1,018 research outputs found

    Carotenoids and Antioxidant Nutrients following Burn Injury a

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72213/1/j.1749-6632.1993.tb26193.x.pd

    Positive Cross Correlations in a Normal-Conducting Fermionic Beam Splitter

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    We investigate a beam splitter experiment implemented in a normal conducting fermionic electron gas in the quantum Hall regime. The cross-correlations between the current fluctuations in the two exit leads of the three terminal device are found to be negative, zero or even positive depending on the scattering mechanism within the device. Reversal of the cross-correlations sign occurs due to interaction between different edge-states and does not reflect the statistics of the fermionic particles which `antibunch'.Comment: 4 pages, 4 figure

    The chameleon groups of Richard J. Thompson: automorphisms and dynamics

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    The automorphism groups of several of Thompson's countable groups of piecewise linear homeomorphisms of the line and circle are computed and it is shown that the outer automorphism groups of these groups are relatively small. These results can be interpreted as stability results for certain structures of PL functions on the circle. Machinery is developed to relate the structures on the circle to corresponding structures on the line

    Microsecond folding dynamics of the F13W G29A mutant of the B domain of staphylococcal protein A by laser-induced temperature jump

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    The small size (58 residues) and simple structure of the B domain of staphylococcal protein A (BdpA) have led to this domain being a paradigm for theoretical studies of folding. Experimental studies of the folding of BdpA have been limited by the rapidity of its folding kinetics. We report the folding kinetics of a fluorescent mutant of BdpA (G29A F13W), named F13W*, using nanosecond laser-induced temperature jump experiments. Automation of the apparatus has permitted large data sets to be acquired that provide excellent signal-to-noise ratio over a wide range of experimental conditions. By measuring the temperature and denaturant dependence of equilibrium and kinetic data for F13W*, we show that thermodynamic modeling of multidimensional equilibrium and kinetic surfaces is a robust method that allows reliable extrapolation of rate constants to regions of the folding landscape not directly accessible experimentally. The results reveal that F13W* is the fastest-folding protein of its size studied to date, with a maximum folding rate constant at 0 M guanidinium chloride and 45°C of 249,000 (s-1). Assuming the single-exponential kinetics represent barrier-limited folding, these data limit the value for the preexponential factor for folding of this protein to at least ≈2 x 10(6) s(-1)

    The Present State of Organic Xenobiotics in the Chesapeake Bay - A Synthesis Paper

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    This manuscript discusses the results of the first two and one half years of a three-year study designed to determine the present state of xenobiotic compounds in the Chesapeake Bay. It shows that polynuclear aromatic hydrocarbons are the most frequently encountered compounds and are the most abundant. Concentrations are highest in the Northern Bay with several sources implicated. During this study an apparent dumping of the pesticide, DDT, occurred. Either the quantity disposed of was small enough or the assimulation capacity was large enough that no adverse effects were noted. The detection by us of 6-phenyldodecane in bottom sediments of the Patapsco River and its detection in a nearby industrial outfall by the Monsanto Research Corporation shows that chemicals entering the River can be dispersed throughout the system and can enter the Chesapeake Bay

    Measurement of two-halo neutron transfer reaction p(11^{11}Li,9^{9}Li)t at 3AA MeV

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    The p(\nuc{11}{Li},\nuc{9}{Li})t reaction has been studied for the first time at an incident energy of 3AA MeV delivered by the new ISAC-2 facility at TRIUMF. An active target detector MAYA, build at GANIL, was used for the measurement. The differential cross sectionshave been determined for transitions to the \nuc{9}{Li} ground andthe first excited states in a wide range of scattering angles. Multistep transfer calculations using different \nuc{11}{Li} model wave functions, shows that wave functions with strong correlations between the halo neutrons are the most successful in reproducing the observation.Comment: 6 pages, 3 figures, submitted to Physical Review Letter

    Clar Sextet Analysis of Triangular, Rectangular and Honeycomb Graphene Antidot Lattices

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    Pristine graphene is a semimetal and thus does not have a band gap. By making a nanometer scale periodic array of holes in the graphene sheet a band gap may form; the size of the gap is controllable by adjusting the parameters of the lattice. The hole diameter, hole geometry, lattice geometry and the separation of the holes are parameters that all play an important role in determining the size of the band gap, which, for technological applications, should be at least of the order of tenths of an eV. We investigate four different hole configurations: the rectangular, the triangular, the rotated triangular and the honeycomb lattice. It is found that the lattice geometry plays a crucial role for size of the band gap: the triangular arrangement displays always a sizable gap, while for the other types only particular hole separations lead to a large gap. This observation is explained using Clar sextet theory, and we find that a sufficient condition for a large gap is that the number of sextets exceeds one third of the total number of hexagons in the unit cell. Furthermore, we investigate non-isosceles triangular structures to probe the sensitivity of the gap in triangular lattices to small changes in geometry

    On the Nonlinear Stability of Asymptotically Anti-de Sitter Solutions

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    Despite the recent evidence that anti-de Sitter spacetime is nonlinearly unstable, we argue that many asymptotically anti-de Sitter solutions are nonlinearly stable. This includes geons, boson stars, and black holes. As part of our argument, we calculate the frequencies of long-lived gravitational quasinormal modes of AdS black holes in various dimensions. We also discuss a new class of asymptotically anti-de Sitter solutions describing noncoalescing black hole binaries.Comment: 26 pages. 5 figure

    Sphincter-sparing surgery after preoperative radiotherapy for low rectal cancers: feasibility, oncologic results and quality of life outcomes

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    The present study assesses the choice of surgical procedure, oncologic results and quality of life (QOL) outcomes in a retrospective cohort of 53 patients with low-lying rectal cancers (within 6 cm of the anal verge) treated surgically following preoperative radiotherapy (RT, median dose 45 Gy) with or without concomitant 5-fluorouracil. QOL was assessed in 23 patients by using two questionnaires developed by the QOL Study Group of the European Organization for Research and Treatment of Cancer: EORTC QLQ-C30 and EORTC QLQ-CR38. After a median interval of 29 days from completion of RT, abdominoperineal resection (APR) was performed in 29 patients (55%), low anterior resection in 23 patients (20 with coloanal anastomosis) and transrectal excision in one patient. The 3-year actuarial overall survival and locoregional control rates were 71.4% and 77.5% respectively, with no differences observed between patients operated by APR or restorative procedures. For all scales of EORTC QLQ-C30 and EORTC QLQ-CR38, no significant differences in median scores were observed between the two surgical groups. Although patients having had APR tended to report a lower body image score (P = 0.12) and more sexual dysfunction in male patients, all APR patients tended to report better physical function, future perspective and global QOL. In conclusion, sphincter-sparing surgery after preoperative RT seems to be feasible, in routine practice, in a significant proportion of low rectal cancers without compromising the oncologic results. However, prospective studies are mandatory to confirm this finding and to clarify the putative QOL advantages of sphincter-conserving approaches. © 2000 Cancer Research Campaig

    WormBase 2007

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    WormBase (www.wormbase.org) is the major publicly available database of information about Caenorhabditis elegans, an important system for basic biological and biomedical research. Derived from the initial ACeDB database of C. elegans genetic and sequence information, WormBase now includes the genomic, anatomical and functional information about C. elegans, other Caenorhabditis species and other nematodes. As such, it is a crucial resource not only for C. elegans biologists but the larger biomedical and bioinformatics communities. Coverage of core areas of C. elegans biology will allow the biomedical community to make full use of the results of intensive molecular genetic analysis and functional genomic studies of this organism. Improved search and display tools, wider cross-species comparisons and extended ontologies are some of the features that will help scientists extend their research and take advantage of other nematode species genome sequences
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