SUSY Particle Production at the Tevatron

The calculation of the next-to-leading order SUSY-QCD corrections to the production of squarks, gluinos and gauginos at the Tevatron is reviewed. The NLO corrections stabilize the theoretical predictions of the various production cross sections significantly and lead to sizeable enhancements of the most relevant cross sections for scales near the average mass of the produced massive particles. We discuss the phenomenological consequences of the results on present and future experimental analyses.Comment: 13 pages, latex, 9 figures, further extended versio

Dynamics of the Narrow-Line Region in the Seyfert 2 Galaxy NGC 1068

We present dynamical models based on a study of high-resolution long-slit spectra of the narrow-line region (NLR) in NGC 1068 obtained with the Space Telescope Imaging Spectrograph (STIS) aboard The Hubble Space Telescope (HST). The dynamical models consider the radiative force due to the active galactic nucleus (AGN), gravitational forces from the supermassive black hole (SMBH), nuclear stellar cluster, and galactic bulge, and a drag force due to the NLR clouds interacting with a hot ambient medium. The derived velocity profile of the NLR gas is compared to that obtained from our previous kinematic models of the NLR using a simple biconical geometry for the outflowing NLR clouds. The results show that the acceleration profile due to radiative line driving is too steep to fit the data and that gravitational forces along cannot slow the clouds down, but with drag forces included, the clouds can slow down to the systemic velocity over the range 100--400 pc, as observed. However, we are not able to match the gradual acceleration of the NLR clouds from ~0 to ~100 pc, indicating the need for additional dynamical studies.Comment: Paper prepared by emulateapj version 10/09/06 and accepted for print in Ap

Resolved Spectroscopy of the Narrow-Line Region in NGC 1068: Kinematics of the Ionized Gas

We have determined the radial velocities of the [O III] emitting gas in the inner narrow-line region (NLR) of the Seyfert 2 galaxy NGC 1068, along a slit at position angle of 202 degrees, from STIS observations at a spatial resolution of 0.1 arcsec and a spectral resolving power of approximately 1000. We use these data to investigate the kinematics of the NLR within 6 arcsec (430 pc) of the nucleus. The emission-line knots show evidence for radial acceleration, to a projected angular distance of 1.7 arcsec in most cases, followed by deceleration that approaches the systemic velocity at a projected distance of about 4 arcsec. We find that a simple kinematic model of biconical radial outflow can match the general trend of observed radial velocities. In this model, the emitting material is evacuated along the bicone axis, and the axis is inclined 5 degrees out of the plane of the sky. The acceleration of the emission-line clouds provides support for dynamical models that invoke radiation and/or wind pressure. We suggest that the deceleration of the clouds is due to their collision with a patchy and anistropically distributed ambient medium.Comment: 18 pages, Latex, includes 3 figures in postscript, to appear in the Astrophysical Journal Letter

Crew interface definition study, phase 1

The timeline analysis of the Shuttle orbiter missions which was conducted in the Phase I Crew Interface Definition Study and the requirements for the man-in-the-loop simulation study are presented. Mission definitions and objectives are presented as they relate to various Shuttle Orbiter missions. The requirements for crew participation and the information required by the crew are discussed, and finally the rationale behind the display concept and calling procedures is given. The simulation objectives, the simulation mechanization, including a detailed presentation of the display and control concept, the simulator test plan and the results are discussed

Application of superconducting coils to the NASA prototype magnetic balance

Application of superconducting coils to a general purpose magnetic balance was studied. The most suitable currently available superconducting cable for coils appears to be a bundle of many fine wires which are transposed and are mechanically confined. Sample coils were tested at central fields up to .5 Tesla, slewing rates up to 53 Tesla/ sec and frequencies up to 30 Hz. The ac losses were measured from helium boil-off and were approximately 20% higher than those calculated. Losses were dominated by hysteresis and a model for loss calculation which appears suitable for design purposes is presented along with computer listings. Combinations of two coils were also tested and interaction losses are reported. Two feasible geometries are also presented for prototype magnetic balance using superconductors

Integrating the Credit-Bearing Information Literacy Course into the Curriculum: Goals, Benefits and Challenges

This presentation provides a model for the design and implementation of a successful credit-bearing information literacy course that addresses the most common objections against stand-alone library instruction. It emphasizes two key principles, making it relevant to students and university administrators alike: integration into the university general education program, and the contextualization of information-seeking mechanics by introducing students to the economic, political and social context in which information is produced, managed and used. These principles lay the foundation for the development of critical information literacy skills that students can transfer to other courses and beyond. Offering stand-alone instruction while integrating it into the curriculum is an innovative strategy that opens the way for the creation of advanced, discipline-specific and program-embedded library instruction. The presenters will show the course syllabus and a sample online module, and will outline strategies to integrate information literacy into the general education program. They will invite participants to debate the potential benefits and pitfalls of stand-alone, credit-bearing library courses and to assess the effectiveness of the solutions offered in the presentation

Vortex nucleation in rotating BEC: the role of the boundary condition for the order parameter

We study the process of vortex nucleation in rotating two-dimensional BEC confined in a harmonic trap. We show that, within the Gross-Pitaevskii theory with the boundary condition of vanishing of the order parameter at infinity, topological defects nucleation occurs via the creation of vortex-antivortex pairs far from the cloud center, where the modulus of the order parameter is small. Then, vortices move towards the center of the cloud and antivortices move in the opposite direction but never disappear. We also discuss the role of surface modes in this process.Comment: 6 pages, 2 figure

Theoretical studies of photoexcitation and ionization in H_2O

Theoretical studies are reported of the complete dipole excitation and ionization spectrum in H_2O employing Franck–Condon and static‐exchange approximations. Large Cartesian Gaussian basis sets are used to represent the required discrete and continuum electronic eigenfunctions at the ground‐state equilibrium geometry, and previously devised moment‐theory techniques are employed in constructing the continuum oscillator‐strength densities from the calculated spectra. Detailed comparisons are made of the calculated excitation and ionization profiles with recent experimental photoabsorption studies and corresponding spectral assignments, electron impact–excitation cross sections, and dipole (e, 2e)/(e, e+ion) and synchrotron‐radiation studies of partial‐channel photoionization cross sections. The various calculated excitation series in the outer‐valence (1b(^−1)_1, 3a(^−1)_1, 1b(^−1)_2) region are found to include contributions from valence‐like 2b_2 (σ*) and 4a_1(γ*) virtual orbitals, as well as appropriate nsa_1, npa_1, nda_1, npb_1, npb_2, ndb_1, ndb_2, and nda_2 Rydberg states. Transition energies and intensities in the ∼7 to 19 eV interval obtained from the present studies are seen to be in excellent agreement with the measured photoabsorption cross section, and to provide a basis for detailed spectral assignments. The calculated (1b(^−1)_1)X(^ 2)B_1, (3a_1(^−1))^2A_1, and (1b_2(^−1))(^2)B_2 partial‐channel cross sections are found to be largely atomic‐like and dominated by 2p→kd components, although the 2b_2(σ*) orbital gives rise to resonance‐like contributions just above threshold in the 3a_1→kb_2 and 1b_2→kb_2 channels. It is suggested that the latter transition couples with the underlying 1b_1→kb_1 channel, accounting for a prominent feature in the recent high‐resolution synchrotron‐radiation measurements. When this feature is taken into account, the calculations of the three outer‐valence channels are in excellent accord with recent synchrotron‐radiation and dipole (e, 2e) photoionization cross‐sectional measurements. The calculated inner‐valence (2a_1(^−1)) cross section is also in excellent agreement with corresponding measured values, although proper account must be taken of the appropriate final‐state configuration‐mixing effects that give rise to a modest failure of the Koopmans approximation, and to the observed broad PES band, in this case. Finally, the origins of the various spectral features present in the measured 1a_1 oxygen K‐edge electron energy‐loss profile in H_2O are seen to be clarified fully by the present calculations

Classical and Quantum-Mechanical Calculations of HCO^+ + e → CO(v) + H

It has been suggested that interstellar CO produced in the dissociative recombination between HCO+ and electrons can be detected via infrared emission from excited vibrational levels. Using classical and quantum mechanical equations of motion, we have calculated the distribution of CO product vibrational states for the dissociative recombination reaction between HCO+ and electrons. We have assumed the dissociation to occur along a purely linear geometry. The CO vibrational distribution has been calculated for two electronic states: (1) the ground X1Σ^+ state and (2) the excited a ^3Π state. For the X state, we have used a newly calculated ab initio potential surface for the dissociation of HCO. Results for the a state can be compared with the results of experimental work by Adams and collaborators. Our results show that in general vibrational excitation of the CO product is not large, so that detection of infrared emission from interstellar clouds will not be facile

Distinguishing seawater from geologic brine in saline coastal groundwater using radium-226; an example from the Sabkha of the UAE

This paper is not subject to U.S. copyright. The definitive version was published in Chemical Geology 371 (2014): 1-8, doi:10.1016/j.chemgeo.2014.01.018.Sabkhat (Salt flats) are common geographic features of low-lying marine coastal areas that develop under hyper-arid climatic conditions. They are characterized by the presence of highly concentrated saline solutions and evaporitic minerals, and have been cited in the geologic literature as present-day representations of hyper-arid regional paleohydrogeology, paleoclimatology, coastal processes, and sedimentation in the geologic record. It is therefore important that a correct understanding of the origin and development of these features be achieved. Knowledge of the source of solutes is an important first step in understanding these features. Historically, two theories have been advanced as to the main source of solutes in sabkha brines: an early concept entailing seawater as the obvious source, and a more recent and dynamic theory involving ascending geologic brine forced upward into the base of the sabkha by a regional hydraulic gradient in the underlying formations. Ra-226 could uniquely distinguish between these sources under certain circumstances, as it is typically present at elevated activity of hundreds to thousands of Bq/m3 (Becquerels per cubic meter) in subsurface formation brines; at exceedingly low activities in open ocean and coastal water; and not significantly supplied to water from recently formed marine sedimentary framework material. The coastal marine sabkha of the Emirate of Abu Dhabi was used to test this hypothesis. The distribution of Ra-226 in 70 samples of sabkha brine (mean: 700 Bq/m3), 7 samples of underlying deeper formation brine (mean: 3416 Bq/m3), the estimated value of seawater (< 16 Bq/m3) and an estimate of supply from sabkha sedimentary framework grains (<~6 Bq/m3) provide the first direct evidence that ascending geologic brine contributes significantly to the solutes of this sabkha system