1,624 research outputs found

    A Thousand Invisible Cords Binding Astronomy and High-Energy Physics

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    The traditional realm of astronomy is the observation and study of the largest objects in the Universe, while the traditional domain of high-energy physics is the study of the smallest things in nature. But these two sciences concerned with opposite ends of the size spectrum are, in Muir's words, bound fast by a thousand invisible cords that cannot be broken. In this essay I propose that collaborations of astronomers and high-energy physicists on common problems are beneficial for both fields, and that both astronomy and high-energy physics can advance by this close and still growing relationship. Dark matter and dark energy are two of the binding cords I will use to illustrate how collaborations of astronomers and high-energy physicists on large astronomical projects can be good for astronomy, and how discoveries in astronomy can guide high-energy physicists in their quest for understanding nature on the smallest scales. Of course, the fields have some different intellectual and collaborative traditions, neither of which is ideal. The cultures of the different fields cannot be judged to be right or wrong; they either work or they don't. When astronomers and high-energy physicists work together, the binding cords can either encourage or choke creativity. The challenge facing the astronomy and high-energy physics communities is to adopt the best traditions of both fields. It is up to us to choose wisely.Comment: Why "Fundamentalist" Physics Is Good for Astronomy (in response to the paper of Simon White, arXiv:0704.2291

    La marche vers l’Europe des moyens de paiement scripturaux : le projet SEPA.

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    SEPA, infrastructures de paiement, inter-opérabilité, instruments de paiement, intégration européenne, Eurosystème.

    Circadian Timing of Food Intake Contributes to Weight Gain

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    Studies of body weight regulation have focused almost entirely on caloric intake and energy expenditure. However, a number of recent studies in animals linking energy regulation and the circadian clock at the molecular, physiological, and behavioral levels raise the possibility that the timing of food intake itself may play a significant role in weight gain. The present study focused on the role of the circadian phase of food consumption in weight gain. We provide evidence that nocturnal mice fed a high‐fat diet only during the 12‐h light phase gain significantly more weight than mice fed only during the 12‐h dark phase. A better understanding of the role of the circadian system for weight gain could have important implications for developing new therapeutic strategies for combating the obesity epidemic facing the human population today

    The size of the longest filament in the Luminous Red Galaxy distribution

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    Filaments are one of the most prominent features visible in the galaxy distribution. Considering the Luminous Red Galaxies (LRGs) in the Sloan Digital Sky Survey Data Release Seven (SDSS DR7), we have analyzed the filamentarity in 11 nearly two dimensional (2D) sections through a volume limited subsample of this data. The galaxy distribution, we find, has excess filamentarity in comparison to a random distribution of points. We use a statistical technique "Shuffle" to determine LMAXL_{\rm MAX}, the largest length-scale at which we have statistically significant filaments. We find that LMAXL_{\rm MAX} varies in the range 100130h1Mpc100-130 \, h^{-1} {\rm Mpc} across the 11 slices, with a mean value LMAX=110±12h1MpcL_{\rm MAX}=110 \pm 12 \, h^{-1}{\rm Mpc}. Longer filaments, though possibly present in our data, are not statistically significant and are the outcome of chance alignments.Comment: 6 pages, 6 figures, Accepted for publication in MNRA

    Dietary beliefs and eating patterns influence metabolic health in type 2 diabetes: A clinic-based study in urban North India

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    Background: Almost 15% of India\u27s urban adult populace now lives with type 2 diabetes. This study aimed to characterize the eating patterns, knowledge, beliefs, and determinants of food choice, and assess associations with the metabolic health among urban Asian Indians with type 2 diabetes. Materials and Methods: A cross-sectional study of 258 individuals (mean age 55.7 ± 10 years; body mass index 27.1 ± 4.8 kg/m 2 ; diabetes duration 10.1 ± 6.5 years) attending two out-patient clinics in New Delhi, India. Food-related information was collected during a semi-structured interview. Clinical, anthropometric, and biochemical data were recorded. Results: Beliefs related to health and diabetes played a role determining food choice and dietary patterns; erroneous views were associated with the poor food choices and greater metabolic perturbations. Average consumption of fruits/vegetables was low. Intakes were positively associated with intentions to manage diabetes; inversely associated with the waist circumference and negatively correlated with one\u27s degree of personal responsibility for food choice. Household saturated fat usage was common. High fat intakes were positively associated with the taste preference, ratings of perceived "health-value;" waist circumference, glycosylated haemoglobin percentage (HbA1c%) and lipids. Conclusions: Strategies to enhance diabetes control among Asian Indians are required and should encourage fruit/vegetable intake, personal accountability, and consider individual beliefs and preferences. Greater emphasis and resources directed to regular dietary and behavioral counseling may assist.

    Effect of a standardized meal on the threshold of exercise-induced myocardial ischemia in patients with stable angina

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    AbstractObjectives. This study was undertaken to determine the effect of a standardized meal on the ischemie threshold and exercise capacity in a series of 20 patients with stable angina, exerciseinduced ischemia and reversible exercise-induced perfusion defects.Background. It is generally accepted that exercise tolerance in patients with angina is reduced after a meal. However, studies that have addressed this phenomenon have yielded results that are contradictory and inconclusive.Methods. Two exercise tests using the Brace protocol with technetium-99m (99mTc)-sestamibi were performed on consecutive days in a randomized order. One test was performed in the fasting state and the other 30 min after a 1,000-calorle meal.Results. In the postprandial state, exercise time to ischemia was reduced by 20% from 248 ± 93 s to 197 ±87 s (p = 0.0007), time to angina by 15% from 340 ± 82 s to 287 ± 94 s (p = 0.002) and exercise tolerance by 9% from 376 ± 65 s to 344 ± 86 s (p = 0.002). Rate-pressure products at these exercise test end points were not significantly different in the fasting and postprandial tests, and the quantitative 99mTc-sestamibi ischemia score was unchanged.Conclusions. In patients with stable angina, a 1,000-calorie meal significantly reduced tine to ischemia, time to angina and exercise tolerance because of a more rapid increase in myocardial oxygen demand with exercise. The extent and severity of exerciseinduced ischemia were unchanged

    Effects of short-term energy restriction on liver lipid content and inflammatory status in severely obese adults: results of a randomised controlled trial (RCT) using two dietary approaches

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    Short-term very low energy diets (VLED) are used in clinical practice prior to bariatric surgery, however, regimens vary and outcomes for a short intervention are unclear. We examined the effect of two VLEDs; a food-based diet (FD) and meal replacement plan (MRP) (LighterLife) over two weeks in a randomised controlled trial (RCT). We collected clinical and anthropometric data, fasting blood samples, and dietary evaluation questionnaires. Surgeons took liver biopsies and made a visual assessment of the liver. We enrolled 60 participants and 54 completed (FD n=26, MRP n=28). Baseline demographic features, reported energy intake, dietary evaluation and liver histology were comparable between groups. Both diets induced significant weight loss. Perceived difficulty of surgery correlated significantly with the degree of steatosis on histology. Circulating inflammatory mediators: CRP, Fetuin-A and IL6 reduced pre to post diet. Diets achieved comparable weight loss and reduction in inflammatory biomarkers, perceived operative difficulty, and patient evaluation. NAFLD histology assessments post-diet were also not significantly different between diets. Results indicate effectiveness of short term very low energy diets and energy restriction irrespective of macronutrient composition although small sample size precluded detection of subtle differences between interventions

    Questions on pure luminosity evolution for ellipticals

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    The explanation for the existence of an excess population of faint blue galaxies (FBGs) has been a mystery for nearly two decades, and remains one of the grand astronomical issues to date. Existing models cannot explain all of the observational data such as galaxy number counts in the optical and infrared passbands and the redshift distributions of galaxies. Here, by modelling the morphological number counts derived from the Hubble Space Telescope, as well as the number counts in optical and infrared passbands, and the redshift and color distributions of galaxies obtained from ground-based observations, we show that the `FBG problem' cannot be resolved if elliptical galaxies are assumed to have formed in an instantaneous burst of star formation at high redshift with no subsequent star formation events, which is just the conventional scenario for formation and evolution of ellipticals. There exist great discrepancies between the observed BKB-K color distribution and the predicted distribution for ellipticals by such a pure luminosity evolution (PLE) model in the context of the conventional scenario. Neither can the mild evolution (i.e., the star formation events have lasted for a longer time than those of the instantaneous burst and passive evolution since the formation of galaxies) for ellipticals be accepted in the context of PLE assumption. The introduction of dust extinction also cannot save the PLE models. This conclusion holds for each of the three cosmological models under consideration: flat, open and Λ\Lambda-dominated. Hence, our investigation suggests that PLE assumption for elliptical galaxies is questionable, and number evolution may be essential for ellipticals.Comment: 20pages (AASTeX), 10 eps figures, 4 tables, to appear in ApJ, 1999, Vol. 51

    Bells and 'Burdens'

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