170 research outputs found

    Robotic Laser-Adaptive-Optics Imaging of 715 Kepler Exoplanet Candidates using Robo-AO

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    The Robo-AO Kepler Planetary Candidate Survey is designed to observe every Kepler planet candidate host star with laser adaptive optics imaging to search for blended nearby stars, which may be physically associated companions and/or responsible for transit false positives. In this paper we present the results from the 2012 observing season, searching for stars close to 715 representative Kepler planet candidate hosts. We find 53 companions, 44 of which are new discoveries. We detail the Robo-AO survey data reduction methods including a method of using the large ensemble of target observations as mutual point-spread-function references, along with a new automated companion-detection algorithm designed for large adaptive optics surveys. Our survey is sensitive to objects from 0.15" to 2.5" separation, with contrast ratios up to delta-m~6. We measure an overall nearby-star-probability for Kepler planet candidates of 7.4% +/- 1.0%, and calculate the effects of each detected nearby star on the Kepler-measured planetary radius. We discuss several KOIs of particular interest, including KOI-191 and KOI-1151, which are both multi-planet systems with detected stellar companions whose unusual planetary system architecture might be best explained if they are "coincident multiple" systems, with several transiting planets shared between the two stars. Finally, we detect 2.6-sigma evidence for <15d-period giant planets being 2-3 times more likely be found in wide stellar binaries than smaller close-in planets and all sizes of further-out planets.Comment: Accepted by ApJ. Minor updates & improved statistical analysis; no changes to results. 15 pages, 13 figure

    Functionalization of Pentaphosphorus Cations by Complexation

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    The chemistry of polyphosphorus cations has rapidly developed in recent years, but their coordination behavior has remained mostly unexplored. Herein, we describe the reactivity of [P5R2]+ cations with cyclopentadienyl metal complexes. The reaction of [CpArFe(μ‐Br)]2 (CpAr=C5(C6H4‐4‐Et)5) with [P5R2][GaCl4] (R=iPr and 2,4,6‐Me3C6H2 (Mes)) afforded bicyclo[1.1.0]pentaphosphanes (1‐R, R=iPr and Mes), showing an unsymmetric “butterfly” structure. The same products 1‐R were formed from K[CpAr] and [P5R2][GaCl4]. The cationic complexes [CpArCo(η4‐P5R2)][GaCl4] (2‐R[GaCl4], R=iPr and Cy) and [(CpArNi)2(η3:3‐P5R2)][GaCl4] (3‐R[GaCl4]) were obtained from [P5R2][GaCl4] and [CpArM(μ‐Br)]2 (M=Co and Ni) as well as by using low‐valent “CpArMI” sources. Anion metathesis of 2‐R[GaCl4] and 3‐R[GaCl4] was achieved with Na[BArF24]. The P5 framework of the resulting salts 2‐R[BArF24] can be further functionalized with nucleophiles. Thus reactions with [Et4N]X (X=CN and Cl) give unprecedented cyano‐ and chloro‐functionalized complexes, while organo‐functionalization was achieved with CyMgCl

    MMP-1 serum levels predict coronary atherosclerosis in humans

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    <p/> <p>Background</p> <p>Myocardial infarction results as a consequence of atherosclerotic plaque rupture, with plaque stability largely depending on the lesion forming extracellular matrix components. Lipid enriched non-calcified lesions are considered more instable and rupture prone than calcified lesions. Matrix metalloproteinases (MMPs) are extracellular matrix degrading enzymes with plaque destabilisating characteristics which have been implicated in atherogenesis. We therefore hypothesised MMP-1 and MMP-9 serum levels to be associated with non-calcified lesions as determined by CT-angiography in patients with coronary artery disease.</p> <p>Methods</p> <p>260 patients with typical or atypical chest pain underwent dual-source multi-slice CT-angiography (0.6-mm collimation, 330-ms gantry rotation time) to exclude coronary artery stenosis. Atherosclerotic plaques were classified as calcified, mixed or non-calcified.</p> <p>Results</p> <p>In multivariable regession analysis, MMP-1 serum levels were associated with total plaque burden (OR: 1.37 (CI: 1.02-1.85); p < 0.05) in a model adjusted for age, sex, BMI, classical cardiovascular risk factors, hsCRP, adiponectin, pericardial fat volume and medication. Specification of plaque morphology revealed significant association of MMP-1 serum levels with non-calcified plaques (OR: 1.16 (CI: 1.0-1.34); p = 0.05) and calcified plaques (OR: 1.22 (CI: 1,03-1.45); p < 0.05) while association with mixed plaques was lost in the fully adjusted model. No associations were found between MMP9 serum levels and total plaque burden or plaque morphology.</p> <p>Conclusion</p> <p>MMP-1 serum levels are associated with total plaque burden but do not allow a specification of plaque morphology.</p

    Synthesis and Characterization of Bidentate Isonitrile Iron Complexes

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    Divalent iron complexes trans-[FeBr2(BINC)2], [Cp*FeCl(BINC)] (Cp* = Me5C5) and [FeBr2(CNAr3NC)2] with chelat-ing bis(isonitrile) ligands BINC (bis(2-isocyanophenyl)phenylphosphonate) and CNAr3NC (2,2’’-diisocyano-3,5,3’’,5’’tetramethyl-1,1’:3’,1’’-terphenyl) have been prepared and characterized. Their subsequent reduction yields di- and trinuclear compounds [Fe3(BINC)6], [Cp*Fe(BINC)]2, [Fe(CNAr3NC)2]2 and [K(Et2O)]2[Fe(CNAr3NC)2]2. The molecular structures of all new species were determined by X-ray crystallography. The molecular structures are compared to related iron carbonyl complexes. The complexes were further characterized by NMR and IR spectroscopy, and the electrochemical properties of selected compounds were analyzed by UV-Vis-NIR spectroelectrochemistry

    An angiopoietin 2, FGF23, and BMP10 biomarker signature differentiates atrial fibrillation from other concomitant cardiovascular conditions

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    Abstract Early detection of atrial fibrillation (AF) enables initiation of anticoagulation and early rhythm control therapy to reduce stroke, cardiovascular death, and heart failure. In a cross-sectional, observational study, we aimed to identify a combination of circulating biomolecules reflecting different biological processes to detect prevalent AF in patients with cardiovascular conditions presenting to hospital. Twelve biomarkers identified by reviewing literature and patents were quantified on a high-precision, high-throughput platform in 1485 consecutive patients with cardiovascular conditions (median age 69 years [Q1, Q3 60, 78]; 60% male). Patients had either known AF (45%) or AF ruled out by 7-day ECG-monitoring. Logistic regression with backward elimination and a neural network approach considering 7 key clinical characteristics and 12 biomarker concentrations were applied to a randomly sampled discovery cohort (n = 933) and validated in the remaining patients (n = 552). In addition to age, sex, and body mass index (BMI), BMP10, ANGPT2, and FGF23 identified patients with prevalent AF (AUC 0.743 [95% CI 0.712, 0.775]). These circulating biomolecules represent distinct pathways associated with atrial cardiomyopathy and AF. Neural networks identified the same variables as the regression-based approach. The validation using regression yielded an AUC of 0.719 (95% CI 0.677, 0.762), corroborated using deep neural networks (AUC 0.784 [95% CI 0.745, 0.822]). Age, sex, BMI and three circulating biomolecules (BMP10, ANGPT2, FGF23) are associated with prevalent AF in unselected patients presenting to hospital. Findings should be externally validated. Results suggest that age and different disease processes approximated by these three biomolecules contribute to AF in patients. Our findings have the potential to improve screening programs for AF after external validation

    Predictive value of coronary calcifications for future cardiac events in asymptomatic patients with diabetes mellitus: A prospective study in 716 patients over 8 years

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    <p>Abstract</p> <p>Background</p> <p>To establish an efficient prophylaxis of coronary artery disease reliable risk stratification is crucial, especially in the high risk population of patients suffering from diabetes mellitus. This prospective study determined the predictive value of coronary calcifications for future cardiovascular events in asymptomatic patients with diabetes mellitus.</p> <p>Methods</p> <p>We included 716 patients suffering from diabetes mellitus (430 men, 286 women, age 55.2 ± 15.2 years) in this study. On study entry all patients were asymptomatic and had no history of coronary artery disease. In addition, all patients showed no signs of coronary artery disease in ECG, stress ECG or echocardiography. Coronary calcifications were determined with the Imatron C 150 XP electron beam computed tomograph. For quantification of coronary calcifications we calculated the Agatston score. After a mean observation period of 8.1 ± 1.1 years patients were contacted and the event rate of cardiac death (CD) and myocardial infarction (MI) was determined.</p> <p>Results</p> <p>During the observation period 40 patients suffered from MI, 36 patients died from acute CD. The initial Agatston score in patients that suffered from MI or died from CD (475 ± 208) was significantly higher compared to those without cardiac events (236 ± 199, p < 0.01). An Agatston score above 400 was associated with a significantly higher annualised event rate for cardiovascular events (5.6% versus 0.7%, p < 0.01). No cardiac events were observed in patients with exclusion of coronary calcifications. Compared to the Framingham risk score and the UKPDS score the Agatston score showed a significantly higher diagnostic accuracy in the prediction of MI with an area under the ROC curve of 0.77 versus 0.68, and 0.71, respectively, p < 0.01.</p> <p>Conclusion</p> <p>By determination of coronary calcifications patients at risk for future MI and CD could be identified within an asymptomatic high risk group of patients suffering from diabetes mellitus. On the other hand future events could be excluded in patients without coronary calcifications.</p

    Separation – integration – and now …? - An historical perspective on the relationship between German management accounting and financial accounting

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    German accounting has traditionally followed a dual ledger approach with strictly separated internal cost accounting, as the basis for management information, and external financial accounting focusing on creditor protection and based on the commercial law. However, the increased adoption of integrated accounting system implies a significant change in the relationship between financial and management accounting systems. We use Hegelian dialectic to trace the historical development of German accounting from separated systems towards antithetical propositions of full integration, and the emergence of partial integration as the synthesis of this transformation process. For this reason, our paper provides a comprehensive analysis of the literature on the relationship between financial and management accounting in Germany. On this basis, we elaborate how financial accounting in Germany has been shaped by its economic context and legislation, and how financial accounting – accompanied by institutional pressures – in turn influenced management accounting. We argue that the changing relationship between management and financial accounting in the German context illustrates how current accounting practice is shaped not only by its environment, but also by its historical path. Based on this reasoning, we discuss several avenues for future research

    Reproducibility in the absence of selective reporting : An illustration from large-scale brain asymmetry research

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    Altres ajuts: Max Planck Society (Germany).The problem of poor reproducibility of scientific findings has received much attention over recent years, in a variety of fields including psychology and neuroscience. The problem has been partly attributed to publication bias and unwanted practices such as p-hacking. Low statistical power in individual studies is also understood to be an important factor. In a recent multisite collaborative study, we mapped brain anatomical left-right asymmetries for regional measures of surface area and cortical thickness, in 99 MRI datasets from around the world, for a total of over 17,000 participants. In the present study, we revisited these hemispheric effects from the perspective of reproducibility. Within each dataset, we considered that an effect had been reproduced when it matched the meta-analytic effect from the 98 other datasets, in terms of effect direction and significance threshold. In this sense, the results within each dataset were viewed as coming from separate studies in an "ideal publishing environment," that is, free from selective reporting and p hacking. We found an average reproducibility rate of 63.2% (SD = 22.9%, min = 22.2%, max = 97.0%). As expected, reproducibility was higher for larger effects and in larger datasets. Reproducibility was not obviously related to the age of participants, scanner field strength, FreeSurfer software version, cortical regional measurement reliability, or regional size. These findings constitute an empirical illustration of reproducibility in the absence of publication bias or p hacking, when assessing realistic biological effects in heterogeneous neuroscience data, and given typically-used sample sizes
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