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Institution

University of Rhode Island

EducationKingston, Rhode Island, United States
About: University of Rhode Island is a education organization based out in Kingston, Rhode Island, United States. It is known for research contribution in the topics: Population & Bay. The organization has 11464 authors who have published 22770 publications receiving 841066 citations. The organization is also known as: URI & Rhode Island College of Agriculture and the Mechanic Arts.


Papers
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Journal ArticleDOI
TL;DR: In this paper, a procedure has been developed to measure the relative concentrations of N2, O2, Ar, the δ18O of O2 and N2 trapped in Antarctic and Greenland ice cores.
Abstract: A procedure has been developed to measure the relative concentrations of N2, O2, Ar, the δ18O of O2, and the δ15N of N2 trapped in Antarctic and Greenland ice cores. To date, we have analyzed 13 samples of trapped air in recent (<2200 years B.P.) ice from eight sites. The composition of the trapped gases was determined by mass spectrometry and the results expressed in delta notation relative to the present-day atmosphere. The average δ15N of N2 and δ18O of O2 in samples from the various ice cores ranged from +0.05 to +0.41‰ and from +0.18 to +1.1‰, respectively. The heavy isotope enrichments are apparently due to gravitational settling accompanying diffusive equilibrium between the base of the firn and the overlying atmosphere. The δO2/Ar and δN2/Ar values ranged from −9.2 to +1.0‰ and from −4.8 to +4.6‰, respectively. The differences between the elemental composition of ice core trapped gases and air result from gravitational fractionation, as well as separation of O2 and Ar relative to N2 during either bubble close-off or retrieval and storage of the ice cores.

192 citations

Journal ArticleDOI
TL;DR: A marine gram-positive bacterium is presented that secretes secondary metabolites capable of quenching quorum sensing-controlled behaviors in several gram-negative reporter strains, and it is shown that these nontoxic metabolites may act as antagonists of bacterial quorum sensed by competing with N-acyl homoserine lactones for receptor binding.
Abstract: Certain bacteria use cell-to-cell chemical communication to coordinate community-wide phenotypic expression, including swarming motility, antibiotic biosynthesis, and biofilm production. Here we present a marine gram-positive bacterium that secretes secondary metabolites capable of quenching quorum sensing-controlled behaviors in several gram-negative reporter strains. Isolate C42, a Halobacillus salinus strain obtained from a sea grass sample, inhibits bioluminescence production by Vibrio harveyi in cocultivation experiments. With the use of bioassay-guided fractionation, two phenethylamide metabolites were identified as the active agents. The compounds additionally inhibit quorum sensing-regulated violacein biosynthesis by Chromobacterium violaceum CV026 and green fluorescent protein production by Escherichia coli JB525. Bacterial growth was unaffected at concentrations below 200 μg/ml. Evidence is presented that these nontoxic metabolites may act as antagonists of bacterial quorum sensing by competing with N-acyl homoserine lactones for receptor binding.

191 citations

Journal ArticleDOI
TL;DR: In this paper, 13 runs were made in a small recirculating flume to simulate the deposition of the climbingripple sequences commonly present in fine-grained facies of fluvial and deltaic deposits.
Abstract: Thirteen runs were made in a small recirculating flume to simulate the deposition of the climbingripple sequences commonly present in fine-grained facies of fluvial and deltaic deposits. These sequences consist of intergradational climbing-ripple cross laminae and draped laminae. The experiments were based on the assumption that stratification type depends mainly on near-bottom flow structure and uniform sediment fallout from an overloaded flow. Various combinations of curves of velocity versus time and of sediment feed versus time in runs lasting from 45 to 840 min were used in an exploratory program; conditions for each run were selected on the basis of experience in previous runs. The runs verified that Type A (erosional-stoss) climbing ripples are produced by aggradation rates that are small relative to ripple migration rate, and Type B (depositional-stoss) climbing ripples are produced by aggradation rates that are large relative to ripple migration rate. Draped lamination results from continued fallout of sediment from suspension after ripple migration ceases or almost ceases. Comparison of geometric details of the ripple stratification produced in the flume runs with that in natural sequences, supplemented by considerations on maximum and minimum migration rates of ripples, suggests times of no more than a few tens of hours for the deposition of the climbing-ripple portions of sequences 10-20 cm thick. Runs in which deposition of a 20 cm sequence took more than 10 h produced such atypical features of ripple geometry as sharp crests, planar lee-side laminae, and angular toeset-foreset contacts.

191 citations

Journal ArticleDOI
TL;DR: Examination of the effectiveness of pulsing electromagnetic fields and core decompression in the treatment of osteonecrosis of the femoral head finds that both techniques reduce the incidence of clinical and roentgenographic progression.
Abstract: Once roentgenographic changes are apparent, osteonecrosis of the femoral head in the adult generally progresses to osteoarthritis within two to three years. A variety of conservative surgical procedures have been devised to conserve the femoral head with varying success. This study examines the effectiveness of pulsing electromagnetic fields and core decompression in the treatment of osteonecrosis of the femoral head. Both techniques reduce the incidence of clinical and roentgenographic progression. Exposure to pulsing electromagnetic fields appears to be more effective in hips with Ficat II lesions than in hips with more advanced lesions.

191 citations

Journal ArticleDOI
19 May 2016-Nature
TL;DR: Water measurements of total energy expenditure in humans, chimpanzees, bonobos, gorillas and orangutans are used to test the hypothesis that the human lineage has experienced an acceleration in metabolic rate, providing energy for larger brains and faster reproduction without sacrificing maintenance and longevity.
Abstract: Humans are distinguished from the other living apes in having larger brains and an unusual life history that combines high reproductive output with slow childhood growth and exceptional longevity. This suite of derived traits suggests major changes in energy expenditure and allocation in the human lineage, but direct measures of human and ape metabolism are needed to compare evolved energy strategies among hominoids. Here we used doubly labelled water measurements of total energy expenditure (TEE; kcal day(-1)) in humans, chimpanzees, bonobos, gorillas and orangutans to test the hypothesis that the human lineage has experienced an acceleration in metabolic rate, providing energy for larger brains and faster reproduction without sacrificing maintenance and longevity. In multivariate regressions including body size and physical activity, human TEE exceeded that of chimpanzees and bonobos, gorillas and orangutans by approximately 400, 635 and 820 kcal day(-1), respectively, readily accommodating the cost of humans' greater brain size and reproductive output. Much of the increase in TEE is attributable to humans' greater basal metabolic rate (kcal day(-1)), indicating increased organ metabolic activity. Humans also had the greatest body fat percentage. An increased metabolic rate, along with changes in energy allocation, was crucial in the evolution of human brain size and life history.

191 citations


Authors

Showing all 11569 results

NameH-indexPapersCitations
James M. Tiedje150688102287
Roberto Kolter12031552942
Robert S. Stern12076162834
Michael S. Feld11955251968
William C. Sessa11738352208
Kenneth H. Mayer115135164698
Staffan Kjelleberg11442544414
Kevin C. Jones11474450207
David R. Nelson11061566627
Peter K. Smith10785549174
Peter M. Groffman10645740165
Ming Li103166962672
Victor Nizet10256444193
Anil Kumar99212464825
James O. Prochaska9732073265
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202344
2022161
20211,105
20201,058
2019996
2018888