3,448 research outputs found

    A Spin Modulated Telescope to Make Two Dimensional CMB Maps

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    We describe the HEMT Advanced Cosmic Microwave Explorer (HACME), a balloon borne experiment designed to measure sub-degree scale Cosmic Microwave Background anisotropy over hundreds of square degrees, using a unique two dimensional scanning strategy. A spinning flat mirror that is canted relative to its spin axis modulates the direction of beam response in a nearly elliptical path on the sky. The experiment was successfully flown in February of 1996, achieving near laboratory performance for several hours at float altitude. A map free of instrumental systematic effects is produced for a 3.5 hour observation of 630 square degrees, resulting in a flat band power upper limit of (l(l+1)C_l/2 pi)^0.5 < 77 microK at l = 38 (95% confidence). The experiment design, flight operations and data, including atmospheric effects and noise performance, are discussed.Comment: 4 pages, 3 figure

    Alliances in the Shadow of Conflict

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    Victorious alliances often fight about the spoils of war. This paper presents an experiment on the determinants of whether alliances break up and fight internally after having defeated a joint enemy. First, if peaceful sharing yields an asymmetric rent distribution, this increases the likelihood of fighting. In turn, anticipation of the higher likelihood of internal fight reduces the alliance’s ability to succeed against the outside enemy. Second, the option to make non-binding declarations on non-aggression in the relationship between alliance members does not make peaceful settlement within the alliance more likely. Third, higher differences in the alliance players’ contributions to alliance effort lead to more internal conflict and more intense fighting

    Bone Mineral Density is an Independent Determinant of Left Ventricular Mass Index in the General Female Population

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    Background and Objectives: Left ventricular hypertrophy (LVH) is a well known cardiovascular prognostic predictor. Osteoporosis has been suggested to be associated with cardiovascular disease. According to studies of primary hyperparathyroidism, a pathophysiological association between calcium metabolism and LVH has been suggested but is not yet fully understood. This study was performed to investigate the association between bone mineral density (BMD) and left ventricular mass index (LVMI) in a general population. Subjects and Methods: Data from 460 subjects among 543 subjects sampled from a general population in a rural area in Korea were analyzed. BMD, echocardiography, brachial-ankle pulse wave velocity (baPWV), carotid intima-media thickness (IMT) measurement as well as the measurements of blood pressure, blood chemistry and metabolic parameters were analyzed. BMD was measured using the Sahara Clinical Bone Sonometer (Hologic Inc., Mass., USA). Results: Age of the subjects was 59.4??12.4 years. Males were 42.2% (n=194). In a simple correlation analysis on female subjects, age and waist circumference showed negative correlation, and body mass index (BMI) showed positive correlation with BMD. However, only age showed negative correlation with BMD in male subjects. After adjusting baPWV and carotid IMT, we found that BMD was an independent determinant of LVMI in female subjects (??=-13.703, p=0.016), but not in male subjects (??=-1.235, p=0.841). Conclusion: BMD is a consistent and independent determining factor of LVMI, BMI and carotid IMT in postmenopausal women. Copyright ?? 2010 The Korean Society of Cardiology

    Self-rated health in middle-aged and elderly Chinese : distribution, determinants and associations with cardio-metabolic risk factors

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    Background: Self-rated health (SRH) has been demonstrated to be an accurate reflection of a person's health and a valid predictor of incident mortality and chronic morbidity. We aimed to evaluate the distribution and factors associated with SRH and its association with biomarkers of cardio-metabolic diseases among middle-aged and elderly Chinese. Methods: Survey of 1,458 men and 1,831 women aged 50 to 70 years, conducted in one urban and two rural areas of Beijing and Shanghai in 2005. SRH status was measured and categorized as good (very good and good) vs. not good (fair, poor and very poor). Determinants of SRH and associations with biomarkers of cardio-metabolic diseases were evaluated using logistic regression. Results: Thirty two percent of participants reported good SRH. Males and rural residents tended to report good SRH. After adjusting for potential confounders, residence, physical activity, employment status, sleep quality and presence of diabetes, cardiovascular disease, and depression were the main determinants of SRH. Those free from cardiovascular disease (OR 3.68; 95%CI 2.39; 5.66), rural residents (OR 1.89; 95% CI 1.47; 2.43), non-depressed participants (OR 2.50; 95% CI 1.67; 3.73) and those with good sleep quality (OR 2.95; 95% CI 2.22; 3.91) had almost twice or over the chance of reporting good SRH compared to their counterparts. There were significant associations -and trend- between SRH and levels of inflammatory markers, insulin levels and insulin resistance. Conclusion: Only one third of middle-aged and elderly Chinese assessed their health status as good or very good. Although further longitudinal studies are required to confirm our findings, interventions targeting social inequalities, lifestyle patterns might not only contribute to prevent chronic morbidity but as well to improve populations' perceived health

    Low-frequency cortical activity is a neuromodulatory target that tracks recovery after stroke.

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    Recent work has highlighted the importance of transient low-frequency oscillatory (LFO; &lt;4 Hz) activity in the healthy primary motor cortex during skilled upper-limb tasks. These brief bouts of oscillatory activity may establish the timing or sequencing of motor actions. Here, we show that LFOs track motor recovery post-stroke and can be a physiological target for neuromodulation. In rodents, we found that reach-related LFOs, as measured in both the local field potential and the related spiking activity, were diminished after stroke and that spontaneous recovery was closely correlated with their restoration in the perilesional cortex. Sensorimotor LFOs were also diminished in a human subject with chronic disability after stroke in contrast to two non-stroke subjects who demonstrated robust LFOs. Therapeutic delivery of electrical stimulation time-locked to the expected onset of LFOs was found to significantly improve skilled reaching in stroke animals. Together, our results suggest that restoration or modulation of cortical oscillatory dynamics is important for the recovery of upper-limb function and that they may serve as a novel target for clinical neuromodulation
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