2,191 research outputs found
Comparative Larvicidal Properties and Detoxification Machinery of Bioactive Fractions of Leaf Extracts of Hyptis Suaveolens and Chromolaena Odorata on Anopheles gambiae s.l from North West Nigeria.
Malaria is endemic in Nigeria and the impact of chemical insecticides is being undermined by widespread resistance in mosquito vectors. This calls for development of alternative bio-insecticidal approach. The aim of this work was to determine the active fractions of leaves of Hyptis. suaveolens and Chromolena. odorata with insecticidal potential on the larva of Anopheles gambiae s.l. Leaf extracts of the two plants were screen for phytochemicals and the active fractions were subjected to GC-MS analysis. In addition, the detoxification enzymes (GST, esterase and cytochromes P450) as well Glutathione levels on the susceptible and resistant individuals of the larvae were biochemically assayed. Larval bioassay was carried out by the standard procedure described by WHO. The phytochemicals detected include flavonoids, tannins, saponins, terpenoids, alkaloids, phenols and phlobatannins. Butanol fracton of H. suaveolens displayed higher larvicidal activity (LC50 2167.92ppm) followed by the aqueous fraction (LC50 2613.01ppm). Both butanol and aqueous fractions of C. odorata also displayed larvicidal activities (LC50 3117.97ppm; LC50 3497.27ppm) respectively, but were lower than that observed in Hyptis suaveolens. Biochemical assay of the detoxification enzymes showed significance difference at P <0.05 between the resistant and susceptible larvae for all enzymes. There was however no significant difference in the levels detoxification enzymes in both resistant and susceptible individuals for butanol and aqueous fractions of H. suaveolens when compared with their corresponding fractions of C. odorata at P< 0.05 respectively. The observations recorded in this study showed a promising larvicidal potential of these two plants which if further characterized could offer a promising novel bioinsecticide compound that could substitute the present classes of chemical insecticides used in malaria vector control
Theseus: A Library for Differentiable Nonlinear Optimization
We present Theseus, an efficient application-agnostic open source library for
differentiable nonlinear least squares (DNLS) optimization built on PyTorch,
providing a common framework for end-to-end structured learning in robotics and
vision. Existing DNLS implementations are application specific and do not
always incorporate many ingredients important for efficiency. Theseus is
application-agnostic, as we illustrate with several example applications that
are built using the same underlying differentiable components, such as
second-order optimizers, standard costs functions, and Lie groups. For
efficiency, Theseus incorporates support for sparse solvers, automatic
vectorization, batching, GPU acceleration, and gradient computation with
implicit differentiation and direct loss minimization. We do extensive
performance evaluation in a set of applications, demonstrating significant
efficiency gains and better scalability when these features are incorporated.
Project page: https://sites.google.com/view/theseus-a
Bold coupling between lesioned and healthy brain is associated with glioma patients’ recovery
Predicting functional outcomes after surgery and early adjuvant treatment is difficult due to the complex, extended, interlocking brain networks that underpin cognition. The aim of this study was to test glioma functional interactions with the rest of the brain, thereby identifying the risk factors of cognitive recovery or deterioration. Seventeen patients with diffuse non-enhancing glioma (aged 22–56 years) were longitudinally MRI scanned and cognitively assessed before and after surgery and during a 12-month recovery period (55 MRI scans in total after exclusions). We initially found, and then replicated in an independent dataset, that the spatial correlation pattern between regional and global BOLD signals (also known as global signal topography) was associated with tumour occurrence. We then estimated the coupling between the BOLD signal from within the tumour and the signal extracted from different brain tissues. We observed that the normative global signal topography is reorganised in glioma patients during the recovery period. Moreover, we found that the BOLD signal within the tumour and lesioned brain was coupled with the global signal and that this coupling was associated with cognitive recovery. Nevertheless, patients did not show any apparent disruption of functional connectivity within canonical functional networks. Understanding how tumour infiltration and coupling are related to patients’ recovery represents a major step forward in prognostic development.</p
Search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks using a matrix element method
A search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks is presented. Events with hadronic jets and one or two oppositely charged leptons are selected from a data sample corresponding to an integrated luminosity of 19.5 fb[superscript -1] collected by the CMS experiment at the LHC in pp collisions at a centre-of-mass energy of 8 TeV. In order to separate the signal from the larger t[bar over t] + jets background, this analysis uses a matrix element method that assigns a probability density value to each reconstructed event under signal or background hypotheses. The ratio between the two values is used in a maximum likelihood fit to extract the signal yield. The results are presented in terms of the measured signal strength modifier, μ, relative to the standard model prediction for a Higgs boson mass of 125 GeV. The observed (expected) exclusion limit at a 95 % confidence level is μ < 4.2 (3.3), corresponding to a best fit value [^ over μ] = 1.2[+1.6 over −1.5].United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
Military maladaptation : counterinsurgency and the politics of failure
Tactical learning is critical to battlefield success, especially in a counterinsurgency. This article tests the existing model of military adaption against a ‘most-likely’ case: the British Army’s counterinsurgency in the Southern Cameroons (1960–61). Despite meeting all preconditions thought to enable adaptation – decentralization, leadership turnover, supportive leadership, poor organizational memory, feedback loops, and a clear threat – the British still failed to adapt. Archival evidence suggests politicians subverted bottom-up adaptation, because winning came at too high a price in terms of Britain’s broader strategic imperatives. Our finding identifies an important gap in the extant adaptation literature: it ignores politics.PostprintPeer reviewe
Search for third-generation scalar leptoquarks in the tτ channel in proton-proton collisions at √s = 8 TeV
A search for pair production of third-generation scalar leptoquarks decaying to top quark and τ lepton pairs is presented using proton-proton collision data at a center-of-mass energy of √s = 8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 fb[superscript −1]. The search is performed using events that contain an electron or a muon, a hadronically decaying τ lepton, and two or more jets. The observations are found to be consistent with the standard model predictions. Assuming that all leptoquarks decay to a top quark and a τ lepton, the existence of pair produced, charge −1/3, third-generation leptoquarks up to a mass of 685 GeV is excluded at 95% confidence level. This result constitutes the first direct limit for leptoquarks decaying into a top quark and a τ lepton, and may also be applied directly to the pair production of bottom squarks decaying predominantly via the R-parity violating coupling λ [subscript 333] ′.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
Search for Pair-Produced Resonances Decaying to Quark Pairs in Proton-Proton Collisions at √s = 13 TeV
A general search for the pair production of resonances, each decaying to two quarks, is reported. The search is conducted separately for heavier resonances (masses above 400 GeV), where each of the four final-state quarks generates a hadronic jet resulting in a four-jet signature, and for lighter resonances (masses between 80 and 400 GeV), where the pair of quarks from each resonance is collimated and reconstructed as a single jet resulting in a two-jet signature. In addition, a b-tagged selection is applied to target resonances with a bottom quark in the final state. The analysis uses data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 35.9 fb⁻¹, from proton-proton collisions at a center-of-mass energy of 13 TeV. The mass spectra are analyzed for the presence of new resonances, and are found to be consistent with standard model expectations. The results are interpreted in the framework of R-parity-violating supersymmetry assuming the pair production of scalar top quarks decaying via the hadronic coupling λ′′312 or λ′′323 and upper limits on the cross section as a function of the top squark mass are set. These results probe a wider range of masses than previously explored at the LHC, and extend the top squark mass limits in the ˜t→qq′ scenario
Search for electroweak production of charginos and neutralinos in multilepton final states in proton-proton collisions at √s = 13 TeV
Results are presented from a search for the direct electroweak production of charginos and neutralinos in signatures with either two or more leptons (electrons or muons) of the same electric charge, or with three or more leptons, which can include up to two hadronically decaying tau leptons. The results are based on a sample of proton-proton collision data collected at s√=13 TeV, recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9 fb⁻¹. The observed event yields are consistent with the expectations based on the standard model. The results are interpreted in simplified models of supersymmetry describing various scenarios for the production and decay of charginos and neutralinos. Depending on the model parameters chosen, mass values between 180 GeV and 1150 GeV are excluded at 95% CL. These results significantly extend the parameter space probed for these particles in searches at the LHC. In addition, results are presented in a form suitable for alternative theoretical interpretations
Search for Standard Model Production of Four Top Quarks with Same-Sign and Multilepton Final States in Proton–proton Collisions at √s = 13 TeV
A search for standard model production of four top quarks (tt¯tt¯) is reported using events containing at least three leptons (e,μ) or a same-sign lepton pair. The events are produced in proton–proton collisions at a center-of-mass energy of 13TeV at the LHC, and the data sample, recorded in 2016, corresponds to an integrated luminosity of 35.9fb[superscript −1]. Jet multiplicity and flavor are used to enhance signal sensitivity, and dedicated control regions are used to constrain the dominant backgrounds. The observed and expected signal significances are, respectively, 1.6 and 1.0 standard deviations, and the tt¯tt¯ cross section is measured to be 16.9[superscript +13.8][subscript −11.4] fb, in agreement with next-to-leading-order standard model predictions. These results are also used to constrain the Yukawa coupling between the top quark and the Higgs boson to be less than 2.1 times its expected standard model value at 95% confidence level
Measurement of the transverse momentum spectrum of the Higgs boson produced in pp collisions at √s=8 TeV using H → WW decays
The cross section for Higgs boson production in pp collisions is studied using the H → W[superscript +]W[superscript −] decay mode, followed by leptonic decays of the W bosons to an oppositely charged electron-muon pair in the final state. The measurements are performed using data collected by the CMS experiment at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.4 fb[superscript −1]. The Higgs boson transverse momentum (p[subscript T]) is reconstructed using the lepton pair p[subscript T] and missing p[subscript T]. The differential cross section times branching fraction is measured as a function of the Higgs boson pTin a fiducial phase space defined to match the experimental acceptance in terms of the lepton kinematics and event topology. The production cross section times branching fraction in the fiducial phase space is measured to be 39 ± 8 (stat) ± 9 (syst) fb. The measurements are found to agree, within experimental uncertainties, with theoretical calculations based on the standard model. Keywords: Hadron-Hadron scattering (experiments), Higgs physicsNational Science Foundation (U.S.)United States. Department of Energ
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