1,262 research outputs found

    A Vector-Integration-to-Endpoint Model for Performance of Viapoint Movements

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    Viapoint (VP) movements are movements to a desired point that are constrained to pass through an intermediate point. Studies have shown that VP movements possess properties, such as smooth curvature around the VP, that are not explicable by treating VP movements as strict concatenations of simpler point-to-point (PTP) movements. Such properties have led some theorists to propose whole-trajectory optimization models, which imply that the entire trajectory is pre-computed before movement initiation. This paper reports new experiments conducted to systematically compare VP with PTP trajectories. Analyses revealed a statistically significant early directional deviation in VP movements but no associated curvature change. An explanation of this effect is offered by extending the Vector-Integration-To-Endpoint (VITE) model (Bullock and Grossberg, 1988), which postulates that voluntary movement trajectories emerge as internal gating signals control the integration of continuously computed vector commands based on the evolving, perceptible difference between desired and actual position variables. The model explains the observed trajectories of VP and PTP movements as emergent properties of a dynamical system that does not precompute entire trajectories before movement initiation. The new model includes a working memory and a stage sensitive to time-to-contact information. These cooperate to control serial performance. The structural and functional relationships proposed in the model are consistent with available data on forebrain physiology and anatomy.Office of Naval Research (N00014-92-J-1309, N00014-93-1-1364, N0014-95-1-0409

    Development of an intervention aimed at increasing awareness and acknowledgement of victimisation and its consequences among people with severe mental illness

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    Individuals with severe mental illness have a significant risk of (anticipated) discrimination and (criminal) victimisation, which is not structurally and systematically addressed by mental health practitioners. The aim of this study was to develop and pilot an intervention which supports professionals to address victimisation and its consequences, in order to reinforce safe social participation and improve recovery. Following the rehabilitation and positive risk management literature, in addition to current practice, intervention components were developed in two focus groups and four subsequent expert meetings. The intervention was piloted in two outpatient teams before being finalised. The Victoria intervention includes positive risk management, focusing on clients’ narratives and strengths, and awareness of unsafe (home) environments: it comprises four steps: exploring issues with social participation, analysing victimisation experiences, clarifying the context of these experiences, and determining future steps, including victimisation-sensitive rehabilitation planning and optional trauma treatment. Future research should further test this intervention

    Addressing victimization to enable societal participation in flexible assertive community treatment:A process evaluation of the implementation of a new intervention

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    BACKGROUND: Individuals with severe mental illness experience more victimization and discrimination than other persons in the community. Effective rehabilitation and recovery-oriented care interventions aimed at addressing this issue are lacking. We therefore developed a victimization-informed intervention (accompanied by a training module for professionals) called the Victoria intervention. The purpose of the present study was to understand the trial effects by examining the implementation process and the factors that influenced it. MATERIALS AND METHODS: A process evaluation was conducted using a mixed-methods design. During the professionals’ intervision sessions, we used observations to understand the learning processes (n = 25). Subsequently, we studied the use of the intervention in practice through structured questionnaires (n = 215) and semi-structured interviews (n = 34) with clients and professionals. We used descriptive and inferential statistics for the quantitative data and the framework method for the analyses of the qualitative data. RESULTS: The observations showed that the trainings were well received. The professionals shared the urgency of paying attention to victimization and discrimination and its harmful effects on participation. They also found the intervention steps to be logical and the intervention protocol easy to use. Nevertheless, they mentioned in the interviews that they had experienced difficulties initiating a conversation about victimization, and if they started one, they did not always follow the steps of the intervention as intended. Few clients said that victimization was placed on the agenda, though those who had discussed victimization with their caregivers expressed their appreciation in the interviews; they felt acknowledged and supported. DISCUSSION: The findings indicate that the intervention was considered helpful in raising awareness and the acknowledgment of victimization. However, professionals remain reluctant to talk about the subject, and the results show they need more practical training in this regard. This process evaluation has an important added value in that it helps us to understand the results of the effect evaluation of the intervention. The findings will facilitate the development and implementation of interventions that address clients’ victimization experiences in community mental healthcare settings and subsequently enable their participation in society

    Mental healthcare goes online:Practitioners' experiences of providing mental healthcare during the COVID-19 pandemic

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    The outbreak of the COVID-19 pandemic has necessitated sudden and radical changes in mental health care delivery, as strict social distancing and lockdown measures were imposed in the early phases of the pandemic. Almost overnight, practitioners were forced to transfer their face-to-face care practice to online means. To understand the implications of this drastic change for mental health care, and to improve the online care offerings, an online qualitative survey was held among mental health care professionals in Netherlands (n = 51). Our findings indicate that technological and usability problems pose a significant challenge, as do difficulties to establish rapport with clients. Moreover, not all mental health issues and treatment forms are equally amenable to online interaction. In contrast, in many instances, practitioners were positive about the effectiveness of treatment, and reported flexibility, a lower threshold for contact, and lack of travel time as advantages. Their most prominent needs concern better technological, organizational, and logistical support. It is critical that these needs are acted upon by institutions and governments. In addition, current results inform future research on the improvement of e-mental health technologies

    Homogeneous Gold Catalysis through Relativistic Effects: Addition of Water to Propyne

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    In the catalytic addition of water to propyne the Au(III) catalyst is not stable under non-relativistic conditions and dissociates into a Au(I) compound and Cl2. This implies that one link in the chain of events in the catalytic cycle is broken and relativity may well be seen as the reason why Au(III) compounds are effective catalysts.Comment: 12 pages, 3 figures, 1 tabl

    CO2 Conversion in Nonuniform Discharges: Disentangling Dissociation and Recombination Mechanisms

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    Motivated by environmental applications such as synthetic fuel synthesis, plasma-driven conversion shows promise for efficient and scalable gas conversion of CO2 to CO. Both discharge contraction and turbulent transport have a significant impact on the plasma processing conditions, but are, nevertheless, poorly understood. This work combines experiments and modeling to investigate how these aspects influence the CO production and destruction mechanisms in the vortex-stabilized CO2 microwave plasma reactor. For this, a two-dimensional axisymmetric tubular chemical kinetics model of the reactor is developed, with careful consideration of the nonuniform nature of the plasma and the vortex-induced radial turbulent transport. Energy efficiency and conversion of the dissociation process show a good agreement with the numerical results over a broad pressure range from 80 to 600 mbar. The occurrence of an energy efficiency peak between 100 and 200 mbar is associated with a discharge mode transition. The net CO production rate is inhibited at low pressure by the plasma temperature, whereas recombination of CO to CO2 dominates at high pressure. Turbulence-induced cooling and dilution of plasma products limit the extent of the latter. The maxima in energy efficiency observed experimentally around 40% are related to limits imposed by production and recombination processes. Based on these insights, feasible approaches for optimization of the plasma dissociation process are discussed.</p

    The trajectory of caregiver burden and risk factors in dementia progression:A systematic review

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    Background: Caring for patients with dementia at home is often a long-term process, in which the independence of the patient declines, and more responsibility and supervision time is required from the informal caregiver. Objective: In order to minimize and reduce caregiver burden, it is important to explore its trajectory and the accompanying risk factors as dementia progresses; the objective of this systematic review. Methods: PRISMA guidelines were followed in this systematic review. Three databases, PubMed, PsycINFO, and EMbase, were systematically searched in November 2019 using specific keywords. Results: 1,506 hits emerged during the systematic search but only eleven articles actually met the inclusion criteria for this review. The trajectory of caregiver burden is highly variable and depends on multiple factors. Important risk factors included: patients’ behavioral and neuropsychiatric symptoms, and their decline in functioning in (I)ADL; the caregiver’s age, gender, and physical and mental health; and, within the dyads (patient/caregiver), cohabitation and kinship. Conclusion: There is no one-size-fits-all for predicting how caregiver burden will change over time, but specific factors (like being a spouse and increased behavioral impairment and decline in functional status in the patient) may heighten the risk. Other factors, not yet comprehensively included in the published studies, might also prove to be important risk factors. Future research in the field of reducing caregiver burden is recommended to integrate the patient, caregiver, and context characteristics in the trajectory of caregiver burden, and to assess more clearly the phase of the dementia progression and use of external resources

    The design of a game-based training environment to enhance health care professionals’ skills in using eMental health:Study protocol for the user requirements analysis

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    Background: E–mental health (EMH) offers various possibilities for mental health care delivery, with many studies demonstrating its clinical efficacy. However, the uptake of EMH technologies by mental health care professionals remains to be low. One of the reasons for this is the lack of knowledge and skills in using these technologies. Skill enhancement by means of serious gaming has been shown to be effective in other areas but has not yet been applied to the development of EMH skills of mental health care professionals. Objective: The aim of this paper is to describe a study protocol for the user requirements analysis for the design of a game-based training environment for mental health care professionals to enhance their skills in EMH. Methods: The user requirements are formulated using three complementary outputs: personas (lively descriptions of potential users), scenarios (situations that require EMH skills), and prerequisites (required technical and organizational conditions). We collected the data using a questionnaire, co-design sessions, and interviews. The questionnaire was used to determine mental health care professionals’ characteristics, attitudes, and skill levels regarding EMH and was distributed among mental health care professionals in the Netherlands. This led to a number of recognizable subuser groups as the basis for personas. Co-design sessions with mental health care professionals resulted in further specification of the personas and an identification of different user scenarios for the game-based training environment. Interviews with mental health care professionals helped to determine the preferences of mental health care professionals regarding training in EMH and the technical and organizational conditions required for the prospective game-based training environment to be used in practice. This combination of requirement elicitation methods allows for a good representation of the target population in terms of both a broad view of user needs (through the large N questionnaire) and an in-depth understanding of specific design requirements (through interviews and co-design). Results: The questionnaire was filled by 432 respondents; three co-design sessions with mental health care professionals and 17 interviews were conducted. The data have been analyzed, and a full paper on the results is expected to be submitted in the first half of 2021. Conclusions: To develop an environment that can effectively support professionals’ EMH skill development, it is important to offer training possibilities that address the specific needs of mental health care professionals. The approach described in this protocol incorporates elements that enable the design of a playful training environment that is user driven and flexible and considers the technical and organizational prerequisites that influence its implementation in practice. It describes a protocol that is replicable and provides a methodology for user requirements analyses in other projects and health care areas

    Integration of Phytochrome and Cryptochrome Signals Determines Plant Growth during Competition for Light.

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    Plants in dense vegetation perceive their neighbors primarily through changes in light quality. Initially, the ratio between red (R) and far-red (FR) light decreases due to reflection of FR by plant tissue well before shading occurs. Perception of low R:FR by the phytochrome photoreceptors induces the shade avoidance response [1], of which accelerated elongation growth of leaf-bearing organs is an important feature. Low R:FR-induced phytochrome inactivation leads to the accumulation and activation of the transcription factors PHYTOCHROME-INTERACTING FACTORs (PIFs) 4, 5, and 7 and subsequent expression of their growth-mediating targets [2, 3]. When true shading occurs, transmitted light is especially depleted in red and blue (B) wavelengths, due to absorption by chlorophyll [4]. Although the reduction of blue wavelengths alone does not occur in nature, long-term exposure to low B light induces a shade avoidance-like response that is dependent on the cryptochrome photoreceptors and the transcription factors PIF4 and PIF5 [5-7]. We show in Arabidopsis thaliana that low B in combination with low R:FR enhances petiole elongation similar to vegetation shade, providing functional context for a low B response in plant competition. Low B potentiates the low R:FR response through PIF4, PIF5, and PIF7, and it involves increased PIF5 abundance and transcriptional changes. Low B attenuates a low R:FR-induced negative feedback loop through reduced gene expression of negative regulators and reduced HFR1 levels. The enhanced response to combined phytochrome and cryptochrome inactivation shows how multiple light cues can be integrated to fine-tune the plant's response to a changing environment
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