Search Constraints
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Search Results
- Creator:
- Hall, Raymond E. and D0 Collaboration
- Description:
- A search for direct production of scalar bottom quarks ((b) over bar) is performed with 310 pb(-1) of data collected by the D0 experiment in p (p) over bar collisions at root s = 1.96 TeV at the Fermilab Tevatron Collider. The topology analyzed consists of two b jets and an imbalance in transverse momentum due to undetected neutralinos (chi(0)(1)), with chi(0)(1) assumed to be the lightest supersymmetric particle. We find the data consistent with standard model expectations, and set a 95% C.L. exclusion domain in the (m(b), m(chi 1)(0)) mass plane, improving significantly upon the results from run I of the Tevatron.
- Resource Type:
- Article
- Identifier:
- Publisher version: dx.doi.org/10.1103/PhysRevLett.97.171806
- Campus Tesim:
- Fresno
- Creator:
- Gao, Yongsheng and ATLAS Collaboration
- Description:
- The relationship between jet production in the central region and the underlying-event activity in a pseudorapidity-separated region is studied in 4.0 pb(-1) of root s = 2.76 TeV pp collision data recorded with the ATLAS detector at the LHC. The underlying event is characterised through measurements of the average value of the sum of the transverse energy at large pseudorapidity downstream of one of the protons, which are reported here as a function of hard-scattering kinematic variables. The hard scattering is characterised by the average transverse momentum and pseudorapidity of the two highest transverse momentum jets in the event. The dijet kinematics are used to estimate, on an event-by-event basis, the scaled longitudinal momenta of the hard-scattered partons in the target and projectile beam-protons moving toward and away from the region measuring transverse energy, respectively. Transverse energy production at large pseudorapidity is observed to decrease with a linear dependence on the longitudinal momentum fraction in the target proton and to depend only weakly on that in the projectile proton. The results are compared to the predictions of various Monte Carlo event generators, which qualitatively reproduce the trends observed in data but generally underpredict the overall level of transverse energy at forward pseudorapidity.
- Resource Type:
- Article
- Identifier:
- Publisher version: http://dx.doi.org/10.1016/j.physletb.2016.02.056
- Campus Tesim:
- Fresno
- Creator:
- Mahalik, Nitaigour and Kim, Kiseon
- Description:
- This paper presents work on retrofitting of high-tech systems (HTS) in land-based aquaculture system for improving production efficiency. The objective is to develop architecture for an automated system for aquaculture farming. We call this development an automated expert system architecture (AESA). The article has been organized into four parts. First, it reviews the background and business opportunity on aquaculture, which includes fish and seaweed farming. We have proposed a six-layer model for the development of a fully contained total automation system along with approaches and methods. The developed software platform was tested with a laboratory based demonstration rig.
- Resource Type:
- Article
- Identifier:
- doi: 10.1080/02564602.2014.892752
- Campus Tesim:
- Fresno
- Creator:
- Dansby, Robin E. and Attard, Thomas L.
- Description:
- A control nonlinear time-history analysis program, dubbed CONON, was developed to simulate the stress-strain responses of structural members and to compute the optimal control forces per time step. The minimization of the cost function is independent of weighing matrices, thus alleviating cumbersome calculations that also lack physical description. Instead, an iterative Riccati matrix is computed per time step and is used to generate the evolutionary gain for the system leading to an appropriate evolution of the state transition between time steps. The calculated control responses are compared to uncontrolled responses. The results are also compared using various methods of gain calculation by examining the force-deflection hysteresis plots, the strain energy dissipation in the structural members, and the member accelerations of a steel frame. The proposed optimal system shows an excellent capability to control the desired target responses and meet acceptable performance objectives. An evolutionary gain formulation is proposed for minimizing the performance damage index of steel buildings subjected to earthquake forces. The gain formulation herein is used to develop the evolutionary control law of a control algorithm applied to inelastic systems. The optimal evolutionary gain is subsequently used to control building damages by satisfying desired performance objectives per time step "as needed". The performance objectives are defined for various "damage-safe" and elastic demands. When the structure responds in the post-yield (inelastic) state, the material is assumed to follow a kinematic rule for strain hardening, which consequently may redefine the performance objective window at each unload/reload response state (cyclic control).
- Resource Type:
- Article
- Identifier:
- dx.doi.org/10.2140/jomms.2009.4.855
- Campus Tesim:
- Fresno
- Creator:
- Gao, Yongsheng and ATLAS Collaboration
- Description:
- We report a search for first generation scalar leptoquarks using 1.03 fb(-1) of proton-proton collisions data produced by the Large Hadron Collider at root s = 7 TeV and recorded by the ATLAS experiment. Leptoquarks are sought via their decay into an electron or neutrino and a quark, producing events with two oppositely charged electrons and at least two jets, or events with an electron, missing transverse momentum and at least two jets. Control data samples are used to validate background predictions from Monte Carlo simulation. In the signal region, the observed event yields are consistent with the background expectations. We exclude at 95% confidence level the production of first generation scalar leptoquark with masses m(LQ) < 660 (607) GeV when assuming the branching fraction of a leptoquark to a charged lepton is equal to 1.0 (0.5).
- Resource Type:
- Article
- Identifier:
- Publisher version: http://dx.doi.org/10.1016/j.physletb.2012.02.004
- Campus Tesim:
- Fresno
- Creator:
- Gao, Yongsheng and ATLAS Collaboration
- Description:
- Measurements of differential production cross-sections of a Z boson in association with b-jets in pp collisions at root s = 7 TeV are reported. The data analysed correspond to an integrated luminosity of 4.6 fb(-1) recorded with the ATLAS detector at the Large Hadron Collider. Particle-level cross-sections are determined for events with a Z boson decaying into an electron or muon pair, and containing b-jets. For events with at least one b-jet, the cross-section is presented as a function of the Z boson transverse momentum and rapidity, together with the inclusive b-jet cross-section as a function of b-jet transverse momentum, rapidity and angular separations between the b-jet and the Z boson. For events with at least two b-jets, the cross-section is determined as a function of the invariant mass and angular separation of the two highest transverse momentum b-jets, and as a function of the Z boson transverse momentum and rapidity. Results are compared to leading-order and next-to-leading-order perturbative QCD calculations.
- Resource Type:
- Article
- Identifier:
- Publisher version: http://dx.doi.org/10.1007/JHEP10(2014)141
- Campus Tesim:
- Fresno
- Creator:
- Ringwald, Frederick, Still, K., and Mukai, K.
- Description:
- DQ Herculis (Nova Herculis 1934) is a deeply eclipsing cataclysmic variable containing a magnetic white dwarf primary.The accretion disk is thought to block our line of sight to the white dwarf at all orbital phases due to its extreme inclination angle. Nevertheless, soft X-rays were detected from DQ Her with ROSAT PSPC. To probe the origin of these soft X-rays, we have performed Chandra ACIS observations. We confirm that DQ Her is an X-ray source. The bulk of the rays are from a point-like source and exhibit a shallow partial eclipse. We interpret this as due to scattering of the unseen central X-ray source, probably in an accretion disk wind. At the same time, we detect weak extended X-ray features around DQ Her, which we interpret as an X-ray emitting knot in the nova shell.
- Resource Type:
- Article
- Identifier:
- Publisher version: http://dx.doi.org/10.1086/376752
- Campus Tesim:
- Fresno
- Creator:
- Müller, Ulrike K., Cao, Yu, Mekdara, Nalong Tom, Yingst, Nicholas, Goto, Joy June, Choudhury, Songita, Berg, Otto, and Mekdara, Prasong Jerry
- Description:
- Drosophila melanogaster has become an important invertebrate model organism in biological and medical research, for mutational and genetic analysis, and in toxicological screening. Many screening assays have been developed that assess the flies’ mortality, reproduction, development, morphology, or behavioral competence. In this study, we describe a new assay for locomotor competence. It comprises a circular walking arena with a lenticular floor and a flat cover (the slope of the floor increases gradually from the center to the edge of the arena) plus automated fly tracking and statistical analysis. This simple modification of a flat arena presents a graduated physical challenge, with which we can assess fine gradations of motor ability, since a fly’s time average radial distance from the arena center is a direct indicator of its climbing ability. The time averaged distribution of flies as a function of slope, activity levels, and walking speed, yields a fine grained picture of locomotory ability and motivation levels. We demonstrate the strengths and weaknesses of this assay (compared with a conventional tap-down test) by observing flies treated with a neurotoxin (BMAA) that acts as a glutamate agonist. The assay proves well suited to detect dose effects and progression effects with higher statistical power than the traditional tap-down, but it has a higher detection limit, making it less sensitive to treatment effects.
- Resource Type:
- Article
- Identifier:
- doi: 10.1002/jez.1731
- Campus Tesim:
- Fresno