1,358 research outputs found
Isoform-selective susceptibility of DISC1/phosphodiesterase-4 complexes to dissociation by elevated intracellular cAMP levels
Disrupted-in-schizophrenia 1 (DISC1) is a genetic susceptibility factor for schizophrenia and related severe psychiatric conditions. DISC1 is a multifunctional scaffold protein that is able to interact with several proteins, including the independently identified schizophrenia risk factor phosphodiesterase-4B (PDE4B). Here we report that the 100 kDa full-length DISC1 isoform (fl-DISC1) can bind members of each of the four gene, cAMP-specific PDE4 family. Elevation of intracellular cAMP levels, so as to activate protein kinase A, caused the release of PDE4D3 and PDE4C2 isoforms from fl-DISC1 while not affecting binding of PDE4B1 and PDE4A5 isoforms. Using a peptide array strategy, we show that PDE4D3 binds fl-DISC1 through two regions found in common with PDE4B isoforms, the interaction of which is supplemented because of the presence of additional PDE4B-specific binding sites. We propose that the additional binding sites found in PDE4B1 underpin its resistance to release during cAMP elevation. We identify, for the first time, a functional distinction between the 100 kDa long DISC1 isoform and the short 71 kDa isoform. Thus, changes in the expression pattern of DISC1 and PDE4 isoforms offers a means to reprogram their interaction and to determine whether the PDE4 sequestered by DISC1 is released after cAMP elevation. The PDE4B-specific binding sites encompass point mutations in mouse Disc1 that confer phenotypes related to schizophrenia and depression and that affect binding to PDE4B. Thus, genetic variation in DISC1 and PDE4 that influence either isoform expression or docking site functioning may directly affect psychopathology
Three-particle entanglement versus three-particle nonlocality
The notions of three-particle entanglement and three-particle nonlocality are
discussed in the light of Svetlichny's inequality [Phys. Rev. D 35, 3066
(1987)]. It is shown that there exist sets of measurements which can be used to
prove three-particle entanglement, but which are nevertheless useless at
proving three-particle nonlocality. In particular, it is shown that the quantum
predictions giving a maximal violation of Mermin's three-particle Bell
inequality [Phys. Rev. Lett. 65, 1838 (1990)] can be reproduced by a hybrid
hidden variables model in which nonlocal correlations are present only between
two of the particles. It should be possible, however, to test the existence of
both three-particle entanglement and three-particle nonlocality for any given
quantum state via Svetlichny's inequality.Comment: REVTeX4, 4 pages, journal versio
Characterization of ovine strains of Mycobacterium paratuberculosis by restriction endonuclease analysis and DNA hybridization
Restriction endonuclease analysis and DNA hybridization revealed five ovine strains of Mycobacterium paratuberculosis from South Africa had identical DNA patterns to an ovine strain from Canada.
Genetically this strain type has features in common with the two major groups of M. paratuberculosis.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201
Hydrogen-Helium Mixtures at High Pressure
The properties of hydrogen-helium mixtures at high pressure are crucial to
address important questions about the interior of Giant planets e.g. whether
Jupiter has a rocky core and did it emerge via core accretion? Using path
integral Monte Carlo simulations, we study the properties of these mixtures as
a function of temperature, density and composition. The equation of state is
calculated and compared to chemical models. We probe the accuracy of the ideal
mixing approximation commonly used in such models. Finally, we discuss the
structure of the liquid in terms of pair correlation functions.Comment: Proceedings article of the 5th Conference on Cryocrystals and Quantum
Crystals in Wroclaw, Poland, submitted to J. Low. Temp. Phys. (2004
Strengthening mechanisms in an Al-Fe-Cr-Ti nano-quasicrystalline alloy and composites
We report a study of the structure-processing-property relationships in a high strength AlFeCrTi nano-quasicrystalline alloy and composites containing 10 and 20 vol% ductilising pure Al fibres. The superimposed contributions of several different strengthening mechanisms have been modelled analytically using data obtained from systematic characterisation of the monolithic alloy bar. An observed yield strength of 544 MPa has been substantiated from a combination of solid solution strengthening, work hardening, precipitation hardening and Hall-Petch grain size dependent effects. These materials have been shown by other authors in previous published work to be highly sensitive to the size distribution of particles in the powder from which they are made, and the subsequent thermomechanical processing conditions. The processing condition employed in this study provided micron-sized grains with a strong [111] preferential orientation along the extrusion direction and a bimodal size distribution of the icosahedral nano-quasicrystalline precipitates. Both were deemed to be a significant contributor to the high yield strength observed. The addition of pure Al fibres was found to decrease the yield strength linearly with increasing Al content, and to augment the ductility of the composites.Industrial collaborator ALPOCO Ltd. (and more specifically Steve McArthur) provided the powders. Dr. Karen Kruska and Dr. Alan Xu assisted with sample preparation of FIB lift-out specimens of the atomised powder for TEM analysis. EPSRC Project EP/E040608/1 provided financial support. M. Galano thanks the RAEng for their support by means of a Research Fellowship. F. Audebert and M. Galano thank PICT-Oxford2010/2831. F. Audebert also thanks UBACyT20020130100663 and FONARSEC FS Nano 2010/11 for financial support.Peer Reviewe
Black holes and Hawking radiation in spacetime and its analogues
These notes introduce the fundamentals of black hole geometry, the thermality
of the vacuum, and the Hawking effect, in spacetime and its analogues.
Stimulated emission of Hawking radiation, the trans-Planckian question, short
wavelength dispersion, and white hole radiation in the setting of analogue
models are also discussed. No prior knowledge of differential geometry, general
relativity, or quantum field theory in curved spacetime is assumed.Comment: 31 pages, 9 figures; to appear in the proceedings of the IX SIGRAV
School on 'Analogue Gravity', Como (Italy), May 2011, eds. D. Faccio et. al.
(Springer
The effect of hyperbaric oxygen and blood platelet injection therapy on the healing of hamstring injuries in rugby players
There are a number of ultra-structural and immuno-histochemical studies involving hyperbaric
oxygen treatment in skeletal muscle, as well as soft tissue healing. Hyperbaric oxygen therapy, in
conjunction with blood platelet injection therapy, serves as a valuable addition to previously
known and trusted rehabilitation techniques and protocols for the healing of musculoskeletal or
soft tissue injuries. The primary aim of this case report is to describe the effect on the recovery
time of hamstring injuries when combining hyperbaric oxygen therapy (HBOT) and platelet rich
plasma (PRP) injection therapy with exercise rehabilitation. A retrospective, post-intervention
data analysis was used in this case series report. Data, obtained through collaboration with a
professional rugby union and an accredited Hyperbaric Medicine (HBOT) Centre, were analysed
using the Statistical Programme for the Social Sciences (SPSS) software. The significance value
was set at 5%. A significant decrease in the injury time of the hamstring injuries in rugby players
was noted, with a 38% reduction in injury time in players with a grade-one injury, and 45.7%
reduction in players with a grade-two injury. In terms of recurrent injuries, 62% of players with
grade-one injuries remained uninjured after treatment, and the percentage of re-injured players
with grade-two injuries was 0% after HBOT, PRP and physical therapy treatment. The notion
that the healing time of hamstring injuries will decrease when HBOT and PRP are administered
in conjunction with traditional rehabilitation therapy is indicated by the data of this report.http://www.ajol.info/journal_index.php?jid=153&ab=ajpherd2017-11-30am201
Nuclear effects in the Drell-Yan process at very high energies
We study Drell-Yan (DY) dilepton production in proton(deuterium)-nucleus and
in nucleus-nucleus collisions within the light-cone color dipole formalism.
This approach is especially suitable for predicting nuclear effects in the DY
cross section for heavy ion collisions, as it provides the impact parameter
dependence of nuclear shadowing and transverse momentum broadening, quantities
that are not available from the standard parton model. For p(D)+A collisions we
calculate nuclear shadowing and investigate nuclear modification of the DY
transverse momentum distribution at RHIC and LHC for kinematics corresponding
to coherence length much longer than the nuclear size. Calculations are
performed separately for transversely and longitudinally polarized DY photons,
and predictions are presented for the dilepton angular distribution.
Furthermore, we calculate nuclear broadening of the mean transverse momentum
squared of DY dileptons as function of the nuclear mass number and energy. We
also predict nuclear effects for the cross section of the DY process in heavy
ion collisions. We found a substantial nuclear shadowing for valence quarks,
stronger than for the sea.Comment: 46 pages, 18 figures, title changed and some discussion added,
accepted for publication in PR
Low-noise AlGaAsSb avalanche photodiodes for 1550 nm light detection
Avalanche photodiodes (APD) can improve the signal to noise ratio in applications such as LIDAR, range finding and optical time domain reflectometry. However, APDs operating at eye-safe wavelengths around 1550 nm currently limit the sensitivity because the APDs’ impact ionization coefficients in the avalanche layers are too similar, leading to poor excess noise performance. The material AlGaAsSb has highly dissimilar impact ionization coefficients (with electrons dominating the avalanche gain) so is an excellent avalanche material for 1550 nm wavelength APDs. We previously reported a 1550 nm wavelength AlGaAsSb SAM APD with extremely low excess noise factors, 1.93 at a gain of 10 and 2.94 at a gain of 20. Using a more optimized design, we have now realized an AlGaAsSb SAM APD with a lower dark current (7 nA at a gain of 10 from a 230 μm diameter APD), a higher responsivity (0.97 A/W) and a lower excess noise (1.9 at a gain of 40), compared to our previous SAM APD. Noise-equivalent-power (NEP) measurements of our APD with a simple transimpedance amplifier circuit produced an NEP 12 times lower than a state-of-the-art APD under identical test conditions, confirming the advantage of low-noise AlGaAsSb SAM APDs
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