Examining consent for interventional research in potential deceased organ donors: a narrative review

In the last decade, research in transplant medicine has focused on developing interventions in the management of the deceased organ donor to improve the quality and quantity of transplantable organs. Despite the promise of interventional donor research, there remain debates about the ethics of this research, specifically regarding gaining research consent. Here, we examine the concerns and ambiguities around consent for interventional donor research, which incorporate questions about who should consent for interventional donor research and what people are being asked to consent for. We highlight the US and UK policy responses to these concerns and argue that, whereas guidance in this area has done much to clarify these ambiguities, there is little consideration of the nature, practicalities and context around consent in this area, particularly regarding organ donors and their families. We review wider studies of consent in critical care research and social science studies of consent in medical research, to gain a broader view of consent in this area as a relational and contextual process. We contend a lack of consideration has been given to: what it might mean to consent to interventional donor research; how families, patients and health professionals might experience providing and seeking this consent; who is best placed to have these discussions; and the socio‐institutional contexts affecting these processes. Further, empirical research is required to establish an ethical and sensitive model for consent in interventional donor research, ensuring the principles enshrined in research ethics are met and public trust in organ donation is maintained

Influence of free-stream disturbances on boundary-layer transition

Considerable experimental evidence exists which shows that free stream disturbances (the ratio of root-mean-square pressure fluctuations to mean values) in conventional wind tunnels increase with increasing Mach number at low supersonic to moderate hypersonic speeds. In addition to local conditions, the free stream disturbance level influences transition behavior on simple test models. Based on this observation, existing noise transition data obtained in the same test facility were correlated for a large number of reference sharp cones and flat plates and are shown to collapse along a single curve. This result is a significant improvement over previous attempts to correlate noise transition data

Offshore Space Center (offshore launch site)

Any activity requiring the development of the HLLV can benefit by operations from an offshore space center (OSC) since operating near the equator provides a twenty percent increase in payload in an ecliptic plan orbit. Some OSC concepts considered include a moored floating (semisubmersible) design, a stationary design supported by fixed piles, and a combination of these two. The facility supports: a 15,000 foot long, 300 foot wide runway, designed to accommodate a two staged winged launch vehicle, with a one million pound payload capacity to low earth orbit; an industrial area for HLLV maintenance; an airport terminal, control and operation center, and observation tower; liquid hydrogen and liquid oxygen production and storage, and fuel storage platforms; a power generation station, docks with an unloading area; two separate launch sites; and living accommodations for 10,000 people. Potential sites include the Paramount Seamount in the Pacific Ocean off the north coast of South America. Cost estimates are considered

Instrument accurately measures small temperature changes on test surface

Calorimeter apparatus accurately measures very small temperature rises on a test surface subjected to aerodynamic heating. A continuous thin sheet of a sensing material is attached to a base support plate through which a series of holes of known diameter have been drilled for attaching thermocouples to the material

Transverse spreading of electrons in high-intensity laser fields

We show that for collisions of electrons with a high-intensity laser, discrete photon emissions introduce a transverse beam spread which is distinct from that due to classical (or beam shape) effects. Via numerical simulations, we show that this quantum induced transverse momentum gain of the electron is manifest in collisions with a realistic laser pulse of intensity within reach of current technology, and we propose it as a measurable signature of strong-field quantum electrodynamics.Comment: 5 pages, 3 figures. Accepted for publication in Physical Review Letter

Solitary Waves in Optical Fibers Governed by Higher Order Dispersion

An exact solitary wave solution is presented for the nonlinear Schrodinger equation governing the propagation of pulses in optical fibers including the effects of second, third and fourth order dispersion. The stability of this soliton-like solution with sech2 shape is proven by the sign-definiteness of the operator and an integral of the Sobolev type. The main criteria governing the existence of such stable localized pulses propagating in optical fibers are also formulated. A unique feature of these soliton-like optical pulses propagating in a fiber with higher order dispersion is that their parameters satisfy efficient scaling relations. The main soliton solution term given by perturbation theory is also presented when absorption or gain is included in the nonlinear Schrodinger equation. We anticipate that this type of stable localized pulses could find practical applications in communications, slow-light devices and ultrafast lasers.Comment: 4 pages 3 Figure

Heat sensing instrument Patent

Heat sensing instrument, using thermocouple junction connected under heavy conducting materia

Raman spectroscopy with ultrashort coherent excitation. Narrowing of spectral lines beyond the dephasing linewidth

Spectroscopists are constantly faced with the task of improved spectral resolution. Two points are of major interest: (i) The precise frequency of the quantized transition and (ii) the detection of new neighboring transitions. Besides experimental factors the ultimate spectral resolution is determined by the inherent linewidth of the transition. Optical spectroscopists have to deal with different line-broadening processes; for instance with the Doppler effect or with collision broadening in gases, with dephasing processes in condensed systems and with the population relaxation which results in the natural linewidth. In recent years, different novel techniques have been devised which provide spectral resolution beyond the transition linewidth. For instance, Doppler broadening can be eliminated by saturation spectroscopy or by two counter-propagating beams for two-photon transitions/I/. Even measurements beyond the natural linewidth have been performed taking biased signals from the fluorescent decay /2-5/. Techniques have been proposed where the difference between the decay rates of the two states rather than their sum determines the linewidth /6,7/, and narrowing of the natural linewidth by decaying-pulse excitation has been discussed /8/. Very recently, we have demonstrated substantial line narrowing of Raman type transitions in condensed phases /9-11/. The lines were broadened by vibrational dephasing. New information was obtained in congestedspectral regions

Wind tunnel blockage tests at Mach 5 of vacuum duct models for two sound radiation shields

Two sound shield models with dummy vacuum exhaust ducts were tested in a Mach 5 pilot quiet tunnel. The first model simulates a new sound shield of 3 in. (7.62 cm) inside diameter and the second model is a shield of 4 in. (10.16 cm) inside diameter. The dummy vacuum exhaust ducts were attached to the external housing of the models. The flow in the first model, which had a by pass mass flow ratio of about 0.6, could not be started except at the two highest test Reynolds numbers where only the central core flow region was started. The flow in the second model with a mass ratio of approximately 0.3 was fully started except at the lowest unit Reynolds number where some unsteadiness and partial flow separation at the wall was observed. Since the external housing and dummy vacuum ducts were the same for both models, these results indicate that the ratio of by pass mass flow to total mass flow for a wind tunnel sound shield of this particular design must be less than about 0.3. Hence, a lower limit is imposed on the inlet diameter of the sound shield in relation to the exit diameter of the wind tunnel nozzle. This lower limit on the inlet diameter may possibly be reduced by improvements in streamlining of the external housing and ducts, by reductions in blockage area, or by the use of external ducting shrouds