Electron capture rates in a plasma

A new general expression is derived for nuclear electron capture rates within dense plasmas. Its qualitative nature leads us to question some widely accepted assumptions about how to calculate the effects of the plasma on the rates. A perturbative evaluation, though not directly applicable to the strongly interacting case, appears to bear out these suspicions.Comment: 9 page

Life considerations of the shuttle orbiter densified-tile thermal protection system

The Shuttle orbiter themal protection system (TPS) incorporates ceramic reusable surface insulation tiles bonded to the orbiter substructure through a strain isolation pad. Densification of the bonding surface of the tiles increases the static strength of the tiles. The densification proces does not, however, necessarily lead to an equivalent increase in fatigue strength. Investigation of the expected lifetime of densified tile TPS under both sinusoidal loading and random loading simulating flight conditions indicates that the strain isolation pads are the weakest components of the TPS under fatigue loading. The felt pads loosen under repetitive loading and, in highly loaded regions, could possibly cause excessive step heights between tiles causing burning of the protective insulation between tiles. A method of improving the operational lifetime of the TPS by using a strain isolation pad with increased stiffness is presented as is the consequence of the effect of increased stiffness on the tile inplane strains and transverse stresses

Generation of long time creep data of refractory alloys at elevated temperatures Eleventh quarterly report, 26 Dec. 1965 - 26 Mar. 1966

Creep tests of arc-cast and vapor deposited tungsten, molybdenum alloys, niobium, and tantalum base alloys for use in advanced power system

Coping styles associated with post-traumatic stress and depression symptoms following childbirth in croatian women

Childbirth is a normative event in a woman's life and is considered as a positive event. However, one in three women perceive childbirth as a physical threat to themselves or their new-born and 3% of women develop posttraumatic stress disorder (PTSD) following childbirth. Poor coping strategies have been associated with PTSD following childbirth. However, previous studies mainly utilised unidimensional measures of coping strategies, therefore, it remains to be investigated which specific dimensions of coping are more predictive of PTSD after childbirth. The aims of this study were to explore whether women in Croatia report PTSD symptoms following childbirth, and how different coping styles were related to PTSD and depression symptoms. Women (N = 160) who gave birth in the last two years, completed an online questionnaire measuring PTSD symptoms (Impact of Event Scale – IES), postnatal depression symptoms (Edinburgh Postnatal Depression Scale – EPDS) and coping styles (Brief Cope). In this sample, 1.9% reported severe PTSD symptoms following childbirth and 21.9% reported depression symptoms. Many women (66.7%) with PTSD symptoms reported depression symptoms. On the other hand, 28.6% of women with depression symptoms also reported PTSD symptoms, showing that there is a higher co-morbidity of PTSD and depression than vice versa. Avoidant coping styles, specifically, denial and self-blame were positively correlated with both PTSD and depression symptoms. Moreover, of avoidant coping styles, behavioural disengagement was positively correlated with PTSD symptoms only, while self-distraction was positively correlated with depression symptoms only. Also, lower levels of planning and higher levels of emotional support were related to higher levels of depression. However, after controlling for postnatal psychopathology symptoms, coping styles were not significant predictors of PTSD symptoms, but self-blame was a significant predictor of depression symptoms. Psychopathological symptoms following childbirth are reported by Croatian women and are related to coping styles. The avoidant coping style, self-blame, is particularly associated with depression symptoms. Future studies should explore predictors of postpartum PTSD in Croatian women in more representative samples during pregnancy and with the follow-up after childbirth. Also, screening for postnatal psychopathological symptoms should be performed both for depression and PTSD symptoms

Turbulence, combustion, pollutant, and stability characterization of a premixed, step combustor

A two dimensional combustion tunnel was constructed to study a lean premixed turbulent propane/air flame stablized behind a rearward facing step. Studied were: (1) the existence and importance of large coherent structures in turbulent reacting and nonreacting free shear layers behind the steps; (2) the effect of inlet temperature and reference velocity on combustion efficiency; (3) CO, NO2 and NO sub x production in the flame; and (4) the blowout and upstream propagation of the flame. In the ranges studied, the large coherent structures dominated both the reacting and the nonreacting free shear layers behind the step. The growth of the vortices and the propagation of the flamer were intimately linked. Vortex pairing was observed to be one of the mechanisms for introduction of fresh reactants into the shear layer and growth of the shear layer. Probe composition measurements of the flame showed that, in the recirculation zone, the reaction was above 99 percent complete, CO and unburnt hydrocarbons were above the equilibrium level NO sub x concentration was far below the equilibrium level and NO2 comprised a negligible fraction of NO sub x

Nuclear radiation problems, unmanned thermionic reactor ion propulsion spacecraft

A nuclear thermionic reactor as the electric power source for an electric propulsion spacecraft introduces a nuclear radiation environment that affects the spacecraft configuration, the use and location of electrical insulators and the science experiments. The spacecraft is conceptually configured to minimize the nuclear shield weight by: (1) a large length to diameter spacecraft; (2) eliminating piping penetrations through the shield; and (3) using the mercury propellant as gamma shield. Since the alumina material is damaged by the high nuclear radiation environment in the reactor it is desirable to locate the alumina insulator outside the reflector or develop a more radiation resistant insulator

Generation of long time creep data on refractory alloys at elevated temperatures eighth quarterly report

Creep resistance of refractory alloys at elevated temperatures under ultrahigh vacuum condition

Generation of long time creep data on refractory alloys at elevated temperatures Twelfth quarterly report, 26 Mar. - 26 Jun. 1966

Long time creep data on refractory alloys at high temperature