Biomedical subjects
Publications and source records attributed to D Turcan.
Muon neutrino disappearance probability as a function of neutrino flight length L over neutrino energy E was studied. A dip in the L/E distribution was observed in the data, as predicted from the sinusoidal flavor transition probability of neutrino oscillation. The observed L/E distribution constrained nu(micro)<-->nu(tau) neutrino oscillation parameters; 1.9x10(-3) 0.90 at 90% confidence level.
A search for a nonzero neutrino magnetic moment has been conducted using 1496 live days of solar neutrino data from Super-Kamiokande-I. Specifically, we searched for distortions to the energy spectrum of recoil electrons arising from magnetic scattering due to a nonzero neutrino magnetic moment. In the absence of a clear signal, we found micro(nu)</=(3.6x10(-10))micro(B) at 90% C.L. by fitting to the Super-Kamiokande day-night spectra. The fitting took into account the effect of neutrino oscillation on the shapes of energy spectra. With additional information from other solar neutrino and KamLAND experiments constraining the oscillation region, a limit of micro(nu)</=(1.1x10(-10))micro(B) at 90% C.L. was obtained.
We present the results of a search for low energy nu(e) from the Sun using 1496 days of data from Super-Kamiokande-I. We observe no significant excess of events and set an upper limit for the conversion probability to nu(e) of the 8B solar neutrino. This conversion limit is 0.8% (90% C.L.) of the standard solar model's neutrino flux for total energy=8-20 MeV. We also set a flux limit for monochromatic nu(e) for E(nu(e))=10-17 MeV.
A search for the relic neutrinos from all past core-collapse supernovae was conducted using 1496 days of data from the Super-Kamiokande detector. This analysis looked for electron-type antineutrinos that had produced a positron with an energy greater than 18 MeV. In the absence of a signal, 90% C.L. upper limits on the total flux were set for several theoretical models; these limits ranged from 20 to 130 macro nu(e) cm(-2) s(-1). Additionally, an upper bound of 1.2 macro nu(e) cm(-2) s(-1) was set for the supernova relic neutrino flux in the energy region E(nu)>19.3 MeV.
Solar neutrino measurements from 1258 days of data from the Super-Kamiokande detector are presented. The measurements are based on recoil electrons in the energy range 5.0-20.0 MeV. The measured solar neutrino flux is 2.32+/-0.03(stat)+0.08-0.07(syst)x10(6) cm(-2) x s(-1), which is 45.1+/-0.5(stat)+1.6-1.4(syst)% of that predicted by the BP2000 SSM. The day vs night flux asymmetry (Phi(n)-Phi(d))/Phi(average) is 0.033+/-0.022(stat)+0.013-0.012(syst). The recoil electron energy spectrum is consistent with no spectral distortion. For the hep neutrino flux, we set a 90% C.L. upper limit of 40x10(3) cm(-2) x s(-1), which is 4.3 times the BP2000 SSM prediction.
We report the result of a search for neutrino oscillations using precise measurements of the recoil electron energy spectrum and zenith angle variations of the solar neutrino flux from 1258 days of neutrino-electron scattering data in Super-Kamiokande. The absence of significant zenith angle variation and spectrum distortion places strong constraints on neutrino mixing and mass difference in a flux-independent way. Using the Super-Kamiokande flux measurement in addition, two allowed regions at large mixing are found.
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Perinatal intensive care had been introduced in University College Hospital, London, by 1966. In the succeeding 10 years, 28-day mortality rates fell among infants of birth weight 1500 g or less. Among the survivors, the incidence of major handicap was 10% or less and the mean IQ increased to within the range expected for a normal population. Of the children aged 8 years or more 76% had no handicaps and were attending normal schools; 18% had minor handicaps or problems for which they were receiving extra help in normal schools; and only 6% were attending special schools. Throughout the 10 years of the study, the overall prognosis for these infants of very low birth weight improved significantly. Results among other high-risk groups were equally encouraging. Analysis of variance of the data from the infants who weighed 1500 g or less at birth indicated that perinatal complications, particularly illnesses associated with abnormal neurological signs or acidaemia in the infants around the time of birth, were the principal factors determining the condition of the survivors at follow-up. Thus, it is likely that additional refinements in the management of the perinatal period may result in further improvements in the prognosis of these and other high-risk newborns.
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On hundred and sixty babies of birth weight less than or equal to 1500 g who survived after perinatal intensive care have been followed up and observations have been made on their parents. In spite of attempts to minimize maternal separation and the distressing aspects of the birth and management of a baby of very low birth weight, an emotional crisis was observed in the mothers which was not fully resolved until the parents had been looking after the baby at home. The duration and degree of the crisis varied but the mothers who received sympathy and support from the baby's father appeared to have least difficulty. A rigid maternal personality and circumstances surrounding the birth which predisposed to feelings of failure and guilt appeared to prolong the crisis. Nevertheless, most of these parents subsequently formed satisfactory relationships with their children, although they tended to be over-protective and anxious. Failure to establish an adequate relationship was rare and occurred only among mothers with personality or psychiatric disorders. Although serious behaviour disorders among the children were rare, more children than would be expected were mildly over-dependent, shy and anxious at follow-up.