Role of the lattice in the gamma-->alpha phase transition of Ce: a high-pressure neutron and x-ray diffraction study.

The temperature and pressure dependence of the thermal displacements and lattice parameters were obtained across the gamma-->alpha phase transition of Ce using high-pressure, high-resolution neutron and synchrotron x-ray powder diffraction. The estimated vibrational entropy change per atom in the gamma-->alpha phase transition, DeltaS(gamma-alpha)(vib) approximately (0.75+/-0.15)k(B), is about half of the total entropy change. The bulk modulus follows a power-law pressure dependence that is well described using the framework of electron-phonon coupling. These results clearly demonstrate the importance of lattice vibrations, in addition to the spin and charge degrees of freedom, for a complete description of the gamma-->alpha phase transition in elemental Ce.

Specific heat of Mg11B2: evidence for a second energy gap.

Measurements of the specific heat of Mg11B2 from 1 to 50 K, in magnetic fields to 9 T, give the Debye temperature, Theta = 1050 K, the coefficient of the normal-state electron contribution, gamma(n) = 2.6 mJ mol(-1) K-2, and a discontinuity in the zero-field specific heat of 133 mJ mol(-1) K-1 at T(c) = 38.7 K. The estimated value of the electron-phonon coupling parameter, lambda = 0.62, could account for the observed T(c) only if the important phonon frequencies are unusually high relative to Theta. At low T, there is a strongly field-dependent feature that suggests the existence of a second energy gap, about 4 times smaller than the major gap.

The complex nature of superconductivity in MgB2 as revealed by the reduced total isotope effect.

Magnesium diboride, MgB2, was recently observed to become superconducting at 39 K, which is the highest known transition temperature for a non-copper-oxide bulk material. Isotope-effect measurements, in which atoms are substituted by isotopes of different mass to systematically change the phonon frequencies, are one of the fundamental tests of the nature of the superconducting mechanism in a material. In a conventional Bardeen-Cooper-Schrieffer (BCS) superconductor, where the mechanism is mediated by electron-phonon coupling, the total isotope-effect coefficient (in this case, the sum of both the Mg and B coefficients) should be about 0.5. The boron isotope effect was previously shown to be large and that was sufficient to establish that MgB2 is a conventional superconductor, but the Mg effect has not hitherto been measured. Here we report the determination of the Mg isotope effect, which is small but measurable. The total reduced isotope-effect coefficient is 0.32, which is much lower than the value expected for a typical BCS superconductor. The low value could be due to complex materials properties, and would seem to require both a large electron-phonon coupling constant and a value of mu* (the repulsive electron-electron interaction) larger than found for most simple metals.

Efficacy of recombinant human erythropoietin administered subcutaneously to CAPD patients once weekly.

OBJECTIVE: The purpose of the present study was to compare the dosage requirements of recombinant human erythropoletin (rHuEPO) administered subcutaneously (SC) either one or three times weekly. DESIGN: A randomized, prospective study. SETTING: The patients were recruited from two university hospitals and five county hospitals. PATIENTS: Thirty-three anemic patients on continuous ambulatory peritoneal dialysis (CAPD) treatment for end-stage renal failure completed the study. INTERVENTIONS: Initially, all were treated with rHuEPO SC three times a week until hemoglobin blood levels (Hb) remained constant between 105 and 121 g/L for three months. Following randomization, 17 patients continued the same treatment schedule (group A), while 16 patients received the same dose, but administered only once weekly for three months (group B). MAIN OUTCOME MEASURES: The Hb levels and rHuEPO doses at the start and at the end of the three-month study period. RESULTS: In group A the median Hb at randomization was 118 g/L (109-119) (25-75 percentiles) and, after three months, was 113 g/L (106-119) (p = 0.13), while in group B the median Hb was 114 g/L (108-119) and 114 g/L (106-120), respectively (p = 0.50). In group A the weekly dose of rHuEPO remained virtually unchanged during the study period, 65 (55-86) and 66.3 (55-95) U/kg/week, respectively, while in group B it was increased from 60.2 (46-88) to 77 (60-90) U/kg/week. The 22% increase (p = 0.03) took place during the last two weeks. CONCLUSIONS: Our findings indicate that a once-weekly SC dosing regimen of rHuEPO in anemic CAPD patients was equally effective in maintaining a stable hemoglobin level as a thrice-weekly dosing regimen.

The health care supervisor and the early communication patterns of new employees: the uncertainty of assimilation.

Without a doubt, a supervisor's most valuable resources are the employees placed in trust with that supervisor. It is the challenge of every supervisor to focus the vast energies of this resource on accomplishing the mission of the organization. Within the context of new employees, what happens during those first days of employment may determine how well they will contribute, if at all, to accomplishing this organizational mission. While new employee assimilation has many factors that affect its success or failure, the nature of communication that occurs with the supervisor is critical. As was shown in this study, new employees do, in fact, have a specific set of communication needs of which the supervisor should be cognizant.