8,349 research outputs found
An electrothermally actuated micro valve
Microminiature slide action valve requires power only during actuation and can be used as an on-off or single inlet to alternately selected outlets
Pneumatic system for controlling and actuating pneumatic cyclic devices
Pneumatic system for cyclic control of fluid flow in pneumatic devic
Spool valve cycles at controlled frequency
Spool valve accurately controls the cycle of a pneumatically-actuated system over long periods. Regulation of pressure from the external source, positioning of the adjusting plugs, and magnet selection, together afford wide variation in cyclic timing and speed of closure in either direction
Distortion of Globular Clusters by Galactic Bulges
One of the external fields that influences the population of globular
clusters is that due to galactic bulges. In extreme situations, perigalactic
distances pc, globular clusters could suffer total disruption in
a single passage. A more common scenario is that for cluster orbits with pc. We investigate the effects of tidal forces from a bulge on the
shape of globular clusters for this type of encounters. We find distortions
characterized by ``twisting isophotes'' and consider the potential for
observability of this effect. In the Milky Way, a typical globular cluster must
pass within several hundred pc of the center to experience substantial
distortion, and it is possible that this has happened recently to one or two
present day clusters. We estimate that this distortion could be observed even
for globulars in dense fields toward the bulge. In more extreme environments
such as giant ellipticals or merger products with newly formed globulars, this
effect could be more common, extending out to orbits that pass within 1 kpc of
the bulge center. This would lead to a substantial shift in the eccentricity
distribution of globulars in those galaxies.Comment: 12 pages, 8 figure
From research to policy in chronic disease prevention: mandatory salt reduction in South Africa
Abstract of a poster that presented at 20th International Congress of Nutrition, Granada, Spain, September 15-20, 2013
Southern Africa is good place to research role of fetal malnutrition in chronic diseases
Editor — We are interested in Scrimshaw\u27s allusion to populations in Latin America in his editorial on the relation between fetal malnutrition and chronic disease in later life. There, in the 1960s, despite a high prevalence of low birth weight, the preva lence of atherosclerosis and of myocardial infarction was low
East salt sparingly - sprinkle, don\u27t shake!
The salt-blood pressure hypothesis states that an excessive salt intake leads to an increase in blood pressure in genetically susceptible persons and, if high intake is maintained long term, ultimately leads to sustained hypertension. It is estimated that about 3.3 million South Africans (12.6% and 16.3% of adult men and women, respectively) are hypertensive. However, not all subjects within a particular population respond equally to exposure to high-salt diets. Methods to identify those who are \u27salt sensitive\u27 remain in the research domain; therefore a population approach to the restriction of dietary salt intake is warranted. The message to \u27eat salt sparingly\u27 will not interfere with the current nutritional and legal requirements regarding iodation of table salt. A salt intake as low as 5 g per day would provide an adequate amount of iodine, provided the salt is sufficiently iodated. Dietary factors other than sodium which have been shown to influence blood pressure include potassium, magnesium, calcium and alcohol. The \u27Dietary Approaches to Stop Hypertension\u27 (DASH) randomised controlled trial found that subjects fed a diet rich in fruit and vegetables for 8 weeks significantly reduced both systolic and diastolic blood pressure, compared with subjects on a typical American control diet. A \u27combination\u27 diet, rich in fruit, vegetables and low-fat dairy products, and with a reduced saturated and total fat intake, resulted in an even greater reduction in blood pressure. Translated into a practical diet, this information suggests a daily diet that includes large amounts of fruit and vegetables, a moderate intake of low-fat dairy products, lean meat and chicken, and a prudent alcohol intake. Salt should be used sparingly, if at all, at the table and in the preparation of meals, and the intake of processed foods high in salt should be limited. This would result in a reduction in intake from an average of around 9 g salt to about 6 g salt per day, which is the current USA recommendation. These blood pressure-related recommendations incorporate many of the various foodbased dietary guidelines, emphasising that the recommendations are congruent and mutually substantiative
The Revealing Dust: Mid-Infrared Activity in Hickson Compact Group Galaxy Nuclei
We present a sample of 46 galaxy nuclei from 12 nearby (z<4500 km/s) Hickson
Compact Groups (HCGs) with a complete suite of 1-24 micron 2MASS+Spitzer
nuclear photometry. For all objects in the sample, blue emission from stellar
photospheres dominates in the near-IR through the 3.6 micron IRAC band.
Twenty-five of 46 (54%) galaxy nuclei show red, mid-IR continua characteristic
of hot dust powered by ongoing star formation and/or accretion onto a central
black hole. We introduce alpha_{IRAC}, the spectral index of a power-law fit to
the 4.5-8.0 micron IRAC data, and demonstrate that it cleanly separates the
mid-IR active and non-active HCG nuclei. This parameter is more powerful for
identifying low to moderate-luminosity mid-IR activity than other measures
which include data at rest-frame lambda<3.6 micron that may be dominated by
stellar photospheric emission. While the HCG galaxies clearly have a bimodal
distribution in this parameter space, a comparison sample from the Spitzer
Nearby Galaxy Survey (SINGS) matched in J-band total galaxy luminosity is
continuously distributed. A second diagnostic, the fraction of 24 micron
emission in excess of that expected from quiescent galaxies, f_{24D}, reveals
an additional 3 nuclei to be active at 24 micron. Comparing these two mid-IR
diagnostics of nuclear activity to optical spectroscopic identifications from
the literature reveals some discrepancies, and we discuss the challenges of
distinguishing the source of ionizing radiation in these and other lower
luminosity systems. We find a significant correlation between the fraction of
mid-IR active galaxies and the total HI mass in a group, and investigate
possible interpretations of these results in light of galaxy evolution in the
highly interactive system of a compact group environment.Comment: 20 pages, 17 figures (1 color), uses emulateapj. Accepted for
publication by Ap
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