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  1. Free, publicly-accessible full text available January 1, 2023
  2. Abstract The accurate simulation of additional interactions at the ATLAS experiment for the analysis of proton–proton collisions delivered by the Large Hadron Collider presents a significant challenge to the computing resources. During the LHC Run 2 (2015–2018), there were up to 70 inelastic interactions per bunch crossing, which need to be accounted for in Monte Carlo (MC) production. In this document, a new method to account for these additional interactions in the simulation chain is described. Instead of sampling the inelastic interactions and adding their energy deposits to a hard-scatter interaction one-by-one, the inelastic interactions are presampled, independent of the hardmore »scatter, and stored as combined events. Consequently, for each hard-scatter interaction, only one such presampled event needs to be added as part of the simulation chain. For the Run 2 simulation chain, with an average of 35 interactions per bunch crossing, this new method provides a substantial reduction in MC production CPU needs of around 20%, while reproducing the properties of the reconstructed quantities relevant for physics analyses with good accuracy.« less
    Free, publicly-accessible full text available December 1, 2023
  3. Abstract The ATLAS experiment at the Large Hadron Collider has a broad physics programme ranging from precision measurements to direct searches for new particles and new interactions, requiring ever larger and ever more accurate datasets of simulated Monte Carlo events. Detector simulation with Geant4 is accurate but requires significant CPU resources. Over the past decade, ATLAS has developed and utilized tools that replace the most CPU-intensive component of the simulation—the calorimeter shower simulation—with faster simulation methods. Here, AtlFast3, the next generation of high-accuracy fast simulation in ATLAS, is introduced. AtlFast3 combines parameterized approaches with machine-learning techniques and is deployed tomore »meet current and future computing challenges, and simulation needs of the ATLAS experiment. With highly accurate performance and significantly improved modelling of substructure within jets, AtlFast3 can simulate large numbers of events for a wide range of physics processes.« less
    Free, publicly-accessible full text available December 1, 2023
  4. Destruction of pharmaceuticals excreted in urine can be an efficient approach to eliminate these environmental pollutants. However, urine contains high concentrations of chloride, ammonium, and bicarbonate, which may hinder treatment processes. This study evaluated the application of ferrate(VI) (FeVIO42-, Fe(VI)) to oxidize pharmaceuticals (carbamazepine (CBZ), naproxen (NAP), trimethoprim (TMP) and sulfonamide antibiotics (SAs)) in synthetic hydrolyzed human urine and uncovered new effects from urine’s major inorganic constituents. Chloride slightly decreased pharmaceuticals’ removal rate by Fe(VI) due to the ionic strength effect. Ammonium (0.5 M) in undiluted hydrolyzed urine posed a strong scavenging effect, but lower concentrations (≤ 0.25 M) ofmore »ammonium enhanced the pharmaceuticals’ degradation by 300 µM Fe(VI), likely due to the reactive ammonium complex form of Fe(V)/Fe(IV). For the first time, bicarbonate was found to significantly promote the oxidation of aniline-containing SAs by Fe(VI) and alter the reaction stoichiometry of Fe(VI) and SA from 4:1 to 3:1. In-depth investigation indicated that bicarbonate not only changed the Fe(VI):SA complexation ratio from 1:2 to 1:1, but provided stabilizing effect for Fe(V) intermediate formed in situ, enabling its degradation of SAs. Overall, results of this study suggested that Fe(VI) is a promising oxidant for the removal of pharmaceuticals in hydrolyzed urine.« less
  5. An extruded AZ31B (Mg-3Al-1Zn-0.5Mn) magnesium alloy with a twin volume fraction of 60% was subjected to fully reversed strain-controlled tension-compression along the extrusion direction at strain amplitudes ranging from 0.23% to 0.45%. Dislocation slips were the dominant plastic deformation mechanisms without involving persistent twinning-detwinning. At an identical strain amplitude, the fatigue life of the pre-twinned alloy was much lower than that of the as-extruded alloy. Fatigue cracks were mainly initiated on the prismatic or prismatic-basal slip bands in the parent grains. The material volume reduction of the parent grains in the pre-twinned alloy enhanced fatigue damage. Twin cracks were notmore »observed.« less
  6. This paper presents ferrate(VI) (FeVIO42-, FeVI) oxidation of a wide range of sulfonamide antibiotics (SAs) containing five- and six-membered heterocyclic moieties (R) in their molecular structures. Kinetics measurements of the reactions between FeVI and SAs at different pH (6.5 – 10.0) give species-specific second-order rate constants, k5 and k6 of the reactions of protonated FeVI (HFeO4-) and unprotonated FeVI (FeVIO42-) with protonated SAs (HX), respectively. The values of k5 varied from (1.2 ± 0.1) × 103 to (2.2 ± 0.2) × 104 M-1 s-1, while the range of k6 was from (1.1 ± 0.1) × 102 to (1.0 ± 0.1)more »× 103 M-1 s-1 for different SAs. The transformation products of reaction between FeVI and sulfadiazine (SDZ, contains a six-membered R) include SO2 extrusion oxidized products (OPs) and aniline hydroxylated products. Comparatively, oxidation of sulfisoxazole (SIZ, a five-membered R) by FeVI has OPs that have no SO2 extrusion in their structures. Density functional theory (DFT) calculations are performed to demonstrate SO2 extrusion in oxidation of SDZ by FeVI. The detailed mechanisms of oxidation are proposed to describe the differences in the oxidation of six- and five-membered heterocyclic moieties (R) containing SAs (i.e., SDZ versus SIZ) by FeVI.« less
  7. The electrically pumped vertical-cavity surface- emitting laser (VCSEL) was first demonstrated with metal cavities by Iga (1979); however, the device threshold current was too high. Distributed Bragg reflector cavities proposed by Scifres and Burnham (1975) were adopted to improve the optical cavity loss. Yet, it was not a practical use until the discovery of the native oxide of AlGaAs and the insertion of quantum wells to provide simultaneous current and optical confinement in semiconductor laser by Holonyak and Dallesasse (1990). Later, the first “low- threshold” oxide-confined VCSEL was realized by Deppe (1994) and opened the door of commercial application formore »a gigabit energy-efficient optical links. At present, we demonstrated that the oxide-confined VCSELs have advanced error-free data trans- mission [bit-error rate (BER) ≤ 10−12]to 57 Gb/s at 25 °C and 50 Gb/s at 85 °C, and also demonstrated that the pre-leveled 16-quadrature amplitude modulation orthogonal frequency- division multiplexing data were achieved at 104 Gbit/s under back-to-back transmission with the received error vector mag- nitude, SNR, and BER of 17.3%, 15.2 dB, and 3.8 × 10−3, respectively.« less
  8. Genetic screens have been used to identify genes involved in the regulation of different biological processes. We identified growth mutants in a Flp/FRT screen using the Drosophila melanogaster eye to identify conditional regulators of cell growth and cell division. One mutant identified from this screen, B.2.16, was mapped and characterized by researchers in undergraduate genetics labs as part of the Fly-CURE. We find that B.2.16 is a non-lethal genetic modifier of the Dark82 mosaic eye phenotype.
  9. Free, publicly-accessible full text available May 1, 2023