247 research outputs found

    The relation between accretion rate and jet power in X-ray luminous elliptical galaxies

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    Using Chandra X-ray observations of 9 nearby, X-ray luminous ellipticals with good optical velocity dispersion measurements, we show that a tight correlation exists between the Bondi accretion rates calculated from the X-ray data and estimated black hole masses, and the power emerging from these systems in relativistic jets. The jet powers, inferred from the energies and timescales required to inflate the cavities observed in the surrounding X-ray emitting gas, can be related to the accretion rates by a power law model. A significant fraction (2.2^{+1.0}_{-0.7} per cent, for P_jet=10^{43} erg/s) of the energy associated with the rest mass of material entering the accretion radius eventually emerges in the jets. The data also hint that this fraction may rise slightly with increasing jet power. Our results have significant implications for studies of accretion, jet formation and galaxy formation. The tight correlation between P_Bondi and P_jet suggests that the Bondi formulae provide a reasonable description of the accretion process, despite the likely presence of magnetic pressure and angular momentum in the accreting gas, and that the accretion flows are approximately stable over timescales of a few million years. Our results show that the black hole `engines' at the hearts of large elliptical galaxies and groups can feed back sufficient energy to stem cooling and star formation, leading naturally to the observed exponential cut off at the bright end of the galaxy luminosity function.Comment: Accepted for publication in MNRAS. 10 pages, 4 figures. Includes an enhanced statistical analysis and some additional data. Conclusions unchange

    Pulmonary artery stiffness in chronic obstructive pulmonary disease (copd) and emphysema: The Multi-Ethnic Study of Atherosclerosis (MESA) COPD Study

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    Purpose: Chronic obstructive pulmonary disease (COPD) and particularly emphysema are characterized by stiffness of the aorta, due in part to accelerated elastin degradation in the lungs and aorta. Stiffness of the pulmonary arteries (PAs) may also be increased in COPD and emphysema, but data are lacking. We assessed PA stiffness using MRI in patients with COPD and related these measurements to COPD severity and percent emphysema. Materials and Methods: The Multi-Ethnic Study of Atherosclerosis (MESA) COPD Study recruited 290 participants, age 50–79 years with 10 or more packyears and free of clinical cardiovascular disease. COPD severity were defined on postbronchodilator spirometry by ATS/ERS criteria. Percent emphysema was defined as the percentage of regions of the lung < -950 Hounsfield units on full-lung computed tomography (CT). PA stain was defined by the percent change in cross-sectional PA area between systole and diastole on MRI. Blood flow across the tricuspid and mitral valves was assessed by phase-contrast MRI for determination of the ventricular diastolic dysfunction (E/A ratio). Results: PA strain was reduced in COPD compared with controls (P = 0.002) and was inversely correlated with COPD severity (P = 0.004). PA strain was inversely associated to percent emphysema (P = 0.01). PA strain was also markedly correlated with right ventricular diastolic dysfunction measured by E/A ratios in the fully adjusted mix models (P = 0.02). Conclusion: PA strain is reduced in COPD, related in part to percent emphysema on CT scan, which may have implications for pulmonary small vessel flow and right ventricular function. Level of Evidence: 2 Technical Efficacy: Stage

    Human muscle-derived cell populations isolated by differential adhesion rates: Phenotype and contribution to skeletal muscle regeneration in Mdx/SCID mice

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    Muscle-derived stem cells (MDSCs) isolated from murine skeletal tissue by the preplate method have displayed the capability to commit to the myogenic lineage and regenerate more efficiently than myoblasts in skeletal and cardiac muscle in murine Duchenne Muscular Dystrophy mice (mdx). However, until now, these studies have not been translated to human muscle cells. Here, we describe the isolation, by a preplate technique, of candidate human MDSCs, which exhibit myogenic and regenerative characteristics similar to their murine counterparts. Using the preplate isolation method, we compared cells that adhere faster to the flasks, preplate 2 (PP2), and cells that adhere slower, preplate 6 (PP6). The human PP6 cells express several markers of mesenchymal stem cells and are distinct from human PP2 (a myoblast-like population) based on their expression of CD146 and myogenic markers desmin and CD56. After transplantation to the gastrocnemius muscle of mdx/SCID mice, we observe significantly higher levels of PP6 cells participating in muscle regeneration as compared with the transplantation of PP2 cells. This study supports some previous findings related to mouse preplate cells, and also identifies some differences between mouse and human muscle preplate cells

    On-line polymerisation monitoring in scCO2: a reliable and inexpensive sampling method in high pressure applications

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    A versatile and reliable on-line sampling system for polymerisation reactions in supercritical fluids was developed. By withdrawing a small volume of a high-pressure reaction mixture and expanding it in a controlled volume, reliable kinetic data were obtained for a range of reactions in scCO2, avoiding the need for costly equipment or setup modifications. All experiments were carried out in a stainless-steel high-pressure autoclave with mechanical stirring and a volume of 60 ml. With the polymerisation of methyl methacrylate (MMA) in scCO2 being widely adopted for research in the past, the free-radical and RAFT controlled dispersion polymerisations of MMA were analysed in detail using the sampling system as a proof-of-concept. Additionally, initial implementation of the sampling system to a range of different reactions showed the facile applicability of the monitoring method

    Hypertension and Smoking Are Associated With Reduced Regional Left Ventricular Function in Asymptomatic Individuals The Multi-Ethnic Study of Atherosclerosis

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    ObjectivesThis study sought to test the hypothesis that reduced regional left ventricular (LV) function is associated with traditional risk factors including hypertension, hypercholesterolemia, and smoking in asymptomatic individuals.BackgroundCoronary artery disease is the main etiology of congestive heart failure in the U.S. and Europe. However, the relationship between risk factors for coronary artery disease and decreased myocardial function has not been studied systematically in asymptomatic individuals.MethodsThe Multi-Ethnic Study of Atherosclerosis (MESA) is a cohort study designed to investigate the nature of atherosclerosis in asymptomatic individuals. A total of 1,184 participants (45 to 84 years old) underwent tagged cardiac magnetic resonance imaging. Regional LV function was quantified by analyzing peak systolic circumferential strain (Ecc) in regions corresponding to the left anterior descending (LAD), circumflex (LCX), and right coronary (RCA) territories. The association between risk factors and strains was studied using multiple linear regression.ResultsHigher diastolic blood pressure (DBP) was associated with lower Ecc (p ≤ 0.002). The Ecc’s in the LAD territory of participants with DBP <80, 80 to 84, 85 to 89, and ≥90 mm Hg were −15.6%, −14.8%, −14.2%, and −13.7%, respectively (p < 0.001). Similar results were documented in other territories and after multivariable analysis. Smokers had lower Ecc in the LAD and RCA regions compared with nonsmokers. Furthermore, dose response relationship between cigarette consumption measured in pack-years and regional LV dysfunction by Ecc was noted (p ≤ 0.01 in LAD and RCA territories). Finally, combined diastolic hypertension and smoking was associated with a greater reduction of regional LV function.ConclusionsHigher diastolic blood pressure and smoking are associated with decreased regional LV function in asymptomatic individuals

    Unitary Standard Model from Spontaneous Dimensional Reduction and Weak Boson Scattering at the LHC

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    Spontaneous dimensional reduction (SDR) is a striking phenomenon predicted by a number of quantum gravity approaches which all indicate that the spacetime dimensions get reduced at high energies. In this work, we formulate an effective theory of electroweak interactions based upon the standard model, incorporating the spontaneous reduction of space-dimensions at TeV scale. The electroweak gauge symmetry is nonlinearly realized with or without a Higgs boson. We demonstrate that the SDR ensures good high energy behavior and predicts unitary weak boson scattering. For a light Higgs boson of mass 125GeV, the TeV-scale SDR gives a natural solution to the hierarchy problem. Such a light Higgs boson can have induced anomalous gauge couplings from the TeV-scale SDR. We find that the corresponding WW scattering cross sections become unitary at TeV scale, but exhibit different behaviors from that of the 4d standard model. These can be discriminated by the WW scattering experiments at the LHC.Comment: 38pp, Eur.Phys.J.(in Press); extended discussions for testing non-SM Higgs boson(125GeV) via WW scattering; minor clarifications added; references added; a concise companion is given in the short PLB letter arXiv:1301.457

    Defining Advance Care Planning for Adults: A Consensus Definition From a Multidisciplinary Delphi Panel

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    Despite increasing interest in advance care planning (ACP) and prior ACP descriptions, a consensus definition does not yet exist to guide clinical, research, and policy initiatives
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