Nonlinear Preconditioning: How to use a Nonlinear Schwarz Method to Precondition Newton's Method

For linear problems, domain decomposition methods can be used directly as iterative solvers, but also as preconditioners for Krylov methods. In practice, Krylov acceleration is almost always used, since the Krylov method finds a much better residual polynomial than the stationary iteration, and thus converges much faster. We show in this paper that also for non-linear problems, domain decomposition methods can either be used directly as iterative solvers, or one can use them as preconditioners for Newton's method. For the concrete case of the parallel Schwarz method, we show that we obtain a preconditioner we call RASPEN (Restricted Additive Schwarz Preconditioned Exact Newton) which is similar to ASPIN (Additive Schwarz Preconditioned Inexact Newton), but with all components directly defined by the iterative method. This has the advantage that RASPEN already converges when used as an iterative solver, in contrast to ASPIN, and we thus get a substantially better preconditioner for Newton's method. The iterative construction also allows us to naturally define a coarse correction using the multigrid full approximation scheme, which leads to a convergent two level non-linear iterative domain decomposition method and a two level RASPEN non-linear preconditioner. We illustrate our findings with numerical results on the Forchheimer equation and a non-linear diffusion problem

Effects of 9-hour time zone changes on fatigue and circadian rhythms of sleep/wake and core temperature

Physiological and psychological disruptions caused by transmeridian flights may affect the ability of flight crews to meet operational demands. To study these effects, 9 Royal Norwegian Airforces P3-Orion crewmembers flew from Norway to California (-9 hr), and back (+9 hr). Rectal temperature, heart rate and wrist activity were recorded every 2 min, fatigue and mood were rated every 2 hr during the waking day, and logs were kept of sleep times and ratings. Subjects also completed 4 personality inventories. The time-zone shifts produced negative changes in mood which persisted longer after westward flights. Sleep quality (subjective and objective) and duration were slightly disrupted (more after eastward flights). The circadian rhythms of sleep/wake and temperature both completed the 9-hr delay by day 5 in California, although temperature adjusted more slowly. The size of the delay shift was significantly correlated with scores on extraversion and achievement need personality scales. Response to the 9-hr advance were more variable. One subject exhibited a 15-hr delay in his temperature rhythm, and an atypical sleep/nap pattern. On average, the sleep/wake cycle (but not the temperature rhythm), completed the 9-hr advance by the end of the study. Both rhythms adapted more slowly after the eastward flight

Shared Memory Pipelined Parareal

For the parallel-in-time integration method Parareal, pipelining can be used to hide some of the cost of the serial correction step and improve its efficiency. The paper introduces an OpenMP implementation of pipelined Parareal and compares it to a standard MPI-based variant. Both versions yield almost identical runtimes, but, depending on the compiler, the OpenMP variant consumes about 7% less energy and has a significantly smaller memory footprint. However, its higher implementation complexity might make it difficult to use in legacy codes and in combination with spatial parallelisation

Alertness management in two-person long-haul flight operations

Long-haul flight operations involve cumulative sleep loss, circadian disruption, and extended and irregular duty schedules. These factors reduce pilot alertness and performance on the flightdeck. Conceptually and operationally, alertness management in flight operations can be divided into preventive strategies and operational countermeasures. Preventive strategies are utilized prior to a duty period to mitigate or reduce the effects of sleep loss, circadian disruption and fatigue during subsequent flight operations. Operational countermeasures are used during operations as acute techniques for maintaining performance and alertness. Results from previous NASA Ames field studies document the sleep loss and circadian disruption in three-person long-haul flying and illustrate the application of preventive strategies and operational countermeasures. One strategy that can be used in both a preventive and operational manner is strategic napping. The application and effectiveness of strategic napping in long-haul operations will be discussed. Finally, long-haul flying in two-person highly automated aircraft capable of extended range operations will create new challenges to maintaining pilot alertness and performance. Alertness management issues in this flight environment will be explored

The good character at work: an initial study on the contribution of character strengths in identifying healthy and unhealthy work-related behavior and experience patterns

Purpose: Positive psychological functioning has been related to various positive work-related outcome variables, such as job satisfaction or work engagement. The aim of the present study was to examine the relations between morally positively valued traits (i.e., strengths of character) and work-related behaviors. Method: A sample of 887 adult women completed the Values in Action Inventory of Strengths (VIA-IS) and the Work-related Behavior and Experience Patterns Questionnaire (AVEM) in an online survey. Results: Those assigned to healthy work-related behavior and experience patterns differed in their strengths profiles from those that demonstrated unhealthy patterns (i.e., burnout type) in a predictable way. Especially the strengths of zest, persistence, hope, and curiosity seemed to play a key role in healthy and ambitious work behavior. Conclusions: The study underlines the relevance of character strengths in work settings and suggests that interventions based on character strengths could substantiate interventions already existing at the workplace in order to enhance positive work outcomes further (e.g., work satisfaction, engagement

A Practice-Led and Autoethnographic Engagement with Solo Performance and Stigmatised Objects

This research took a practice-led and autoethnographic approach to querying themes of empowerment and objectification in relation to objects used in pole dance – high heels and the vertical pole. Throughout the course of this four-year study, I have created and performed three solo works, The Ten Inch Heels (2019), Unstable (2019) and Pol(e)arity of Self (2020), whilst simultaneously collecting data about the processes on which the works were built, as well as sharing the performances with audiences and gaining feedback from them. The data stands in a variety of forms including journal entry of my creative process and the autobiographical impulses that fuelled the works, video documentation of the live and digital performance pieces, and audience discussion from peer review groups, survey, written feedback, and verbal exchange. All data collected was thematically analysed and triangulated to find a recursive five-part model that clearly shows the ways in which I have used the pole and high heels, objects that have been accused of objectifying women, to achieve a heightened sense of agency in my practice. The found Creative and Reflective Model for Navigating Autobiographical Objects in Solo Performance to Achieve Agency demonstrates specifically how I have blended elements of my own autobiography, with that of the biography of the objects, to find creative ways of working with the objects that resulted in a heightened sense of knowledge and agency for me as the performer. The model details five components, including autobiography of the performer / choice to work with object, object biography via literature search, object (auto) biography and creative use of the object, audience gaze and achieving agency. The hybridity of this research, and its equal 50/50 weighting to both practical work (three works outlined above) and a written thesis (40,000 words) combines personal knowledge, found knowledge and practical knowledge, all of which come together to form an original contribution to knowledge. This knowledge extends discourse in areas of practice-led research, autoethnography, female solo performance practice, autobiographical research, pole dance, and performing with objects

Light as a chronobiologic countermeasure for long-duration space operations

Long-duration space missions require adaptation to work-rest schedules which are substantially shifted with respect to earth. Astronauts are expected to work in two-shift operations and the environmental synchronizers (zeitgebers) in a spacecraft differ significantly from those on earth. A study on circadian rhythms, sleep, and performance was conducted by exposing four subjects to 6 deg head-down tilt bedrest (to simulate the effects of the weightless condition) and imposing a 12-h shift (6 h delay per day for two days). Bright light was tested in a cross-over design as a countermeasure for achieving faster resynchronization and regaining stable conditions for sleep and circadian rhythmicity. Data collection included objective sleep recording, temperature, heart rate, and excretion of hormones and electrolytes as well as performance and responses to questionnaires. Even without a shift in the sleep-wake cycle, the sleep quantity, circadian amplitudes and 24 h means decreased in many functions under bedrest conditions. During the shift days, sleepiness and fatigue increased, and alertness decreased. However, sleep quantity was regained, and resynchronization was completed within seven days after the shift for almost all functions, irrespective of whether light was administered during day-time or night-time hours. The time of day of light exposure surprisingly appeared not to have a discriminatory effect on the resynchronization speed under shift and bedrest conditions. The results indicate that simulated weightlessness alters circadian rhythms and sleep, and that schedule changes induce additional physiological disruption with decreased subjective alertness and increased fatigue. Because of their operational implications, these phenomena deserve additional investigation

Transformação de algodão (Gossypium Hirsutum L.) através do uso de policátion.

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Cholesterol oxidase effects on reproduction and embryonic development of the cotton boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae).

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A Brain System for Auditory Working Memory

The brain basis for auditory working memory, the process of actively maintaining sounds in memory over short periods of time, is controversial. Using functional magnetic resonance imaging in human participants, we demonstrate that the maintenance of single tones in memory is associated with activation in auditory cortex. In addition, sustained activation was observed in hippocampus and inferior frontal gyrus. Multivoxel pattern analysis showed that patterns of activity in auditory cortex and left inferior frontal gyrus distinguished the tone that was maintained in memory. Functional connectivity during maintenance was demonstrated between auditory cortex and both the hippocampus and inferior frontal cortex. The data support a system for auditory working memory based on the maintenance of sound-specific representations in auditory cortex by projections from higher-order areas, including the hippocampus and frontal cortex