2,972 research outputs found

    On the Forward-Backward Asymmetry of Leptonic Decays of ttˉt\bar{t} at the Fermilab Tevatron

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    We report on a study of the measurement techniques used to determine the leptonic forward-backward asymmetry of top anti-top quark pairs in Tevatron experiments with a proton anti-proton initial state. Recently it was shown that a fit of the differential asymmetry as a function of qlηlq_{l}\eta_{l} (where qlq_{l} is the charge of the lepton from the cascade decay of the top quarks and ηl\eta_{l} is the final pseudorapidity of the lepton in the detector frame) to a hyperbolic tangent function can be used to extrapolate to the full leptonic asymmetry. We find this empirical method to well reproduce the results from current experiments, and present arguments as to why this is the case. We also introduce two more models, based on Gaussian functions, that better model the qlηlq_{l}\eta_{l} distribution. With our better understanding, we find that the asymmetry is mainly determined by the shift of the mean of the qlηlq_{l}\eta_{l} distribution, the main contribution to the inclusive asymmetry comes from the region around qlηl=1|q_{l}\eta_{l}| = 1, and the extrapolation from the detector-covered region to the inclusive asymmetry is stable via a multiplicative scale factor, giving us confidence in the previously reported experimental results.Comment: 26 pages, 12 figure

    A Comparison of an Unhooded and Hooded Sprayer for Pesticide Drift Reduction

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    Management of drift from pesticide applications is important for human and environmental health concerns. It is also necessary to ensure adequate dosage of the pesticide meets the target species(s). A variety of factors can affect the drift potential of a pesticide application, including nozzle selection, solution chemistry, and application equipment. In the present study, a comparison of two ground sprayers, one with a hood and one without a hood, is made using three common ground nozzles in the US. The hooded sprayer reduced the drift potential of the pesticide application for all nozzles tested. In addition, higher spray coverage under the boom was measured when using the hooded sprayer. The results of this study indicate that incorporating a hood will lead to reduced drift potential from a pesticide application

    Fidelity enhancement by logical qubit encoding

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    We demonstrate coherent control of two logical qubits encoded in a decoherence free subspace (DFS) of four dipolar-coupled protons in an NMR quantum information processor. A pseudo-pure fiducial state is created in the DFS, and a unitary logical qubit entangling operator evolves the system to a logical Bell state. The four-spin molecule is partially aligned by a liquid crystal solvent, which introduces strong dipolar couplings among the spins. Although the system Hamiltonian is never fully specified, we demonstrate high fidelity control over the logical degrees of freedom. In fact, the DFS encoding leads to higher fidelity control than is available in the full four-spin Hilbert space.Comment: 10 pages, 2 figure

    An Evaluation of Three Drift Reduction Adjuvants for Aerial Application of Pesticides

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    Preventing pesticide drift from aerial applications is important for environmental and application efficiency reasons. Proper analysis of drift reduction technologies or techniques is an essential component of the drift prevention process. In the current study, three drift reduction adjuvants were tested with two herbicides under several application conditions used by rotary-wing and fixed-wing aircraft in the U.S. Data was collected using a high speed wind tunnel and laser diffraction equipment. The results of the study indicated application conditions, and not adjuvant inclusion, were the largest drivers of the droplet size distribution and drift potential. Data was further computed in the drift prediction program, AGDISP, where little differences were observed between the treatments. This study highlighted the importance of testing drift reduction technologies or techniques from multiple viewpoints

    National Estimates of Emergency Department Visits for Pediatric Severe Sepsis in the United States

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    Objective. We sought to determine the characteristics of children presenting to United States (US) Emergency Departments (ED) with severe sepsis. Study design. Cross-sectional analysis using data from the National Hospital Ambulatory Medical Care Survey (NHAMCS). Using triage vital signs and ED diagnoses (defined by the International Classification of Diseases, Ninth Revision codes), we identified children(triage fever or ICD-9 infection) and organ dysfunction (triage hypotension or ICD-9 organ dysfunction). Results. Of 28.2 million pediatric patients presenting to US EDs each year, severe sepsis was present in 95,055 (0.34%; 95% CI: 0.29-0.39%). Fever and respiratory infection were the most common indicators of an infection. Hypotension and respiratory failure were the most common indicators of organ dysfunction. Most severe sepsis occurred in children ages 31 days-1 year old (32.1%). Most visits for pediatric severe sepsis occurred during winter months (37.4%), and only 11.1% of patients arrived at the ED by ambulance. Over half of severe sepsis cases were self-pay or insured by Medicaid. A large portion (44.1%) of pediatric severe sepsis ED visits occurred in the South census region. ED length of stay was over 3 h, and 16.5% were admitted to the hospital. Conclusion. Nearly 100,000 children annually present to US EDs with severe sepsis. The findings of this study highlight the unique characteristics of children treated in the ED for severe sepsis

    CANDELS: The Contribution of the Observed Galaxy Population to Cosmic Reionization

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    We present measurements of the specific ultraviolet luminosity density from a sample of 483 galaxies at 6<z<8. These galaxies were selected from new deep near-infrared HST imaging from the CANDELS, HUDF09 and ERS programs. In contrast to the majority of previous analyses, which assume that the distribution of galaxy ultraviolet (UV) luminosities follows a Schechter distribution, and that the distribution continues to luminosities far below our observable limit, we investigate the contribution to reionization from galaxies which we can observe, free from these assumptions. We find that the observable population of galaxies can sustain a fully reionized IGM at z=6, if the average ionizing photon escape fraction (f_esc) is ~30%. A number of previous studies have measured UV luminosity densities at these redshifts that vary by 5X, with many concluding that galaxies could not complete reionization by z=6 unless a large population of galaxies fainter than the detection limit were invoked, or extremely high values of f_esc were present. The observed UV luminosity density from our observed galaxy samples at z=7-8 is not sufficient to maintain a fully reionized IGM unless f_esc>50%. Combining our observations with constraints on the emission rate of ionizing photons from Ly-alpha forest observations at z=6, we can constrain f_esc<34% (2-sigma) if the observed galaxies are the only contributors to reionization, or <13% (2-sigma) if the luminosity function extends to M_UV = -13. These escape fractions are sufficient to complete reionization by z=6. These constraints imply that the volume ionized fraction of the IGM becomes less than unity at z>7, consistent with a number of complementary reionization probes. If faint galaxies dominate reionization, future JWST observations will probe deep enough to see them, providing an indirect constraint on the ionizing photon escape fraction [abridged].Comment: 16 pages, 7 figures, Submitted to the Astrophysical Journa

    Evaluation of Student Pharmacists’ Attitudes and Perceptions of Hormonal Contraception Prescribing in Indiana

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    Community pharmacists’ scope of practice is expanding to include hormonal contraceptive prescribing. Prior to introducing statewide legislation, it is important to assess the perceptions of future pharmacists. A cross-sectional survey was distributed to 651 third- and fourth-year professional students enrolled at three colleges of pharmacy in Indiana. Data were collected between September and October 2019 to assess students’ attitudes about prescribing hormonal contraceptives, readiness to prescribe, perceived barriers, and desire for additional training. In total, 20.9% (n = 136) students responded. Most (89%, n = 121) believe that pharmacist-prescribed hormonal contraceptives would be beneficial to women in Indiana, and 91% (n = 124) reported interest in providing this service. Liability, personal beliefs, and religious beliefs were the most commonly cited perceived barriers. Most students felt they received adequate teaching on hormonal contraceptive methods (90%, n = 122) and hormonal contraceptive counseling (79%, n = 107); only 5% (n = 7) felt ready to provide the service at the time of survey completion. Student pharmacists in their final two years of pharmacy school are interested in prescribing hormonal contraceptives and believe that this service would be beneficial. This expansion of pharmacy practice would likely be supported by future pharmacists who feel the service could provide benefit to women seeking hormonal contraceptives in Indiana

    The distribution of satellites around massive galaxies at 1<z<3 in ZFOURGE/CANDELS: dependence on star formation activity

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    We study the statistical distribution of satellites around star-forming and quiescent central galaxies at 1<z<3 using imaging from the FourStar Galaxy Evolution Survey (ZFOURGE) and the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS). The deep near-IR data select satellites down to log(M/M)>9\log(M/M_\odot)>9 at z<3. The radial satellite distribution around centrals is consistent with a projected NFW profile. Massive quiescent centrals, log(M/M)>10.78\log(M/M_\odot)>10.78, have \sim2 times the number of satellites compared to star-forming centrals with a significance of 2.7σ\sigma even after accounting for differences in the centrals' stellar-mass distributions. We find no statistical difference in the satellite distributions of intermediate-mass quiescent and star-forming centrals, 10.48<log(M/M)<10.7810.48<\log(M/M_\odot)<10.78. Comparing to the Guo2011 semi-analytic model, the excess number of satellites indicates that quiescent centrals have halo masses 0.3 dex larger than star-forming centrals, even when the stellar-mass distributions are fixed. We use a simple toy model that relates halo mass and quenching, which roughly reproduces the observed quenched fractions and the differences in halo mass between star-forming and quenched galaxies only if galaxies have a quenching probability that increases with halo mass from \sim0 for log(Mh/M)\log(M_h/M_\odot)\sim11 to \sim1 for log(Mh/M)\log(M_h/M_\odot)\sim13.5. A single halo-mass quenching threshold is unable to reproduce the quiescent fraction and satellite distribution of centrals. Therefore, while halo quenching may be an important mechanism, it is unlikely to be the only factor driving quenching. It remains unclear why a high fraction of centrals remain star-forming even in relatively massive halos.Comment: 19 pages, 17 figures, accepted by ApJ. Information on ZFOURGE can be found at http://zfourge.tamu.ed

    The Pan-STARRS Moving Object Processing System

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    We describe the Pan-STARRS Moving Object Processing System (MOPS), a modern software package that produces automatic asteroid discoveries and identifications from catalogs of transient detections from next-generation astronomical survey telescopes. MOPS achieves > 99.5% efficiency in producing orbits from a synthetic but realistic population of asteroids whose measurements were simulated for a Pan-STARRS4-class telescope. Additionally, using a non-physical grid population, we demonstrate that MOPS can detect populations of currently unknown objects such as interstellar asteroids. MOPS has been adapted successfully to the prototype Pan-STARRS1 telescope despite differences in expected false detection rates, fill-factor loss and relatively sparse observing cadence compared to a hypothetical Pan-STARRS4 telescope and survey. MOPS remains >99.5% efficient at detecting objects on a single night but drops to 80% efficiency at producing orbits for objects detected on multiple nights. This loss is primarily due to configurable MOPS processing limits that are not yet tuned for the Pan-STARRS1 mission. The core MOPS software package is the product of more than 15 person-years of software development and incorporates countless additional years of effort in third-party software to perform lower-level functions such as spatial searching or orbit determination. We describe the high-level design of MOPS and essential subcomponents, the suitability of MOPS for other survey programs, and suggest a road map for future MOPS development.Comment: 57 Pages, 26 Figures, 13 Table
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