229,117 research outputs found
Dropouts in magnetic tape recording and reproduction
Judicious selection and maintenance of tape and tape transports minimizes dropouts
Scattering in one dimension: The coupled Schroedinger equation, threshold behaviour and Levinson's theorem
We formulate scattering in one dimension due to the coupled Schr\"{o}dinger
equation in terms of the matrix, the unitarity of which leads to
constraints on the scattering amplitudes. Levinson's theorem is seen to have
the form , where is the phase of
the matrix at zero energy, the number of bound states with nonzero
binding energy, the number of half-bound states, and the number of
coupled equations. In view of the effects due to the half-bound states, the
threshold behaviour of the scattering amplitudes is investigated in general,
and is also illustrated by means of particular potential models.Comment: to appear in Journal of Mathematic Physics, RevTex, 16 pages, 3
figures (PostScript
A Submillimeter Selected Quasar in the Field of Abell 478
We report the discovery of a z=2.83 quasar in the field of the cooling flow
galaxy cluster Abell 478. This quasar was first detected in a submm survey of
star forming galaxies at high redshifts, as the brightest source. We discuss
the optical spectrum and far-IR spectral energy distribution (SED) of this
object.Comment: 4 pages, 3 figures, in "Deep Millimeter Surveys: Implications for
Galaxy Formation and Evolution", ed. J. Lowenthal and D. Hughes, World
Scientific Publisher
Spool valve cycles at controlled frequency
Spool valve accurately controls the cycle of a pneumatically-actuated system over long periods. Regulation of pressure from the external source, positioning of the adjusting plugs, and magnet selection, together afford wide variation in cyclic timing and speed of closure in either direction
Rayleigh-Brillouin light scattering spectroscopy of nitrous oxide (NO)
High signal-to-noise and high-resolution light scattering spectra are
measured for nitrous oxide (NO) gas at an incident wavelength of 403.00 nm,
at 90 scattering, at room temperature and at gas pressures in the range
bar. The resulting Rayleigh-Brillouin light scattering spectra are
compared to a number of models describing in an approximate manner the
collisional dynamics and energy transfer in this gaseous medium of this
polyatomic molecular species. The Tenti-S6 model, based on macroscopic gas
transport coefficients, reproduces the scattering profiles in the entire
pressure range at less than 2\% deviation at a similar level as does the
alternative kinetic Grad's 6-moment model, which is based on the internal
collisional relaxation as a decisive parameter. A hydrodynamic model fails to
reproduce experimental spectra for the low pressures of 0.5-1 bar, but yields
very good agreement (\%) in the pressure range bar. While these
three models have a different physical basis the internal molecular relaxation
derived can for all three be described in terms of a bulk viscosity of Pas. A 'rough-sphere' model, previously
shown to be effective to describe light scattering in SF gas, is not found
to be suitable, likely in view of the non-sphericity and asymmetry of the N-N-O
structured linear polyatomic molecule
Mindfulness and other Buddhist-derived interventions in correctional settings: a systematic review
Background: Throughout the last decade, there has been a growth of interest into the rehabilitative utility of Buddhist-derived interventions (BDIs) for incarcerated populations. The purpose of this study was to systematically review the evidence for BDIs in correctional settings. Method: MEDLINE, Science Direct, ISI Web of Knowledge, PsychInfo, and Google Scholar electronic databases were systematically searched. Reference lists of retrieved articles and review papers were also examined for any further studies. Controlled intervention studies of BDIs that utilised incarcerated samples were included. Jaded scoring was used to evaluate methodological quality. PRISMA (preferred reporting items for systematic reviews and meta-analysis) guidelines were followed. Results: The initial comprehensive literature search yielded 85 papers but only eight studies met all the inclusion criteria. The eight eligible studies comprised two mindfulness studies, four vipassana meditation studies, and two studies utilizing other BDIs. Intervention participants demonstrated significant improvements across five key criminogenic variables: (i) negative affective, (ii) substance use (and related attitudes), (iii) anger and hostility, (iv) relaxation capacity, and (v) self-esteem and optimism. There were a number of major quality issues. Conclusion: It is concluded that BDIs may be feasible and effective rehabilitative interventions for incarcerated populations. However, if the potential suitability and efficacy of BDIs for prisoner populations is to be evaluated in earnest, it is essential that methodological rigour is substantially improved. Studies that can overcome the ethical issues relating to randomisation in correctional settings and employ robust randomised controlled trial designs are favoured
Completing HI observations of galaxies II. The Coma Supercluster
High sensitivity 21-cm HI line observations, with an rms noise level of \sim
0.5 mJy, were made of 35 spiral galaxies in the Coma Supercluster, using the
refurbished Arecibo telescope, which resulted in the detection of 25 objects.
These data, combined with the measurements available from the literature,
provide the set of HI data for 94% of all late-type galaxies in the Coma
Supercluster with an apparent photographic magnitude m_p <15.7 mag. We confirm
that the typical scale of HI deficiency around the Coma cluster is 2 Mpc, i.e.
one virial radius. Comparing the HI mass function (HIMF) of cluster with
non-cluster members of the Coma Supercluster we detect a shortage of high HI
mass galaxies among cluster members that can be ascribed to the pattern of HI
deficiency found in rich clusters.Comment: 16 pages, 8 figures, 4 tables. Accepted for publication on A&
Evidence on a DSGE Business Cycle model subject to Neutral and Investment-Specific Technology Shocks using Bayesian Model Averaging
The empirical support for a DSGE type of real business cycle model with two technology shocks is evaluated using a Bayesian model averaging procedure that makes use of a finite mixture of many models within the class of vector autoregressive (VAR) processes. The linear VAR model is extended to permit equilibrium restrictions and restrictions on long-run responses to technology shocks apart from having a range of lag structures and deterministic processes. These model features are weighted as posterior probabilites and computed using MCMC and analytical methods. Uncertainty exists as to the most appropriate model for our data, with five models receiving significant support. The model set used has substantial implications for the results obtained. We do find support for a number of features implied by the real business cycle model. Business cycle volatility seems more due to investment specific technology shocks than neutral technology shocks and this result is robust to model specification. These techonolgy schocks appear to account for all stochastic trends in our system after 1984. we provide evidence on the uncertainty bands associated with these results.
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