An Investigation of Selection Criteria for Admission to an Ontario University

The study investigated the effectiveness of five methods of university admission criteria in relation to academic results achieved after one year of university study. The admission criteria used were open admission, interview, teacher recommendations, Grade 13 academic achievement and SACU test scores. In addition these procedures were compared with a traditional method of admission at the university where the study was carried out. The characteristics of the admission groups were not significantly related to geographical distribution, sex distribution, government financial assistance, and attitude and personality questionnaire data. These characteristics were no different for these groups than the traditional method of selection and there was no significant difference between groups as to final first year grade point average or academic penalty i.e., probations and rustications. The open admissions group compared favourably on these latter variables with other admissions groups and particularly with the university's traditional method of admission

The 3-53 keV Spectrum of the Quasar 1508+5714: X-rays from z = 4.3

We present a high-quality X-ray spectrum in the 3--53 keV rest-frame band of the radio-loud quasar 1508+5714, by far the brightest known X-ray source at z > 4. A simple power-law model with an absorption column density equal to the Galactic value in the direction of the source provides an excellent and fully adequate fit to the data; the measured power-law photon index Gamma = 1.42 (+0.13,-0.10). Upper limits to Fe K alpha line emission and Compton-reflection components are derived. We offer evidence for both X-ray and radio variability in this object and provide the first contemporaneous radio spectrum (alpha = -0.25). The data are all consistent with a picture in which the emission from this source is dominated by a relativistically beamed component in both the X-ray and radio bands.Comment: 8 pages, TeX, 2 postscript figures; to appear in ApJ Letter

Chromatic correlations at injection and related ejection problems in separated sector cyclotrons

International audienceInjection into a cyclotron, in order to preventemittance and phase spread dilution, requires propercouplings in the matching. One must first introduce aAP/r' associated with an r/AW coupling (through simplecticconditions) ; according to the angle of theaccelerating dees and the choice of harmonic numberthe(r,r') acceptance may also have to be tilted. Allthese effects are investigated in the case of theGANIL SSC's. At extraction corresponding correlationsexist. For a resonant system, extraction may be difficultwhen the energy spread is large because of thelarge coupling induced by resonance. A precessionalextraction which has been studied might in this casebe more efficient. Other ways for making extractioneasier are also considered. Moreover a new method ofphase compression at injection into the SSC is presentlyunder study at GANIL

A strongly changing accretion morphology during the outburst decay of the neutron star X-ray binary 4U 1608−52

It is commonly assumed that the properties and geometry of the accretion flow in transient low-mass X-ray binaries (LMXBs) significantly change when the X-ray luminosity decays below ∼10⁻² of the Eddington limit (L_(Edd)). However, there are few observational cases where the evolution of the accretion flow is tracked in a single X-ray binary over a wide dynamic range. In this work, we use NuSTAR and NICER observations obtained during the 2018 accretion outburst of the neutron star LMXB 4U 1608−52, to study changes in the reflection spectrum. We find that the broad Fe–Kα line and Compton hump, clearly seen during the peak of the outburst when the X-ray luminosity is ∼10³⁷ erg s⁻¹ (∼0.05 L_(Edd)), disappear during the decay of the outburst when the source luminosity drops to ∼4.5 × 10³⁵ erg s⁻¹ (∼0.002 L_(Edd)). We show that this non-detection of the reflection features cannot be explained by the lower signal-to-noise ratio at lower flux, but is instead caused by physical changes in the accretion flow. Simulating synthetic NuSTAR observations on a grid of inner disc radius, disc ionization, and reflection fraction, we find that the disappearance of the reflection features can be explained by either increased disc ionization (log ξ ≳ 4.1) or a much decreased reflection fraction. A changing disc truncation alone, however, cannot account for the lack of reprocessed Fe–Kα emission. The required increase in ionization parameter could occur if the inner accretion flow evaporates from a thin disc into a geometrically thicker flow, such as the commonly assumed formation of a radiatively inefficient accretion flow at lower mass accretion rates

Durability of Therapeutic Response to Milnacipran Treatment for Fibromyalgia. Results of a Randomized, Double-Blind, Monotherapy 6-Month Extension Study

To evaluate the durability of improvement and long-term efficacy of milnacipran treatment in fibromyalgia, to assess efficacy in patients re-randomized from placebo to milnacipran, and to collect additional information on the tolerability and efficacy of long-term treatment with milnacipran.A total of 449 patients who successfully completed a 6-month lead-in study enrolled in this 6-month extension study (87.7% of eligible subjects). Patients initially receiving milnacipran 200 mg/day during the lead-in study were maintained at 200 mg/day (n = 209); patients initially assigned to placebo or milnacipran 100 mg/day were re-randomized (1:4) to either 100 mg/day (n = 48) or 200 mg/day (n = 192) of milnacipran for an additional 6 months of treatment. Efficacy assessments included visual analog scale pain ratings, Fibromyalgia Impact Questionnaire (FIQ) total score, and Patient Global Impression of Change (PGIC).Patients continuing on milnacipran demonstrated a sustained reduction in pain over the full 12-month period. Additional beneficial effects were also maintained, as indicated by the PGIC and FIQ. Patients initially assigned to either placebo or milnacipran 100 mg/day in the lead-in study and subsequently re-randomized to milnacipran 200 mg/day in the extension study experienced further improvements in their mean pain scores, FIQ total scores, and PGIC ratings at 1 year. Milnacipran treatment was generally well tolerated. The most commonly reported newly emergent adverse event was nausea.In addition to confirming that milnacipran safely and effectively improves the multiple symptoms of fibromyalgia, these data indicate that milnacipran provides 1-year durable efficacy in this patient population.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78636/1/j.1526-4637.2009.00755.x.pd

A Persistent Disk Wind in GRS 1915+105 with NICER

The bright, erratic black hole X-ray binary GRS 1915+105 has long been a target for studies of disk instabilities, radio/infrared jets, and accretion disk winds, with implications that often apply to sources that do not exhibit its exotic X-ray variability. With the launch of NICER, we have a new opportunity to study the disk wind in GRS 1915+105 and its variability on short and long timescales. Here we present our analysis of 39 NICER observations of GRS 1915+105 collected during five months of the mission data validation and verification phase, focusing on Fe XXV and Fe XXVI absorption. We report the detection of strong Fe XXVI in 32 (>80%) of these observations, with another four marginal detections; Fe XXV is less common, but both likely arise in the well-known disk wind. We explore how the properties of this wind depends on broad characteristics of the X-ray lightcurve: mean count rate, hardness ratio, and fractional RMS variability. The trends with count rate and RMS are consistent with an average wind column density that is fairly steady between observations but varies rapidly with the source on timescales of seconds. The line dependence on spectral hardness echoes known behavior of disk winds in outbursts of Galactic black holes; these results clearly indicate that NICER is a powerful tool for studying black hole winds.Comment: Accepted for publication in ApJL. Comments welcom

Formation Control for the MAXIM Mission

Over the next twenty years, a wave of change is occurring in the space-based scientific remote sensing community. While the fundamental limits in the spatial and angular resolution achievable in spacecraft have been reached, based on today s technology, an expansive new technology base has appeared over the past decade in the area of Distributed Space Systems (DSS). A key subset of the DSS technology area is that which covers precision formation flying of space vehicles. Through precision formation flying, the baselines, previously defined by the largest monolithic structure which could fit in the largest launch vehicle fairing, are now virtually unlimited. Several missions including the Micro-Arcsecond X-ray Imaging Mission (MAXIM), and the Stellar Imager will drive the formation flying challenges to achieve unprecedented baselines for high resolution, extended-scene, interferometry in the ultraviolet and X-ray regimes. This paper focuses on establishing the feasibility for the formation control of the MAXIM mission. MAXIM formation flying requirements are on the order of microns, while Stellar Imager mission requirements are on the order of nanometers. This paper specifically addresses: (1) high-level science requirements for these missions and how they evolve into engineering requirements; and (2) the development of linearized equations of relative motion for a formation operating in an n-body gravitational field. Linearized equations of motion provide the ground work for linear formation control designs

Miniaturized High-Speed Modulated X-Ray Source

A miniaturized high-speed modulated X-ray source (MXS) device and a method for rapidly and arbitrarily varying with time the output X-ray photon intensities and energies. The MXS device includes an ultraviolet emitter that emits ultraviolet light, a photocathode operably coupled to the ultraviolet light-emitting diode that emits electrons, an electron multiplier operably coupled to the photocathode that multiplies incident electrons, and an anode operably coupled to the electron multiplier that is configured to produce X-rays. The method for modulating MXS includes modulating an intensity of an ultraviolet emitter to emit ultraviolet light, generating electrons in response to the ultraviolet light, multiplying the electrons to become more electrons, and producing X-rays by an anode that includes a target material configured to produce X-rays in response to impact of the more electrons