9,368 research outputs found
Pair Production of Two-Higgs-Doublet_Model Light Higgs Bosons in Collisions
We study the production of a pair of light, neutral, CP-even Higgs bosons in
photon--photon collisions within the general Two Higgs Doublet Model (THDM).
This is a process for which the lowest order contribution in both, the Standard
Model and the THDM, appears at one loop. We find that the cross section for
this process can be much larger in the THDM than in the Standard Model and the
number of events expected at the Photon Collider will allow a determination of
some of the parameters in the scalar potential.Comment: 10 pages, 4 figure
‘Tenderstem’ Broccoli for Export Markets: an Analysis Study on the AgroFood Company
Decision case, horticulture, agriculture economics, broccoli production, protected vegetable production, Agricultural Finance, Crop Production/Industries, Production Economics,
Methylation Status of Imprinted Genes and Repetitive Elements in Sperm DNA from Infertile Males
Stochastic, environmentally and/or genetically induced disturbances in the genome-wide epigenetic reprogramming processes during male germ-cell development may contribute to male infertility. To test this hypothesis, we have studied the methylation levels of 2 paternally (H19 and GTL2) and 5 maternally methylated (LIT1, MEST, NESPAS, PEG3, and SNRPN) imprinted genes, as well as of ALU and LINE1 repetitive elements in 141 sperm samples, which were used for assisted reproductive technologies (ART), including 106 couples with strictly male-factor or combined male and female infertility and 28 couples with strictly female-factor infertility. Aberrant methylation imprints showed a significant association with abnormal semen parameters, but did not seem to influence ART outcome. Repeat methylation also differed significantly between sperm samples from infertile and presumably fertile males. However, in contrast to imprinted genes, ALU methylation had a significant impact on pregnancy and live-birth rate in couples with male-factor or combined infertility. ALU methylation was significantly high-er in sperm samples leading to pregnancy and live-birth than in those that did not. Sperm samples leading to abortions showed significantly lower ALU methylation levels than those leading to the birth of a baby. Copyright (C) 2011 S. Karger AG, Base
Valued rank-metric codes
In this paper, we study linear spaces of matrices defined over discretely
valued fields and discuss their dimension and minimal rank drops over the
associated residue fields. To this end, we take first steps into the theory of
rank-metric codes over discrete valuation rings by means of skew algebras
derived from Galois extensions of rings. Additionally, we model
projectivizations of rank-metric codes via Mustafin varieties, which we then
employ to give sufficient conditions for a decrease in the dimension.Comment: 33 page
(S)norlaudanosoline synthase. the first enzyme in the benzylisoquinoline biosynthetic pathway
1. introduction Isoquinoline alkaloids form the largest group of alkaloids in the plant kingdom. Numerous publications deal with aspects of the biosynthesis of these compounds in vivo [ 11, while isoquinoline biosynthesis at the cell-free level had hardly been touched [Z]. The initial reaction in isoquinoline biosynthesis has long [3] been assumed to be a condensation of two aromatic units, both derived from tyrosine, namely dopamine and 3,4-d~ydroxyphenylacet~dehyde [4]. This scheme was later modified [5] where it was reported that condensation of dopamine with 3,4-dihydroxyphenylpyruvate would lead to an amino acid, norlaudanosoline-l-carboxylic acid, which in turn, by decarboxylation, would yield norlaudanosoline
The regulation of RhoA at focal adhesions by StarD13 is important for astrocytoma cell motility
Malignant astrocytomas are highly invasive into adjacent and distant regions of the normal brain. Rho GTPases are small monomeric G proteins that play important roles in cytoskeleton rearrangement, cell motility and tumor invasion. In the present study, we show that the knock down of StarD13, a GTPase activating protein (GAP) for RhoA and Cdc42, inhibits astrocytoma cell migration through modulating focal adhesion dynamics and cell adhesion. This effect is mediated by the resulting constitutive activation of RhoA and the subsequent indirect inhibition of Rac. Using Total Internal Reflection Fluorescence (TIRF)-based Forster Resonance Energy Transfer (FRET), we show that RhoA activity localizes with focal adhesions at the basal surface of astrocytoma cells. Moreover, the knock down of StarD13 inhibits the cycling of RhoA activation at the rear edge of cells, which makes them defective in retracting their tail. This study highlights the importance of the regulation of RhoA activity in focal adhesions of astrocytoma cells and establishes StarD13 as a GAP playing a major role in this process. (C) 2013 Elsevier Inc All rights reserved
A randomized comparison between three types of irrigating fluids during transurethral resection in benign prostatic hyperplasia
<p>Abstract</p> <p>Background</p> <p>Central nervous system changes, circulatory and electrolyte imbalances are the main complications of endoscopic transurethral resection of the prostate (TURP) which is known as transurethral resection (TUR) syndrome, which occurs as result of excessive absorption of irrigating fluid. We compare glycine 1.5% versus glucose 5% and normal saline 0.9% as irrigating solutions during TURP in patients with moderate to severe bladder outlet obstruction due to benign prostatic hyperplasia (BPH).</p> <p>Methods</p> <p>Three hundred sixty patients with symptomatic BPH were randomized into a prospective, controlled trial comparing the three irrigation modalities. One-hundred twenty patients used glycine 1.5% solution as irrigating fluid (glycine group), 120 patients used glucose 5% solution (glucose group) and 120 patients used normal saline 0.9% solution (saline group). Patient's demographics, operation time, hospital stay, postoperative amino acid glycine assay, postoperative serum cardiac troponin I and perioperative complications were noted.</p> <p>Results</p> <p>No difference was found between the groups in the immediate postoperative levels of hemoglobin and hematocrite. A high glycine level was associated with the TUR syndrome. Seventeen patients had TUR syndrome; all were in glycine group and they had the highest postoperative amino acid glycine levels. Slight increase in serum sodium (142.6 ± 12.6 mmol/l) was detected in saline group. Transient Hyperglycemia (170 ± 35.9 mg/dl) and hypokalemia (3.67 ± 0.92 mmol/l) occurred in the immediate postoperative period in the glucose group.</p> <p>Conclusion</p> <p>Endoscopic TURP performed using either glucose 5% or saline 0.9% irrigating solution during and after surgery is associated with lower incidence of TUR syndrome, lower catheterization period, shorter hospital stay and no cardiac toxicity in comparison with glycine 1.5% solution.</p> <p>Trial Registration</p> <p>This clinical trail had been approved and registered in PACT Registry; with identification number for the registry is ATMR2010010001793131.</p
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Influence of Atomic Surface Structure on the Activity of Ag for the Electrochemical Reduction of CO 2 to CO
The present work was undertaken to elucidate the facet-dependent activity of Ag for the electrochemical reduction of CO to CO. To this end, CO reduction was investigated over Ag thin films with (111), (100), and (110) orientations prepared via epitaxial growth on single-crystal Si wafers with the same crystallographic orientations. This preparation technique yielded larger area electrodes than can be achieved using single-crystals, which enabled the electrocatalytic activity of the corresponding Ag surfaces to be quantified in the Tafel regime. The Ag(110) thin films exhibited higher CO evolution activity compared to the Ag(111) and Ag(100) thin films, consistent with previous single-crystal studies. Density functional theory calculations suggest that CO reduction to CO is strongly facet-dependent, and that steps are more active than highly coordinated terraces. This is the result of both a higher binding energy of the key intermediate COOH as well as an enhanced double-layer electric field stabilization over undercoordinated surface atoms located at step edge defects. As a consequence, step edge defects likely dominate the CO reduction activity observed over the Ag(111) and Ag(100) thin films. The higher activity observed over the Ag(110) thin film is then related to the larger density of undercoordinated sites compared to the Ag(111) and Ag(100) thin films. Our conclusion that undercoordinated sites dominate the CO reduction activity observed over close-packed surfaces highlights the need to consider the contribution of such defects in studies of single-crystal electrodes. 2 2 2 2
Single Higgs-boson production through gamma-gamma scattering within the general 2HDM
The production of a single neutral Higgs boson h through (loop-induced)
gamma-gamma collisions is explored in the context of the linear colliders
within the general Two-Higgs-Doublet Model (2HDM). Two different mechanisms are
analyzed: on the one hand, the scattering gamma gamma-> h of two real photons
in a gamma-gamma collider; on the other, the more traditional mechanism of
virtual photon fusion, e+e- -->e+e- + h. Owing to the peculiar properties of
the Higgs boson self-interactions within the general 2HDM, we find that the
overall production rates can be boosted up significantly, provided the charged
Higgs mass is not too heavy. For example, if the latter is slightly above 100
GeV and, in addition, the lightest CP-even Higgs boson falls in the ballpark of
the LEP bound on the SM Higgs mass up to a few hundred GeV, the cross-sections
may typically render \sigma(gamma gamma-> h)= 0.1-1 pb and \sigma(e+e- --> e+e-
+ h)\sim 0.01 pb -- in both cases well above the SM prediction. Although for
charged Higgs masses above 300 GeV the rates become virtually insensitive to
the Higgs boson self-couplings, a significant tail of non-SM effects produced
by the combined contribution of the Yukawa couplings and gauge bosons could
still reveal a smoking gun.Comment: References and comments added. Accepted in Phys. Lett.
Composite-pulse magnetometry with a solid-state quantum sensor
The sensitivity of quantum magnetometers is challenged by control errors and,
especially in the solid-state, by their short coherence times. Refocusing
techniques can overcome these limitations and improve the sensitivity to
periodic fields, but they come at the cost of reduced bandwidth and cannot be
applied to sense static (DC) or aperiodic fields. Here we experimentally
demonstrate that continuous driving of the sensor spin by a composite pulse
known as rotary-echo (RE) yields a flexible magnetometry scheme, mitigating
both driving power imperfections and decoherence. A suitable choice of RE
parameters compensates for different scenarios of noise strength and origin.
The method can be applied to nanoscale sensing in variable environments or to
realize noise spectroscopy. In a room-temperature implementation based on a
single electronic spin in diamond, composite-pulse magnetometry provides a
tunable trade-off between sensitivities in the microT/sqrt(Hz) range,
comparable to those obtained with Ramsey spectroscopy, and coherence times
approaching T1
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