160 research outputs found

    Nitrotyrosine Density of Rabbit Urinary Bladder Muscle and Mucosa Measured via Western Blotting and 96-Well Plate Analysis

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    Purpose. Nitrotyrosine was quantitated in rabbit bladder muscle and mucosa using two analytical systems: Western blotting analyses and a 96-well plate quantitative analysis kit. Materials and Methods. Rabbit bladder muscle and mucosa were obtained from control rabbits. For the Western analysis, the samples were loaded into a SDS page gel and then transferred to a PVDF membrane. The optical density was measured using a Kodak Scanner. Using the 96-well plate, the samples and standards were loaded, incubated with primary and secondary antibody, washed and vacuumed with 10x wash buffer three times between each incubation period. Stop buffer was added to the plate and the results were quantified via the plate reader. Results. For both muscle and mucosa tissue, the optical density readings were linear with tissue concentration; the concentration of nitrotyrosine in the mucosa was significantly higher than in the muscle. However, whereas the Western blot analysis is based on relative optical densities, the 96-well plate kit provides a truly quantitative analysis. Discussion. Mucosa tissue displayed a higher density of nitrotyrosine than did detrusor muscle tissue. This may well be due to the significantly higher metabolic activity of the mucosa compared to the muscle

    Critical Temperature and Energy Gap for the BCS Equation

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    We derive upper and lower bounds on the critical temperature TcT_c and the energy gap Ξ\Xi (at zero temperature) for the BCS gap equation, describing spin 1/2 fermions interacting via a local two-body interaction potential λV(x)\lambda V(x). At weak coupling λ1\lambda \ll 1 and under appropriate assumptions on V(x)V(x), our bounds show that TcAexp(B/λ)T_c \sim A \exp(-B/\lambda) and ΞCexp(B/λ)\Xi \sim C \exp(-B/\lambda) for some explicit coefficients AA, BB and CC depending on the interaction V(x)V(x) and the chemical potential μ\mu. The ratio A/CA/C turns out to be a universal constant, independent of both V(x)V(x) and μ\mu. Our analysis is valid for any μ\mu; for small μ\mu, or low density, our formulas reduce to well-known expressions involving the scattering length of V(x)V(x).Comment: RevTeX4, 23 pages. Revised version, to appear in Phys. Rev.

    The BCS Critical Temperature for Potentials with Negative Scattering Length

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    We prove that the critical temperature for the BCS gap equation is given by Tc=μ(8/πeγ2+o(1))eπ/(2μa)T_c = \mu (8/\pi e^{\gamma -2} + o(1)) e^{\pi/(2\sqrt \mu a)} in the low density limit μ0\mu\to 0. The formula holds for a suitable class of interaction potentials with negative scattering length aa in the absence of bound states.Comment: AMSLaTeX, 7 pages; Revised version, to appear in Lett. Math. Phys

    Material-specific gap function in the high-temperature superconductors

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    We present theoretical arguments and experimental support for the idea that high-Tc superconductivity can occur with s-wave, d-wave, or mixed-wave pairing in the context of a magnetic mechanism. The size and shape of the gap is different for different materials. The theoretical arguments are based on the t-J model as derived from the Hubbard model so that it necessarily includes three-site terms. We argue that this should be the basic minimal model for high-Tc systems. We analyze this model starting with the dilute limit which can be solved exactly, passing then to the Cooper problem which is numerically tractable, then ending with a mean field approach. It is found that the relative stability of s-wave and d-wave depends on the size and the shape of the Fermi surface. We identify three striking trends. First, materials with large next-nearest-neighbor hopping (such as YBa(2)Cu(3)O(7-x)) are nearly pure d-wave, whereas nearest-neighbor materials (such as La(2-x)Sr(x)CuO(4)) tend to be more s-wave-like. Second, low hole doping materials tend to be pure d-wave, but high hole doping leads to s-wave. Finally, the optimum hole doping level increases as the next-nearest-neighbor hopping increases. We examine the experimental evidence and find support for this idea that gap function in the high-temperature superconductors is material-specific.Comment: 20 pages; requires revtex.sty v3.0, epsf.sty; includes 6 EPS figures; Postscript version also available at http://lifshitz.physics.wisc.edu/www/koltenbah/papers/gapfunc2.ps . This version contains an extensive amount of new work including theoretical background, an additional mean field treatment with new figures, and a more thorough experimental surve

    Clouds in the Coldest Brown Dwarfs: FIRE Spectroscopy of Ross 458C

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    Condensate clouds are a salient feature of L dwarf atmospheres, but have been assumed to play little role in shaping the spectra of the coldest T-type brown dwarfs. Here we report evidence of condensate opacity in the near-infrared spectrum of the brown dwarf candidate Ross 458C, obtained with the Folded-Port Infrared Echellette (FIRE) spectrograph at the Magellan Telescopes. These data verify the low-temperature nature of this source, indicating a T8 spectral classification, log Lbol/Lsun = -5.62+/-0.03, Teff = 650+/-25 K, and a mass at or below the deuterium burning limit. The data also reveal enhanced emission at K-band associated with youth (low surface gravity) and supersolar metallicity, reflecting the properties of the Ross 458 system (age = 150-800 Myr, [Fe/H] = +0.2 to +0.3). We present fits of FIRE data for Ross 458C, the T9 dwarf ULAS J133553.45+113005.2, and the blue T7.5 dwarf SDSS J141624.08+134826.7B, to cloudless and cloudy spectral models from Saumon & Marley. For Ross 458C we confirm a low surface gravity and supersolar metallicity, while the temperature differs depending on the presence (635 [+25,-35] K) or absence (760 [+70,-45] K) of cloud extinction. ULAS J1335+1130 and SDSS J1416+1348B have similar temperatures (595 [+25,-45] K), but distinct surface gravities (log g = 4.0-4.5 cgs versus 5.0-5.5 cgs) and metallicities ([M/H] ~ +0.2 versus -0.2). In all three cases, cloudy models provide better fits to the spectral data, significantly so for Ross 458C. These results indicate that clouds are an important opacity source in the spectra of young cold T dwarfs, and should be considered when characterizing the spectra of planetary-mass objects in young clusters and directly-imaged exoplanets. The characteristics of Ross 458C suggest it could itself be regarded as a planet, albeit one whose cosmogony does not conform with current planet formation theories.Comment: Accepted for publication to ApJ: 18 pages, 11 figures in emulateapj forma

    Mean-field analysis of collapsing and exploding Bose-Einstein condensates

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    The dynamics of collapsing and exploding trapped Bose-Einstein condensat es caused by a sudden switch of interactions from repulsive to attractive a re studied by numerically integrating the Gross-Pitaevskii equation with atomic loss for an axially symmetric trap. We investigate the decay rate of condensates and the phenomena of bursts and jets of atoms, and compare our results with those of the experiments performed by E. A. Donley {\it et al.} [Nature {\bf 412}, 295 (2001)]. Our study suggests that the condensate decay and the burst production is due to local intermittent implosions in the condensate, and that atomic clouds of bursts and jets are coherent. We also predict nonlinear pattern formation caused by the density instability of attractive condensates.Comment: 7 pages, 8 figures, axi-symmetric results are adde

    From Monochrome to Technicolor: Simple Generic Approaches to Multicomponent Protein Nanopatterning Using Siloxanes with Photoremovable Protein-Resistant Protecting Groups.

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    We show that sequential protein deposition is possible by photodeprotection of films formed from a tetraethylene-glycol functionalized nitrophenylethoxycarbonyl-protected aminopropyltriethoxysilane (NPEOC-APTES). Exposure to near-UV irradiation removes the protein-resistant protecting group, and allows protein adsorption onto the resulting aminated surface. The protein resistance was tested using proteins with fluorescent labels and microspectroscopy of two-component structures formed by micro- and nanopatterning and deposition of yellow and green fluorescent proteins (YFP/GFP). Nonspecific adsorption onto regions where the protecting group remained intact was negligible. Multiple component patterns were also formed by near-field methods. Because reading and writing can be decoupled in a near-field microscope, it is possible to carry out sequential patterning steps at a single location involving different proteins. Up to four different proteins were formed into geometric patterns using near-field lithography. Interferometric lithography facilitates the organization of proteins over square cm areas. Two-component patterns consisting of 150 nm streptavidin dots formed within an orthogonal grid of bars of GFP at a period of ca. 500 nm could just be resolved by fluorescence microscopy

    Absolute properties of the low-mass eclipsing binary CM Draconis

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    Spectroscopic and eclipsing binary systems offer the best means for determining accurate physical properties of stars, including their masses and radii. The data available for low-mass stars have yielded firm evidence that stellar structure models predict smaller radii and higher effective temperatures than observed, but the number of systems with detailed analyses is still small. In this paper we present a complete reanalysis of one of such eclipsing systems, CM Dra, composed of two dM4.5 stars. New and existing light curves as well as a radial velocity curve are modeled to measure the physical properties of both components. The masses and radii determined for the components of CM Dra are M1=0.2310+/-0.0009 Msun, M2=0.2141+/-0.0010 Msun, R1=0.2534+/-0.0019 Rsun, and R2=0.2396+/-0.0015 Rsun. With relative uncertainties well below the 1% level, these values constitute the most accurate properties to date for fully convective stars. This makes CM Dra a valuable benchmark for testing theoretical models. In comparing our measurements with theory, we confirm the discrepancies reported previously for other low-mass eclipsing binaries. These discrepancies seem likely to be due to the effects of magnetic activity. We find that the orbit of this system is slightly eccentric, and we have made use of eclipse timings spanning three decades to infer the apsidal motion and other related properties.Comment: 19 pages, 9 figures. Accepted for publication in Ap

    The USNO-B Catalog

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    USNO-B is an all-sky catalog that presents positions, proper motions, magnitudes in various optical passbands, and star/galaxy estimators for 1,042,618,261 objects derived from 3,643,201,733 separate observations. The data were obtained from scans of 7,435 Schmidt plates taken for the various sky surveys during the last 50 years. USNO-B1.0 is believed to provide all-sky coverage, completeness down to V = 21, 0.2 arcsecond astrometric accuracy at J2000, 0.3 magnitude photometric accuracy in up to five colors, and 85% accuracy for distinguishing stars from non-stellar objects. A brief discussion of various issues is given here, but the actual data are available from http://www.nofs.navy.mil and other sites.Comment: Accepted by Astronomical Journa
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