1,142 research outputs found

    Use of Combined Economic Threshold Level to Control Insect Pests

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    The economic threshold level (ETL) is a key factor to be studied for insect pests control. It is difficult to monitor cotton insect pests separately, and it is not reasonable to base decision-making for spraying on an ETL of individual insects and ignore sub-levels of other cotton insect pests. So, we want to use a combined ETL in a way of insect units, to put all major insect pests to consideration as an insect pests‘ complex. This means delaying the first spray to give a chance for natural enemies to develop and then lower the number of sprays and consequently reduce the cost of production

    Screening of some sorghum genotypes for resistance to sorghum midge, Stenodiplosis (= Contarinia) sorghicola Coqillet (diptera: Cecidomyiidae) under gedarif rainfed conditions

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    Preliminary experiments were conducted at Northern area, Gedarif State during seasons of 2002-03, 2006-07.Where as advanced trials during 2008/2009 to 2012/2013 at northern and Southern areas. The objective was to evaluate selected sorghum genotypes for sorghum midge resistance. A total of 3000 accessions were obtained from Gene Bank Resources. Resistant genotype, DJ 6514 (Resistant Check already released in 2007) was obtained from International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). Result showed that the midge damage rating was significantly different among genotypes. The midge damage rating scores ranged between, 1.3- 8.6; 1.1- 9.2; 1.4- 9.0; 1.1 – 9.4; and 1.2- 9.2 for all seasons (2008/09; 2009/10; 2010/11; 2011/12 and 2012/13). However, the lowest midge damage rating was recorded by DJ 6514 (Resistant check), followed by P₁ 570162 (Hag Abbakar); GBM 30 (Early Feterita); Wad Baco; and Safra (1.4; 1.5; 1.5, 1.6 and 1.7), respectively. Genotypes, P₁ 570162 (Hag Abbakar); GBM 30 (Early Feterita); Wad Baco; Safra and Harerai showed lowest % yield loss and performed similar to the resistant check (14.2; 14.5; 14.5; 17.0 and 17.3%), respectively. The combined analysis showed that a significant difference was observed between genotypes. The genotypes were significantly different in panicle types, compact and semi-compact headed genotypes showed lower % glumes coverage (1.3- 4.5%), while semi-compact headed genotypes ranged between 5.5 – 7.8%. Genotypes, Wad Baco; P₁ 570162 (Hag Abbakar); GBM 30 (Early Feterita); Safra; Wad Ahmed; Harerai and Wad Akar showed the shortest glumes coverage (1.3; 1.3; 1.5; 1.5; 1.6; 1.7 and 1.8 %). Compact headed genotypes recorded lowest midge density (6.5 adults/ 5 heads), while the semi-compact headed genotypes were recorded 15.7 adults/ 5 heads compared with others types of heads

    Remarks on the KLS conjecture and Hardy-type inequalities

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    We generalize the classical Hardy and Faber-Krahn inequalities to arbitrary functions on a convex body Ω⊂Rn\Omega \subset \mathbb{R}^n, not necessarily vanishing on the boundary ∂Ω\partial \Omega. This reduces the study of the Neumann Poincar\'e constant on Ω\Omega to that of the cone and Lebesgue measures on ∂Ω\partial \Omega; these may be bounded via the curvature of ∂Ω\partial \Omega. A second reduction is obtained to the class of harmonic functions on Ω\Omega. We also study the relation between the Poincar\'e constant of a log-concave measure ÎŒ\mu and its associated K. Ball body KÎŒK_\mu. In particular, we obtain a simple proof of a conjecture of Kannan--Lov\'asz--Simonovits for unit-balls of ℓpn\ell^n_p, originally due to Sodin and Lata{\l}a--Wojtaszczyk.Comment: 18 pages. Numbering of propositions, theorems, etc.. as appeared in final form in GAFA seminar note

    Enhanced corrosion protection of Epoxy/ZnO-NiO nanocomposite coatings on steel

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    ZnO-NiO nanocomposite with epoxy coating on mild steel has been fabricated by the sol–gel assisted method. The synthesized sample was used to study corrosion protection. The analysis was performed by electrochemical impedance spectroscopy in 3.5% NaCl solution. The structural and morphological characterization of the metal oxide nanocomposite was carried out using XRD and SEM with Energy Dispersive Absorption X-ray (EDAX) analysis. XRD reveals the ZnO-NiO (hexagonal and cubic) structure with an average ZnO-NiO crystallite size of 26 nm. SEM/EDAX analysis of the ZnO-NiO nanocomposite confirms that the chemical composition of the samples consists of: Zn (8.96 ± 0.11 wt.%), Ni (10.53 ± 0.19 wt.%) and O (80.51 ± 3.12 wt.%). Electrochemical Impedance Spectroscopy (EIS) authenticated that the corrosion resistance has improved for the nanocomposites of ZnO-NiO coated along with epoxy on steel in comparison to that of the pure epoxy-coated steelThis research was funded by the Undergraduate Research Experience Program project no. UREP24-133-2-036 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. This work was supported by the UREP grant # UREP24-133-2-036 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. The authors would like to thank the Central laboratory Unit (CLU), Qatar University, 2713, Doha, Qatar, for SEM with EDAX analysis facility.Scopu

    Phase Separation of Rigid-Rod Suspensions in Shear Flow

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    We analyze the behavior of a suspension of rigid rod-like particles in shear flow using a modified version of the Doi model, and construct diagrams for phase coexistence under conditions of constant imposed stress and constant imposed strain rate, among paranematic, flow-aligning nematic, and log-rolling nematic states. We calculate the effective constitutive relations that would be measured through the regime of phase separation into shear bands. We calculate phase coexistence by examining the stability of interfacial steady states and find a wide range of possible ``phase'' behaviors.Comment: 23 pages 19 figures, revised version to be published in Physical Review

    Epidermal Growth Factor–PEG Functionalized PAMAM-Pentaethylenehexamine Dendron for Targeted Gene Delivery Produced by Click Chemistry

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    Aim of this study was the site-specific conjugation of an epidermal growth factor (EGF)-polyethylene glycol (PEG) chain by click chemistry onto a poly(amido amine) (PAMAM) dendron, as a key step toward defined multifunctional carriers for targeted gene delivery. For this purpose, at first propargyl amine cored PAMAM dendrons with ester ends were synthesized. The chain terminal ester groups were then modified by oligoamines with different secondary amino densities. The oligoamine-modified PAMAM dendrons were well biocompatible, as demonstrated in cytotoxicity assays. Among the different oligoamine-modified dendrons, PAMAM-pentaethylenehexamine (PEHA) dendron polyplexes displayed the best gene transfer ability. Conjugation of PAMAM-PEHA dendron with PEG spacer was conducted via click reaction, which was performed before amidation with PEHA. The resultant PEG-PAMAM-PEHA copolymer was then coupled with EGF ligand. pDNA transfections in HuH-7 hepatocellular carcinoma cells showed a 10-fold higher efficiency with the polyplexes containing conjugated EGF as compared to the ligand-free ones, demonstrating the concept of ligand targeting. Overall gene transfer efficiencies, however, were moderate, suggesting that additional measures for overcoming subsequent intracellular bottlenecks in delivery have to be taken

    The regulatory subunit of PKA-I remains partially structured and undergoes ÎČ-aggregation upon thermal denaturation

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    Background: The regulatory subunit (R) of cAMP-dependent protein kinase (PKA) is a modular flexible protein that responds with large conformational changes to the binding of the effector cAMP. Considering its highly dynamic nature, the protein is rather stable. We studied the thermal denaturation of full-length RIα and a truncated RIα(92-381) that contains the tandem cyclic nucleotide binding (CNB) domains A and B. Methodology/Principal Findings: As revealed by circular dichroism (CD) and differential scanning calorimetry, both RIα proteins contain significant residual structure in the heat-denatured state. As evidenced by CD, the predominantly α-helical spectrum at 25°C with double negative peaks at 209 and 222 nm changes to a spectrum with a single negative peak at 212-216 nm, characteristic of ÎČ-structure. A similar α→ÎČ transition occurs at higher temperature in the presence of cAMP. Thioflavin T fluorescence and atomic force microscopy studies support the notion that the structural transition is associated with cross-ÎČ-intermolecular aggregation and formation of non-fibrillar oligomers. Conclusions/Significance: Thermal denaturation of RIα leads to partial loss of native packing with exposure of aggregation-prone motifs, such as the B' helices in the phosphate-binding cassettes of both CNB domains. The topology of the ÎČ-sandwiches in these domains favors inter-molecular ÎČ-aggregation, which is suppressed in the ligand-bound states of RIα under physiological conditions. Moreover, our results reveal that the CNB domains persist as structural cores through heat-denaturation. © 2011 Dao et al

    Peptide exchange on MHC-I by TAPBPR is driven by a negative allostery release cycle.

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    Chaperones TAPBPR and tapasin associate with class I major histocompatibility complexes (MHC-I) to promote optimization (editing) of peptide cargo. Here, we use solution NMR to investigate the mechanism of peptide exchange. We identify TAPBPR-induced conformational changes on conserved MHC-I molecular surfaces, consistent with our independently determined X-ray structure of the complex. Dynamics present in the empty MHC-I are stabilized by TAPBPR and become progressively dampened with increasing peptide occupancy. Incoming peptides are recognized according to the global stability of the final pMHC-I product and anneal in a native-like conformation to be edited by TAPBPR. Our results demonstrate an inverse relationship between MHC-I peptide occupancy and TAPBPR binding affinity, wherein the lifetime and structural features of transiently bound peptides control the regulation of a conformational switch located near the TAPBPR binding site, which triggers TAPBPR release. These results suggest a similar mechanism for the function of tapasin in the peptide-loading complex

    Some Results on Average-Case Hardness Within the Polynomial Hierarchy

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    Abstract. We prove several results about the average-case complexity of problems in the Polynomial Hierarchy (PH). We give a connection among average-case, worst-case, and non-uniform complexity of optimization problems. Specifically, we show that if P NP is hard in the worst-case then it is either hard on the average (in the sense of Levin) or it is non-uniformly hard (i.e. it does not have small circuits). Recently, Gutfreund, Shaltiel and Ta-Shma (IEEE Conference on Computational Complexity, 2005) showed an interesting worst-case to averagecase connection for languages in NP, under a notion of average-case hardness defined using uniform adversaries. We show that extending their connection to hardness against quasi-polynomial time would imply that NEXP doesn’t have polynomial-size circuits. Finally we prove an unconditional average-case hardness result. We show that for each k, there is an explicit language in P Σ2 which is hard on average for circuits of size n k.

    GAPS-megacities: A new global platform for investigating persistent organic pollutants and chemicals of emerging concern in urban air

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    A pilot study was initiated in 2018 under the Global Atmospheric Passive Sampling (GAPS) Network named GAPS-Megacities. This study included 20 megacities/major cities across the globe with the goal of better understanding and comparing ambient air levels of persistent organic pollutants and other chemicals of emerging concern, to which humans residing in large cities are exposed. The first results from the initial period of sampling are reported for 19 cities for several classes of flame retardants (FRs) including organophosphate esters (OPEs), polybrominated diphenyl ethers (PBDEs), and halogenated flame retardants (HFRs) including new flame retardants (NFRs), tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDD). The two cities, New York (USA) and London (UK) stood out with ∌3.5 to 30 times higher total FR concentrations as compared to other major cities, with total concentrations of OPEs of 15,100 and 14,100 pg/m, respectively. Atmospheric concentrations of OPEs significantly dominated the FR profile at all sites, with total concentrations in air that were 2–5 orders of magnitude higher compared to other targeted chemical classes. A moderately strong and significant correlation (r = 0.625, p < 0.001) was observed for Gross Domestic Product index of the cities with total OPEs levels. Although large differences in FR levels were observed between some cities, when averaged across the five United Nations regions, the FR classes were more evenly distributed and varied by less than a factor of five. Results for Toronto, which is a ‘reference city’ for this study, agreed well with a more in-depth investigation of the level of FRs over different seasons and across eight sites representing different urban source sectors (e.g. traffic, industrial, residential and background). Future sampling periods under this project will investigate trace metals and other contaminant classes, linkages to toxicology, non-targeted analysis, and eventually temporal trends. The study provides a unique urban platform for evaluating global exposome.A global study across 20 megacities/major cities reporting urban air concentrations of flame retardants and plasticizers.Authors thank the United Nations Environment Programme (UNEP) and the Chemicals Management Plan (CMP) for financial support. The worldwide implementation of the Global Monitoring Plan is made possible thanks to the generous contributions to the Stockholm Convention Voluntary Trust Fund from the Governments of Japan, Norway, Sweden, and through the European Commission’s Thematic Programme for Environment andSustainable Management of Natural Resources, including Energy (ENRTP). Further, the contribution of the projects to support POPs monitoring activities in regions, funded through the Global Environment Facility (GEF) and the Strategic Approach to International Chemicals Management (SAICM), is greatly acknowledged. Monitoring activities and data collection and analysis are implemented in the five UN regions in cooperation with strategic partners and through the involvement of Regional Organization Groups and Global Coordination Group. We also thank Yasuyuki Shibata and Yoshikatsu Takazawa (Tokyo, Japan); Juan Mu~noz-Arnanz (Madrid, Spain) and Dilek €Ozkan and Sinan Kızıltug (_Istanbul, Turkey) for their help and assistance in the sampling campaign
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