Quantum heat engines: limit cycles and exceptional points

We show that the inability of a quantum Otto cycle to reach a limit cycle is connected with the propagator of the cycle being non-compact. For a working fluid consisting of quantum harmonic oscillators, the transition point in parameter space where this instability occurs is associated with a non-hermitian degeneracy (exceptional point) of the eigenvalues of the propagator. In particular, a third-order exceptional point is observed at the transition from the region where the eigenvalues are complex numbers to the region where all the eigenvalues are real. Within this region we find another exceptional point, this time of second order, at which the trajectory becomes divergent. The onset of the divergent behavior corresponds to the modulus of one of the eigenvalues becoming larger than one. The physical origin of this phenomenon is that the hot and cold heat baths are unable to dissipate the frictional internal heat generated in the adiabatic strokes of the cycle. This behavior is contrasted with that of quantum spins as working fluid which have a compact Hamiltonian and thus no exceptional points. All arguments are rigorously proved in terms of the systems' associated Lie algebras

A review of stress corrosion cracking of austenitic stainless steels in PWR primary water

Initial cases of stress corrosion cracking (SCC) in pressurized water reactors (PWRs) occurred mostly but not exclusively in stagnant areas like dead-legs, but recently more extensive IGSCC has occurred in normal free-flowing PWR primary water. Operational experience and laboratory data reveal that the main parameters in IGSCC include cold work and weld residual strain, oxygen, and residual and applied stress. Residual strain, which arises from manufacturing, surface grinding, and welding, should be limited by optimizing manufacturing procedures, minimizing alignment and fit-up stresses and using high-quality weld procedures. Preventing oxygen ingress in the make-up water should be pursued. Stresses created by thermal fluctuations (thermal mixing, low-leakage core operation, and start-ups) deserve more attention. Weld residual stress, fit-up stresses and local stresses from load follow must be maintained below the annealed yield stress. IGSCC should be considered in aging management and in-service inspection. Detection techniques capable of identifying IGSCC should be employed

Stages of recovery instrument: development of a measure of recovery from serious mental illness.

Objective: In order to realize the vision of recovery-orientated mental health services, there is a need for a model and a method of measuring recovery as the concept is described by mental health consumers. A preliminary five-stage model based on consumer accounts was developed in an earlier study by the authors. This next stage of the research program describes the development and initial testing of a stage measure which, when validated, can be used in testing that model. Method: Existing measures of recovery were reviewed to assess their concordance with the model, and a new measure, the Stages of Recovery Instrument (STORI) was subsequently developed. A postal survey was conducted of 94 volunteers from the NISAD Schizophrenia Research Register. Participants completed the STORI and measures of mental health, psychological wellbeing, hope, resilience and recovery. Results: The STORI correlated with all of the psychological health variables, and the five stage subscales were found to be internally consistent. An ordinal relationship between the stage subscales was demonstrated by the intercorrelations of the subscale scores and the pattern of correlations between the subscales and the other measures. However, a cluster analysis of items revealed an overlap in measurement of adjacent stages, with only three clear clusters emerging. Conclusions: The results provide preliminary empirical validation of the STORI as a measure of the consumer definition of recovery. However, refinement of the measure is needed to improve its capacity to discriminate between the stages of the model. The model could then be comprehensively tested using longitudinal methods and the inclusion of objective measures

Differential Uptake of Gold Nanoparticles by 2 Species of Tadpole, the Wood Frog (Lithobates Sylvaticus) and the Bullfrog (Lithobates Catesbeianus)

Engineered nanoparticles are aquatic contaminants of emerging concern that exert ecotoxicological effects on a wide variety of organisms. We exposed cetyltrimethylammonium bromide–capped spherical gold nanoparticles to wood frog and bullfrog tadpoles with conspecifics and in combination with the other species continuously for 21 d, then measured uptake and localization of gold. Wood frog tadpoles alone and in combination with bullfrog tadpoles took up significantly more gold than bullfrogs. Bullfrog tadpoles in combination with wood frogs took up significantly more gold than controls. The rank order of weight-normalized gold uptake was wood frogs in combination \u3e wood frogs alone \u3e bullfrogs in combination \u3e bullfrogs alone \u3e controls. In all gold-exposed groups of tadpoles, gold was concentrated in the anterior region compared with the posterior region of the body. The concentration of gold nanoparticles in the anterior region of wood frogs both alone and in combination with bullfrogs was significantly higher than the corresponding posterior regions. We also measured depuration time of gold in wood frogs. After 21 d in a solution of gold nanoparticles, tadpoles lost \u3e83% of internalized gold when placed in gold-free water for 5 d. After 10 d in gold-free water, tadpoles lost 94% of their gold. After 15 d, gold concentrations were below the level of detection. Our finding of differential uptake between closely related species living in similar habitats with overlapping geographical distributions argues against generalizing toxicological effects of nanoparticles for a large group of organisms based on measurements in only one species

Meeresspiegelschwankungen und ihre geologische Überlieferung im Karbonatsystem

The dependency between carbonate sediment production on a carbonate platform and its relation to sea-level changes is discusses here. The topography of the upper slope plays an important role in determining the way in which sedimentation continues during lowstands in sea level. The mineralogy and composition of sediments produced on the platform can clearly be related to those found in sediments deposited in the adjacent basin. Two examples from the Recent are described: (1) Sanganeb Atoll (Red Sea), and (2) Pedro Bank (caribbean). The applicability of the "highstand shedding" principle is shown for ancient carbonate platforms