913 resultados para Corner Rise seamounts


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We present a set of new volume scaling relationships specific to Svalbard glaciers, derived from a sample of 60 volume–area pairs. Glacier volumes are computed from ground-penetrating radar (GPR)-retrieved ice thickness measurements, which have been compiled from different sources for this study. The most precise scaling models, in terms of lowest cross-validation errors, are obtained using a multivariate approach where, in addition to glacier area, glacier length and elevation range are also used as predictors. Using this multivariate scaling approach, together with the Randolph Glacier Inventory V3.2 for Svalbard and Jan Mayen, we obtain a regional volume estimate of 6700 ± 835 km3, or 17 ± 2 mm of sea-level equivalent (SLE). This result lies in the mid- to low range of recently published estimates, which show values as varied as 13 and 24 mm SLE. We assess the sensitivity of the scaling exponents to glacier characteristics such as size, aspect ratio and average slope, and find that the volume of steep-slope and cirque-type glaciers is not very sensitive to changes in glacier area.

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IL-7 functions as a trophic factor during T lymphocyte development by a mechanism that is partly based on the induction of Bcl-2, which protects cells from apoptosis. Here we report a mechanism by which cytokine withdrawal activates the prodeath protein Bax. On loss of IL-7 in a dependent cell line, Bax protein translocated from the cytosol to the mitochondria, where it integrated into the mitochondrial membrane. This translocation was attributable to a conformational change in the Bax protein itself. We show that a rise in intracellular pH preceded mitochondrial translocation and triggered the change in Bax conformation. Intracellular pH in the IL-7-dependent cells rose steadily to peak over pH 7.8 by 6 hr after cytokine withdrawal, paralleling the time point of Bax translocation (a similar alkalinization and Bax translocation was also observed after IL-3 withdrawal from a dependent cell line). The conformation of Bax was directly altered by pH of 7.8 or higher and was demonstrated by increased protease sensitivity, exposure of N terminus epitopes, and exposure of a hydrophobic domain in the C terminus. Eliminating charged amino acids at the C or N termini of Bax induced a conformational change similar to that induced by raising pH, implicating these residues in the pH effect. Therefore, we have shown that by either cytokine withdrawal, experimental manipulation of pH, or site-directed mutagenesis, Bax protein changes conformation, exposing membrane-seeking domains, thereby inducing mitochondrial translocation and initiating the cascade of events leading to apoptotic death.

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The relationship between the development of mediated online literature searching and the recruitment of medical librarians to fill positions as online searchers was investigated. The history of database searching by medical librarians was outlined and a content analysis of thirty-five years of job advertisements in MLA News from 1961 through 1996 was summarized. Advertisements for online searchers were examined to test the hypothesis that the growth of mediated online searching was reflected in the recruitment of librarians to fill positions as mediated online searchers in medical libraries. The advent of end-user searching was also traced to determine how this trend affected the demand for mediated online searching and job availability of online searchers. Job advertisements were analyzed to determine what skills were in demand as end-user searching replaced mediated online searching as the norm in medical libraries. Finally, the trend away from mediated online searching to support of other library services was placed in the context of new roles for medical librarians.

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We recorded miniature endplate currents (mEPCs) using simultaneous voltage clamp and extracellular methods, allowing correction for time course measurement errors. We obtained a 20-80% rise time (tr) of approximately 80 micros at 22 degrees C, shorter than any previously reported values, and tr variability (SD) with an upper limit of 25-30 micros. Extracellular electrode pressure can increase tr and its variability by 2- to 3-fold. Using Monte Carlo simulations, we modeled passive acetylcholine diffusion through a vesicle fusion pore expanding radially at 25 nm x ms(-1) (rapid, from endplate omega figure appearance) or 0.275 nm x ms(-1) (slow, from mast cell exocytosis). Simulated mEPCs obtained with rapid expansion reproduced tr and the overall shape of our experimental mEPCs, and were similar to simulated mEPCs obtained with instant acetylcholine release. We conclude that passive transmitter diffusion, coupled with rapid expansion of the fusion pore, is sufficient to explain the time course of experimentally measured synaptic currents with trs of less than 100 micros.

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This dissertation examines African-American Islamic culture from 1920 through 1959, a period I label the "African-American Islamic Renaissance" (AAIR). The AAIR is characterized by a significant increase in interest in Islam, extreme diversity in views about Islam, and the absence of a single organization dominating African-American Islamic culture for a significant amount of time. Previous works dealing with African-American Islam in this period have failed to fully recognize these features, particularly the last of these. As a result, explanations for the rise of the Nation of Islam (NOI) have not satisfactorily explained why it was only the NOI--and not other Islamic groups that were more popular than the NOI up until the mid-1950s--that became a "mass movement," gaining the allegiance of tens of thousands of African Americans. There has been some tendency, for instance, to assume that the NOI was the most popular African-American Islamic group by the early 1950s, a notion that is probably an inference drawn from two other popular but inaccurate assumptions: that the NOI's rise was due primarily to its radical racialized doctrines and its charismatic leaders, particularly Malcolm X, who became a popular minister for the group in the early 1950s. I argue, however, that the NOI was in fact not the most popular African-American Islamic group until at least 1955, and even as late as 1959 its official membership numbers were not particularly large by AAIR standards. Also, its doctrines were not especially unique in the AAIR, nor was its having extremely charismatic leaders. I contend that the success of the NOI in the mid-to-late 1950s was the result of three levels of changes at the time: internal, external in the AAIR community, and external in the broader U.S, culture.

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Increased population growth of the Northwest Corner of Arkansas is straining the natural resources of the Lake Fayetteville Nature Trail, Fayetteville, AR. Recreational activities conducted on this single track multi-use trail are mountain biking, walking, jogging and wildlife viewing. Impacts evident on the NE section of the trail consist of erosion, vegetation, wildlife and conflict disturbances. Throughout this paper recommendations of management solutions and maintenance ideas are presented. Control of recreation impacts will help the longevity of the trail and maintain the aesthetics for present and future trail users.

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This paper investigates the impact of how the Chinese government will react to the West if China regains its superpower status. Using traditional research methods, this paper traced the cultural misunderstandings that initiated the confrontation with the West and the resulting humiliation China suffered for nearly 175 years by the Western powers. The findings of this paper show that China bitterly resents the treatment suffered during the Colonial period. Although certain factions in China wish to punish the West, this paper argues that the interconnected nature of the world's economy will force China to temper its feelings and build bridges with the West as it attains superpower status.

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We describe a case report of a patient that was implanted with a posterior chamber phakic intraocular lens (Phakic Refractive Lens, PRL) for the correction of moderate myopia and who developed postoperatively a fixed mydriasis compatible with an Urrets-Zavalia Syndrome (UZS). Specifically, a sudden acute increase of IOP in the left eye was observed in the immediate postoperative period. After IOP stabilization, the refractive result was good, but a fixed and mydriatic pupil appeared. This condition led the patient to experience visual discomfort, halos, and glare associated with high levels of higher-order aberrations in spite of the good visual result. A tinted-contact lens was fitted in order to minimize those symptoms. The UZS should be considered as a possible complication after implantation of posterior chamber phakic intraocular lenses.

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Contains prints of floor plans of Harvard College used for publication by Samuel E. Morison.

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The estimate includes projected costs for the materials and labor required for each renovation. The anatomical room needed its circular seats raised and altered. The renovation of the lower room included making new window frames and sashes (including replacing glass), installing new doors, and repairing the floors.