20,161 research outputs found
Flight measured downwash of the QSRA
Several reports have been written on the performance of the Quiet Short-Haul Research Aircraft, which shows the advantages of upper-surface blowing or the propulsive-lift wing as it applies to lift, maneuverability, and short takeoff and landing. This high lift generation at low speeds results in substantial downwash, especially in the low-aft fuselage tail position. The high T-tail of the Quiet Short-Haul Research Aircraft minimizes the undesirable downwash effects from the propulsive-lift wing. Queries from Department of Defense agencies and industry for quantitative values prompted a series of flight-measured downwash tests at the high T-tail and the low aft fuselage position. The results are presented in a summarized format, showing downwash, Delta epsilon/Delta a, for both locations. As would be expected, downwash increases for increased power and USB flap settings. The downwash is greater in the low aft-fuselage position as compared to the high T-tail area
Accretion Disk Temperatures of QSOs: Constraints from the Emission Lines
QSO emission-line spectra are compared to predictions based on theoretical
ionizing continua of accretion disks. Observed line intensities do not show the
expected trend of higher ionization with higher accretion disk temperature as
derived from the black hole mass and accretion rate. This suggests that, at
least for accretion rates close to the Eddington limit, the inner disk does not
reach temperatures as high as expected from standard disk theory. Modified
radial temperature profiles, taking account of winds or advection in the inner
disk, achieve better agreement with observation. This conclusion agrees with an
earlier study of QSO continuum colors as a function of disk temperature. The
emission lines of radio-detected and radio-undetected sources show different
trends as a function of disk temperature.Comment: 9 pages, 8 figures, submitted to Ap
Trypanosomes are monophyletic: evidence from genes for glyceraldehyde phosphate dehydrogenase and small subunit ribosomal RNA.
The genomes of Trypanosoma brucei, Trypanosoma cruzi and Leishmania major have been sequenced, but the phylogenetic relationships of these three protozoa remain uncertain. We have constructed trypanosomatid phylogenies based on genes for glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) and small subunit ribosomal RNA (SSU rRNA). Trees based on gGAPDH nucleotide and amino acid sequences (51 taxa) robustly support monophyly of genus Trypanosoma, which is revealed to be a relatively late-evolving lineage of the family Trypanosomatidae. Other trypanosomatids, including genus Leishmania, branch paraphyletically at the base of the trypanosome clade. On the other hand, analysis of the SSU rRNA gene data produced equivocal results, as trees either robustly support or reject monophyly depending on the range of taxa included in the alignment. We conclude that the SSU rRNA gene is not a reliable marker for inferring deep level trypanosome phylogeny. The gGAPDH results support the hypothesis that trypanosomes evolved from an ancestral insect parasite, which adapted to a vertebrate/insect transmission cycle. This implies that the switch from terrestrial insect to aquatic leech vectors for fish and some amphibian trypanosomes was secondary. We conclude that the three sequenced pathogens, T. brucei, T. cruzi and L. major, are only distantly related and have distinct evolutionary histories
Variations of the amplitudes of oscillation of the Be star Achernar
We report on finding variations in amplitude of the two main oscillation
frequencies found in the Be star Achernar, over a period of 5 years. They were
uncovered by analysing photometric data of the star from the SMEI instrument.
The two frequencies observed, 0.775 c/d and 0.725 c/d, were analysed in detail
and their amplitudes were found to increase and decrease significantly over the
5-year period, with the amplitude of the 0.725 c/d frequency changing by up to
a factor of eight. The nature of this event has yet to be properly understood,
but the possibility of it being due to the effects of a stellar outburst or a
stellar cycle are discussed.Comment: 6 pages, 6 figures, 1 table, to be published in MNRA
Orbital-quenching-induced magnetism in Ba_2NaOsO_6
The double perovskite \bnoo with heptavalent Os () is observed to remain
in the ideal cubic structure ({\it i.e.} without orbital ordering) despite
single occupation of the orbitals, even in the ferromagnetically
ordered phase below 6.8 K. Analysis based on the {\it ab initio} dispersion
expressed in terms of an Os -based Wannier function picture, spin-orbit
coupling, Hund's coupling, and strong Coulomb repulsion shows that the magnetic
OsO cluster is near a moment-less condition due to spin and orbital
compensation. Quenching (hybridization) then drives the emergence of the small
moment. This compensation, unprecedented in transition metals, arises in a
unified picture that accounts for the observed Mott insulating behavior.Comment: in press at Europhysics Letter
Proceedings of the Spacecraft Charging Technology Conference: Executive Summary
Aerospace environments are reviewed in reference to spacecraft charging. Modelling, a theoretical scheme which can be used to describe the structure of the sheath around the spacecraft and to calculate the charging currents within, is discussed. Materials characterization is considered for experimental determination of the behavior of typical spacecraft materials when exposed to simulated geomagnetic substorm conditions. Materials development is also examined for controlling and minimizing spacecraft charging or at least for distributing the charge in an equipotential manner, using electrical conductive surfaces for materials exposed to space environment
BREAKING BAD NEWS IN HEALTHCARE ORGANIZATIONS: APPLICATION OF THE SPIKES PROTOCOL
Organizational downsizing has increased exponentially worldwide and is also affecting the healthcare industry. It is one thing to speak abstractly of the need to reduce costs and quite another to actually tell a worker the bad news that he or she has been laid off. This paper offers practical advice to healthcare managers on conducting unpleasant conversations with employees based on a widely used medical model—the SPIKES protocol. This strategy has been extensively employed by physicians and other health care professionals who frequently communicate negative information to patients and is offered as an approach that can be easily and effectively adapted by healthcare managers when they must tell a person they have been terminated. Although breaking the bad news of a cutback will never be easy, having a plan of action that entails sound business and medical advice and is also the necessary thing to do can help firms carefully manage and execute reorganizations for the well-being of the organization and the terminated worker
Algebraic geometric methods for the stabilizability and reliability of multivariable and of multimode systems
The extent to which feedback can alter the dynamic characteristics (e.g., instability, oscillations) of a control system, possibly operating in one or more modes (e.g., failure versus nonfailure of one or more components) is examined
Ecological Studies of Wolves on Isle Royale, 1980-1981
Annual Report 1980-1981 (Covering the twenty-third year of research)https://digitalcommons.mtu.edu/wolf-annualreports/1040/thumbnail.jp
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