Johnston Describes is Meeting with Lufbery, the Noted Ace

A newspaper article about a United States Army Lieutenant, Archibald Johnson, meeting the Noted \u27Ace\u27 pilot, Raoul Lufbery.https://corescholar.libraries.wright.edu/special_ms502_newspapers/1005/thumbnail.jp

Blue Hill, Maine. Reunion Song.

https://digitalcommons.library.umaine.edu/mmb-me/1503/thumbnail.jp

The physical properties of coal measures rocks and their bearing on the technique of roof bolting

The investigations here described can be sub-divided into four main sections, viz. (A) The Physical Properties of Coal Measures Rock, (B) Photo-elastic Investigations, (C) Underground Observations and (D) The Testing of Plaster Models. The contents of each section are outlined below. SECTION A: The various methods employed for the determination of the physical properties of rock are discussed. The use of electrical resistance strain gauges for the measurement of Young's Modulus and Poisson's Ratio of several rock types from the Scottish Coalfields is described. The factors which affect the ultimate strength of stratified rocks are discussed and an attempt is made to predict the total strain which will develop in rock under a given stress after a known time. The results obtained indicate the influence of "time-strain" in computing the stress distribution around an underground excavation. Micro-graphs of the specimens tested are included in an appendix. SECTION B: Details of the apparatus used and the models con-structed for the two-dimensional photo-elastic investigations of any roof bolting systems are given. The functions of roof bolts as a "suspension support" and in the formation of a "compound beam" are analysed. The use of bolting to form a "keystone" in arched shaped roadways is also investigated. The results show the value of bolts in minimising shear stresses at the interfaces of the beds. The Importance of pre-tensioning the bolts by equal amounts is also emphasised by the isochromatic diagrams. SECTION C: The behaviour of roof bolts installed in an advancing longwall roadway is described. The performance of three types of steel bolts - slot and wedge, expansion shell, wedge and sleeve - and several "wooden bolts" is discussed. Details of the apparatus used for the measurement of bolt tension and strata movements are given. An attempt to measure 'in situ' rock strain by electrical resistance strain gauges is described. The results show a relaxation of bolt tension a few days after installation. The several factors which Influence the behaviour of bolts installed in moving strata are discussed. Several illustrations shewing the improvements in roadway maintenance where roof bolting is used in conjunction with arched girders are given. SECTION D: To study the behaviour of bolts after the strata around the excavation have been loaded beyond the "elastic limit", plaster models of the underground roadways were made and tested to destruction in the laboratory. The models were loaded in a vertical compression testing machine. A photographic record of the tests and a detailed analysis of the results are given

Attitudes towards sub-domains of professionalism in medical education: defining social accountability in the globalizing world

Background: Unmet health needs of populations around the world are a major contributor to lagging health outcomes globally. Medical professionals have a duty to address the health needs of their communities. In a globalizing world, the needs may seem limitless. Yet, most training involves immersion in one health system and its resources. How do practitioners reconcile this potentially limitless demand with their focused training and in understanding their duty to the populations they serve?Methods: A mixed-method design was used. We distributing a pre-validated survey examining all facets of professionalism to the Department of Family Medicine at the University of Ottawa. This was followed by interviewing a purposive sample of residents and faculty with different levels of interest in working with underserved populations, to examine attitudes towards social accountability.Results: Quantitative results did not replicate the factor structure of the pre-validated survey in our cohort. This and other gaps in individual responses were used to construct an interview guide. Interviews revealed differences between residents and faculty. Residents were likely to see social accountability as flowing from personal interest as opposed to a professional duty; and residents’ sense of duty can be met through good care of individual patients under their sphere of care. Faculty were more likely to discuss facets of care that they could influence at the health system level nationally and beyond. Conclusion: More usable and succinct instruments are needed to capture individual attitudes on social accountability. Our results identify how new physicians in family medicine in Ottawa, Canada wish to apply learning in global health to local needs, responding to the call to “think global, act local.

Correspondence to General William Robertson Boggs, 1870s: January 21, 1875 - November 6, 1878

Boggs Papers, Box 1, Folder 2 Correspondence to General William Robertson Boggs, 1870s: January 21, 1875 - November 6, 1878https://digitalcommons.wofford.edu/littlejohnboggs/1001/thumbnail.jp

Upper Limits on Pulsed Radio Emission from the 6.85 s X-ray Pulsar XTE J0103-728 in the Small Magellanic Cloud

X-ray pulsations with a 6.85 s period were recently detected in the SMC and were subsequently identified as originating from the Be/X-ray binary system XTE J0103-728. The recent localization of the source of the X-ray emission has made a targeted search for radio pulsations from this source possible. The detection of pulsed radio emission from XTE J0103-728 would make it only the second system after PSR B1259-63 that is both a Be/X-ray binary and a radio pulsar. We observed XTE J0103-728 in Feb 2008 with the Parkes 64-m radio telescope soon after the identification of the source of X-ray pulsations was reported in order to search for corresponding radio pulsations. We used a continuous 6.4 hour observation with a 256 MHz bandwidth centered at 1390 MHz using the center beam of the Parkes multibeam receiver. In the subsequent data analysis, which included a folding search, a Fourier search, a fast-folding algorithm search, and a single-pulse search, no pulsed signals were found for trial dispersion measures (DMs) between 0 and 800 pc cm^-3. This DM range easily encompasses the expected values for sources in the SMC. We place an upper limit of ~45 mJy kpc^2 on the luminosity of periodic radio emission from XTE J0103-728 at the epoch of our observation, and we compare this limit to a range of luminosities measured for PSR B1259-63, the only Be/X-ray binary currently known to emit radio pulses. We also compare our limit to the radio luminosities of neutron stars having similarly long spin periods to XTE J0103-728. Since the radio pulses from PSR B1259-63 are eclipsed and undetectable during the portion of the orbit near periastron, repeated additional radio search observations of XTE J0103-728 may be valuable if it is undergoing similar eclipsing and if such observations are able to sample the orbital phase of this system well.Comment: 16 pages, including 1 table. Accepted for publication in Ap

The High Time Resolution Universe Pulsar Survey I: System configuration and initial discoveries

We have embarked on a survey for pulsars and fast transients using the 13-beam Multibeam receiver on the Parkes radio telescope. Installation of a digital backend allows us to record 400 MHz of bandwidth for each beam, split into 1024 channels and sampled every 64 us. Limits of the receiver package restrict us to a 340 MHz observing band centred at 1352 MHz. The factor of eight improvement in frequency resolution over previous multibeam surveys allows us to probe deeper into the Galactic plane for short duration signals such as the pulses from millisecond pulsars. We plan to survey the entire southern sky in 42641 pointings, split into low, mid and high Galactic latitude regions, with integration times of 4200, 540 and 270 s respectively. Simulations suggest that we will discover 400 pulsars, of which 75 will be millisecond pulsars. With ~30% of the mid-latitude survey complete, we have re-detected 223 previously known pulsars and discovered 27 pulsars, 5 of which are millisecond pulsars. The newly discovered millisecond pulsars tend to have larger dispersion measures than those discovered in previous surveys, as expected from the improved time and frequency resolution of our instrument.Comment: Updated author list. 10 pages, 7 figures. For publication in MNRA

Long-term timing and emission behavior of the young Crab-like pulsar PSR B0540-69

We present timing solutions and spin properties of the young pulsar PSR B0540-69 from analysis of 15.8 years of data from the Rossi X-Ray Timing Explorer. We perform a partially phase-coherent timing analysis in order to mitigate the pronounced effects of timing noise in this pulsar. We also perform fully coherent timing over large subsets of the data set in order to arrive at a more precise solution. In addition to the previously reported first glitch undergone by this pulsar, we find a second glitch, which occurred at MJD 52927 +/- 4, with fractional changes in spin frequency Delta nu/nu = (1.64 +/- 0.05) x 10(-9) and spin-down rate Delta(nu) over dot/(nu) over dot = (0.930 +/- 0.011) x 10(-4) (taken from our fully coherent analysis). We measure a braking index that is consistent over the entire data span, with a mean value n = 2.129 +/- 0.012, from our partially coherent timing analysis. We also investigated the emission behavior of this pulsar, and have found no evidence for significant flux changes, flares, burst-type activity, or pulse profile shape variations. While there is strong evidence for the much-touted similarity of PSR B0540-69 to the Crab pulsar, they nevertheless differ in several aspects, including glitch activity, where PSR B0540-69 can be said to resemble certain other very young pulsars. It seems clear that the specific processes governing the formation, evolution, and interiors of this population of recently born neutron stars can vary significantly, as reflected in their observed properties

Double and single recycled pulsars: an evolutionary puzzle?

We investigate the statistics of isolated recycled pulsars and double neutron star binaries in the Galactic disk. Since recycled pulsars are believed to form through accretion and spinup in close binaries, the isolated objects presumably originate from disrupted progenitors of double neutron stars. There are a comparable number of double neutron star systems compared to isolated recycled pulsars. We find that standard evolutionary models cannot explain this fact, predicting several times the number of isolated recycled pulsars than those in double neutron star systems. We demonstrate, through population synthesis calculations, that the velocity distribution of isolated recycled pulsars is broader than for binary systems. When this is accounted for in a model for radio pulsar survey selection effects, which include the effects of Doppler smearing for the double neutron star binaries, we find that there is a small (25%) bias towards the detection of double neutron star systems. This bias, however, is not significant enough to explain the observational discrepancy if standard (sigma = 265 km/s) neutron star natal kick velocities are invoked in binary population syntheses. Population syntheses in which the 1D Maxwellian velocity dispersion of the natal kick is sigma=170 km/s are consistent with the observations. These conclusions further support earlier findings the neutron stars formed in close interacting binaries receive significantly smaller natal kicks than the velocities of Galactic single pulsars would seem to indicate.Comment: 12 pages, MNRAS (accepted

The High Time Resolution Universe Survey II: Discovery of 5 Millisecond Pulsars

We present the discovery of 5 millisecond pulsars found in the mid-Galactic latitude portion of the High Time Resolution Universe (HTRU) Survey. The pulsars have rotational periods from ~2.3 to ~7.5 ms, and all are in binary systems with orbital periods ranging from ~0.3 to ~150 d. In four of these systems, the most likely companion is a white dwarf, with minimum masses of ~0.2 Solar Masses. The other pulsar, J1731-1847, has a very low mass companion and exhibits eclipses, and is thus a member of the "black widow" class of pulsar binaries. These eclipses have been observed in bands centred near frequencies of 700, 1400 and 3000 MHz, from which measurements have been made of the electron density in the eclipse region. These measurements have been used to examine some possible eclipse mechanisms. The eclipse and other properties of this source are used to perform a comparison with the other known eclipsing and "black widow" pulsars. These new discoveries occupy a short-period and high-dispersion measure (DM) region of parameter space, which we demonstrate is a direct consequence of the high time and frequency resolution of the HTRU survey. The large implied distances to our new discoveries makes observation of their companions unlikely with both current optical telescopes and the Fermi Gamma-ray Space Telescope. The extremely circular orbits make any advance of periastron measurements highly unlikely. No relativistic Shapiro delays are obvious in any of the systems, although the low flux densities would make their detection difficult unless the orbits were fortuitously edge-on.Comment: 11 pages, 5 figures, 4 tables, for publication in MNRA