Protoneutron Star Winds

Neutrino-driven winds are thought to accompany the Kelvin-Helmholtz cooling phase of nascent protoneutron stars in the first seconds after a core-collapse supernova. These outflows are a likely candidate as the astrophysical site for rapid neutron-capture nucleosynthesis (the r-process). In this chapter we review the physics of protoneutron star winds and assess their potential as a site for the production of the heavy r-process nuclides. We show that spherical transonic protoneutron star winds do not produce robust $r$-process nucleosynthesis for `canonical' neutron stars with gravitational masses of 1.4 M_sun and coordinate radii of 10 km. We further speculate on and review some aspects of neutrino-driven winds from protoneutron stars with strong magnetic fields.Comment: 29 pages, 4 figures, in "Core Collapse of Massive Stars", Ed. C. L. Fryer, Kluwer Academic Publisher

Book Review: Religion in a New Key

A review of M. Darrol Bryant\u27s Religion in a New Key

The effects of a satellite power system on ground-based astronomy

The effects of power transmission from the solar power satellite and of radiation from the ground based rectennas on radio astronomy, radar astronomy, and optical astronomy are discussed. Interference sources, acceptable signal and noise levels, and conflicting site requirements for observatories and rectennas are considered

Slow Diffusive Gravitational Instability Before Decoupling

Radiative diffusion damps acoustic modes at large comoving wavenumber (k) before decoupling (``Silk damping''). In a simple WKB analysis, neglecting moments of the temperature distribution beyond the quadrupole, damping appears in the acoustic mode as a term of order ik^2/(taudot) where taudot is the scattering rate per unit conformal time. Although the Jeans instability is stabilized on scales smaller than the adiabatic Jeans length, I show that the medium is linearly unstable to first order in (1/taudot) to a slow diffusive mode. At large comoving wavenumber, the characteristic growth rate becomes independent of spatial scale and constant: (t_{KH}a)^-1 ~ (128 pi G/9 kappa_T c)(rho_m/rho_b), where "a" is the scale factor, rho_m and rho_b are the matter and baryon energy density, respectively, and kappa_T is the Thomson opacity. This is the characteristic timescale for a fluid parcel to radiate away its thermal energy content at the Eddington limit, analogous to the Kelvin-Helmholz (KH) time for a massive star or the Salpeter time for black hole growth. Although this mode grows at all times prior to decoupling and on scales smaller than the horizon, the growth time is long, about 100 times the age of the universe at decoupling. Thus, it modifies the density and temperature perturbations on small scales only at the percent level. The physics of this mode is already accounted for in the popular codes CMBFAST and CAMB, but is typically neglected in analytic studies of the growth of primordial perturbations. This work clarifies the physics of this instability in the epoch before decoupling, and emphasizes that the universe is formally unstable on scales below the horizon, even in the limit of large taudot. Analogous instabilities at yet earlier epochs are also mentioned. (Abridged)Comment: 6 pages, 1 figure, emulateapj, comments welcom

Fail-safe numerical control

System provides duplicate set of control logic circuitry. Comparators insure that the same data is present in both circuits. If any discrepancy is found, the machine is automatically stopped, before damage can occur

Practices of Nurse Practitioners in Screening for Hepatitis C

Presented to the Faculty of the University of Alaska Anchorage in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCEThe purpose of this project was to determine both hepatitis C virus (HCV) screening rates and the percentage of cases diagnosed among adults born between 1945 and 1965 in a general practice clinic staffed by nurse practitioners (NPs). A descriptive study was conducted using a chart review of all patients born between 1945 and 1965 seen by NPs in a primary care clinic during a three month period of time. Data was collected on the total number of patients in the target group, those born between 1945 and 1965, as well as each patient’s gender, birth date, if screened for HCV, result of screening, and the reason for screening. Findings revealed that screening rates were suboptimal, with only six out of 178 patients in the target group having been screened for HCV. Age and gender did not appear to be a factor in whether or not a patient was screened