial planet transiting a nearby UCD would be amenable for a thorough atmospheric characterization, including the search for possible biosignatures, with near-future facilities such as the James Webb Space Telescope. In this chapter, we first describe the physical properties of UCDs as well as the unique potential they offer for the detection of potentially habitable Earth-sized planets suitable for atmospheric characterization. Then, we present the SPECULOOS ground-based transit survey, that will search for Earth-sized planets transiting the nearest UCDs, as well as its prototype survey on the TRAPPIST telescopes. We conclude by discussing the prospects offered by the recent detection by this prototype survey of a system of seven temperate Earth-sized planets transiting a nearby UCD, TRAPPIST-1.Comment: Submitted as a chapter in the "Handbook of Exoplanets" (editors: H. Deeg & J.A. Belmonte; Section Editor: N. Narita). 16 pages, 4 figure

    Moderate alcohol consumption is associated with better endothelial function: a cross sectional study

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    <p>Abstract</p> <p>Background</p> <p>Moderate alcohol consumption is protective against coronary artery disease. Endothelial dysfunction contributes to atherosclerosis and the pathogenesis of cardiovascular disease. The effects of alcohol consumption on endothelial function may be relevant to these cardiovascular outcomes, but very few studies have examined the effect of alcohol consumption on endothelial function assessed by flow-mediated dilation (FMD) of the brachial artery in humans.</p> <p>Methods</p> <p>In the population-based Northern Manhattan Study (NOMAS), we performed a cross-sectional analysis of lifetime alcohol intake and brachial artery FMD during reactive hyperemia using high-resolution B-mode ultrasound images among 884 stroke-free participants (mean age 66.8 years, women 56.6%, Hispanic 67.4%, black 17.4%, and white 15.2%).</p> <p>Results</p> <p>The mean brachial FMD was 5.7% and the median was 5.5%. Compared to non-drinkers, those who drank >1 drink/month to 2 drinks/day were more likely to have FMD above the median FMD (5.5%) (unadjusted OR 1.7, 95% CI 1.2–2.4, p = 0.005). In multivariate analysis, the relationship between moderate alcohol consumption and FMD remained significant after adjusting for multiple traditional cardiovascular risk factors, including sex, race-ethnicity, body mass index, diabetes mellitus, coronary artery disease, Framingham risk score, medication use (adjusted OR 1.8, 95%CI 1.1–3.0, p = 0.03). No beneficial effect on FMD was seen for those who drank more than 2 drinks/day.</p> <p>Conclusion</p> <p>In conclusion, consumption of up to 2 alcoholic beverages per day was independently associated with better FMD compared to no alcohol consumption in this multiethnic population. This effect on FMD may represent an important mechanism in explaining the protective effect of alcohol intake on cardiovascular disease.</p

    Performance of non-uniform tidal turbine arrays in uniform flow

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    Theoretical models suggest that in order to maximise their collective power out put, tidal turbines should be arranged in a single cross-stream row and optimally spaced to exploit local blockage effects. However, because it is assumed that the turbines within these arrays are identical, such models do not consider the possibility of enhanced power production through the exploitation of spanwise variations in local blockage and resistance. In this paper, we use depth-averaged numerical simulations to investigate whether the performance of a tidal turbine array can be further enhanced by varying solely the local blockage, solely the local resistance, or both local blockage and resistance together, across the array width. Our results suggest that for an initially uniform flow field, the optimal tidal turbine array is also uniform, that is to say that it comprises turbines of equal size, spacing, and resistance. This finding is encouraging because it is more cost-effective and much simpler to design each turbine to be the same and to operate in the same way. Together with earlier findings, these results also suggest a more general, and perhaps unsurprising, conclusion that tidal turbine arrays perform best when designed to match site-specific natural flow conditions

    Search for Gravitational Waves from Primordial Black Hole Binary Coalescences in the Galactic Halo

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    We use data from the second science run of the LIGO gravitational-wave detectors to search for the gravitational waves from primordial black hole (PBH) binary coalescence with component masses in the range 0.2--1.0M1.0 M_\odot. The analysis requires a signal to be found in the data from both LIGO observatories, according to a set of coincidence criteria. No inspiral signals were found. Assuming a spherical halo with core radius 5 kpc extending to 50 kpc containing non-spinning black holes with masses in the range 0.2--1.0M1.0 M_\odot, we place an observational upper limit on the rate of PBH coalescence of 63 per year per Milky Way halo (MWH) with 90% confidence.Comment: 7 pages, 4 figures, to be submitted to Phys. Rev.

    Laparoscopic and open resection for colorectal cancer: an evaluation of cellular immunity

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    <p>Abstract</p> <p>Background</p> <p>Colorectal cancer is one kind of frequent malignant tumors of the digestive tract which gets high morbidity and mortality allover the world. Despite the promising clinical results recently, less information is available regarding the perioperative immunological effects of laparoscopic surgery when compared with the open surgery. This study aimed to compare the cellular immune responses of patients who underwent laparoscopic(LCR) and open resections(OCR) for colorectal cancer.</p> <p>Methods</p> <p>Between Mar 2009 and Sep 2009, 35 patients with colorectal carcinoma underwent LCR by laparoscopic surgeon. These patients were compared with 33 cases underwent conventional OCR by colorectal surgeon. Clinical data about the patients were collected prospectively. Comparison of the operative details and postoperative outcomes between laparoscopic and open resection was performed. Peripheral venous blood samples from these 68 patients were taken prior to surgery as well as on postoperative days(POD) 1, 4 and 7. Cell counts of total white blood cells, neutrophils, lymphocyte subpopulations, natural killer(NK) cells as well as CRP were determined by blood counting instrument, flow cytometry and hematology analyzer.</p> <p>Results</p> <p>There was no difference in the age, gender and tumor status between the two groups. The operating time was a little longer in the laparoscopic group (<it>P </it>> 0.05), but the blood loss was less (<it>P </it>= 0.039). Patients with laparoscopic resection had earlier return of bowel function and earlier resumption of diet as well as shorter median hospital stay (<it>P </it>< 0.001). Compared with OCR group, cell numbers of total lymphocytes, CD4<sup>+</sup>T cells and CD8<sup>+</sup>T cells were significant more in LCR group (<it>P </it>< 0.05) on POD 4, while there was no difference in the CD45RO<sup>+</sup>T or NK cell numbers between the two groups. Cellular immune responds were similar between the two groups on POD1 and POD7.</p> <p>Conclusions</p> <p>Laparoscopic colorectal resection gets less surgery stress and short-term advantages compared with open resection. Cellular immune respond appears to be less affected by laparoscopic colorectal resection when compared with open resection.</p

    Laparoscopic versus open left lateral segmentectomy

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    <p>Abstract</p> <p>Background</p> <p>Laparoscopic liver surgery is becoming increasingly common. This cohort study was designed to directly compare perioperative outcomes of the left lateral segmentectomy via laparoscopic and open approach.</p> <p>Methods</p> <p>Between 2002 and 2006 43 left lateral segmentectomies were performed at King's College Hospital. Those excluded from analysis included previous liver resections, polycystic liver disease, liver cirrhosis and synchronous operations. Of 20 patients analysed, laparoscopic (n = 10) were compared with open left lateral segmentectomy (n = 10). Both groups had similar patient characteristics.</p> <p>Results</p> <p>Morbidity rates were similar with no wound or chest infection in either group. The conversion rate was 10% (1/10). There was no difference in operating time between the groups (median time 220 minutes versus 179 minutes, p = 0.315). Surgical margins for all lesions were clear. Less postoperative opiate analgesics were required in the laparoscopic group (median 2 days versus 5 days, p = 0.005). The median postoperative in-hospital stay was less in the laparoscopic group (6 days vs 9 days, p = 0.005). There was no mortality.</p> <p>Conclusion</p> <p>Laparoscopic left lateral segmentectomy is safe and feasible. Laparoscopic patients may benefit from requiring less postoperative opiate analgesia and a shorter post-operative in-hospital stay.</p

    The Evolution of Compact Binary Star Systems

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    We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure
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