8,586 research outputs found
Life without water
Anhydrobiosis, or life without water is commonly demonstrated by a number of plants and animals. These organisms have the capacity to loose all body water, remain dry for various periods, and then be revived by rehydration. While in the anhydrobiotic state, these organisms become highly resistant to several environmental stresses such as extremely low temperatures, elevated temperatures, ionizing radiation, and high vacuum. Since water is commonly thought to be essential for life, survival of anhydrobiotic organisms with an almost total loss of water is examined. A search of literature reveal that many anhydrobiotic organisms make large quantities of trehalose or other carbohydrates. Laboratory experiments have shown that trehalose is able to stabilize and preserve microsomes of sarcoplasmic reticulum and artificial liposomes. It was demonstrated that trehalose and other disaccharides can interact directly with phosopipid headgroups and maintain membranes in their native configuration by replacing water in the headgroup region. Recent studies show that trehalose is an effective stabilizer of proteins during drying and that it does so by direct interaction with groups on the protein. If life that is able to withstand environmental extremes has ever developed on Mars, it is expected that such life would have developed some protective compounds which can stabilize macromolecular structure in the absence of water and at cold temperatures. On Earth, that role appears to be filled by carbohydrates that can stabilize both membrane and protein stuctures during freezing and drying. By analog with terrestrial systems, such life forms might develop resistance either during some reproductive stage or at any time during adult existence. If the resistant form is a developmental stage, the life cycle of the organism must be completed with a reasonable time period relative to time when environmental conditions are favorable. This would suggest that simple organisms with a short life cycle might be most sucessful
Processing of satellite imagery at the National Environmental Satellite Service
The National Environmental Satellite Service (NESS) image product processing system is described. Other topics discussed include: (1) image processing of polar-orbiter satellite data; (2) image processing of geostationary satellite data; and (3) quality assurance and product monitoring
Probabilistic hyperspace analogue to language
Song and Bruza introduce a framework for Information Retrieval(IR) based on Gardenfor's three tiered cognitive model; Conceptual Spaces. They instantiate a conceptual space using Hyperspace Analogue to Language (HAL to generate higher order concepts which are later used for ad-hoc retrieval. In this poster, we propose an alternative implementation of the conceptual space by using a probabilistic HAL space (pHAL). To evaluate whether converting to such an implementation is beneficial we have performed an initial investigation comparing the concept combination of HAL against pHAL for the task of query expansion. Our experiments indicate that pHAL outperforms the original HAL method and that better query term selection methods can improve performance on both HAL and pHAL
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Presumed Neuroglycopenia Caused by Severe Hypoglycemia in Horses.
BackgroundNeuroglycopenia refers to a shortage of glucose in the brain resulting in neuronal dysfunction and death if left untreated. Presumed neuroglycopenia has not been described in horses.ObjectiveTo report neurological signs in horses with presumed neuroglycopenia as the result of severe hypoglycemia.AnimalsNinety horses (hours to 28 years of age) diagnosed with hypoglycemia (blood glucose concentration < 75 mg/dL [< 4.2 mmol/L]).MethodsRetrospective study. Electronic medical records were searched. Signalment, history, complaint, clinical signs, laboratory findings including CSF analysis, electroencephalogram, clinical or definitive diagnosis, and outcome were recorded. Kruskal-Wallis analysis of variance and logistic regression were used to investigate association between blood glucose concentration and data extracted. Statistical significance was set at P < 0.05.ResultsThirty-eight and 52 horses had mild (50-74 mg/dL [2.8-4.1 mmol/L]), and severe hypoglycemia (< 50 mg/dL [< 2.8 mmol/L]), respectively. Most common causes of hypoglycemia included liver and gastrointestinal (40%) disease, sepsis (33%), neoplasia (7%), and insulin-induced (4%). Most common neurologic deficits included obtundation (100%), seizures (42%), and disorientation (22%). CSF-glucose was severely low (mean 2.5 mg/dL [0.1 mmol/L], median 0 mg/dL). Paroxysmal discharges in support of seizures were identified in the occipital (visual) and parietal (closest to temporal-auditory) cortical regions upon EEG examination (8/8 horses).Conclusions and clinical importanceNeuroglycopenia is presumed to occur in horses as the result of severe hypoglycemia. Subclinical seizures, and intermittent blindness and deafness of cortical origin can occur. Severe altered state of consciousness and seizures can be observed at a blood glucose cut-off value of < 42 mg/dL (< 2.3 mmol/L)
Clustering and collisions of heavy particles in random smooth flows
Finite-size impurities suspended in incompressible flows distribute
inhomogeneously, leading to a drastic enhancement of collisions. A description
of the dynamics in the full position-velocity phase space is essential to
understand the underlying mechanisms, especially for polydisperse suspensions.
These issues are here studied for particles much heavier than the fluid by
means of a Lagrangian approach. It is shown that inertia enhances collision
rates through two effects: correlation among particle positions induced by the
carrier flow and uncorrelation between velocities due to their finite size. A
phenomenological model yields an estimate of collision rates for particle pairs
with different sizes. This approach is supported by numerical simulations in
random flows.Comment: 12 pages, 9 Figures (revTeX 4) final published versio
Some issues concerning Large-Eddy Simulation of inertial particle dispersion in turbulent bounded flows
The problem of an accurate Eulerian-Lagrangian modeling of inertial particle
dispersion in Large Eddy Simulation (LES) of turbulent wall-bounded flows is
addressed. We run Direct Numerical Simulation (DNS) for turbulent channel flow
at shear Reynolds numbers equal to 150 and 300 and corresponding a-priori and
a-posteriori LES on differently coarse grids. We then tracked swarms of
different inertia particles and we examined the influence of filtering and of
Sub-Grid Scale (SGS) modeling for the fluid phase on particle velocity and
concentration statistics. We also focused on how particle preferential
segregation is predicted by LES. Results show that even ``well-resolved'' LES
is unable to reproduce the physics as demonstrated by DNS, both for particle
accumulation at the wall and for particle preferential segregation. Inaccurate
prediction is observed for the entire range of particles considered in this
study, even when the particle response time is much larger than the flow
timescales not resolved in LES. Both a-priori and a-posteriori tests indicate
that recovering the level of fluid and particle velocity fluctuations is not
enough to have accurate prediction of near-wall accumulation and local
segregation. This may suggest that reintroducing the correct amount of
higher-order moments of the velocity fluctuations is also a key point for SGS
closure models for the particle equation. Another important issue is the
presence of possible flow Reynolds number effects on particle dispersion. Our
results show that, in small Reynolds number turbulence and in the case of heavy
particles, the shear fluid velocity is a suitable scaling parameter to quantify
these effects
Student Affairs Connection: Promoting the Library through Co-Curricular Activities
Librarians at the University of North Carolina at Greensboro (UNCG) University Libraries developed the “Student Affairs Connection” program in order to market the Libraries to students in co-curricular settings and to collaborate more closely with the Student Affairs Division. The program also provides the opportunity to seek student input on Libraries’ services and resources and to communicate directly with them in a variety of ways. The program has multiple facets: a liaison program where librarians are assigned to specific student organizations and services such as Student Government and Residence Life, a Student Libraries Advisory Council (SLAC) representing diverse groups of students that meets with librarians several times a year, staffing a Libraries’ table and providing information and giveaways at information fairs, and sponsoring special events such as Game Night each semester
A Sign
A Sign is a narrative about the experience of grief and how relationships are strengthened by shared experience. It tells the story of two different women who come together and inhabit a space of mutual understanding in the wake of their mother\u27s death
A Sign
A Sign is a narrative about the experience of grief and how relationships are strengthened by shared experience. It tells the story of two different women who come together and inhabit a space of mutual understanding in the wake of their mother\u27s death
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