2,428 research outputs found

    Standard Model H→ZZ(∗)→ℓℓℓℓH\rightarrow ZZ^{(*)}\rightarrow \ell\ell\ell\ell, ℓℓνν\ell\ell\nu\nu, ℓℓqq\ell\ell qq Searches with ATLAS at the LHC

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    The latest results on the direct experimental search for a Standard Model Higgs boson decaying to a pair of Z bosons are presented. Three distinct final states are considered: H→ZZ(∗)→ℓℓℓℓH\rightarrow ZZ^{(*)}\rightarrow \ell\ell\ell\ell, H→ZZ→ℓℓννH\rightarrow ZZ\rightarrow \ell\ell\nu\nu, and H→ZZ→ℓℓqqH\rightarrow ZZ\rightarrow \ell\ell qq, where ℓ=e,μ\ell = e, \mu. A dataset of more than 1fb−1^{-1} of proton-proton collisions at s=7\sqrt{s} = 7 TeV collected by the ATLAS detector at the CERN LHC during the on-going 2011 run is used. In this model and for these final states, Higgs boson masses in the ranges 192 GeV <mH<< m_H < 196 GeV, 214 <mH< < m_H < 222 GeV, and 340 <mH<< m_H < 460 GeV have been excluded at the 95% confidence level.Comment: 3 pages, 4 figures, PIC 2011, XXXI PHYSICS IN COLLISION, Vancouver, BC Canada, August 28 - September 1, 201

    Improved Bandwidth Carbon Fiber Reinforced Plastic Structural Antenna Design for near-HF Remote Sensing Applications

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    This work presents an improved bandwidth antenna design for the HF Sounder radar installed on a Twin Otter. This is achieved by replacing the original steel tube dipole antenna with a larger and more aerodynamic carbon fiber reinforced plastic (CFRP) antenna. CFRP is a sufficiently conductive material and its density is about 20% the density of 4130-steel, so by replacing the original steel design with a CFRP design, a larger antenna can be supported, resulting in an expected wider operational bandwidth. Initially several aerodynamic cross-sections are considered for the larger antenna, and a trade study is performed to compare the various designs to the original tube design. This trade study considers electrical performance (specifically bandwidth), implications to aircraft range, and assessment of the structural design. From the initial trade study, two aerodynamic shapes are considered for further assessment—an ellipse with a t/c ratio of 0.33 and a NACA 0024 airfoil. Based on this study, a 2 in. x 8 in. NACA 0024 antenna is manufactured and physically tested. Experimental electrical testing has verified that the newly developed CFRP antenna works as simulated and has 1.7 times improved bandwidth compared to the tube antenna. The airfoil antenna design is expected to improve the bandwidth, is expected to improve the vehicle range, and initial sizing suggests that the structural concept is feasible

    Toward scalable stochastic unit commitment. Part 1: load scenario generation

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    Unit commitment decisions made in the day-ahead market and during subsequent reliability assessments are critically based on forecasts of load. Tra- ditional, deterministic unit commitment is based on point or expectation-based load forecasts. In contrast, stochastic unit commitment relies on multiple load sce- narios, with associated probabilities, that in aggregate capture the range of likely load time-series. The shift from point-based to scenario-based forecasting necessi- tates a shift in forecasting technologies, to provide accurate inputs to stochastic unit commitment. In this paper, we discuss a novel scenario generation method- ology for load forecasting in stochastic unit commitment, with application to real data associated with the Independent System Operator for New England (ISO- NE). The accuracy of the expected scenario generated using our methodology is consistent with that of point forecasting methods. The resulting sets of realistic scenarios serve as input to rigorously test the scalability of stochastic unit com- mitment solvers, as described in the companion paper. The scenarios generated by our method are available as an online supplement to this paper, as part of a novel, publicly available large-scale stochastic unit commitment benchmark

    Battery-operated Independent Radiation Detector Data Report from Exploration Flight Test 1

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    Citation: Bahadori AA, Semones EJ, Gaza R, Kroupa M, Rios RR, Stoffle NN, Campbell-Ricketts T, Pinsky LS, and Turecek D 2015 Battery-operated Independent Radiation Detector Data Report from Exploration Flight Test 1 NASA/TP-2015-218575 NASA Johnson Space Center: Houston, TX http://ston.jsc.nasa.gov/collections/TRS/397.refer.htmlThis report summarizes the data acquired by the Battery-operated Independent Radiation Detector (BIRD) during Exploration Flight Test 1 (EFT-1). The BIRD, consisting of two redundant subsystems isolated electronically from the Orion Multi-Purpose Crew Vehicle (MPCV), was developed to fly on the Orion EFT-1 to acquire radiation data throughout the mission. The BIRD subsystems successfully triggered using on-board accelerometers in response to launch accelerations, acquired and archived data through landing, and completed the shut down routine when battery voltage decreased to a specified value. The data acquired are important for understanding the radiation environment within the Orion MPCV during transit through the trapped radiation belts

    Enhancing Quantum Dot Solar Cells Stability with a Semiconducting Single-Walled Carbon Nanotubes Interlayer Below the Top Anode

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    Semiconducting single-walled carbon nanotubes (s-SWNTs) are used as a protective interlayer between the lead sulfide colloidal quantum dot (PbS CQD) active layer and the anode of the solar cells (SCs). The introduction of the carbon nanotubes leads to increased device stability, with 85% of the initial performance retained after 100 h exposure to simulated solar light in ambient condition. This is in sharp contrast with the behavior of the device without s-SWNTs, for which the photoconversion efficiency, the open circuit voltage, the short-circuit current, and the fill factor all experiencing a sharp decrease. Therefore, the inclusion of s-SWNT as interlayer in CQD SCs, give rise to SCs of identical efficiency (above 8.5%) and prevents their performance degradation

    Ageless Aluminum-Cerium-Based Alloys in High-Volume Die Casting for Improved Energy Efficiency

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    Strong chemical reactions between Al and Ce lead to the formation of intermetallics with exceptional thermal stability. The rapid formation of intermetallics directly from the liquid phase during solidification of Al-Ce alloys leads to an ultrafine microconstituent structure that effectively strengthens as-cast alloys without further microstructural optimization via thermal processing. Die casting is a high-volume manufacturing technology that accounts for greater than 40% of all cast Al products, whereas Ce is highly overproduced as a waste product of other rare earth element (REE) mining. Reducing heat treatments would stimulate significant improvements in manufacturing energy efficiency, exceeding (megatonnes/year) per large-scale heat-treatment line. In this study, multiple compositions were evaluated with wedge mold castings to test the sensitivity of alloys to the variable solidification rate inherent in high-pressure die casting. Once a suitable composition was determined, it was successfully demonstrated at 800 lbs/h in a 600-ton die caster, after which the as-die cast parts performed similarly to ubiquitous A380 in the same geometry without requiring heat treatment. This work demonstrates the compatibility of Al REE alloys with high-volume die-casting applications with minimal heat treatments

    The cartilage matrisome in adolescent idiopathic scoliosis

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    The human spinal column is a dynamic, segmented, bony, and cartilaginous structure that protects the neurologic system and simultaneously provides balance and flexibility. Children with developmental disorders that affect the patterning or shape of the spine can be at risk of neurologic and other physiologic dysfunctions. The most common developmental disorder of the spine is scoliosis, a lateral deformity in the shape of the spinal column. Scoliosis may be part of the clinical spectrum that is observed in many developmental disorders, but typically presents as an isolated symptom in otherwise healthy adolescent children. Adolescent idiopathic scoliosis (AIS) has defied understanding in part due to its genetic complexity. Breakthroughs have come from recent genome-wide association studies (GWAS) and next generation sequencing (NGS) of human AIS cohorts, as well as investigations of animal models. These studies have identified genetic associations with determinants of cartilage biogenesis and development of the intervertebral disc (IVD). Current evidence suggests that a fraction of AIS cases may arise from variation in factors involved in the structural integrity and homeostasis of the cartilaginous extracellular matrix (ECM). Here, we review the development of the spine and spinal cartilages, the composition of the cartilage ECM, the so-called "matrisome" and its functions, and the players involved in the genetic architecture of AIS. We also propose a molecular model by which the cartilage matrisome of the IVD contributes to AIS susceptibility

    Annual Clovers Around the World: Current Status and Future Prospects

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    This paper reviews the distribution and importance of annual clover (Trifolium) species for pasture and fodder production systems globally. Of the 158 recorded annual Trifolium species, 65.2% are endemic to the Mediterranean basin and surrounding areas, 14.6% to sub-Saharan Africa, 17.7% to the United States of America and 2.5% to Chile. Fourteen species have been commercialised, while other endemic and naturalised annual clovers are also utilised. Key species for self-regenerating pastures include T. subterraneum, T. michelianum and T. respinatum var. resupinatum, while major dual-purpose grazing and fodder species include T. incarnatum, T. vesiculosum, T. alexandrinum and T. respinatum var. majus. Less important commercial species include T. hirtum, T. squarrosum, T. nigrescens and T. cherleri. Australian scientists have also recently domesticated T. glanduliferum, T. spumosum, T. purpureum and T. dasyurum. The areas sown to annual clovers may increase in future years, due to increasing nitrogen (N) fertiliser costs, environmental concerns with N runoff. Climate change brings new challenges and opportunities for annual clovers. The forage plant genetic resource centres will be crucial for developing new adapted cultivars

    First survey of centimeter-scale AC-LGAD strip sensors with a 120 GeV proton beam

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    We present the first beam test results with centimeter-scale AC-LGAD strip sensors, using the Fermilab Test Beam Facility and sensors manufactured by the Brookhaven National Laboratory. Sensors of this type are envisioned for applications that require large-area precision 4D tracking coverage with economical channel counts, including timing layers for the Electron Ion Collider (EIC), and space-based particle experiments. A survey of sensor designs is presented, with the aim of optimizing the electrode geometry for spatial resolution and timing performance. Several design considerations are discussed towards maintaining desirable signal characteristics with increasingly larger electrodes. The resolutions obtained with several prototypes are presented, reaching simultaneous 18 micron and 32 ps resolutions from strips of 1 cm length and 500 micron pitch. With only slight modifications, these sensors would be ideal candidates for a 4D timing layer at the EIC
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