The entrainment rate for a row of turbulent jets

Entrainment rates for a row of isothermal circular air jets issuing into a quiescent environment are found by integrating velocity distributions measured by a linearized hot-wire anemometer. Jet spacing to jet diameter ratios of 2.5, 5, 10, and 20 are studied at jet Reynold's numbers ranging from 5110 to 12070. Velocity distributions are determined at regular downstream intervals at axial distances equal to 16.4 to 164 jet diameters from the jet source. The entrainment rates for the four spacing configurations vary monotonically with increasing spacing/diameter between the limiting case of the slot jet entrainment rate (where the jet spacing to diameter ratio is zero) and the circular jet entrainment rate (in which the spacing to diameter ratio is infinity)

Noise of a model counterrotation propeller with reduced aft rotor diameter at simulated takeoff/approach conditions (F7/A3)

A model high-speed advanced counterrotation propeller, F7/A3, was tested in the NASA Lewis Research Center 9 by 15 foot Anechoic Wind Tunnel at simulated takeoff/approach conditions of 0.2 Mach number. Acoustic measurements were taken with an axially translating microphone probe, and with a polar microphone probe which was fixed to the propeller nacelle and could take both sideline and circumferential acoustic surveys. Aerodynamic measurements were also made to establish propeller operating conditions. The propeller was run at two setting angles (front angle/rear angle) of 36.4/43.5 and 41.1/46.4 degrees, forward rotor tip speeds from 165 to 259 m/sec, rotor spacings from 8.48 to 14.99 cm based on pitch change axis separation, and angles of attack to 16 degrees. The aft rotor diameter was 85 percent of the forward rotor diameter to reduce tip vortex-aft rotor interaction as a major interaction noise source. Results are compared with equal diameter F7/A7 data which was previously obtained under similar operating conditions. The aft rotor-alone tone was 7 dB lower for the reduced diameter aft rotor, due to reduced tip speed at constant rpm. Interaction tone levels for the F7/A3 propeller were higher at minimum row spacing and lower at maximum spacing

The discursive properties of "hope": A qualitative analysis of cancer patients' speech

© 2002 SAGE PublicationsThe authors of this article question the usefulness of the empirico-realist search for a definitive definition of hope. Semistructured interviews on “do-not-resuscitate” issues with 23 oncology clinic outpatients were tape-recorded, transcribed, and analyzed following grounded-theory methodology and discursive analytical methodology. Twelve patients spontaneously spoke about hope as objective or subjective, a burden or a resource. Hope represented an evaluation of empirical states of affairs or the wish for desired outcomes and was a warrant for action or an excuse for inaction. It was attributed to both patient and caregiver, to individuals or situations. Hope was present or future oriented, both vulnerable and enduring. The variety of versions of hope has implications for interactions between health care workers and patients. Recognizing a taxonomy of hope might prove more useful than searching for definitions.Jaklin Eliott ; Ian Olve

Complications of Subspecialty Ophthalmic Care: Systemic Complications from the Intravitreal Administration of Agents that Target the Vascular Endothelial Growth Factor Pathway

The treatment of neovascular age-related macular degeneration (AMD) and other pathologic ocular conditions that overexpress the vascular endothelial growth factor (VEGF) has been revolutionized in the last decade by the introduction of intravitreal agents that target the VEGF pathway. Since treatment trials are designed primarily to assess the prevention of vision loss caused by ocular conditions, they are inadequate for detecting rare, but potentially serious, systemic side effects. The aim of this article is to present what the ophthalmologist needs to know about systemic complications from anti-VEGF therapy and review the likelihood that these side effects occur in the context of small, but often-repeated, intravitreal doses of these potent biological medications. Preferred practice patterns need to be developed that weigh the ability of these medications to mitigate potentially blinding conditions, while at the same time minimizing the risk of adverse outcomes in specific patient populations that possess multiple and often interrelated medical comorbidities