The Hydraulic External Pre-Isolator (HEPI) is the first 6 degrees of freedom active seismic isolation system implemented at the Laser Interferometer Gravitational Wave Observatory (LIGO). ...Implementation was first completed at the LIGO Livingston Observatory (LLO) prior to LIGO's 5th science run, successfully cutting down the disturbance seen by LLO's suspended optics in the two most prominent seismic disturbance bands, the microseism (0.1-0.3Hz) and the anthropogenic (1-3Hz) bands, by a factor of a few to tens. The improvement in seismic isolation contributed directly to LLO's much improved duty cycle of 66.7% and LIGO's triple coincident duty cycle of 53%. We report the design, control scheme, and isolation performance of HEPI at LLO in this paper. Aided with this success, funding for incorporating HEPI into the LIGO Hanford Observatory was approved and installation is currently underway.
Although there have been major improvements in crop production performance, there's still potential for even better results—and proper drainage ditch maintenance is one factor that can contribute to ...crop performance efficiency.
Cytokine-induced CNS inflammation has been theorized to contribute to cognitive dysfunction in sickness and neurodegenerative disease. We investigated the effects of systemic endotoxin-induced acute ...immune activation and inflammation on working memory and attention functions in pigeons assessed through two variations of an operant symbolic matching-to-sample (SMTS) task, employing doses of lipopolysaccharide (LPS) sufficient to induce fever. LPS produced moderate impairments in comparison to saline on the SMTS task designed to measure visual vigilance and attention, but the impairments were not as marked as those produced by chlordiazepoxide (CDP) which is known to disrupt attention. In contrast, LPS had no significant effect on short-term working memory performance compared to saline, while scopolamine, a cholinergic antagonist known to disrupt working memory, did impair performance. The results have implications for the cognitive impairments seen in illnesses characterized by chronic cytokine activation (e.g., Alzheimer's disease) as well as illnesses treated with cytokines (e.g., multiple sclerosis) suggesting that some cognitive failures attributed to working memory impairments
per se may better be attributed to prior attention impairments.
The neurobiology of stress ulcers Glavin, G B; Murison, R; Overmier, J B ...
Brain research. Brain research reviews,
09/1991, Letnik:
16, Številka:
3
Journal Article
Recenzirano
We have reviewed the neurobiology of stress ulcers from animal models to potential pharmacotherapeutic mechanisms. The evidence strongly supports the hypothesis that certain stress-related gastric ...lesions are 'brain-driven' events which may be more effectively managed through central manipulations than by altering local, gastric factors. Recent advances in the use of anxiolytic and antidepressant drugs in the management of stress-related gastric mucosal injury further supports the contention that a brain-gut axis, which may have nervous, peptidergic and classic monoaminergic components, modulates the intricate and complicated pattern of communication between the brain and the stomach. Delineation of the precise pathways which make up this communication as well as their manipulation by various pharmacological agents will be the focus of future research endeavour.
Both gastric ulceration and activation of the hypothalamo-pituitary adrenal axis are considered integral to the stress response, and a causal relationship between the two has been suggested. In the ...present study, corticosterone secretion in rats was either stimulated with CRF or lowered with metyrapone during a known ulcerogenic stress. Reduction of circulating corticosterone during the stress had no effect on ulceration severity compared to saline-treated stressed control rats. Treatment with CRF in stressed animals reduced ulceration severity. The mechanism of this protective effect remains unclear. The findings do not support a simple causal relationship between adrenocortical activity and gastric ulceration.
Small, highly absorbing points are randomly present on the surfaces of the main interferometer optics in Advanced LIGO. The resulting nano-meter scale thermo-elastic deformations and substrate lenses ...from these micron-scale absorbers significantly reduces the sensitivity of the interferometer directly though a reduction in the power-recycling gain and indirect interactions with the feedback control system. We review the expected surface deformation from point absorbers and provide a pedagogical description of the impact on power build-up in second generation gravitational wave detectors (dual-recycled Fabry-Perot Michelson interferometers). This analysis predicts that the power-dependent reduction in interferometer performance will significantly degrade maximum stored power by up to 50% and hence, limit GW sensitivity, but suggests system wide corrections that can be implemented in current and future GW detectors. This is particularly pressing given that future GW detectors call for an order of magnitude more stored power than currently used in Advanced LIGO in Observing Run 3. We briefly review strategies to mitigate the effects of point absorbers in current and future GW wave detectors to maximize the success of these enterprises.
Gastric ulceration in rats is exacerbated by allowing a so-called recovery period after exposure to an ulcerogenic stressor. One hypothesis, which has support from pharmacological studies, argues ...that this effect is brought about by a rebound of parasympathetic activation. We tested this parasympathetic rebound hypothesis by presenting animals with a fear-inducing (sympathetic-activating) conditioned stimulus (CS) after 2 hr of water-restraint stress. Contrary to the hypothesis, presentation of such a CS increased severity of ulceration compared with those animals that did not receive the CS after restraint stress and control animals. These ulceration data favor instead a sustained activation hypothesis for ulceration, whereby presentation of the CS effectively prolonged the length of time during which animals were under stress, thus enhancing the degree of ulceration. Measurement of plasma corticosterone however indicated a negative correlation between adrenocortical activity and degree of gastric ulceration, contrary to that expected by a sustained activation hypothesis. It is suggested that this inconsistency may be because of the activating of a pituitary-endorphinogenic mediated stress analgesia.
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