962 research outputs found
Association between GH encoding gene polymorphism and semen characteristics in Iranian Holstein bulls
The objective of this present study was to investigate relationships between the growth hormone gene restriction fragment length polymorphism (RFLP) and bull sperm characteristics. A total of 89 bullsfrom two semen evaluation stations were genotyped for the bovine growth hormone (bGH)-AluI polymorphism by polymerase chain reaction and followed by 4% metaphor agaros gel electrophoresis. The overall allele frequencies for two L and V alleles were 0.50, respectively. The relationship between the bGH-AluI polymorphism and semen characteristics was evaluated according 1500 ejaculated records. Five sperm characteristics were analyzed. Sperm characteristics showed significant variabilityin relation to bGH genotypes. LL bulls had a lower ejaculated volume and higher percentage of live sperm, and VV bulls had higher fresh sperm concentration and minimum effect after cryopreservation. This polymorphism could be further used for semen evaluation process in artificial insemination program in Iranian Holstein bulls.Key word: Semen characteristics, growth hormone (GH) polymorphism, Holstein bulls
Correlation of reconstructed scaphoid morphology with clinical outcomes
Background: Scaphoid malunion alters the carpal kinematics and impairs clinical outcome because of pain, weakness, restricted range of motion and predisposing the wrist joint to early osteoarthritis. The aim of this study was to evaluate the influence of the scaphoid morphological angles on clinical outcomes in patients with reconstructed scaphoid by non-vascularized bone graft. Methods: Seventeen male patients with the mean age of 31.7±3.7 years and mean non-union time of 31.5±14.7 months were enrolled in this retrospective study. Average follow up was 48.8±9.4 months. At the last follow-up, the patients were evaluated clinically for pain, wrist range of motion, grip strength, and wrist functional status. They were also evaluated radiologically by wrist radiographs and computerized tomography (CT). The overall clinical outcomes were evaluated by the Cooney wrist function score. The morphology of the reconstructed scaphoids was evaluated by the lateral intrascaphoid angle, antroposterior intrascaphoid angle, dorsal cortical angle, measuring the length (mm), and height-to-length ratio on CT scan. The radiological measurements were compared against the overall clinical outcomes. Results: There were 7 excellent, 7 good, 3 fair clinical results. The mean Cooney wrist function score was 83±4. The mean lateral intrascaphoid angle was 34.8±1.4 degrees, mean antroposterior intrascaphoid angle was 33.4±2.2 degrees, mean dorsal cortical angle was 158.3±4.8 degrees, mean scaphoid length was 22.1± 0.7 mm, and mean scaphoid height-to-length ratio was 0.74±0.04. There were no significant statistical correlations between the lateral intrascaphoid angles, antroposterior intrascaphoid angles, dorsal cortical angles, scaphoid lengths and scaphoid height-to-length ratios and Cooney wrist scores in the patients. Conclusion: In the current study, all the patients had some degree of scaphoid malunion; however, the radiological measurements of the reconstructed scaphoids did not correlate with the clinical outcomes. © 2015 BY THE ARCHIVES OF BONE AND JOINT SURGERY
Interacting spin-2 fields in three dimensions
Using the frame formulation of multi-gravity in three dimensions, we show
that demanding the presence of secondary constraints which remove the
Boulware-Deser ghosts restricts the possible interaction terms of the theory
and identifies invertible frame field combinations whose effective metric may
consistently couple to matter. The resulting ghost-free theories can be
represented by theory graphs which are trees. In the case of three frame
fields, we explicitly show that the requirement of positive masses and energies
for the bulk spin-2 modes in AdS is consistent with a positive central
charge for the putative dual CFT.Comment: 26 pages, 3 figures, v2: minor changes, matches published versio
Anisotropy of the Seebeck Coefficient in the Cuprate Superconductor YBaCuO: Fermi-Surface Reconstruction by Bidirectional Charge Order
The Seebeck coefficient of the cuprate YBaCuO was
measured in magnetic fields large enough to suppress superconductivity, at hole
dopings and , for heat currents along the and
directions of the orthorhombic crystal structure. For both directions,
decreases and becomes negative at low temperature, a signature that the Fermi
surface undergoes a reconstruction due to broken translational symmetry. Above
a clear threshold field, a strong new feature appears in , for
conduction along the axis only. We attribute this feature to the onset of
3D-coherent unidirectional charge-density-wave modulations seen by x-ray
diffraction, also along the axis only. Because these modulations have a
sharp onset temperature well below the temperature where starts to drop
towards negative values, we infer that they are not the cause of Fermi-surface
reconstruction. Instead, the reconstruction must be caused by the quasi-2D
bidirectional modulations that develop at significantly higher temperature.Comment: 7 pages, 5 figure
Fermi-surface transformation across the pseudogap critical point of the cuprate superconductor LaNdSrCuO
The electrical resistivity and Hall coefficient R of the
tetragonal single-layer cuprate Nd-LSCO were measured in magnetic fields up to
T, large enough to access the normal state at , for closely
spaced dopings across the pseudogap critical point at .
Below , both coefficients exhibit an upturn at low temperature, which
gets more pronounced with decreasing . Taken together, these upturns show
that the normal-state carrier density at drops upon entering the
pseudogap phase. Quantitatively, it goes from at to at . By contrast, the mobility does not change appreciably, as
revealed by the magneto-resistance. The transition has a width in doping and
some internal structure, whereby R responds more slowly than to the
opening of the pseudogap. We attribute this difference to a Fermi surface that
supports both hole-like and electron-like carriers in the interval , with compensating contributions to R. Our data are in excellent
agreement with recent high-field data on YBCO and LSCO. The quantitative
consistency across three different cuprates shows that a drop in carrier
density from to is a universal signature of the pseudogap
transition at . We discuss the implication of these findings for the
nature of the pseudogap phase.Comment: 11 pages, 12 figure
Spread of efflux pump overexpressing-mediated fluoroquinolone resistance and multidrug resistance in Pseudomonas aeruginosa by using an efflux pump inhibitor
Background: Fluoroquinolone resistance in Pseudomonas aeruginosa may be due to efflux pump overexpression and/or target mutations. We designed this study to investigate the efflux pump mediated fluoroquinolone resistance and check the increasing effectiveness of fluoroquinolones in combination with an efflux pumps inhibitor among P. aeruginosa isolates from burn wounds infections. Materials and Methods: A total of 154 consecutive strains of P. aeruginosa were recovered from separate patients hospitalized in a burn hospital, Tehran, Iran. The isolates first were studied by disk diffusion antibiogram for 11 antibiotics and then minimum inhibitory concentration (MIC) experiments were performed to detect synergy between ciprofloxacin and the efflux pump inhibitor, carbonyl cyanide-m-chlorophenyl hydrazone (CCCP). Then to elucidate the inducing of multi drug resistance due to different efflux pumps activation in Fluoroquinolone resistant isolates, synergy experiments were also performed in random ciprofloxacin resistant isolates which have overexpressed efflux pumps phenotypically, using CCCP and selected antibiotics as markers for Beta-lactams and Aminoglycosides. The isolates were also tested by polymerase chain reaction (PCR) for the presence of the MexA, MexC and MexE, which encode the efflux pumps MexAB-OprM, MexCD-OprJ and MexEF-OprN. Results: Most of the isolates were resistant to 3 or more antibiotics tested. More than half of the ciprofloxacin resistant isolates exhibited synergy between ciprofloxacin and CCCP, indicating the efflux pump activity contributed to the ciprofloxacin resistance. Also increased susceptibility of random ciprofloxacin resistant isolates of P. aeruginosa to other selected antibiotics, in presence of CCCP, implied multidrug extrusion by different active efflux pump in fluoroquinolones resistant strains. All of Ciprofloxacin resistant isolates were positive for MexA, MexC and MexE genes simultaneously. Conclusion: In this burn hospital, where multidrug resistant P. aeruginosa isolates were prevalent, ciprofloxacin resistance and multidrug resistance due to the overexpression of fluoroquinolones mediated efflux pumps has also now emerged. Early recognition of this resistance mechanism should allow the use of alternative antibiotics and use an efflux pumps inhibitor in combination with antibiotic therapy. © 2015 by The Korean Society of Infectious Diseases
Microdust impact on leaf gas exchange parameters in oak species of Northern Zagros forests, west of Iran
In recent years, the microdust phenomenon has greatly changed in concentration, duration and continuity as well
as the frequency of occurrence in comparison with dust storms in the past which has caused a great deal of concern.
Microdust is one of the most devastating factors in the environment threatening all animal and plant species.
Regarding to the microdust impending threat, its ecological and economic impacts on scarce species is critical.
Zagros forests act as an intrinsic filter for microdust in the western region of Iran. This study investigates the effect
of microdust on oak, the most important tree in the Zagros forests. So that, three-year old seedlings of three oak
species (Quercus branti, Q. libni and Q. infectoria) were exposed to microdust under natural conditions during spring
and summer 2016. We examined the rate of photosynthesis, stomatal conductance, transpiration, internal CO2,
mesophyll conductance, water use efficiency in control and treated plants. The results indicated that microdust
had a significant impact on the examined parameters of the three oak species (P≤0.01). The gas exchange and
photosynthetic rates of the treated plants were significantly reduced. In Q. infectoria, microdust had the greatest
impact on photosynthesis, stomatal conductance, leaf internal CO2, transpiration and mesophyll conductance.
Accordingly, microdust had a substantial influence on photosynthesis and mesophyll conductance in Q. brantii as
well as the leaf internal CO2 and mesophyll conductance in Q. libani. Therefore, based on these findings, it can be
concluded that microdust can disrupt the physiological activities of the examined species. Hence, continuous -
exposure to microdust will accelerate the process of destruction of these forests
The GRA Beam-Splitter Experiments and Particle-Wave Duality of Light
Grangier, Roger and Aspect (GRA) performed a beam-splitter experiment to
demonstrate the particle behaviour of light and a Mach-Zehnder interferometer
experiment to demonstrate the wave behaviour of light. The distinguishing
feature of these experiments is the use of a gating system to produce near
ideal single photon states. With the demonstration of both wave and particle
behaviour (in two mutually exclusive experiments) they claim to have
demonstrated the dual particle-wave behaviour of light and hence to have
confirmed Bohr's principle of complementarity. The demonstration of the wave
behaviour of light is not in dispute. But we want to demonstrate, contrary to
the claims of GRA, that their beam-splitter experiment does not conclusively
confirm the particle behaviour of light, and hence does not confirm
particle-wave duality, nor, more generally, does it confirm complementarity.
Our demonstration consists of providing a detailed model based on the Causal
Interpretation of Quantum Fields (CIEM), which does not involve the particle
concept, of GRA's which-path experiment. We will also give a brief outline of a
CIEM model for the second, interference, GRA experiment.Comment: 24 pages, 4 figure
Covariant coarse-graining of inhomogeneous dust flow in General Relativity
A new definition of coarse-grained quantities describing the dust flow in
General Relativity is proposed. It assigns the coarse--grained expansion, shear
and vorticity to finite-size comoving domains of fluid in a covariant,
coordinate-independent manner. The coarse--grained quantities are all
quasi-local functionals, depending only on the geometry of the boundary of the
considered domain. They can be thought of as relativistic generalizations of
simple volume averages of local quantities in a flat space. The procedure is
based on the isometric embedding theorem for S^2 surfaces and thus requires the
boundary of the domain in question to have spherical topology and positive
scalar curvature. We prove that in the limit of infinitesimally small volume
the proposed quantities reproduce the local expansion, shear and vorticity. In
case of irrotational flow we derive the time evolution for the coarse-grained
quantities and show that its structure is very similar to the evolution
equation for their local counterparts. Additional terms appearing in it may
serve as a measure of the backreacton of small-scale inhomogeneities of the
flow on the large-scale motion of the fluid inside the domain and therefore the
result may be interesting in the context of the cosmological backreaction
problem. We also consider the application of the proposed coarse-graining
procedure to a number of known exact solutions of Einstein equations with dust
and show that it yields reasonable results.Comment: 17 pages, 5 figures. Version accepted in Classical and Quantum
Gravity
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