Establishing Visible Interferometer System Responses: Resolved and Unresolved Calibrators

The propagation of errors through the uniform disk visibility function is examined. Implications of those errors upon measures of absolute visibility through optical and near-infrared interferometers are considered within the context of using calibration stars to establish system visibilities for these instruments. We suggest a simple ratio test to establish empirically whether or not the measured visibilities produced by such an instrument are relative (errors dominated by calibrator angular size prediction error) or absolute (errors dominated by measurement error).Comment: 20 pages, 7 figures, to be published in the PAS

Angiotensin-Converting Enzyme Inhibitor Therapy Affects Left Ventricular Mass in Patients With Ejection Fraction >40% After Acute Myocardial Infarction

AbstractObjectives. We tested the hypothesis that angiotensin-converting enzyme (ACE) inhibitor therapy decreases left ventricular (LV) mass in patients with a left ventricular ejection fraction (LVEF) >40% and no evidence of heart failure after their first acute Q wave myocardial infarction (MI).Background. Recently, ACE inhibitor therapy has been shown to have an early mortality benefit in unselected patients with acute MI, including patients without heart failure and a LVEF >35%. However, the effects on LV mass and volume in this patient population have not been studied.Methods. Thirty-five patients with a LVEF >40% after their first acute Q wave MI were randomized to titrated oral ramipril (n = 20) or conventional therapy (control, n = 15). Magnetic resonance imaging (MRI) performed an average of 7 days and 3 months after MI provided LV volumes and mass from summated serial short-axis slices.Results. Left ventricular end-diastolic volume index did not change in ramipril-treated patients (62 ± 16 [SD] to 66 ± 17 ml/m2) or in control patients (62 ± 16 to 68 ± 17 ml/m2), and stroke volume index increased significantly in both groups. However, LV mass index decreased in ramipril-treated patients (82 ± 18 to 73 ± 19 g/m2, p = 0.0002) but not in the control patients (77 ± 15 to 79 ± 23 g/m2). Systolic arterial pressure did not change in either group at 3-month follow-up.Conclusions. In patients with a LVEF >40% after acute MI, ramipril decreased LV mass, and blood pressure and LV function were unchanged after 3 months of therapy. Whether the decrease in mass represents a sustained effect that is associated with a decrease in morbid events requires further investigation.(J Am Coll Cardiol 1997;29:49–54)

Assumption without representation: the unacknowledged abstraction from communities and social goods

We have not clearly acknowledged the abstraction from unpriceable “social goods” (derived from communities) which, different from private and public goods, simply disappear if it is attempted to market them. Separability from markets and economics has not been argued, much less established. Acknowledging communities would reinforce rather than undermine them, and thus facilitate the production of social goods. But it would also help economics by facilitating our understanding of – and response to – financial crises as well as environmental destruction and many social problems, and by reducing the alienation from economics often felt by students and the public

Genomic Dissection of Bipolar Disorder and Schizophrenia, Including 28 Subphenotypes

publisher: Elsevier articletitle: Genomic Dissection of Bipolar Disorder and Schizophrenia, Including 28 Subphenotypes journaltitle: Cell articlelink: https://doi.org/10.1016/j.cell.2018.05.046 content_type: article copyright: © 2018 Elsevier Inc

Prediction of aquatic treadmill (ATM) energy expenditure and comparison with equivalent land treadmill (LTM) running speeds

The use of aquatic treadmills (ATM) provide an alternative mode of exercise conditioning when exercise on a land treadmill (LTM) is limited due to injury or recovery from surgical intervention. Yet providing an ATM intensity that mimics a corresponding LTM exercise intensity is less clear. PURPOSE:This study sought to examine the metabolic (VO2) relationship between varying jet resistances and running speed on an ATM versus LTM. METHODS: Experienced runners (n = 18) completed an initial VO2 peak test, three LTM trials, and 18 ATM trials. Each ATM trial consisted of running for three minutes at either an individual’s relatively slow, moderate and somewhat fast speed while one of six ATM jet settings ranging from 0 to 100% jet capacity in 20% increments were assigned to each trial. Oxygen consumption (VO2) and heart rate (HR) were measured during each trial while ratings of perceived exertion (RPE) were solicited immediately following each trial. RESULTS: Resulting analysis produced an ATM prediction equation for relative VO2 = -5.4556 + 5.3674*Speed + .3221*Jet Resistance - 0.1649 (Jet Resistance*Speed) with R-squared = 0.92. Differences in the actual (37.6 ± 10.5 ml · kg -1·min-1) vs predicted (38.2 ± 9.1 ml ·kg-1 ·min-1) VO2 for all ATM conditions were similar (p\u3e0.05) however the residual values (4.38 ± 3.37 ml ·kg-1 ·min-1) suggest greater variability. Developing jet resistance specific equations accounted for non-linear impact of jet resistance on energy expenditure. For LTM the prediction equation for relative VO2 was: VO2 = 6.1034 + 4.37*speed, with residual scores of 0.93 ± ml ·kg-1 ·min-1 and a R-squared = 0.95. At a given ATM speed the increased VO2 associated with each jet setting during ATM trials (20, 40, 60, 80 and 100%) corresponded to an average estimated change in comparable LTM speed of -0.96, +0.91, +1.53, +3.05, and +4.16 miles per hour respectively. CONCLUSIONS: These results demonstrate that ATM metabolic costs appear to be more variable than LTM and may be due to jet resistance’s non-linear impact on energy expenditure. Jet resistances of \u3e40% provide an intensity of exercise that mimics running faster on LTM. This provides an added benefit for those individuals who may be limited due to acute overuse-type injuries or returning to full LTM activity following lower extremity surgery

Metabolic cost comparison of running on an aquatic treadmill with water jets and land treadmill with incline

The purpose of this study was to compare the metabolic cost (MC) of running on a land treadmill (TM) at specific inclines with an aquatic treadmill (ATM) at equivalent running speeds with selected jet resistances. Sixteen participants completed two trials on separate days on a TM and ATM. For each trial, subjects either ran against water jet resistances of 0–100% of maximum jet flow capacity in 20% increments (ATM) or inclines of 0–10% in 2% increments (TM). Oxygen consumption (VO2), heart rate (HR), and rating of perceived exertion (RPE) were recorded during each trial. When running at similar speeds with no resistance (jets or incline), ATM yielded lower VO2 than TM (p \u3c .05). Adding 40% jets during ATM matched MC during TM at 0% incline. At 60% jets, ATM MC simulated TM MC while running on a 4% incline. Comparable MC was observed during ATM 80% jets and 8% TM incline, while ATM 100% jets yielded greater MC than TM 10% incline. We concluded the differences in MC during TM incline vs. ATM with jet resistances was likely a result of nonlinear application of drag forces on the torso created by the water velocities of the water jets

Changes in left ventricular mass and volumes in patients receiving angiotensin-converting enzyme inhibitor therapy for left ventricular dysfunction after Q-wave myocardial infarction

We evaluated global and segmental left ventricular (LV) mass and LV mass/volume ratio in patients with LV dysfunction receiving angiotensin-converting enzyme (ACE) inhibitor therapy after acute myocardial infarction (MI). ACE inhibitors attenuate LV dilatation and compensatory hypertrophy after acute MI in animal models. However, LV remodeling in patients after acute MI has been largely defined on the basis of changes in chamber volume alone. Twenty-nine patients with LV ejection fraction <40% received the ACE inhibitor ramipril (range 2.5 to 20 mg/day) within 5 days of their first Q-wave MI. Magnetic resonance imaging was performed at baseline and at 3 months, providing global and regional LV volumes and mass from summated serial short-axis slices. Mean arterial blood pressure was unchanged from baseline to 3-month follow-up (89 +/- 10 to 92 +/- 17 mm Hg). LV mass decreased (90 +/- 25 to 77 +/- 21 gm/m2, p < 0.0005) as LV end-diastolic volumes increased (65 +/- 13 to 73 +/- 22 ml/m2, p < 0.01). Global LV mass to volume ratio decreased from 1.40 +/- 0.28 to 1.08 +/- 0.18 gm/ml (p < 0.0001), as did circumferential wall thickness to volume ratio of noninfarcted myocardium at the base of the LV (0.06 +/- 0.02 to 0.05 +/- 0.02 mm/ml, p < 0.001). LV ejection fraction increased from 35 +/- 6 to 40 +/- 9% (p < 0.001) in the presence of an increase in calculated end-systolic wall stress (185 +/- 57 to 227 +/- 54 gm/cm2, p < 0.01). ACE inhibitor therapy was associated with improved LV function in the face of a decrease in mass to volume ratio of the LV as well as a decrease in wall thickness to volume ratio of noninfarcted myocardium. Whether ACE inhibitor therapy had direct or indirect effects on these changes in LV mass and function are open questions that require further investigation