6,338 research outputs found

    The Euthanasia of Radically Defective Neonates: Some Statutory Considerations

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    Advances in medical technology, discoveries in pharmacology, an developments in bio-engineering have made it possible for the modem physician to save and/or sustain the lives of individuals who but a few decades ago would have died. These developments have proved a mixed blessing. While on the one hand they have allowed the physician to exercise his profession more successfully, on the other they have opened up before him a domain of decision problems that few of his predecessors have had to face. The thrust of these problems may be focussed into a single question: Ought he to employ the techniques, drugs and devices thus at his disposal in all cases, or ought he to proceed selectively

    The Right to Life of Potential Persons

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    The law accords an individual the right to sue for damages sustained in utero when these damages are the result of what would otherwise be described as criminally negligent treatment. Recent court actions involving children subjected to the influence of thalidomide during certain critical stages of their fetal development 1 make this only too clear. 2 At the same time, however, the law also permits abortion: the deliberate and intentional killing of fetuses at precisely those stages of their development at which thalidomide damage would be sustained were the drug to be administered. 3 In adopting these two stances, the law appears to find itself in a position of conflict. For the right to sue for damages is reserved solely for those individuals which in one sense or another are persons; 4 and in taking a favourable stance in the thalidomide cases, 5 the law seems to be operating on the principle that those individuals who suffer morphological damage as a result of exposure to the drug in fact enjoyed the status of persons at that particular time. On the other hand, in permitting abortions to occur at that particular stage of fetal development, the law seems to be operating on the principle that these individuals are not yet persons; 6 for otherwise, the act of abortion would be one of murder

    Diffusion and jump-length distribution in liquid and amorphous Cu33_{33}Zr67_{67}

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    Using molecular dynamics simulation, we calculate the distribution of atomic jum ps in Cu33_{33}Zr67_{67} in the liquid and glassy states. In both states the distribution of jump lengths can be described by a temperature independent exponential of the length and an effective activation energy plus a contribution of elastic displacements at short distances. Upon cooling the contribution of shorter jumps dominates. No indication of an enhanced probability to jump over a nearest neighbor distance was found. We find a smooth transition from flow in the liquid to jumps in the g lass. The correlation factor of the diffusion constant decreases with decreasing temperature, causing a drop of diffusion below the Arrhenius value, despite an apparent Arrhenius law for the jump probability

    Improved limits on the weak, neutral, hadronic axial vector coupling constants from quasielastic scattering of polarized electrons.

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    In scattering polarized electrons (P1 = 44% by 9Be at an energy of 300 MeV at angles 115°⩽ϑ⩽145° a parity violating asymmetry of Acorr = (−3.5 ± 0.7 ± 0.2) × 10−6 was measured. After correction for finite electron polarization and background we deduce an experimental asymmetry of Acx = (−9.4 ± 1.8 ± 0.5) × 10−6. The quoted errors indicate the statistical and the systematic uncertainties, respectively. The asymmetry, which is dominated by the quasielastic cross section, is interpreted in terms of model-independent electron-nucleon coupling constants of the weak neutral current. The error limits in the sector of axial vector coupling constants have been improved by a factor of 3 over previous results. A model-dependent analysis for the Weinberg angle yields the result sin2θw = 0.221 ± 0.014 ± 0.004

    Status and overview of development of the Silicon Pixel Detector for the PHENIX experiment at the BNL RHIC

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    We have developed a silicon pixel detector to enhance the physics capabilities of the PHENIX experiment. This detector, consisting of two layers of sensors, will be installed around the beam pipe at the collision point and covers a pseudo-rapidity of | \eta | < 1.2 and an azimuth angle of | \phi | ~ 2{\pi}. The detector uses 200 um thick silicon sensors and readout chips developed for the ALICE experiment. In order to meet the PHENIX DAQ readout requirements, it is necessary to read out 4 readout chips in parallel. The physics goals of PHENIX require that radiation thickness of the detector be minimized. To meet these criteria, the detector has been designed and developed. In this paper, we report the current status of the development, especially the development of the low-mass readout bus and the front-end readout electronics.Comment: 9 pages, 8 figures and 1 table in DOCX (Word 2007); PIXEL 2008 workshop proceedings, will be published in the Proceedings Section of JINST(Journal of Instrumentation

    Event-based relaxation of continuous disordered systems

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    A computational approach is presented to obtain energy-minimized structures in glassy materials. This approach, the activation-relaxation technique (ART), achieves its efficiency by focusing on significant changes in the microscopic structure (events). The application of ART is illustrated with two examples: the structure of amorphous silicon, and the structure of Ni80P20, a metallic glass.Comment: 4 pages, revtex, epsf.sty, 3 figure

    Pade approximants for the ground-state energy of closed-shell quantum dots

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    Analytic approximations to the ground-state energy of closed-shell quantum dots (number of electrons from 2 to 210) are presented in the form of two-point Pade approximants. These Pade approximants are constructed from the small- and large-density limits of the energy. We estimated that the maximum error, reached for intermediate densities, is less than 3%. Within the present approximation the ground-state is found to be unpolarized.Comment: 4 pages, RevTeX, 3 ps figure

    Isotope Shift Measurements of Stable and Short-Lived Lithium Isotopes for Nuclear Charge Radii Determination

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    Changes in the mean-square nuclear charge radii along the lithium isotopic chain were determined using a combination of precise isotope shift measurements and theoretical atomic structure calculations. Nuclear charge radii of light elements are of high interest due to the appearance of the nuclear halo phenomenon in this region of the nuclear chart. During the past years we have developed a new laser spectroscopic approach to determine the charge radii of lithium isotopes which combines high sensitivity, speed, and accuracy to measure the extremely small field shift of an 8 ms lifetime isotope with production rates on the order of only 10,000 atoms/s. The method was applied to all bound isotopes of lithium including the two-neutron halo isotope Li-11 at the on-line isotope separators at GSI, Darmstadt, Germany and at TRIUMF, Vancouver, Canada. We describe the laser spectroscopic method in detail, present updated and improved values from theory and experiment, and discuss the results.Comment: 34 pages, 24 figures, 14 table

    Isotope shift in the dielectronic recombination of three-electron ^{A}Nd^{57+}

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    Isotope shifts in dielectronic recombination spectra were studied for Li-like ^{A}Nd^{57+} ions with A=142 and A=150. From the displacement of resonance positions energy shifts \delta E^{142,150}(2s-2p_1/2)= 40.2(3)(6) meV (stat)(sys)) and \delta E^{142,150}(2s-2p_3/2) = 42.3(12)(20) meV of 2s-2p_j transitions were deduced. An evaluation of these values within a full QED treatment yields a change in the mean-square charge radius of ^{142,150}\delta = -1.36(1)(3) fm^2. The approach is conceptually new and combines the advantage of a simple atomic structure with high sensitivity to nuclear size.Comment: 10 pages, 3 figures, accepted for publication in Physical Review Letter
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