Robustness of Binary Black Hole Mergers in the Presence of Spurious Radiation

We present an investigation into how sensitive the last orbits and merger of binary black hole systems are to the presence of spurious radiation in the initial data. Our numerical experiments consist of a binary black hole system starting the last couple of orbits before merger with additional spurious radiation centered at the origin and fixed initial angular momentum. As the energy in the added spurious radiation increases, the binary is invariably hardened for the cases we tested, i.e. the merger of the two black holes is hastened. The change in merger time becomes significant when the additional energy provided by the spurious radiation increases the Arnowitt-Deser-Misner (ADM) mass of the spacetime by about 1%. While the final masses of the black holes increase due to partial absorption of the radiation, the final spins remain constant to within our numerical accuracy. We conjecture that the spurious radiation is primarily increasing the eccentricity of the orbit and secondarily increasing the mass of the black holes while propagating out to infinity.Comment: 12 pages, 12 figure

Frequency noise and intensity noise of next-generation gravitational-wave detectors with RF/DC readout schemes

The sensitivity of next-generation gravitational-wave detectors such as Advanced LIGO and LCGT should be limited mostly by quantum noise with an expected technical progress to reduce seismic noise and thermal noise. Those detectors will employ the optical configuration of resonant-sideband-extraction that can be realized with a signal-recycling mirror added to the Fabry-Perot Michelson interferometer. While this configuration can reduce quantum noise of the detector, it can possibly increase laser frequency noise and intensity noise. The analysis of laser noise in the interferometer with the conventional configuration has been done in several papers, and we shall extend the analysis to the resonant-sideband-extraction configuration with the radiation pressure effect included. We shall also refer to laser noise in the case we employ the so-called DC readout scheme.Comment: An error in Fig. 10 in the published version in PRD has been corrected in this version; an erratum has been submitted to PRD. After correction, this figure reflects a significant difference in the ways RF and DC readout schemes are susceptible to laser noise. In addition, the levels of mirror loss imbalances and input laser amplitude noise have also been updated to be more realistic for Advanced LIG

Central Versus Peripheral Cardiovascular Risk in Metabolic Syndrome

Individuals with metabolic syndrome (MetS; i.e., three of five of the following risk factors (RFs): elevated blood pressure, waist circumference, triglycerides, blood glucose, or reduced HDL) are thought to be prone to serious cardiovascular disease and there is debate as to whether the disease begins in the peripheral vasculature or centrally. This study investigates hemodynamics, cardiac function/morphology, and mechanical properties of the central (heart, carotid artery) or peripheral [total peripheral resistance (TPR), forearm vascular bed] vasculature in individuals without (1–2 RFs: n = 28), or with (≥3 RFs: n = 46) MetS. After adjustments for statin and blood pressure medication use, those with MetS had lower mitral valve E/A ratios (<3 RFs: 1.24 ± 0.07; ≥3 RFs: 1.01 ± 0.04; P = 0.025), and higher TPR index (<3 RFs: 48 ± 2 mmHg/L/min/m2; ≥3 RFs: 53 ± 2 mmHg/L/min/m2; P = 0.04). There were no differences in heart size, carotid artery measurements, cardiovagal baroreflex, pulse-wave velocity, stroke volume index, or cardiac output index due to MetS after adjustments for statin and blood pressure medication use. The use of statins was associated with increased inertia in the brachial vascular bed, increased HbA1c and decreased LDL cholesterol. The independent use of anti-hypertensive medication was associated with decreased predicted VO2max, triglycerides, diastolic blood pressure, interventricular septum thickness, calculated left ventricle mass, left ventricle posterior wall thickness, and left ventricle pre-ejection period, but increased carotid stiffness, HDL cholesterol, and heart rate. These data imply that both a central cardiac effect and a peripheral effect of vascular resistance are expressed in MetS. These data also indicate that variance in between-group responses due to pharmacological treatments are important factors to consider in studying cardiovascular changes in these individuals

Changes in Circula ting Angiogenic Cells After Exercise or Flexibility Intervention in Older Men and Women

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Sodium nitroglycerin induces middle cerebral artery vasodilatation in young, healthy adults

© 2018 The Authors Experimental Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society New Findings: What is the central question of this study? Nitric oxide causes dilatation in peripheral vessels; however, whether nitric oxide affects basal cerebral artery dilatation has not been explored. What is the main finding and its importance? This study demonstrated that vasodilatation occurs in the right middle cerebral artery in response to exogenous nitric oxide. However, blood velocity decreased and, therefore, overall cerebral blood flow remained unchanged. This study provides new insight into the role of nitric oxide in cerebral blood flow control. Abstract: Recent evidence indicates that basal cerebral conduit vessels dilate with hypercapnia, with a nitric oxide (NO) mechanism explaining one way in which parenchymal cerebral arterioles dilate. However, whether NO affects basal cerebral artery dilatation remains unknown. This study quantified the effect of an exogenous NO donor [sodium nitroglycerin (NTG); 0.4 mg sublingual spray] on the right middle cerebral artery (rMCA) cross-sectional area (CSA), blood velocity and overall blood flow. Measures of vessel CSA (7 T magnetic resonance imaging) and MCA blood velocity (transcranial Doppler ultrasound) were made at baseline (BL) and after exogenous NTG or placebo (PLO) administration in young, healthy individuals (n = 10, two males, age range 20–23 years). The CSA increased in the rMCA [BL, 5.2 ± 1.2 mm2; PLO, 5.4 ± 1.5 mm2; NTG, 6.6 ± 1.5 mm2, P \u3c 0.05; mean ± SD]. Concurrently, rMCA blood velocity decreased from BL during NTG compared with PLO (BL, 67 ± 10 cm s−1; PLO, 62 ± 10 cm s−1; NTG, 59 ± 9.3 cm s−1, P \u3c 0.05; mean ± SD]. However, total MCA blood flow did not change with NTG or PLO [BL, 221 ± 37.4 ml min−1; PLO, 218 ± 35.0 ml min−1; NTG, 213 ± 46.4 ml min−1). Therefore, exogenous NO mediates a dilatory response in the rMCA, but not in its downstream vascular bed

Faster femoral artery blood velocity kinetics at the onset of exercise following short-term training.

OBJECTIVE: The hypothesis that the adaptation to endurance exercise training included a faster increase in blood flow at the onset of exercise was tested in 12 healthy young men who endurance-trained (ET) 2 h/day, for 10 days at 65% VO2 peak on a cycle ergometer, and in 11 non-training control (C) subjects. METHODS: Blood flow was estimated from changes in femoral artery mean blood velocity (MBV) by pulsed Doppler. Beat-by-beat changes in cardiac output (CO) and mean arterial pressure (MAP) were obtained by impedance cardiography and a Finapres finger cuff, respectively. MBV, MAP and CO were measured at rest and during 5 min of dynamic knee extension exercise. Both legs worked alternately with 2 s raising and lowering a weight (15% maximal voluntary contraction) followed by 2 s rest while the other leg raised and lowered the weight. RESULTS: In the ET group the time to 63% (T63%) of the approximately exponential increase in MBV following 10 days of training (8.6 +/- 1.2 s, mean +/- s.e.) was significantly faster than the Day 0 response (14.2 +/- 2.1 s, P \u3c 0.05). The T63% of femoral artery vascular conductance (VCfa) was also faster following 10 days of ET (9.4 +/- 0.9 s) versus Day 0 (16.0 +/- 2.5 s) (0.05). There was no change in the T63% of both MBV and VCfa for the C group. The kinetics of CO were not significantly affected by ET, but the amplitude of CO in the adaptive phase, and at steady state, were significantly greater (P \u3c 0.05) at Day 10 compared to Day 0 for the ET group with no change in the C group. CONCLUSIONS: These data supported the hypothesis that endurance training resulted in faster adaptation of blood flow to exercising muscle, and further showed that this response occurred early in the training program

MRI measures of middle cerebral artery diameter in conscious humans during simulated orthostasis.

BACKGROUND AND PURPOSE: The relationship between middle cerebral artery (MCA) flow velocity (CFV) and cerebral blood flow (CBF) is uncertain because of unknown vessel diameter response to physiological stimuli. The purpose of this study was to directly examine the effect of a simulated orthostatic stress (lower body negative pressure [LBNP]) as well as increased or decreased end-tidal carbon dioxide partial pressure (P(ET)CO(2)) on MCA diameter and CFV. METHODS: Twelve subjects participated in a CO(2) manipulation protocol and/or an LBNP protocol. In the CO(2) manipulation protocol, subjects breathed room air (normocapnia) or 6% inspired CO(2) (hypercapnia), or they hyperventilated to approximately 25 mm Hg P(ET)CO(2) (hypocapnia). In the LBNP protocol, subjects experienced 10 minutes each of -20 and -40 mm Hg lower body suction. CFV and diameter of the MCA were measured by transcranial Doppler and MRI, respectively, during the experimental protocols. RESULTS: Compared with normocapnia, hypercapnia produced increases in both P(ET)CO(2) (from 36+/-3 to 40+/-4 mm Hg, P CONCLUSIONS: Under the conditions of this study, changes in MCA diameter were not detected. Therefore, we conclude that relative changes in CFV were representative of changes in CBF during the physiological stimuli of moderate LBNP or changes in P(ET)CO(2)

Altered cortical activation patterns associated with baroreflex unloading following 24 h of physical deconditioning

Cardiovascular arousal is associated with patterned cortical activity changes. Head-down-tilt bed rest (HDBR) dimishes the baroreflex-mediated cardiac control. The present study tested the hypothesis that HDBR deconditioning would modify the forebrain organization for heart rate (HR) control during baroreflex unloading. Heart rate variability (HRV), blood pressure and plasma hormones were analysed at rest, whereas HR and cortical autonomic activation patterns (functional magnetic resonance imaging) were measured during graded and randomly assigned lower body negative pressure treatments (LBNP, -15 and -35 mmHg) both before (Pre) and after (Post) a 24 h HDBR protocol (study 1; n= 8). An additional group was tested before and following diuretic-induced hypovolaemia (study 2; n= 9; spironolactone, 100 mg day-1 for 3 days) that mimicked the plasma volume lost during HDBR (-15% in both studies; P \u3c 0.05). Head-down bed rest with hypovolaemia did not affect baseline HR, mean arterial pressure, HRV or plasma catecholamines. Head-down bed rest augmented the LBNP-induced HR response (P \u3c 0.05), and this was associated with bed-rest-induced development of the following changes: (i) enhanced activation within the genual anterior cingulate cortex and the right anterior insular cortex; and (ii) deactivation patterns within the subgenual regions of the anterior cingulate cortex. Diuretic treatment (without HDBR) did not affect baseline HR and mean arterial pressure, but did reduce resting HRV and elevated circulating noradrenaline and plasma renin activity (P \u3c 0.05). The greater HR response to LBNP following diuretic (P \u3c 0.05) was associated with diminished activation of the right anterior insula. Our findings indicate that 24 h of HDBR minimized the impact of diuretic treatment on baseline autonomic and cardiovascular variables. The findings also indicate that despite the similar augmentation of HR responses to LBNP and despite similar pre-intervention cortical activation patterns, HDBR and diuretic treatment produced different effects on the cortical responses, with HDBR affecting anterior cingulate cortex and right insula regions, whereas diuretic treatment affected primarily the right insula alone, but in a direction that was opposite to HDBR. The data indicate that physical deconditioning can induce rapid functional changes within the cortical circuitry associated with baroreflex unloading, changes that are distinct from diuretic-induced hypovolaemia. The results suggest that physical activity patterns exert a rapid and notable impact on the cortical circuitry associated with cardiovascular control. © 2012 The Physiological Society

A mobile app to identify lifestyle indicators related to undergraduate mental health (smart healthy campus): Observational app-based ecological momentary assessment

Background: Undergraduate studies are challenging, and mental health issues can frequently occur in undergraduate students,straining campus resources that are already in demand for somatic problems. Cost-effective measures with ubiquitous devices,such as smartphones, offer the potential to deliver targeted interventions to monitor and affect lifestyle, which may result inimprovements to student mental health. However, the avenues by which this can be done are not particularly well understood,especially in the Canadian context.Objective: The aim of this study is to deploy an initial version of the Smart Healthy Campus app at Western University, Canada,and to analyze corresponding data for associations between psychosocial factors (measured by a questionnaire) and behaviorsassociated with lifestyle (measured by smartphone sensors).Methods: This preliminary study was conducted as an observational app-based ecological momentary assessment. Undergraduatestudents were recruited over email, and sampling using a custom 7-item questionnaire occurred on a weekly basis.Results: First, the 7-item Smart Healthy Campus questionnaire, derived from fully validated questionnaires-such as the BriefResilience Scale; General Anxiety Disorder-7; and Depression, Anxiety, and Stress Scale-21-was shown to significantly correlatewith the mental health domains of these validated questionnaires, illustrating that it is a viable tool for a momentary assessmentof an overview of undergraduate mental health. Second, data collected through the app were analyzed. There were 312 weeklyresponses and 813 sensor samples from 139 participants from March 2019 to March 2020; data collection concluded whenCOVID-19 was declared a pandemic. Demographic information was not collected in this preliminary study because of technicallimitations. Approximately 69.8% (97/139) of participants only completed one survey, possibly because of the absence of anyincentive. Given the limited amount of data, analysis was not conducted with respect to time, so all data were analyzed as a singlecollection. On the basis of mean rank, students showing more positive mental health through higher questionnaire scores tendedto spend more time completing questionnaires, showed more signs of physical activity based on pedometers, and had their devicesrunning less and plugged in charging less when sampled. In addition, based on mean rank, students on campus tended to reportmore positive mental health through higher questionnaire scores compared with those who were sampled off campus. Some datafrom students found in or near residences were also briefly examined.Conclusions: Given these limited data, participants tended to report a more positive overview of mental health when on campusand when showing signs of higher levels of physical activity. These early findings suggest that device sensors related to physical activity and location are useful for monitoring undergraduate students and designing interventions. However, much more sensordata are needed going forward, especially given the sweeping changes in undergraduate studies due to COVID-19

Assessing genetic structure with multiple classes of molecular markers: a case study involving the introduced fire ant Solenopsis invicta

We used 30 genetic markers of 6 different classes to describe hierarchical genetic structure in introduced populations of the fire ant Solenopsis invicta. These included four classes of presumably neutral nuclear loci (allozymes, codominant random amplified polymorphic DNAs (RAPDs), microsatellites, and dominant RAPDs), a class comprising two linked protein-coding nuclear loci under selection, and a marker of the mitochondrial DNA (mtDNA). Patterns of structure revealed by F statistics and exact tests of differentiation were highly concordant among the four classes of neutral nuclear markers, although the microsatellites were the most effective markers for detecting structure. The results from the mtDNA complemented those from the neutral nuclear markers by revealing that strong limitations to female-mediated gene flow were the cause of the local structure registered by the nuclear markers. The pattern of structure inferred from the selected nuclear loci was markedly different from the patterns derived from the other sets of markers but was predictable on the basis of the presumed mode of selection acting on these loci. In general, the results for all six classes of markers can be explained by known features of the social and reproductive biology of fire ants. Thus, the results from these diverse sets of markers, combined with detailed natural history data, provide an unusually complete picture of how the fundamental evolutionary forces of gene flow, drift, and selection govern the distribution of genetic variation within and between fire ant populations