130,799 research outputs found
Can children withhold consent to treatment
A dilemma exists when a doctor is faced with a child or young person who refuses medically indicated treatment. The Gillick case has been interpreted by many to mean that a child of sufficient age and intelligence could validly consent or refuse consent to treatment. Recent decisions of the Court of Appeal on a child's refusal of medical treatment have clouded the issue and undermined the spirit of the Gillick decision and the Children Act 1989. It is now the case that a child patient whose competence is in doubt will be found rational if he or she accepts the proposal to treat but may be found incompetent if he or she disagrees. Practitioners are alerted to the anomalies now exhibited by the law on the issue of children's consent and refusal. The impact of the decisions from the perspectives of medicine, ethics, and the law are examined. Practitioners should review each case of child care carefully and in cases of doubt seek legal advice
Solar radius measurements
Preliminary results of measurements made during 1979-1980 are discussed. Variability in the radius measurements of 0.4 pi is found, of unknown origin
An Independent Calibration of Stellar Ages: HST Observations of White Dwarfs at V=25
The white dwarf luminosity function of a stellar cluster will have a sharp
truncation at a luminosity which is determined by the time since formation of
the first white dwarfs in that cluster. Calculation of the dependence of this
limiting luminosity on age requires relatively well-understood physics and is
independent of stellar evolutionary models. Thus, measurement of the
termination of the white dwarf luminosity function provides an independent
method to determine the age of a cluster, and thereby to calibrate stellar
evolutionary ages. We have obtained HST WFPC2 data in two open clusters,
identified the white dwarf sequence, and proved the feasibility of this
approach, by detecting white dwarfs to V=25. Much deeper data are feasible.
From our present limited data, we show that degenerate cooling ages are not
consistent with some published isochrone ages for clusters with ages of order
1Gyr.Comment: 5 pages plus 3 figures ps format, paper in press in MNRAS: previous
attempt lost the tex
Lamp reliability studies for improved satellite rubidium frequency standard
In response to the premature failure of Rb lamps used in Rb atomic clocks onboard NAVSTAR GPS satellites experimental and theoretical investigations into their failure mechanism were initiated. The primary goal of these studies is the development of an accelerated life test for future GPS lamps. The primary failure mechanism was identified as consumption of the lamp's Rb charge via direct interaction between Rb and the lamp's glass surface. The most effective parameters to accelerate the interaction between the Rb and the glass are felt to be RF excitation power and lamp temperature. Differential scanning calorimetry is used to monitor the consumption of Rb within a lamp as a function of operation time. This technique yielded base line Rb consumption data for GPS lamps operating under normal conditions
Pressure profiles of distant galaxy clusters in the Planck catalog
Successive releases of Planck data have demonstrated the strength of the
Sunyaev--Zeldovich (SZ) effect in detecting hot baryons out to the galaxy
cluster peripheries. To infer the hot gas pressure structure from nearby galaxy
clusters to more distant objects, we developed a parametric method that models
the spectral energy distribution and spatial anisotropies of both the Galactic
thermal dust and the Cosmic Microwave Background, that are mixed-up with the
cluster SZ and dust signals. Taking advantage of the best angular resolution of
the High Frequency Instrument channels (5 arcmin) and using X-ray priors in the
innermost cluster regions that are not resolved with Planck, this modelling
allowed us to analyze a sample of 61 nearby members of the Planck catalog of SZ
sources (, ) using the full mission data, as
well as to examine a distant sample of 23 clusters (, ) that have been recently followed-up with XMM-Newton and Chandra
observations. We find that (i) the average shape of the mass-scaled pressure
profiles agrees with results obtained by the Planck collaboration in the nearby
cluster sample, and that (ii) no sign of evolution is discernible between
averaged pressure profiles of the low- and high-redshift cluster samples. In
line with theoretical predictions for these halo masses and redshift ranges,
the dispersion of individual profiles relative to a self-similar shape stays
well below 10 % inside but increases in the cluster outskirts.Comment: 12 pages, 10 figure
Deep reconditioning of batteries during DSCS 3 flight operations
Deep reconditioning of batteries is defined as discharge below the 1.0 volt/cell level to a value of about 1.0 volt/battery. This type of reconditioning was investigated for use on the Defense Satellite Communications System (DSCS) spacecraft, and has been used during the first year of orbital operation. Prior to launch of the spacecraft, the deep reconditioning was used during the battery life test, which has now complete fourteen eclipse periods. Reconditioning was performed prior to each eclipse period of the life test, and is scheduled to be used prior to each eclipse period in orbit. The battery data for discharge and recharge is presented for one of the life test reconditioning cycles, and for each of the three batteries during the reconditioning cycles between eclipse period no.1 and eclipse period no.2 in Earth orbit
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