Behavior of Spherical Particles at Low Reynolds Numbers in a Fluctuating Translational Flow. Preliminary Experiments

The behavior of small spheres in non-steady translational flow has been studied experimentally' for values of Reynolds nunber from 0 to 3000. The aim of the work was to improve our quantitative understanding of particle transport in turbulent gaseous media, a process of extreme importance in powerplants and energy transfer mechanisms. Particles, subjected to strong sinusoidal oscillations parallel to the direction of steady translation, were found to have changes in average drag coefficient depending upon their translational Reynolds number, the frequency and amplitude of the oscillations. When the Reynolds number based on the sphere diameter was les s than 200, the synunetric translational oscillation had negligible effect on the aver age particle dr ago For Reynolds numbers exceeding 300, the effective drag coefficient was significantly increased in a particular frequency range. For example, an increase in drag coefficient of 25 per cent was observed at a Reynolds nwnber of 3000 when the amplitude of the oscillation was 2 per cent of the sphere diazneter and the disturbance frequency was approximately the Strouhal frequency. The occurrence of the maximum effect at frequencies between one and two times the Stroubal frequency strongly suggests non-linear interaction between wake vortex shedding and the oscillation in translational motions. Flow visualization studies support this suggestion

A Deployment of Voice-over-IP Using Lone

Computational biologists agree that multimodal epistemologies are an interesting new topic in the field of robotics, and cyberneticists concur. After years of significant research into interrupts, we prove the investigation of object-oriented languages. We present new collaborative archetypes, which we call Lone

Formation of acyl and alkenyl glycerol derivatives in Clostridium butyricum

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32807/1/0000180.pd

Recreation and Wildlife Activity in the Wood River Valley

As the human population grows, people increasingly seek to recreate on public lands. Consequently, humans and animals find themselves sharing space. It is important, therefore, to understand how humans and wildlife interact in these natural spaces. The Big Wood River Watershed in Blaine County, Idaho is an excellent example of a natural area with a high density of recreational activity. This study aims to determine whether frequency and/or intensity of recreational activity affects wildlife activity. Data was collected using a combination of camera trapping and use of autonomous recording units. We expected that areas with high levels of recreational activity and high average sound would correlate with low wildlife activity and also that wildlife would change their activity patterns to avoid interaction with recreationists. Early analysis, however, indicates that the relationship between recreation and wildlife activity is more nuanced. These results will provide insight into public land management and how to best balance recreationist demands for access to lands with needs of wildlife

Phosphofructokinase 1 Glycosylation Regulates Cell Growth and Metabolism

Cancer cells must satisfy the metabolic demands of rapid cell growth within a continually changing microenvironment. We demonstrated that the dynamic posttranslational modification of proteins by O-linked β-N-acetylglucosamine (O-GlcNAcylation) is a key metabolic regulator of glucose metabolism. O-GlcNAcylation was induced at serine 529 of phosphofructokinase 1 (PFK1) in response to hypoxia. Glycosylation inhibited PFK1 activity and redirected glucose flux through the pentose phosphate pathway, thereby conferring a selective growth advantage on cancer cells. Blocking glycosylation of PFK1 at serine 529 reduced cancer cell proliferation in vitro and impaired tumor formation in vivo. These studies reveal a previously uncharacterized mechanism for the regulation of metabolic pathways in cancer and a possible target for therapeutic intervention

The control of fatty acid composition in glycerolipids of the endoplasmic reticulum

A functional relationship between constitutive enzymes of the endoplasmic reticulum that are involved in lipid metabolism and the proteins and phosphoglycerides constituting these membranes was examined by altering the protein and fatty acid composition. The specific activity of alkenyl glycerylphosphoryl choline hydrolyase did not change upon fasting, fasting, and refeeding or administration of phenobarbital, whereas the specific activities of both acyl-CoA hydrolyase and acyl-CoA:1-acyl glycerylphosphoryl choline acyltransferase(s) increased upon alteration of the nutritional state. Other enzymic activities also showed changes following the treatments. The constant specific activity of 1-alkenyl glycerylphosphoryl choline hydrolyase suggests that it is a true constitutive enzyme of the endoplasmic reticulum and a useful indicator of membrane biogenesis.Alteration in the fatty acid composition of microsomal phosphoglycerides by maintenance of animals under different dietary conditions, by in situ incorporation of fatty acids into microsomal phosphoglycerides, or by the addition of exogenous, micellar lecithins did not produce adaptive changes in the specificity for esterification of fatty acids to Position 2 of lecithins. Partial removal of microsomal phosphoglycerides by treatment with phospholipases failed to demonstrate a functional requirement for diacyl phosphoglycerides in acyltransferase activity. These considerations indicate that a functional role of phosphoglycerides in acyl-CoA:1-acyl glycerylphosphoryl choline acyltransferase activity is limited to the requirement of phosphoglycerides for the integrity of the membrane.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32808/1/0000181.pd

Radiolytic Gas-Driven Cryovolcanism in the Outer Solar System

Water ices in surface crusts of Europa, Enceladus, Saturn's main rings, and Kuiper Belt Objects can become heavily oxidized from radiolytic chemical alteration of near-surface water ice by space environment irradiation. Oxidant accumulations and gas production are manifested in part through observed H2O2 on Europa. tentatively also on Enceladus, and found elsewhere in gaseous or condensed phases at moons and rings of Jupiter and Saturn. On subsequent chemical contact in sub-surface environments with significant concentrations of primordially abundant reductants such as NH3 and CH4, oxidants of radiolytic origin can react exothermically to power gas-driven cryovolcanism. The gas-piston effect enormously amplifies the mass flow output in the case of gas formation at basal thermal margins of incompressible fluid reservoirs. Surface irradiation, H2O2 production, NH3 oxidation, and resultant heat, gas, and gas-driven mass flow rates are computed in the fluid reservoir case for selected bodies. At Enceladus the oxidant power inputs are comparable to limits on nonthermal kinetic power for the south polar plumes. Total heat output and plume gas abundance may be accounted for at Enceladus if plume activity is cyclic in high and low "Old Faithful" phases, so that oxidants can accumulate during low activity phases. Interior upwelling of primordially abundant NH3 and CH4 hydrates is assumed to resupply the reductant fuels. Much lower irradiation fluxes on Kuiper Belt Objects require correspondingly larger times for accumulation of oxidants to produce comparable resurfacing, but brightness and surface composition of some objects suggest that such activity may be ongoing

Ion Channel Clustering at the Axon Initial Segment and Node of Ranvier Evolved Sequentially in Early Chordates

In many mammalian neurons, dense clusters of ion channels at the axonal initial segment and nodes of Ranvier underlie action potential generation and rapid conduction. Axonal clustering of mammalian voltage-gated sodium and KCNQ (Kv7) potassium channels is based on linkage to the actin–spectrin cytoskeleton, which is mediated by the adaptor protein ankyrin-G. We identified key steps in the evolution of this axonal channel clustering. The anchor motif for sodium channel clustering evolved early in the chordate lineage before the divergence of the wormlike cephalochordate, amphioxus. Axons of the lamprey, a very primitive vertebrate, exhibited some invertebrate features (lack of myelin, use of giant diameter to hasten conduction), but possessed narrow initial segments bearing sodium channel clusters like in more recently evolved vertebrates. The KCNQ potassium channel anchor motif evolved after the divergence of lampreys from other vertebrates, in a common ancestor of shark and humans. Thus, clustering of voltage-gated sodium channels was a pivotal early innovation of the chordates. Sodium channel clusters at the axon initial segment serving the generation of action potentials evolved long before the node of Ranvier. KCNQ channels acquired anchors allowing their integration into pre-existing sodium channel complexes at about the same time that ancient vertebrates acquired myelin, saltatory conduction, and hinged jaws. The early chordate refinements in action potential mechanisms we have elucidated appear essential to the complex neural signaling, active behavior, and evolutionary success of vertebrates

Determining the Physical Properties of the B Stars I. Methodology and First Results

We describe a new approach to fitting the UV-to-optical spectra of B stars to model atmospheres and present initial results. Using a sample of lightly reddened stars, we demonstrate that the Kurucz model atmospheres can produce excellent fits to either combined low dispersion IUE and optical photometry or HST FOS spectrophotometry, as long as the following conditions are fulfilled: 1) an extended grid of Kurucz models is employed, 2) the IUE NEWSIPS data are placed on the FOS absolute flux system using the Massa & Fitzpatrick (1999) transformation, and 3) all of the model parameters and the effects of interstellar extinction are solved for simultaneously. When these steps are taken, the temperatures, gravities, abundances and microturbulence velocities of lightly reddened B0-A0 V stars are determined to high precision. We also demonstrate that the same procedure can be used to fit the energy distributions of stars which are reddened by any UV extinction curve which can be expressed by the Fitzpatrick & Massa (1990) parameterization scheme. We present an initial set of results and verify our approach through comparisons with angular diameter measurements and the parameters derived for an eclipsing B star binary. We demonstrate that the metallicity derived from the ATLAS 9 fits to main sequence B stars is essentially the Fe abundance. We find that a near zero microturbulence velocity provides the best-fit to all but the hottest or most luminous stars (where it may become a surrogate for atmospheric expansion), and that the use of white dwarfs to calibrate UV spectrophotometry is valid.Comment: 17 pages, including 2 pages of Tables and 6 pages of Figures. Astrophysical Jounral, in pres