1,535 research outputs found
John M. Cooper Correspondence
Entries include the typed transcripts of correspondence from the Maine State Library to J.W. Arrowsmith, Ltd., investigating the whereabouts of William Sutherland, Cooper\u27s published pseudonym, and typed and handwritten letters from Cooper
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Transient optical absorptivity of nitrogen dioxide following pulsed illumination
A knowledge of the time rates for intermediate reactions
during the photolysis of nitrogen dioxide enables one to deduce the
possible intermediate reactions which are responsible. An experiment has been devised and constructed which will measure the time
rates for photochemical reactions occurring in ranges of one micro
second to several milliseconds after initiation of a short duration
high intensity photolyzing flash.
The method proposed utilizes the examination of the decrease of nitrogen dioxide as a means for observing the photolysis
of nitrogen dioxide. The experimental apparatus consisting of a
source of light for the photolysis of nitrogen dioxide, a flash tube
capable of 200 joules of energy per flash, and a detector of the variation of nitrogen dioxide concentration are described.
Preliminary results demonstrate that the intermediate
mechanism mainly responsible has a reaction time rate associated with it which is much smaller and influences a greater percentage
of the nitrogen dioxide molecules than what would be expected with a
dissociative process. It is suggested that this greater influence and
smaller time rate can be best explained by a collisional energy
transfer process
A quinazoline-based HDAC inhibitor affects gene expression pathways involved in cholesterol biosynthesis and mevalonate in prostate cancer cells
Chronic inflammation can lead to the development of cancers and resolution of inflammation is an ongoing challenge.</p
Quantification of habitat fragmentation reveals extinction risk in terrestrial mammals
Although habitat fragmentation is often assumed to be a primary driver of extinction, global patterns of fragmentation and its relationship to extinction risk have not been consistently quantified for any major animal taxon. We developed high-resolution habitat fragmentation models and used phylogenetic comparative methods to quantify the effects of habitat fragmentation on the world's terrestrial mammals, including 4,018 species across 26 taxonomic Orders. Results demonstrate that species with more fragmentation are at greater risk of extinction, even after accounting for the effects of key macroecological predictors, such as body size and geographic range size. Species with higher fragmentation had smaller ranges and a lower proportion of high-suitability habitat within their range, andmost high-suitability habitat occurred outside of protected areas, further elevating extinction risk. Our models provide a quantitative evaluation of extinction risk assessments for species, allow for identification of emerging threats in species not classified as threatened, and provide maps of global hotspots of fragmentation for the world's terrestrial mammals. Quantification of habitat fragmentation will help guide threat assessment and strategic priorities for global mammal conservation
Simulation of radiation driven wind from disc galaxies
We present 2-D hydrodynamic simulation of rotating galactic winds driven by
radiation. We study the structure and dynamics of the cool and/or warm
component( K) which is mixed with dust. We have taken into
account the total gravity of a galactic system that consists of a disc, a bulge
and a dark matter halo. We find that the combined effect of gravity and
radiation pressure from a realistic disc drives the gas away to a distance of
kpc in Myr for typical galactic parameters. The outflow
speed increases rapidly with the disc Eddington parameter ) for . We find that the rotation speed of
the outflowing gas is km s. The wind is confined in a
cone which mostly consist of low angular momentum gas lifted from the central
region.Comment: 10 pages, 11 figures, Accepted for publication in MNRA
Leptin-dependent Phosphorylation of PTEN Mediates Actin Restructuring and Activation of ATP-sensitive K+ Channels
Leptin activates multiple signaling pathways in cells, including the
phosphatidylinositol 3-kinase pathway, indicating a degree of cross-talk with
insulin signaling. The exact mechanisms by which leptin alters this signaling
pathway and how it relates to functional outputs are unclear at present. A
previous study has established that leptin inhibits the activity of the
phosphatase PTEN (phosphatase and tensin homolog deleted on chromosome 10), an
important tumor suppressor and modifier of phosphoinositide signaling. In this
study we demonstrate that leptin phosphorylates multiple sites on the
C-terminal tail of PTEN in hypothalamic and pancreatic β-cells, an action
not replicated by insulin. Inhibitors of the protein kinases CK2 and glycogen
synthase kinase 3 (GSK3) block leptin-mediated PTEN phosphorylation. PTEN
phosphorylation mutants reveal the critical role these sites play in
transmission of the leptin signal to F-actin depolymerization. CK2 and GSK3
inhibitors also prevent leptin-mediated F-actin depolymerization and
consequent ATP-sensitive K+ channel opening. GSK3 kinase activity
is inhibited by insulin but not leptin in hypothalamic cells. Both hormones
increase N-terminal GSK3 serine phosphorylation, but in hypothalamic cells
this action of leptin is transient. Leptin, not insulin, increases GSK3
tyrosine phosphorylation in both cell types. These results demonstrate a
significant role for PTEN in leptin signal transmission and identify GSK3 as a
potential important signaling node contributing to divergent outputs for these
hormones
Intervention with citrus flavonoids reverses obesity and improves metabolic syndrome and atherosclerosis in obese Ldlr \u3csup\u3e/\u3c/sup\u3e mice
Copyright © 2018 Burke et al. Obesity and its associated metabolic dysfunction and cardiovascular disease risk represent a leading cause of adult morbidity worldwide. Currently available pharmacological therapies for obesity have had limited success in reversing existing obesity and metabolic dysregulation. Previous prevention studies demonstrated that the citrus flavonoids, naringenin and nobiletin, protect against obesity and metabolic dysfunction in Ldlr/ mice fed a high-fat cholesterol-containing (HFHC) diet. However, their effects in an intervention model are unknown. In this report, we show that, in Ldlr/ mice with diet-induced obesity, citrus flavonoid supplementation to a HFHC diet reversed existing obesity and adipocyte size and number through enhanced energy expenditure and increased hepatic fatty acid oxidation. Caloric intake was unaffected and no evidence of white adipose tissue browning was observed. Reversal of adiposity was accompanied by improvements in hyperlipidemia, insulin sensitivity, hepatic steatosis, and a modest reduction in blood monocytes. Together, this resulted in atherosclerotic lesions that were unchanged in size, but characterized by reduced macrophage content, consistent with a more stable plaque phenotype. These studies further suggest potential therapeutic utility of citrus flavonoids, especially in the context of existing obesity, metabolic dysfunction, and cardiovascular disease
Magnetohydrodynamic stability of broad line region clouds
Hydrodynamic stability has been a longstanding issue for the cloud model of
the broad line region in active galactic nuclei. We argue that the clouds may
be gravitationally bound to the supermassive black hole. If true, stabilisation
by thermal pressure alone becomes even more difficult. We further argue that if
magnetic fields should be present in such clouds at a level that could affect
the stability properties, they need to be strong enough to compete with the
radiation pressure on the cloud. This would imply magnetic field values of a
few Gauss for a sample of Active Galactic Nuclei we draw from the literature.
We then investigate the effect of several magnetic configurations on cloud
stability in axi-symmetric magnetohydrodynamic simulations. For a purely
azimuthal magnetic field which provides the dominant pressure support, the
cloud first gets compressed by the opposing radiative and gravitational forces.
The pressure inside the cloud then increases, and it expands vertically.
Kelvin-Helmholtz and column density instability lead to a filamentary
fragmentation of the cloud. This radiative dispersion continues until the cloud
is shredded down to the resolution level. For a helical magnetic field
configuration, a much more stable cloud core survives with a stationary density
histogram which takes the form of a power law. Our simulated clouds develop
sub-Alfvenic internal motions on the level of a few hundred km/s.Comment: 16 pages, 11 figures, accepted by MNRAS, Figure 6 updated due to
inconsistent linestyles, corrected mistake in Alfven speed formula, some very
minor language corrections. The definitive version is available at
www.blackwell- synergy.co
Bostonia: The Boston University Alumni Magazine. Volume 11
Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs
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