453 research outputs found

    The Incidence of Antibody-Mediated Rejection Is Age-Related, Plateaus Late After Kidney Transplantation, and Contributes Little to Graft Loss in the Older Recipients

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    It is not known whether antibody-mediated rejection (ABMR) is age-related, whether it plateaus late after transplantation, and to what extent it contributes to graft loss in older recipients. Patients transplanted between 2010 and 2015 (n = 1,054) in a single center had regular follow-up until January 2023. Recipients were divided into age groups at transplantation: 18-39 years ("young"), 40-55 years ("middle age"), and >55 years ("elderly"). Ten years after transplantation the cumulative % of recipients with ABMR was 17% in young, 15% in middle age, and 12% in elderly recipients (p < 0.001). The cumulative incidence of ABMR increased over time and plateaued 8-10 years after transplantation. In the elderly, with a median follow-up of 7.5 years, on average 30% of the recipients with ABMR died with a functional graft and ABMR contributed only 4% to overall graft loss in this group. These results were cross-validated in a cohort of recipients with >15 years follow-up. Multivariate cox-regression analysis showed that increasing recipient age was independently associated with decreasing risk for ABMR. In conclusion, the cumulative risk for ABMR is age-dependent, plateaus late after transplantation, and contributes little to overall graft loss in older recipients

    Validation of the stabilometer balance test: Bridging the gap between clinical and research based balance control assessments for stroke patients

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    Background: A pronounced discrepancy exists between balance assessments for stroke survivors that are used for clinical purposes and those used for research. Clinical assessments like the Berg Balance Scale generally have stronger ecological validity, whereas research-based assessments like posturography are generally more reliable and precise. We developed a stabilometer balance test (SBT) that aims to couple measurement reliability and precision to clinical meaningfulness by means of a personalized and adaptive test procedure. Research question: To examine the validity, reliability, and measurement error of the stabilometer balance test in inpatient stroke patients. Methods: In this cross-sectional study, inpatient stroke patients (FAC > 2) were tested on a stabilometer with adjustable resistance to mediolateral movement. A modified staircase procedure was used to adapt task difficulty (i.e., rotational stiffness) on a trial-by-trial basis. The main outcome was the threshold stiffness at which a patient could just stay balanced. Threshold stiffness was correlated with the Berg Balance Scale and posturography measurements to determine concurrent validity (N = 86). Test-retest reliability (N = 23) was analyzed with the Intraclass Correlation Coefficient (ICC). Floor and ceiling effects were assessed. The minimal detectable change was determined at individual and group level. Results: Threshold rotational stiffness moderately correlated with the Berg Balance Scale (r=−0.559, p < 0.001), and the absolute path length of the center of pressure during posturography (r=0.348, p = 0.006). Test-retest reliability was good to excellent (ICC=0.869; 95%CI=0.696–0.944). There were no floor or ceiling effects. The minimal detectable change was sufficiently small to detect relevant changes in balance control both on individual and group level. Relevance: The SBT is both a valid and reliable balance assessment in stroke patients. It is at least as precise as current clinically preferred measures and does not suffer from ceiling effects. Therefore, it is suitable for use in clinical practice as well as research

    Response to novel objects and foraging tasks by common marmoset (Callithrix Jacchus) female Pairs

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    Many studies have shown that environmental enrichment can significantly improve the psychological well-being of captive primates, increasing the occurrence of explorative behavior and thus reducing boredom. The response of primates to enrichment devices may be affected by many factors such as species, sex, age, personality and social context. Environmental enrichment is particularly important for social primates living in unnatural social groupings (i.e. same-sex pairs or singly housed animals), who have very few, or no, benefits from the presence of social companions in addition to all the problems related to captivity (e.g. increased inactivity). This study analyses the effects of enrichment devices (i.e. novel objects and foraging tasks) on the behavior of common marmoset (Callithrix jacchus) female pairs, a species that usually lives in family groups. It aims to determine which aspects of an enrichment device are more likely to elicit explorative behaviors, and how aggressive and stress-related behaviors are affected by its presence. Overall, the marmosets explored foraging tasks significantly longer than novel objects. The type of object, which varied in size, shape and aural responsiveness (i.e. they made a noise when the monkey touched them), did not affect the response of the monkeys, but they explored objects that were placed higher in the enclosure more than those placed lower down.Younger monkeys were more attracted to the enrichment devices than the older ones. Finally, stress-related behavior (i.e. scratching) significantly decreased when the monkeys were presented with the objects; aggressive behavior as unaffected. This study supports the importance of environmental enrichment for captive primates and shows that in marmosets its effectiveness strongly depends upon the height of the device in the enclosure and the presence of hidden food. The findings can be explained ifone considers the foraging behavior of wild common marmosets. Broader applications for the research findings are suggested in relation to enrichment

    Does implicit motor learning lead to greater automatization of motor skills compared to explicit motor learning? A systematic review

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    © 2018 Kal et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Background Implicit motor learning is considered to be particularly effective for learning sports-related motor skills. It should foster movement automaticity and thereby facilitate performance in multitasking and high-pressure environments. To scrutinize this hypothesis, we systematically reviewed all studies that compared the degree of automatization achieved (as indicated by dual-task performance) after implicit compared to explicit interventions for sports-related motor tasks. Methods For this systematic review (CRD42016038249) conventional (MEDLINE, CENTRAL, Embase, PsycINFO, SportDiscus, Web of Science) and grey literature were searched. Two reviewers independently screened reports, extracted data, and performed risk of bias assessment. Implicit interventions of interest were analogy-, errorless-, dual-task-, and external focus learning. Data analysis involved descriptive synthesis of group comparisons on absolute motor dual-task (DT) performance, and motor DT performance relative to single-task motor performance (motor DTCs). Results Of the 4125 reports identified, we included 25 controlled trials that described 39 implicit-explicit group comparisons. Risk of bias was unclear across trials. Most comparisons did not show group differences. Some comparisons showed superior absolute motor DT performance (N = 2), superior motor DTCs (N = 4), or both (N = 3) for the implicit compared to the explicit group. The explicit group showed superior absolute motor DT performance in two comparisons. Conclusions Most comparisons did not show group differences in automaticity. The remaining comparisons leaned more toward a greater degree of movement automaticity after implicit learning than explicit learning. However, due to an overall unclear risk of bias the strength of the evidence is level 3. Motor learning-specific guidelines for design and especially reporting are warranted to further strengthen the evidence and facilitate low-risk-of-bias trials

    A distal external focus of attention facilitates compensatory coordination of body parts

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    Many studies have shown that focusing on an intended movement effect that is farther away from the body (distal external focus) results in performance benefits relative to focusing on an effect that is closer to the body (proximal external focus) or focusing on the body itself (internal focus) (see, Chua, Jimenez-Diaz, Lewthwaite, Kim & Wulf, 2021). Furthermore, the advantages of a distal external focus seem to be particularly pronounced in skilled performers (Singh & Wulf, 2020). The present study examined whether such benefits of more distal attentional focus may be associated with enhanced functional variability. Volleyball players (n = 20) performed 60 overhand volleyball serves to a target. Using a within-participants design, the effects of a distal external focus (bullseye), proximal external focus (ball) and an internal focus (hand) were compared. The distal focus condition resulted in significantly higher accuracy scores than did the proximal and internal focus conditions. In addition, uncontrolled manifold analysis showed that functional variability (as measured by the index of synergy) was greatest in the distal focus condition. These findings suggest that a distal external focus on the task goal may enhance movement outcomes by optimising compensatory coordination of body parts

    Individual differences in working memory capacity and conscious processing do not explain explicit and implicit learning outcomes in physical education

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    Crown Copyright © 2022. This study examined the effects of explicit versus implicit learning methods on motor learning and self-efficacy of 11-to 14-year old students (n = 81) practicing the basketball layup during physical education. The main aim was to test the effects of students' verbal working memory capacity (WMC) and propensity for conscious motor processing (CMP) on explicit and implicit learning outcomes. The students practiced basketball layups for three weeks (one session/week) during regular PE classes under practice conditions that either promoted explicit or implicit learning. Verbal WMC and CMP propensity were measured separately. At the posttest, students had significantly improved their layup performance and technique, and self-efficacy, but no differences were noted between the intervention groups (explicit vs. implicit). Students' verbal WMC and CMP propensity did not differentially predict the learning outcomes for the explicit or implicit learning groups. Therefore, in this PE setting, both explicit and implicit learning methods seemed to similarly improve movement skill. Further study is needed to examine under which conditions individual constraints such as verbal WMC and propensity for conscious processing influence the effects of explicit and implicit learning

    Constitutional Analogies in the International Legal System

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    This Article explores issues at the frontier of international law and constitutional law. It considers five key structural and systemic challenges that the international legal system now faces: (1) decentralization and disaggregation; (2) normative and institutional hierarchies; (3) compliance and enforcement; (4) exit and escape; and (5) democracy and legitimacy. Each of these issues raises questions of governance, institutional design, and allocation of authority paralleling the questions that domestic legal systems have answered in constitutional terms. For each of these issues, I survey the international legal landscape and consider the salience of potential analogies to domestic constitutions, drawing upon and extending the writings of international legal scholars and international relations theorists. I also offer some preliminary thoughts about why some treaties and institutions, but not others, more readily lend themselves to analysis in constitutional terms. And I distinguish those legal and political issues that may generate useful insights for scholars studying the growing intersections of international and constitutional law from other areas that may be more resistant to constitutional analogies
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