Showing papers by "Cairo University published in 2012"

Laser Scribing of High-Performance and Flexible Graphene-Based Electrochemical Capacitors

Abstract: Although electrochemical capacitors (ECs), also known as supercapacitors or ultracapacitors, charge and discharge faster than batteries, they are still limited by low energy densities and slow rate capabilities. We used a standard LightScribe DVD optical drive to do the direct laser reduction of graphite oxide films to graphene. The produced films are mechanically robust, show high electrical conductivity (1738 siemens per meter) and specific surface area (1520 square meters per gram), and can thus be used directly as EC electrodes without the need for binders or current collectors, as is the case for conventional ECs. Devices made with these electrodes exhibit ultrahigh energy density values in different electrolytes while maintaining the high power density and excellent cycle stability of ECs. Moreover, these ECs maintain excellent electrochemical attributes under high mechanical stress and thus hold promise for high-power, flexible electronics.

RegCM4 : model description and preliminary tests over multiple CORDEX domains

Abstract: A new version of the RegCM regional climate modeling system, RegCM4, has been recently developed and made available for public use. Compared to previous versions, RegCM4 includes new land surface, planetary boundary layer, and air–sea flux schemes, a mixed convection and tropical band configuration, modifications to the pre-existing radiative transfer and boundary layer schemes, and a full upgrade of the model code towards improved flexibility, portability, and user friendliness. The model can be interactively coupled to a 1D lake model, a simplified aerosol scheme (including organic carbon, black carbon, SO4, dust, and sea spray), and a gas phase chemistry module (CBM-Z). After a general description of the model, a series of test experiments are presented over 4 domains prescribed under the CORDEX framework (Africa, South America, East Asia, and Europe) to provide illustrative examples of the model behavior and sensitivities under different climatic regimes. These experiments indicate that, overall, RegCM4 shows an improved performance in several respects compared to previous versions, although further testing by the user community is needed to fully explore its sensitivities and range of applications.

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

Abstract: The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta)<2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.

A review and comparison of strategies for multi-step ahead time series forecasting based on the NN5 forecasting competition

Abstract: Multi-step ahead forecasting is still an open challenge in time series forecasting. Several approaches that deal with this complex problem have been proposed in the literature but an extensive comparison on a large number of tasks is still missing. This paper aims to fill this gap by reviewing existing strategies for multi-step ahead forecasting and comparing them in theoretical and practical terms. To attain such an objective, we performed a large scale comparison of these different strategies using a large experimental benchmark (namely the 111 series from the NN5 forecasting competition). In addition, we considered the effects of deseasonalization, input variable selection, and forecast combination on these strategies and on multi-step ahead forecasting at large. The following three findings appear to be consistently supported by the experimental results: Multiple-Output strategies are the best performing approaches, deseasonalization leads to uniformly improved forecast accuracy, and input selection is more effective when performed in conjunction with deseasonalization.

Patterning and Electronic Tuning of Laser Scribed Graphene for Flexible All-Carbon Devices

Abstract: Engineering a low-cost graphene-based electronic device has proven difficult to accomplish via a single-step fabrication process. Here we introduce a facile, inexpensive, solid-state method for generating, patterning, and electronic tuning of graphene-based materials. Laser scribed graphene (LSG) is shown to be successfully produced and selectively patterned from the direct laser irradiation of graphite oxide films under ambient conditions. Circuits and complex designs are directly patterned onto various flexible substrates without masks, templates, post-processing, transferring techniques, or metal catalysts. In addition, by varying the laser intensity and laser irradiation treatments, the electrical properties of LSG can be precisely tuned over 5 orders of magnitude of conductivity, a feature that has proven difficult with other methods. This inexpensive method for generating LSG on thin flexible substrates provides a mode for fabricating a low-cost graphene-based NO2 gas sensor and enables its use as a...

Early Administration of Low-Dose Aspirin for the Prevention of Preterm and Term Preeclampsia: A Systematic Review and Meta-Analysis

Abstract: Objective: To compare the effect of early administration of aspirin on the risk of preterm and term preeclampsia. Method: A systematic review and meta-analysis of randomized controlled trials were performed. Women who were randomized to low-dose aspirin or placebo/no treatment at or before 16 weeks of gestation were included. The outcomes of interest were preterm preeclampsia (delivery Results: The search identified 7,941 citations but only five trials on a combined total of 556 women fulfilled the inclusion criteria. When compared to controls, aspirin initiated ≤16 weeks of gestation was associated with a major reduction of the risk of preterm preeclampsia (RR 0.11, 95% CI 0.04–0.33) but had no significant effect on term preeclampsia (RR 0.98, 95% CI 0.42–2.33). Conclusion: Low-dose aspirin administrated at or before 16 weeks of gestation reduces the risk of preterm but not term preeclampsia.

Observation of sequential Υ suppression in PbPb collisions

Abstract: The suppression of the individual Υ(nS) states in PbPb collisions with respect to their yields in pp data has been measured. The PbPb and pp data sets used in the analysis correspond to integrated luminosities of 150 μb^(-1) and 230 nb^(-1), respectively, collected in 2011 by the CMS experiment at the LHC, at a center-of-mass energy per nucleon pair of 2.76 TeV. The Υ(nS) yields are measured from the dimuon invariant mass spectra. The suppression of the Υ(nS) yields in PbPb relative to the yields in pp, scaled by the number of nucleon-nucleon collisions, R_(AA), is measured as a function of the collision centrality. Integrated over centrality, the R_(AA) values are 0.56±0.08(stat)±0.07(syst), 0.12±0.04(stat)±0.02(syst), and lower than 0.10 (at 95% confidence level), for the Υ(1S), Υ(2S), and Υ(3S) states, respectively. The results demonstrate the sequential suppression of the Υ(nS) states in PbPb collisions at LHC energies.

Suppression of non-prompt J/ψ, prompt J/ψ, and Y(1S) in PbPb collisions at √s NN = 2.76 TeV

Abstract: Yields of prompt and non-prompt J/psi, as well as Y(1S) mesons, are measured by the CMS experiment via their dimuon decays in PbPb and pp collisions at sqrt(sNN) = 2.76 TeV for quarkonium rapidity |y|<2.4. Differential cross sections and nuclear modification factors are reported as functions of y and transverse momentum pt, as well as collision centrality. For prompt J/psi with relatively high pt (6.5

Effect of lead acetate toxicity on experimental male albino rat

Abstract: Objective To evaluate the effect of different doses of lead acetate (1/20, 1/40 and 1/60 of LD50) on body weight gain, blood picture, plasma protein profile and the function of liver, kidney and thyroid gland.

Induced Resistance by a Long-Chain Bacterial Volatile: Elicitation of Plant Systemic Defense by a C13 Volatile Produced by Paenibacillus polymyxa

Abstract: Background Some strains of plant growth-promoting rhizobacteria (PGPR) elicit induced systemic resistance (ISR) by emission of volatile organic compounds (VOCs) including short chain alcohols, acetoin, and 2,3-butanediol. The objective of this study was to evaluate whether species-specific VOCs from PGPR strain Paenibacillus polymyxa E681 can promote growth and induce resistance in Arabidopsis.

Search for dark matter and large extra dimensions in monojet events in pp collisions at √s = 7 TeV

Abstract: A search has been made for events containing an energetic jet and an imbalance in transverse momentum using a data sample of pp collisions at a center-of-mass energy of 7 TeV. This signature is common to both dark matter and extra dimensions models. The data were collected by the CMS detector at the LHC and correspond to an integrated luminosity of 5.0 inverse femtobarns. The number of observed events is consistent with the standard model expectation. Constraints on the dark matter-nucleon scattering cross sections are determined for both spin-independent and spin-dependent interaction models. For the spin-independent model, these are the most constraining limits for a dark matter particle with mass below 3.5 GeV, a region unexplored by direct detection experiments. For the spin-dependent model, these are the most stringent constraints over the 0.1-200 GeV mass range. The constraints on the Arkani-Hamed, Dimopoulos, and Dvali model parameter MD determined as a function of the number of extra dimensions are also an improvement over the previous results.

Search for a light charged Higgs boson in top quark decays in pp collisions at √s = 7 TeV

Abstract: Results are presented on a search for a light charged Higgs boson that can be produced in the decay of the top quark to charged H and b quark and which, in turn, decays into tau and tau neutrino. The analysed data correspond to an integrated luminosity of about 2 inverse femtobarns recorded in proton-proton collisions at sqrt(s) = 7 TeV by the CMS experiment at the LHC. The search is sensitive to the decays of the top quark pairs t anti-t to charged Higgs W b anti-b and t anti-t to charged Higgs b anti-b. Various final states have been studied separately, all requiring presence of a tau lepton from charged Higgs decays, missing transverse energy, and multiple jets. Upper limits on the branching fraction B(t to charged Higgs b) in the range of 2-3% are established for charged Higgs boson masses between 80 and 160 GeV, under the assumption that B(charged Higgs to tau anti-tau neutrino) = 1.

Measurement of the single-top-quark t-channel cross section in pp collisions at √s=7 TeV

Abstract: A measurement of the single-top-quark t-channel production cross section in pp collisions at s√=7 TeV with the CMS detector at the LHC is presented. Two different and complementary approaches have been followed. The first approach exploits the distributions of the pseudorapidity of the recoil jet and reconstructed top-quark mass using background estimates determined from control samples in data. The second approach is based on multivariate analysis techniques that probe the compatibility of the candidate events with the signal. Data have been collected for the muon and electron final states, corresponding to integrated luminosities of 1.17 and 1.56 fb^(−1), respectively. The single-top-quark production cross section in the t-channel is measured to be 67.2±6.1 pb, in agreement with the approximate next-to-next-to-leading-order standard model prediction. Using the standard model electroweak couplings, the CKM matrix element |V_(tb)| is measured to be 1.020 ± 0.046 (meas.) ± 0.017 (theor.).

Bioremoval capacity of three heavy metals by some microalgae species (Egyptian Isolates).

Abstract: Three fresh water microalgal isolates [Phormidium ambiguum (Cyanobacterium), Pseudochlorococcum typicum and Scenedesmus quadricauda var quadrispina (Chlorophyta)] were tested for tolerance and removal of mercury (Hg2+), lead (Pb2+) and cadmium (Cd2+) in aqueous solutions as a single metal species at conc. 5–100 mg / L under controled laboratory conditions. The obtained results showed that Hg2+ was the most toxic of the three metal ions to the test algae even at low concentration (

Centrality dependence of dihadron correlations and azimuthal anisotropy harmonics in PbPb collisions at √SNN = 2.76 Tev

Abstract: Measurements from the CMS experiment at the LHC of dihadron correlations for charged particles produced in PbPb collisions at a nucleon-nucleon centre-of-mass energy of 2.76 TeV are presented. The results are reported as a function of the particle transverse momenta (pt) and collision centrality over a broad range in relative pseudorapidity [Delta(eta)] and the full range of relative azimuthal angle [Delta(phi)]. The observed two-dimensional correlation structure in Delta(eta) and Delta(phi) is characterised by a narrow peak at Delta(eta), Delta(phi) approximately (0, 0) from jet-like correlations and a long-range structure that persists up to at least |Delta(eta)| = 4. An enhancement of the magnitude of the short-range jet peak is observed with increasing centrality, especially for particles of pt around 1-2 GeV/c. The long-range azimuthal dihadron correlations are extensively studied using a Fourier decomposition analysis. The extracted Fourier coefficients are found to factorise into a product of single-particle azimuthal anisotropies up to pt approximately 3-3.5 GeV/c for at least one particle from each pair, except for the second-order harmonics in the most central PbPb events. Various orders of the single-particle azimuthal anisotropy harmonics are extracted for associated particle pt of 1-3 GeV/c, as a function of the trigger particle pt up to 20 GeV/c and over the full centrality range.

Measurement of the rapidity and transverse momentum distributions of Z bosons in pp collisions at √(s)=7TeV

Abstract: Measurements of the normalized rapidity (y) and transverse momentum (qT) distributions of Drell-Yan muon and electron pairs in the Z-boson mass region (60

Licorice abuse: time to send a warning message

Abstract: Licorice extract has always been recognized as a sweetener and a thirst quencher. Its nutritive value is overrated by many who consume significant amounts and are prone to complications. Glycyrrhetic acid, the active metabolite in licorice, inhibits the enzyme 11-s-hydroxysteroid dehydrogenase enzyme type 2 with a resultant cortisol-induced mineralocorticoid effect and the tendency towards the elevation of sodium and reduction of potassium levels. This aldosterone-like action is the fundamental basis for understanding its health benefits and the wide spectrum of adverse effects. Herein, we present a comprehensive review of licorice along with the reported complications related to excess intake. Despite its apparent use in a few clinical scenarios, the daily consumption of licorice is never justified because its benefits are minor compared to the adverse outcomes of chronic consumption. The review highlights the importance of investigating the dietary habits and herbal remedies which are being used worldwide on cultural and habitual bases rather than reliable scientific evidence. Licorice is a US Food and Drug Administration (FDA) approved food supplement used in many products without precise regulations to prevent toxicity. Increased awareness among the public is required through TV commercials, newspapers, internet sites, magazines and product labels regarding the upper limit of ingestion and health hazards associated with excess intake. We hope that this review will serve as a warning message that should be transmitted from physicians to patients to avoid excessive licorice intake as well as a message to the FDA to start regulating the use of this substance.

SEED Servers: High-Performance Access to the SEED Genomes, Annotations, and Metabolic Models

Abstract: The remarkable advance in sequencing technology and the rising interest in medical and environmental microbiology, biotechnology, and synthetic biology resulted in a deluge of published microbial genomes. Yet, genome annotation, comparison, and modeling remain a major bottleneck to the translation of sequence information into biological knowledge, hence computational analysis tools are continuously being developed for rapid genome annotation and interpretation. Among the earliest, most comprehensive resources for prokaryotic genome analysis, the SEED project, initiated in 2003 as an integration of genomic data and analysis tools, now contains >5,000 complete genomes, a constantly updated set of curated annotations embodied in a large and growing collection of encoded subsystems, a derived set of protein families, and hundreds of genome-scale metabolic models. Until recently, however, maintaining current copies of the SEED code and data at remote locations has been a pressing issue. To allow high-performance remote access to the SEED database, we developed the SEED Servers (http://www.theseed.org/servers): four network-based servers intended to expose the data in the underlying relational database, support basic annotation services, offer programmatic access to the capabilities of the RAST annotation server, and provide access to a growing collection of metabolic models that support flux balance analysis. The SEED servers offer open access to regularly updated data, the ability to annotate prokaryotic genomes, the ability to create metabolic reconstructions and detailed models of metabolism, and access to hundreds of existing metabolic models. This work offers and supports a framework upon which other groups can build independent research efforts. Large integrations of genomic data represent one of the major intellectual resources driving research in biology, and programmatic access to the SEED data will provide significant utility to a broad collection of potential users.

Biochemical changes in phenols, flavonoids, tannins, vitamin E, β-carotene and antioxidant activity during soaking of three white sorghum varieties.

Abstract: Objective To investigate the changes in total phenols, flavonoids, tannins, vitamin E, β-carotene and antioxidant activity during soaking of three white sorghum varieties.

Fractional-Order RC and RL Circuits

Abstract: This paper is a step forward to generalize the fundamentals of the conventional RC and RL circuits in fractional-order sense. The effect of fractional orders is the key factor for extra freedom, more flexibility, and novelty. The conditions for RC and RL circuits to act as pure imaginary impedances are derived, which are unrealizable in the conventional case. In addition, the sensitivity analyses of the magnitude and phase response with respect to all parameters showing the locations of these critical values are discussed. A qualitative revision for the fractional RC and RL circuits in the frequency domain is provided. Numerical and PSpice simulations are included to validate this study

An Unmanned Aerial Vehicle-Based Imaging System for 3D Measurement of Unpaved Road Surface Distresses1

Abstract: :i¾?Road condition data are important in transportation management systems. Over the last decades, significant progress has been made and new approaches have been proposed for efficient collection of pavement condition data. However, the assessment of unpaved road conditions has been rarely addressed in transportation research. Unpaved roads constitute approximately 40% of the U.S. road network, and are the lifeline in rural areas. Thus, it is important for timely identification and rectification of deformation on such roads. This article introduces an innovative Unmanned Aerial Vehicle UAV-based digital imaging system focusing on efficient collection of surface condition data over rural roads. In contrast to other approaches, aerial assessment is proposed by exploring aerial imagery acquired from an unpiloted platform to derive a three-dimensional 3D surface model over a road distress area for distress measurement. The system consists of a low-cost model helicopter equipped with a digital camera, a Global Positioning System GPS receiver and an Inertial Navigation System INS, and a geomagnetic sensor. A set of image processing algorithms has been developed for precise orientation of the acquired images, and generation of 3D road surface models and orthoimages, which allows for accurate measurement of the size and the dimension of the road surface distresses. The developed system has been tested over several test sites with roads of various surface distresses. The experiments show that the system is capable for providing 3D information of surface distresses for road condition assessment. Experiment results demonstrate that the system is very promising and provides high accuracy and reliable results. Evaluation of the system using 2D and 3D models with known dimensions shows that subcentimeter measurement accuracy is readily achieved. The comparison of the derived 3D information with the onsite manual measurements of the road distresses reveals differences of 0.50 cm, demonstrating the potential of the presented system for future practice.

Performance of τ-lepton reconstruction and identification in CMS

Abstract: The performance of tau-lepton reconstruction and identification algorithms is studied using a data sample of proton-proton collisions at sqrt(s)=7 TeV, corresponding to an integrated luminosity of 36 inverse picobarns collected with the CMS detector at the LHC. The tau leptons that decay into one or three charged hadrons, zero or more short-lived neutral hadrons, and a neutrino are identified using final-state particles reconstructed in the CMS tracker and electromagnetic calorimeter. The reconstruction efficiency of the algorithms is measured using tau leptons produced in Z-boson decays. The tau-lepton misidentification rates for jets and electrons are determined.

Measurement of jet fragmentation into charged particles in pp and PbPb collisions at √sNN=2.76 TeV

Abstract: Jet fragmentation in pp and PbPb collisions at a centre-of-mass energy of 2.76 TeV per nucleon pair was studied using data collected with the CMS detector at the LHC. Fragmentation functions are constructed using charged-particle tracks with transverse momenta pt > 4 GeV for dijet events with a leading jet of pt > 100 GeV. The fragmentation functions in PbPb events are compared to those in pp data as a function of collision centrality, as well as dijet-pt imbalance. Special emphasis is placed on the most central PbPb events including dijets with unbalanced momentum, indicative of energy loss of the hard scattered parent partons. The fragmentation patterns for both the leading and subleading jets in PbPb collisions agree with those seen in pp data at 2.76 TeV. The results provide evidence that, despite the large parton energy loss observed in PbPb collisions, the high-pt component of the fragmentation function evaluated with respect to the reconstructed jet momentum is not strongly modified in comparison to jet fragmentation in vacuum.