2,840 research outputs found
Potentiation of proton transfer function by electrostatic interactions in photosynthetic reaction centers from Rhodobacter sphaeroides: First results from site-directed mutation of the H subunit.
Debilitation in conidia of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae and implication with respect to viability determinations and mycopesticide quality assessments.
Radiative association and inverse predissociation of oxygen atoms
The formation of \mbox{O}_2 by radiative association and by inverse
predissociation of ground state oxygen atoms is studied using
quantum-mechanical methods. Cross sections, emission spectra, and rate
coefficients are presented and compared with prior experimental and theoretical
results. At temperatures below 1000~K radiative association occurs by approach
along the state of \mbox{O}_2 and above 1000~K inverse
predissociation through the \mbox{B}\,{}^3\Sigma_u^- state is the dominant
mechanism. This conclusion is supported by a quantitative comparison between
the calculations and data obtained from hot oxygen plasma spectroscopy.Comment: submitted to Phys. Rev. A (Sept. 7., 1994), 19 pages, 4 figures,
latex (revtex3.0 and epsf.sty
Aplicacao de conĂdios de Beauveria bassiana (Bals.) Vuill. e metarhizium anisopliae (Metsch.) sor. para controle de larvas de Chalcodermus bimaculatus Boh. (Coleptera:Curculionidae) no solo.
The effect of soil treatment with Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sor. conidia on Chalcodermus bimaculatus Boh. larvae was evaluated in cowpea (Vigna unguiculata L. Walp). In Santo AntĂŽnio de GoiĂĄs, Brazil, it was observed that both fungi reached an average control of 50% after liberation of larvae at different days in treated soil. In QuixadĂĄ, CearĂĄ, the average control was approximately 30% for both fungi. In Caucaia, CearĂĄ, the fungus M. anisoplae induced 46% mortality at the application date and 27.4% after 10 days. Results indicated that the fungi consistently provided 30-50% control of C. bimaculatus. Evaluation of fungi persistence in the soil indicated that this level of control was achieved through a single application
Fungal entomopathogens: new insights on their ecology
An important mechanism for insect pest control should be the use of fungal entomopathogens. Even though these organisms have been studied for more than 100 y, their effective use in the field remains elusive. Recently, however, it has been discovered that many of these entomopathogenic fungi play additional roles in nature. They are endophytes, antagonists of plant pathogens, associates with the rhizosphere, and possibly even plant growth promoting agents. These findings indicate that the ecological role of these fungi in the environment is not fully understood and limits our ability to employ them successfully for pest management. In this paper, we review the recently discovered roles played by many entomopathogenic fungi and propose new research strategies focused on alternate uses for these fungi. It seems likely that these agents can be used in multiple roles in protecting plants from pests and diseases and at the same time promoting plant growth
Acetylcysteine has No Mechanistic Effect in Patients at Risk of Contrast-Induced Nephropathy - A Failure of Academic Clinical Science
Contrastâinduced nephropathy (CIN) is a major complication of imaging in patients with chronic kidney disease (CKD). The publication of an academic randomized controlled trial (RCT; n = 83) reporting oral (N)âacetylcysteine (NAC) to reduce CIN led to > 70 clinical trials, 23 systematic reviews, and 2 large RCTs showing no benefit. However, no mechanistic studies were conducted to determine how NAC might work; proposed mechanisms included renal artery vasodilatation and antioxidant boosting. We evaluated the proposed mechanisms of NAC action in participants with healthy and diseased kidneys. Four substudies were performed. Two randomized, doubleâblind, placeboâcontrolled, threeâperiod crossover studies (n = 8) assessed the effect of oral and intravenous (i.v.) NAC in healthy kidneys in the presence/absence of isoâosmolar contrast (iodixanol). A third crossover study in patients with CKD stage III (CKD3) (n = 8) assessed the effect of oral and i.v. NAC without contrast. A threeâarm randomized, doubleâblind, placeboâcontrolled parallelâgroup study, recruiting patients with CKD3 (n = 66) undergoing coronary angiography, assessed the effect of oral and i.v. NAC in the presence of contrast. We recorded systemic (blood pressure and heart rate) and renal (renal blood flow (RBF) and glomerular filtration rate (GFR)) hemodynamics, and antioxidant status, plus biomarkers of renal injury in patients with CKD3 undergoing angiography. Primary outcome for all studies was RBF over 8 hours after the start of i.v. NAC/placebo. NAC at doses used in previous trials of renal prophylaxis was essentially undetectable in plasma after oral administration. In healthy volunteers, i.v. NAC, but not oral NAC, increased blood pressure (mean area under the curve (AUC) mean arterial pressure (MAP): mean difference 29 hâ
mmHg, PÂ =Â 0.019 vs. placebo), heart rate (28Â hâ
bpm, PÂ <Â 0.001), and RBF (714Â hâ
mL/min, 8.0% increase, PÂ =Â 0.006). Renal vasodilatation also occurred in the presence of contrast (RBF 917Â hâ
mL/min, 12% increase, PÂ =Â 0.005). In patients with CKD3 without contrast, only a rise in heart rate (34Â hâ
bpm, PÂ =Â 0.010) and RBF (288Â hâ
mL/min, 6.0% increase, PÂ =Â 0.001) occurred with i.v. NAC, with no significant effect on blood pressure (MAP rise 26Â hâ
mmHg, PÂ =Â 0.156). Oral NAC showed no effect. In patients with CKD3 receiving contrast, i.v. NAC increased blood pressure (MAP rise 52Â hâ
mmHg, PÂ =Â 0.008) but had no effect on RBF (151Â hâ
mL/min, 3.0% increase, PÂ =Â 0.470), GFR (29Â hâ
mL/min/1.73mÂČ, PÂ =Â 0.122), or markers of renal injury. Neither i.v. nor oral NAC affected plasma antioxidant status. We found oral NAC to be poorly absorbed and have no renoâprotective effects. Intravenous, not oral, NAC caused renal artery vasodilatation in healthy volunteers but offered no protection to patients with CKD3 at risk of CIN. These findings emphasize the importance of mechanistic clinical studies before progressing to RCTs for novel interventions. Thousands were recruited to academic clinical trials without the necessary mechanistic studies being performed to confirm the approach had any chance of working
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC
The uncertainty on the calorimeter energy response to jets of particles is
derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the
calorimeter response to single isolated charged hadrons is measured and
compared to the Monte Carlo simulation using proton-proton collisions at
centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009
and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter
response to specific types of particles (positively and negatively charged
pions, protons, and anti-protons) is measured and compared to the Monte Carlo
predictions. Finally, the jet energy scale uncertainty is determined by
propagating the response uncertainty for single charged and neutral particles
to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3%
for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table,
submitted to European Physical Journal
Bose-Einstein correlations of same-sign charged pions in the forward region in pp collisions at âs=7 TeV
Bose-Einstein correlations of same-sign charged pions, produced in protonproton collisions at a 7 TeV centre-of-mass energy, are studied using a data sample collected
by the LHCb experiment. The signature for Bose-Einstein correlations is observed in the
form of an enhancement of pairs of like-sign charged pions with small four-momentum
difference squared. The charged-particle multiplicity dependence of the Bose-Einstein correlation parameters describing the correlation strength and the size of the emitting source
is investigated, determining both the correlation radius and the chaoticity parameter. The
measured correlation radius is found to increase as a function of increasing charged-particle
multiplicity, while the chaoticity parameter is seen to decreas
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