2,639 research outputs found
An Exceptional Story
The temperature was more than 90 degrees Fahrenheit as I lay on my keister in the shade of an oak tree relaxing at the babbling weir of Anaheim Creek. My enjoyment was enhanced by several heirfers stopping to drink, and a skein of ducks flying at a considerable height above the forest. The event was a nonpareil leisure occurrence
Ants Are All Over
This is a story of an enchanting young man, Anthony Santiago, an immigrant from Antwerp, who became a very important contributor to our society as a result of his penchant for inventions. He was responsible for the development. He created a safety lantern for use in anthracite mines, a sextant that received world-wide acclaim, and he helped perfect a disinfectant for commercial use
Sex-specific computational models of the spontaneously hypertensive rat kidneys: factors affecting nitric oxide bioavailability
Sex-specific
computational models of the spontaneously hypertensive rat kidneys:
factors affecting nitric oxide bioavailability. Am J Physiol Renal
Physiol 313: F174 –F183, 2017. First published March 29, 2017;
doi:10.1152/ajprenal.00482.2016.—The goals of this study were to 1)
develop a computational model of solute transport and oxygenation in
the kidney of the female spontaneously hypertensive rat (SHR), and 2)
apply that model to investigate sex differences in nitric oxide (NO)
levels in SHR and their effects on medullary oxygenation and oxidative stress. To accomplish these goals, we first measured NO synthase
(NOS) 1 and NOS3 protein expression levels in total renal microvessels of male and female SHR. We found that the expression of both
NOS1 and NOS3 is higher in the renal vasculature of females
compared with males. To predict the implications of that finding on
medullary oxygenation and oxidative stress levels, we developed a
detailed computational model of the female SHR kidney. The model
was based on a published male kidney model and represents solute
transport and the biochemical reactions among O2, NO, and superoxide (O2
) in the renal medulla. Model simulations conducted using
both male and female SHR kidney models predicted significant radial
gradients in interstitial fluid oxygen tension (PO2) and NO and O2
concentration in the outer medulla and upper inner medulla. The
models also predicted that increases in endothelial NO-generating
capacity, even when limited to specific vascular segments, may
substantially raise medullary NO and PO2 levels. Other potential sex
differences in SHR, including O2
production rate, are predicted to
significantly impact oxidative stress levels, but effects on NO concentration and PO2 are limited.This research was supported by the National Institute of Diabetes and Digestive and Kidney Diseases Grant R01-DK-106102 to A. T. Layton, and by American Heart Association Grant 14GRNT20480199 to J. C. Sullivan. (R01-DK-106102 - National Institute of Diabetes and Digestive and Kidney Diseases; 14GRNT20480199 - American Heart Association)Accepted manuscrip
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Soil pH governs production rate of calcium carbonate secreted by the earthworm Lumbricus terrestris
Lumbricus terrestris earthworms exposed to 11 soils of contrasting properties produced, on average, 0.8 ± 0.1 mgCaCO3 earthworm−1 day−1 in the form of granules up to 2 mm in diameter. Production rate increased with soil pH (r2 = 0.68, p < 0.01). Earthworms could be a significant source of calcite in soils
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The Effect of Layer Orientation on the Tensile Properties of Net Shape Parts Fabricated in Stereolithography
Stereolithographic technologies create parts in thermoset plastic polymeric mixtures of
acrylates and epoxies. In order to predict the mechanical behavior of these parts, it is critical to
understand the effects that build parameters have on the final properties of the polymer. Using a
statistics based approach, the build parameters of layer orientation, layer thickness, and resin
class are used as inputs. The response variables, peak stress, elongation at break and Young’s
modulus (modulus of elasticity), are examined using the methodology specified in ASTM D638-
01 with modifications as noted. An initial test in Somos 8120 showed the surprising (and
statistically significant) result that load bearing capability in the build direction was greater than
in the in-layer direction. Additional tensile tests in Somos 8120 and Vantico SL-5510 were
undertaken to verify this result, and determine if this effect is present across different classes of
resin. This report details the rationale behind this experiment, presents the results to date, and
outlines future efforts.Mechanical Engineerin
Spectral scaling of the Leray- model for two-dimensional turbulence
We present data from high-resolution numerical simulations of the
Navier-Stokes- and the Leray- models for two-dimensional
turbulence. It was shown previously (Lunasin et al., J. Turbulence, 8, (2007),
751-778), that for wavenumbers such that , the energy
spectrum of the smoothed velocity field for the two-dimensional
Navier-Stokes- (NS-) model scales as . This result is
in agreement with the scaling deduced by dimensional analysis of the flux of
the conserved enstrophy using its characteristic time scale. We therefore
hypothesize that the spectral scaling of any -model in the sub-
spatial scales must depend only on the characteristic time scale and dynamics
of the dominant cascading quantity in that regime of scales. The data presented
here, from simulations of the two-dimensional Leray- model, confirm our
hypothesis. We show that for , the energy spectrum for the
two-dimensional Leray- scales as , as expected by the
characteristic time scale for the flux of the conserved enstrophy of the
Leray- model. These results lead to our conclusion that the dominant
directly cascading quantity of the model equations must determine the scaling
of the energy spectrum.Comment: 11 pages, 4 figure
A note on the rising cost of education in Australia
Human capital, or a better educated labour force, is a major determinant of economic growth and productivity. However, recent trends in the cost of education in Australia may cause growth and productivity to suffer. For example, during the period 1982-2003 inflation rose on average by 4.4 per cent per annum, whereas the cost of education grew overall on average by 7.8 per cent. This has made education a relatively expensive item among Australian households. This paper compares and contrasts the cost of education in Australia and comparable economies with the cost of other goods and services embedded in the CPI (Consumer Price Index) basket using the latest available quarterly data. Finally, the major determinants of the rising cost of education in Australia are examined. It is found, inter alia, that over the period 1986-2003 the increasing number of students enrolled at non-governmental primary and secondary schools and the introduction of the Higher Education Contribution Scheme (HECS) were two important determinants of the rising cost of education
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