FACTORS RELATED TO THE DEVELOPMENT OF BALL SPEED AND TO THE INCIDENCE OF ONE-LEGGED LANDINGS IN THE FRONT-ROW VOLLEYBALL ATTACK

A three-dimensional video analysis was used to identify factors related to the development of ball speed and to the incidence of one-legged landings in high-outside, front-row volleyball attacks. At ball contact, hand speed was 11.9±O.9 m·s-1 (mean±SD). Post-impact ball speed was 19.4±2.3 m·s-1. Shoulder and elbow rotations accounted for about 75% of hand speed at the instant of ball contact while the speed of the CM itself accounted for about 16% of hand speed. Trunk rotation and wrist rotation contributed 11 % and 2% to hand speed, respectively. Attackers possessed forward somersaulting, counterclockwise twisting, and counterclockwise "cartwheeling" angular momentum that resulted in faster hand speeds at contact but also a tendency for one-legged landings. Unfortunately. factors contributing to one-legged landings could not be clearly identified

DETERMINISTIC FACTORS OF OVERALL BALL CONTACT HEIGHT DURING HIGH-OUTSIDE FRONT-ROW VOLLEYBALL ATTACKS

The purpose of this study was to quantify the deterministic factors of overall ball contact height among elite level volleyball attackers. Thirty-two trials collected from nine members of the 1999 USA National A2 Team were subjected to 3D analysis. Results demonstrated that takeoff height (CM height at takeoff) and reach height (vertical distance between the hand and CM at contact) accounted for 86.7% of the overall ball contact height. Flight height (in-flight CM elevation) accounted for only 14% of overall height. Reach height was the only meaningful sUb-height that was significantly correlated with overall ball contact height (r=O.70) and appeared to be most sensitive to technique-related differences in performance. Horizontal approach speeds used by the athletes in this study were relatively slow (3.4±O.3 m·s-1) but were positively correlated with flight height (r=O.60)

A Strategic Planning Intervention Employing Large Group Change: A Scholar/Practitioner Application

We present a scholar-practitioner collaboration applying a large group positive change project, representing the first such application methodology involving first responders. Positive change intervention is based on a multistage process involving Appreciative Inquiry and S.O.A.R. (Strengths, Opportunities, Aspirations and Results), designed to engage the community in inclusion, transparency, and mutual commitment in developing a strategic plan. Part of this plans objective is acquiring national accreditation, which has only been obtained by 217 of 30,052 fire department in the country. The project included 30 interns and 64 interviews with employees, trustees, and community residents, in preparation for the SOAR strategic planning sessio

Advancing subsurface biosphere and paleoclimate research: ECORD–ICDP–DCO–J-DESC–MagellanPlus Workshop Series Program Report

The proper pre-drilling preparation, on-site acquisition and post-drilling preservation of high-qualitysubsurface samples are crucial to ensure significant progress in the scientifically and societally important areasof subsurface biosphere and paleoclimate research. Two of the four research themes of IODP and ICDPand one of the four research areas of the Deep Carbon Observatory (DCO) focus on the subsurface biosphere.Increasing understanding of paleoclimate is a central goal of IODP and incorporated within the scope of theIMPRESS program, the successor of the IMAGES program. Therefore, the goal of our IODP–ICDP–DCO–JDESC–MagellanPlus-sponsored workshop was to help advance deep biosphere and paleoclimate research byidentifying needed improvements in scientific drilling planning and available technology, sample collection andinitial analysis, and long-term storage of subsurface samples and data. Success in these areas will (a) avoidbiological and other contamination during drilling, sampling, storage and shipboard/shore-based experiments;(b) build a repository and database of high-quality subsurface samples for microbiological and paleoclimate researchavailable for the scientific community world-wide over the next decades; and (c) standardize, as much aspossible, microbiological and paleoclimate drilling, sampling and storage workflows to allow results and datato be comparable across both space and time. A result of this workshop is the development and suggested implementationof new advanced methods and technologies to collect high-quality samples and data for the deepbiosphere and paleoclimate scientific communities to optimize expected substantial progress in these fields. Themembers of this workshop will enhance communication within the scientific drilling community by crafting ahandbook focused on pre-drilling, drilling and post-drilling operations

COVID-19 lockdown induces disease-mitigating structural changes in mobility networks

In the wake of the COVID-19 pandemic many countries implemented containment measures to reduce disease transmission. Studies using digital data sources show that the mobility of individuals was effectively reduced in multiple countries. However, it remains unclear whether these reductions caused deeper structural changes in mobility networks, and how such changes may affect dynamic processes on the network. Here we use movement data of mobile phone users to show that mobility in Germany has not only been reduced considerably: Lockdown measures caused substantial and long-lasting structural changes in the mobility network. We find that long-distance travel was reduced disproportionately strongly. The trimming of long-range network connectivity leads to a more local, clustered network and a moderation of the "small-world" effect. We demonstrate that these structural changes have a considerable effect on epidemic spreading processes by "flattening" the epidemic curve and delaying the spread to geographically distant regions.Comment: 20 pages, 8 figure

Explainable AI for higher cognitive functions: How to provide explanations in the face of increasing complexity

Since the introduction of the term explainable artificial intelligence (XAI), many contrasting definitions and methods have been proposed. This lack of a common framework impedes not only further progress in the field but also the realization of existing regulations, such as the EU’s general data protection regulation on the ‘right to an explanation’ (Goodman & Flaxman, 2017). While some researchers use interpretation algorithms as post-hoc explanations (Samek et al., 2021; Ribeiro, 2016), others argue that we should use models which are interpretable in the first place (Rudin, 2019). Although the latter is important, developers are not always willing to sacrifice accuracy by choosing a less complex interpretable model. Here, we propose a working definition of what explaining an AI model means, focusing on robustness, representativeness, and comprehensibility as central properties, and on the importance of causal links (Miller, 2019). In addition, we suggest starting with simple models and gradually scaling up the level of complexity if necessary, whilst setting a case-specific threshold for its trade-off with accuracy and ensuring that we obtain explanations that meet the requirements of our working definition

Nucleus Accumbens is Involved in Human Action Monitoring: Evidence from Invasive Electrophysiological Recordings

The Nucleus accumbens (Nacc) has been proposed to act as a limbic-motor interface. Here, using invasive intraoperative recordings in an awake patient suffering from obsessive-compulsive disease (OCD), we demonstrate that its activity is modulated by the quality of performance of the subject in a choice reaction time task designed to tap action monitoring processes. Action monitoring, that is, error detection and correction, is thought to be supported by a system involving the dopaminergic midbrain, the basal ganglia, and the medial prefrontal cortex. In surface electrophysiological recordings, action monitoring is indexed by an error-related negativity (ERN) appearing time-locked to the erroneous responses and emanating from the medial frontal cortex. In preoperative scalp recordings the patient's ERN was found to be significantly increased compared to a large (n = 83) normal sample, suggesting enhanced action monitoring processes. Intraoperatively, error-related modulations were obtained from the Nacc but not from a site 5 mm above. Importantly, cross-correlation analysis showed that error-related activity in the Nacc preceded surface activity by 40 ms. We propose that the Nacc is involved in action monitoring, possibly by using error signals from the dopaminergic midbrain to adjust the relative impact of limbic and prefrontal inputs on frontal control systems in order to optimize goal-directed behavior