204 research outputs found

    From Sea to Shining Sea: Manifest Destiny and the National Land Use Dilemma

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    Restframe I-band Hubble diagram for type Ia supernovae up to redshift z ~0.5

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    We present a novel technique for fitting restframe I-band light curves on a data set of 42 Type Ia supernovae (SNe Ia). Using the result of the fit, we construct a Hubble diagram with 26 SNe from the subset at 0.01< z<0.1. Adding two SNe at z~0.5 yields results consistent with a flat Lambda-dominated``concordance universe'' (ΩM,ΩΛ\Omega_M,\Omega_\Lambda)=(0.25,0.75). For one of these, SN 2000fr, new near infrared data are presented. The high redshift supernova NIR data are also used to test for systematic effects in the use of SNe Ia as distance estimators. A flat, Lambda=0, universe where the faintness of supernovae at z~0.5 is due to grey dust homogeneously distributed in the intergalactic medium is disfavoured based on the high-z Hubble diagram using this small data-set. However, the uncertainties are large and no firm conclusion may be drawn. We explore the possibility of setting limits on intergalactic dust based on B-I and B-V colour measurements, and conclude that about 20 well measured SNe are needed to give statistically significant results. We also show that the high redshift restframe I-band data points are better fit by light curve templates that show a prominent second peak, suggesting that they are not intrinsically underluminous.Comment: Accepted for publication in A&A (01/04/2005

    Feasibility of Temporary Biventricular Pacing After Off-pump Coronary Artery Bypass Grafting in Patients With Reduced Left Ventricular Function

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    In selected patients undergoing cardiac surgery, our research group previously showed that optimized temporary biventricular pacing can increase cardiac output one hour after weaning from cardiopulmonary bypass. Whether pacing is effective after beating-heart surgery is unknown. Accordingly, in this study we examined the feasibility of temporary biventricular pacing after off-pump coronary artery bypass grafting. The effects of optimized pacing on cardiac output were measured with an electromagnetic aortic flow probe at the conclusion of surgery in 5 patients with a preoperative mean left ventricular ejection fraction of 0.26 (range, 0.15–0.35). Atrioventricular (7) and interventricular (9) delay settings were optimized in randomized order. Cardiac output with optimized biventricular pacing was 4.2 ± 0.7 L/min; in sinus rhythm, it was 3.8 ± 0.5 L/min. Atrial pacing at a matched heart rate resulted in cardiac output intermediate to that of sinus rhythm and biventricular pacing (4 ± 0.6 L/min). Optimization of atrioventricular and interventricular delay, in comparison with nominal settings, trended toward increased flow. This study shows that temporary biventricular pacing is feasible in patients with preoperative left ventricular dysfunction who are undergoing off-pump coronary artery bypass grafting. Further study of the possible clinical benefits of this intervention is warranted

    Search for nearby stars among proper motion stars selected by optical-to-infrared photometry III. Spectroscopic distances of 322 NLTT stars

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    Distance estimates based on low-resolution spectroscopy and Two Micron All Sky Survey (2MASS) J magnitudes are presented for a large sample of 322 nearby candidates from Luyten's NLTT catalogue. Mainly relatively bright (typically 7 < K_s < 11) and red high proper motion stars have been selected according to their 2MASS magnitudes and optical-to-infrared colours (+1 < R-K_s < +7). Some LHS stars previously lacking spectroscopy have also been included. We have classified the majority of the objects as early-M dwarfs (M2-M5). More than 70% of our targets turned out to lie within the 25 pc horizon of the catalogue of nearby stars, with 50 objects placed within 15 pc and 8 objects being closer than 10 pc. Three objects in the 10 pc sample have no previously published spectral type: LP 876-10 (M4), LP 870-65 (M4.5), and LP 869-26 (M5). A large fraction of the objects in our sample (57%) have independent distance estimates, mainly by the recent efforts of Reid and collaborators. Our distance determinations are generally in good agreement with theirs. 11 rather distant (d > 100 pc) objects have also been identified, including a probable halo, but relatively hot (T_eff = 13000 K) white dwarf (LHS 1200) and 10 red dwarfs with extremely large tangential velocities (250 < v_t < 1150 km/s). Altogether, there are 11 red dwarfs (including one within 70 pc) with tangential velocities larger than about 250 km/s. All these objects are suspected to be in fact subdwarfs, if so, their distances would be only about half of our original estimates. The three most extreme objects in that respect are the K and early M dwarfs LP 323-168, LHS 5343 and LP 552-21 with corrected distances between 180 pc and 400 pc and resulting tangential velocities still larger than about 400 km/s.Comment: 19 pages, 14 Figures, complete Table 1 available on request from the first author, paper accepted by Astronomy and Astrophysic

    Reducing the health disparities of Indigenous Australians: time to change focus

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    Background: Indigenous peoples have worse health than non-Indigenous, are over-represented amongst the poor and disadvantaged, have lower life expectancies, and success in improving disparities is limited. To address this, research usually focuses on disadvantaged and marginalised groups, offering only partial understanding of influences underpinning slow progress. Critical analysis is also required of those with the power to perpetuate or improve health inequities. In this paper, using Australia as a case example, we explore the effects of ‘White’, Anglo-Australian cultural dominance in health service delivery to Indigenous Australians. We address the issue using race as an organising principle, underpinned by relations of power.Methods: Interviews with non-Indigenous medical practitioners in Western Australia with extensive experience in Indigenous health encouraged reflection and articulation of their insights into factors promoting or impeding quality health care to Indigenous Australians. Interviews were audio-taped and transcribed. An inductive, exploratory analysis identified key themes that were reviewed and interrogated in light of existing literature on health care to Indigenous people, race and disadvantage. The researchers’ past experience, knowledge and understanding of health care and Indigenous health assisted with data interpretation. Informal discussions were also held with colleagues working professionally in Indigenous policy, practice and community settings.Results: Racism emerged as a key issue, leading us to more deeply interrogate the role ‘Whiteness’ plays in Indigenous health care. While Whiteness can refer to skin colour, it also represents a racialized social structure where Indigenous knowledge, beliefs and values are subjugated to the dominant western biomedical model in policy and practice. Racism towards Indigenous patients in health services was institutional and interpersonal. Internalised racism was manifest when Indigenous patients incorporated racist attitudes and beliefs into their lived experience, lowering expectations and their sense of self-worth.Conclusions: Current health policies and practices favour standardised care where the voice of those who are marginalised is often absent. Examining the effectiveness of such models in reducing health disparities requires health providers to critically reflect on whether policies and practices promote or compromise Indigenous health and wellbeing - an important step in changing the discourse that places Indigenous people at the centre of the problem
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