Hardness and Electrical Resistivity of Copper-Iron Powder Metal Compacts

Although powder metallurgical methods have been used for years to fabricate tungsten and platinum, very little scientific data have been recorded until the beginning of this century. A large percentage of all commercial production at present is based upon past practice rather than upon scientific knowledge

DataComm in Flight Deck Surface Trajectory-Based Operations

The purpose of this pilot-in-the-loop aircraft taxi simulation was to evaluate a NextGen concept for surface trajectory-based operations (STBO) in which air traffic control (ATC) issued taxi clearances with a required time of arrival (RTA) by Data Communications (DataComm). Flight deck avionics, driven by an error-nulling algorithm, displayed the speed needed to meet the RTA. To ensure robustness of the algorithm, the ability of 10 two-pilot crews to meet the RTA was tested in nine experimental trials representing a range of realistic conditions including a taxi route change, an RTA change, a departure clearance change, and a crossing traffic hold scenario. In some trials, these DataComm taxi clearances or clearance modifications were accompanied by preview information, in which the airport map display showed a preview of the proposed route changes, including the necessary speed to meet the RTA. Overall, the results of this study show that with the aid of the RTA speed algorithm, pilots were able to meet their RTAs with very little time error in all of the robustness-testing scenarios. Results indicated that when taxi clearance changes were issued by DataComm only, pilots required longer notification distances than with voice communication. However, when the DataComm was accompanied by graphical preview, the notification distance required by pilots was equivalent to that for voice

Flight Deck Robustness/Conformance Testing with a Surface Management System: An Integrated Pilot-Controller Human-in-the-Loop Surface Operations Simulation

An integrated flight deck and controller human-in-the-loopsimulation was conducted with a total of 120 Dallas-Ft.Worth (DFW) taxi-out operations. In this first integratedPilot-Controller Spot and Runway Departure Advisor(SARDA) simulation, ATC Ground and Local Controllersused the SARDA decision support tool to plan and issuespot release clearances and departure clearances. TheAirport and Terminal Area Simulator (ATAS), a simulatedB737NG piloted, in turn, by 10 commercial transportparticipant pilots, was integrated into the realisticsimulation traffic environment. In the simulation,controllers used SARDA advisories to issue spot release,taxi route, and runway/departure radio voice clearances toall aircraft on the airport surface. Simulation resultsindicated that under a variety of observed pilot/aircraftperformance variations, SARDA yielded controlleradvisories that were: Supportive of current-day time-basedoperations; Compatible with controllers expectations;Predictive of actual take-off times; and, Adaptable to offnominalevents. An Information Sharing Display, thatpresented SARDA sequence and timing information on theflight deck, was considered useful for both NextGenoperations and current-day time-based Traffic ManagementInitiative (TMI) operations

Arm & Interarm Star Formation in Spiral Galaxies

We investigate the relationship between spiral arms and star formation in the grand-design spirals NGC 5194 and NGC 628 and in the flocculent spiral NGC 6946. Filtered maps of near-IR (3.6 micron) emission allow us to identify "arm regions" that should correspond to regions of stellar mass density enhancements. The two grand-design spirals show a clear two-armed structure, while NGC 6946 is more complex. We examine these arm and interarm regions, looking at maps that trace recent star formation - far-ultraviolet (GALEX NGS) and 24 micron emission (Spitzer, SINGS) - and cold gas - CO (Heracles) and HI (Things). We find the star formation tracers and CO more concentrated in the spiral arms than the stellar 3.6 micron flux. If we define the spiral arms as the 25% highest pixels in the filtered 3.6 micron images, we find that the majority (60%) of star formation tracers occurs in the interarm regions; this result persists qualitatively even when considering the potential impact of finite data resolution and diffuse interarm 24 micron emission. Even with a generous definition of the arms (45% highest pixels), interarm regions still contribute at least 30% to the integrated star formation rate tracers. We look for evidence that spiral arms trigger star or cloud formation using the ratios of star formation rate (SFR, traced by a combination of FUV and 24 micron emission) to H_2 (traced by CO) and H_2 to HI. Any enhancement of SFR / M(H_2) in the arm region is very small (less than 10%) and the grand design spirals show no enhancement compared to the flocculent target. Arm regions do show a weak enhancement in H_2/HI compared to the interarm regions, but at a fixed gas surface density there is little clear enhancement in the H_2/HI ratio in the arm regions. Thus, it seems that spiral arms may only act to concentrate the gas to higher densities in the arms.Comment: 11 pages, 9 Figures, accepted by Ap

Cold Dust but Warm Gas in the Unusual Elliptical Galaxy NGC 4125

Data from the Herschel Space Observatory have revealed an unusual elliptical galaxy, NGC 4125, which has strong and extended submillimeter emission from cold dust but only very strict upper limits to its CO and Hi emission. Depending on the dust emissivity, the total dust mass is 2-5 x 10(6) M-circle dot. While the neutral gas-to-dust mass ratio is extremely low (= 10(4) K faster than the dust is evaporated. If galaxies like NGC 4125, where the far-infrared emission does not trace neutral gas in the usual manner, are common at higher redshift, this could have significant implications for our understanding of high redshift galaxies and galaxy evolution.Canadian Space AgencyNatural Sciences and Engineering Research Council of CanadaAgenzia Spaziale Italiana (ASI) I/005/11/0BMVIT (Austria)ESA-PRODEX (Belgium)CEA/CNES (France)DLR (Germany)ASI/INAF (Italy)CICYT/MCYT (Spain)CSA (Canada)NAOC (China)CEA, (France)CNES (France)CNRS (France)ASI (Italy)MCINN (Spain)SNSB (Sweden)STFC (UK)NASA (USA)National Aeronautics and Space AdministrationAstronom

Observational Evidence Against Long-Lived Spiral Arms in Galaxies

We test whether the spiral patterns apparent in many large disk galaxies should be thought of as dynamical features that are stationary in a co-rotating frame for > t_{dyn}, as implied by the density wave approach for explaining spiral arms. If such spiral arms have enhanced star formation (SF), observational tracers for different stages of the SF sequence should show a spatial ordering, from up-stream to downstream in the corotating frame: dense HI, CO, tracing molecular hydrogen gas, 24 micron emission tracing enshrouded SF and UV emission tracing unobscured young stars. We argue that such a spatial ordering should be reflected in the angular cross-correlation (CC, in polar coordinates) using all azimuthal positions among pairs of these tracers; the peak of the CC should be offset from zero, in different directions inside and outside the corotation radius. Recent spiral SF simulations by Dobbs & Pringle, show explicitly that for the case of a stationary spiral arm potential such angular offsets between gas and young stars of differing ages should be observable as cross-correlation offsets. We calculate the angular cross-correlations for different observational SF sequence tracers in 12 nearby spiral galaxies, drawing on a data set with high quality maps of the neutral gas HI, THINGS), molecular gas (CO, HERACLES) along with 24 micron emission (Spitzer, SINGS); we include FUV images (GALEX) and 3.6 $\mu$m emission (Spitzer, IRAC) for some galaxies, tracing aging stars and longer timescales. In none of the resulting tracer cross-correlations for this sample do we find systematic angular offsets, which would be expected for a stationary dynamical spiral pattern of well-defined pattern speed. This result indicates that spiral density waves in their simplest form are not an important aspect of explaining spirals in large disk galaxies.Comment: 13 pages, 16 figure

Long-term survival of a woman with well differentiated papillary mesothelioma of the peritoneum: a case report and review of the literature

<p>Abstract</p> <p>Introduction</p> <p>Well-differentiated papillary mesothelioma of the peritoneum (WDPMP) is a rare subtype of epitheloid mesothelioma, which is usually seen in young women. WDPMP is generally considered of low malignant potential, however the long-term nature of the tumor remains poorly defined.</p> <p>Case presentation</p> <p>We describe the long-term follow-up of a 60-year-old woman of West African descent who has survived 24 years with WDPMP after receiving extensive local and systemic adjuvant chemotherapy. Her clinical course has included three exploratory laparotomies with intraperitoneal and intravenous chemotherapy over two decades. Her course was complicated by anthracycline-induced cardiomyopathy, for which she underwent an orthotopic heart transplant. Our patient is alive with stable radiological evidence of peritoneal disease, and continues to suffer from chronic abdominal pain.</p> <p>Conclusion</p> <p>No consensus exists regarding optimal treatment strategies for WDPMP. However, given the low malignant potential of the tumor, careful consideration should be made before proceeding with aggressive interventions. Further, long-term follow-up reports are required to fully characterize this tumor.</p

The Swift/UVOT catalogue of NGC4321 star forming sources: A case against density wave theory

We study the star forming regions in the spiral galaxy NGC4321, taking advantage of the spatial resolution (2.5 arcsec FWHM) of the Swift/UVOT camera and the availability of three UV passbands in the region 1600-3000 A, in combination with optical and IR imaging from SDSS, KPNO/Ha and Spitzer/IRAC, to obtain a catalogue of 787 star forming regions out to three disc scale lengths. We determine the properties of the young stellar component and its relationship with the spiral arms. The Ha luminosities of the sources have a strong decreasing radial trend, suggesting more massive star forming regions in the central part of the galaxy. When segregated with respect to NUV-optical colour, blue sources have a significant excess of flux in the IR at 8 micron, revealing the contribution from PAHs, although the overall reddening of these sources stays below E(B-V)=0.2 mag. The distribution of distances to the spiral arms is compared for subsamples selected according to Ha luminosity, NUV-optical colour, or ages derived from a population synthesis model. An offset is expected between these subsamples as a function of radius if the pattern speed of the spiral arm were constant - as predicted by classic density wave theory. No significant offsets are found, favouring instead a mechanism where the pattern speed has a radial dependence.Comment: 12 pages, 11 figures, 4 tables. MNRAS, in pres

The properties of the local spiral arms from RAVE data: two-dimensional density wave approach

Using the RAVE survey, we recently brought to light a gradient in the mean galactocentric radial velocity of stars in the extended solar neighbourhood. This gradient likely originates from non-axisymmetric perturbations of the potential, among which a perturbation by spiral arms is a possible explanation. Here, we apply the traditional density wave theory and analytically model the radial component of the two-dimensional velocity field. Provided that the radial velocity gradient is caused by relatively long-lived spiral arms that can affect stars substantially above the plane, this analytic model provides new independent estimates for the parameters of the Milky Way spiral structure. Our analysis favours a two-armed perturbation with the Sun close to the inner ultra-harmonic 4:1 resonance, with a pattern speed \Omega_p=18.6^{+0.3}_{-0.2} km/s/kpc and a small amplitude A=0.55 \pm 0.02% of the background potential (14% of the background density). This model can serve as a basis for numerical simulations in three dimensions, additionally including a possible influence of the galactic bar and/or other non-axisymmetric modes.Comment: 9 pages, 4 figures, accepted for publication in MNRA