1,786 research outputs found

    Beyond Topologies, Part I

    Full text link
    Arguments on the need, and usefulness, of going beyond the usual Hausdorff-Kuratowski-Bourbaki, or in short, HKB concept of topology are presented. The motivation comes, among others, from well known {\it topological type processes}, or in short TTP-s, in the theories of Measure, Integration and Ordered Spaces. These TTP-s, as shown by the classical characterization given by the {\it four Moore-Smith conditions}, can {\it no longer} be incorporated within the usual HKB topologies. One of the most successful recent ways to go beyond HKB topologies is that developed in Beattie & Butzmann. It is shown in this work how that extended concept of topology is a {\it particular} case of the earlier one suggested and used by the first author in the study of generalized solutions of large classes of nonlinear partial differential equations

    Preflight Adaptation Training for Spatial Orientation and Space Motion Sickness

    Get PDF
    Two part-task preflight adaptation trainers (PATs) are being developed at the NASA Johnson Space Center to preadapt astronauts to novel sensory stimulus conditions similar to those present in microgravity to facilitate adaptation to microgravity and readaptation to Earth. This activity is a major component of a general effort to develop countermeasures aimed at minimizing sensory and sensorimotor disturbances and Space Motion Sickness (SMS) associated with adaptation to microgravity and readaptation to Earth. Design principles for the development of the two trainers are discussed, along with a detailed description of both devices. In addition, a summary of four ground-based investigations using one of the trainers to determine the extent to which various novel sensory stimulus conditions produce changes in compensatory eye movement responses, postural equilibrium, motion sickness symptoms, and electrogastric responses are presented. Finally, a brief description of the general concept of dual-adopted states that underly the development of the PATs, and ongoing and future operational and basic research activities are presented

    Self-attitude awareness training: An aid to effective performance in microgravity and virtual environments

    Get PDF
    This paper describes ongoing development of training procedures to enhance self-attitude awareness in astronaut trainees. The procedures are based on observations regarding self-attitude (perceived self-orientation and self-motion) reported by astronauts. Self-attitude awareness training is implemented on a personal computer system and consists of lesson stacks programmed using Hypertalk with Macromind Director movie imports. Training evaluation will be accomplished by an active search task using the virtual Spacelab environment produced by the Device for Orientation and Motion Environments Preflight Adaptation Trainer (DOME-PAT) as well as by assessment of astronauts' performance and sense of well-being during orbital flight. The general purpose of self-attitude awareness training is to use as efficiently as possible the limited DOME-PAT training time available to astronauts prior to a space mission. We suggest that similar training procedures may enhance the performance of virtual environment operators

    Development and implementation of Inflight Neurosensory Training for Adaptation/Readaptation (INSTAR)

    Get PDF
    Resolution of space motion sickness, and improvements in spatial orientation, posture and motion control, and compensatory eye movements occur as a function of neurosensory and sensorimotor adaptation to microgravity. These adaptive responses, however, are inappropriate for return to Earth. Even following relatively brief space Shuttle missions, significant re-adaptation disturbances related to visual performance, locomotion, and perceived self-motion have been observed. Russian reports suggest that these disturbances increase with mission duration and may be severe following landing after prolonged microgravity exposure such as during a voyage to Mars. Consequently, there is a need to enable the astronauts to be prepared for and more quickly re-adapt to a gravitational environment following extended space missions. Several devices to meet this need are proposed including a virtual environment - centrifuge device (VECD). A short-arm centrifuge will provide centripetal acceleration parallel to the astronaut's longitudinal body axis and a restraint system will be configured to permit head movements only in the plane of rotation (to prevent 'cross-coupling'). A head-mounted virtual environment system will be used to develop appropriate 'calibration' between visual motion/orientation signals and inertial motion/orientation signals generated by the centrifuge. This will permit vestibular, visual and somatosensory signal matches to bias central interpretation of otolith signals toward the 'position' responses and to recalibrate the vestibulo-ocular reflex (VOR)

    Chaperones in Polyglutamine Aggregation:Beyond the Q-Stretch

    Get PDF
    Expanded polyglutamine (polyQ) stretches in at least nine unrelated proteins lead to inherited neuronal dysfunction and degeneration. The expansion size in all diseases correlates with age at onset (AO) of disease and with polyQ protein aggregation, indicating that the expanded polyQ stretch is the main driving force for the disease onset. Interestingly, there is marked interpatient variability in expansion thresholds for a given disease. Between different polyQ diseases the repeat length vs. AO also indicates the existence of modulatory effects on aggregation of the upstream and downstream amino acid sequences flanking the Q expansion. This can be either due to intrinsic modulation of aggregation by the flanking regions, or due to differential interaction with other proteins, such as the components of the cellular protein quality control network. Indeed, several lines of evidence suggest that molecular chaperones have impact on the handling of different polyQ proteins. Here, we review factors differentially influencing polyQ aggregation: the Q-stretch itself, modulatory flanking sequences, interaction partners, cleavage of polyQ-containing proteins, and post-translational modifications, with a special focus on the role of molecular chaperones. By discussing typical examples of how these factors influence aggregation, we provide more insight on the variability of AO between different diseases as well as within the same polyQ disorder, on the molecular level

    Stability of coping and the role of self-efficacy in the first year following mild traumatic brain injury

    Get PDF
    Background and aims: Coping, the psychological adaptation to stressors and serious life events, has been found to have a great influence on the development and persistence of posttraumatic complaints. Coping has received much attention for having been found to be modifiable in treatment following mild traumatic brain injury (mTBI) and for its potential to identify the Patients who are at risk of suffering from long-term complaints. Currently, coping styles are assumed to be stable over time. Although interventions to facilitate adaptive coping are given at different time intervals after the injury, little is known about spontaneous changes in preferred strategies over time following mTBI. This study aimed to investigate the stability of different coping styles over a one-year period following mTBI (at two weeks', six and twelve months' post-injury) and to investigate the relation between coping styles and feelings of self-efficacy.Methods: We included 425 mTBI patients (Glasgow Coma Scale [GCS] score 13-15) admitted to three Level-1 trauma centers in the Netherlands as part of a prospective follow-up study. All participants filled out The Utrecht Coping List (UCL) to determine their position on seven coping subscales.Results: Most coping styles showed a decrease over time, except for positive reframing, which showed a decrease and then increased. Interestingly, the passive coping style was found to stabilize over time within the year after injury. High feelings of self-efficacy were related to a high active coping style (r = 0.36), and low feelings of self-efficacy with passive coping (r =-032).Conclusions: These results hold important possibilities for the use of the passive coping strategy as an inclusion criterion for intervention studies and an entry point for treatment itself. Considering the intertwinement of coping with self-efficacy, improving feelings of self-efficacy could form an effective part of an intervention to improve outcome. (C) 2017 Elsevier Ltd. All rights reserved.</p

    Is ketamine an appropriate alternative to ECT for patients with treatment resistant depression? A systematic review:A systematic review

    Get PDF
    OBJECTIVE: Ketamine has repeatedly shown to have rapid and robust antidepressant effects in patients with treatment resistant depression (TRD). An important question is whether ketamine is as effective and safe as the current gold standard electroconvulsive therapy (ECT). METHODS: The literature was searched for trials comparing ketamine treatment with ECT for depression in the Pubmed/MEDLINE database and Cochrane Trials Library. RESULTS: A total of 137 manuscripts were identified, 6 articles were included in this review. Overall quality of the included studies was diverse with relevant risk of bias for some of the studies. Results suggest that ketamine treatment might give faster but perhaps less durable antidepressant effects. Side effects differed from ECT, in particular less cognitive impairment was apparent in ketamine treatment. LIMITATIONS: The included studies have limited sample sizes, use different treatment protocols and in most trials, longer term follow up is lacking. Furthermore, allocation bias appears likely in the non-randomized trials. CONCLUSIONS: Current available literature does not yet provide convincing evidence to consider ketamine as an equally effective treatment alternative to ECT in patients with TRD. There are indications for a more favourable short term cognitive side effect profile after ketamine treatment. Methodologically well-designed studies with larger sample sizes and longer follow up duration are warranted
    • …
    corecore