TY - THES A1 - Roos, Stephanie T1 - Unternehmensperformance und Vorstandswechsel - eine empirische Analyse zur Effizienz deutscher Aufsichtsräte T1 - Performance and management turnover - an empirical study on the efficiency of German supervisory boards N2 - Nach Unternehmensskandalen wie bei Enron, Worldcom oder Comroad steht das Thema Corporate Governance in vielen Ländern wieder ganz oben auf der Agenda. Als Reaktion auf die spektakulären Unternehmenskrisen wird weltweit in zahlreichen Ausschüssen über die optimale Ausgestaltung und Qualität der Unternehmensführung und -kontrolle diskutiert. Im Zentrum der Diskussionen in Deutschland steht dabei häufig die Frage nach der Qualität der internen Managementkontrolle durch den Aufsichtsrat. Den Kontrolleuren wird vorgeworfen, ihrer Überwachungsfunktion nur unzureichend nachzukommen und die Zielvorstellungen der Anteilseigner weitgehend aus den Augen zu verlieren. Inwieweit sich die in der Öffentlichkeit lancierte Kritik an der Effizienz deutscher Aufsichtsräte empirisch bestätigen lässt, wird in der vorliegenden Studie überprüft. Die Annäherung an die Fragestellung erfolgt über eine Analyse des systematischen Zusammenhangs zwischen Unternehmensperformance und Wechseln in den Vorständen der DAX100-Gesellschaften über den Zeitraum von 1994 bis 2001. Neben den Turnover-Performance-Beziehungen wird die Reaktion der Kapitalmarktteilnehmer auf die Wechselankündigungen betrachtet. Die Kursanalysen geben Aufschluss über die Bedeutung der personellen Eingriffe durch den Aufsichtsrat für die weitere Unternehmensentwicklung aus Sicht des Kapitalmarktes. Die Untersuchung des gesamten Wechselprozesses bildet die Basis für die Ableitung interessanter Erkenntnisse über die Anreiz- und Disziplinierungswirkung des vom Aufsichtsrat praktizierten Absetzungsmechanismus. N2 - After company failures as with Enron, Worldcom or Comroad, Corporate Governance discussions have significantly increased all over the world. Numerous committees concern themselves with the optimal arrangement and the quality of corporate management and control. In Germany, most of the discussions focus on the quality of management control by the supervisory board. Frequently, the members of the supervisory board are accused to fulfil their monitoring function insufficiently and to lose sight of their clients’ interests. The study examines to what extent the criticism of the efficiency of German supervisory boards, launched in the public, can be confirmed empirically. The approach to the question is conducted by the analysis of the systematic relationship between company performance and turnover in the management boards of the DAX100 companies over the period from 1994 to 2001. In addition to the turnover performance relationships, the reactions of the capital market to the turnover announcements are determined. Capital market effects inform about the impact of management changes for the further company development from investors’ point of view. The empirical analysis of the complete turnover process provides interesting insights into the incentive and disciplining effects resulting from the dismissal mechanism practiced by the supervisory board. KW - Aktiengesellschaft KW - Vorstandsvorsitzender KW - Fluktuation KW - Unternehmensergebnis KW - Aufsichtsrat KW - Corporate Governance KW - Corporate Governance KW - Aufsichtsrat KW - Management KW - Vorstandswechsel KW - Performance KW - Corporate Governance KW - supervisory board KW - management turnover KW - performance Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-20816 ER - TY - JOUR A1 - Zinner, Christoph A1 - Morales-Alamo, David A1 - Ørtenblad, Niels A1 - Larsen, Filip J. A1 - Schiffer, Tomas A. A1 - Willis, Sarah J. A1 - Gelabert-Rebato, Miriam A1 - Perez-Valera, Mario A1 - Boushel, Robert A1 - Calbet, Jose A. L. A1 - Holmberg, Hans-Christer T1 - The Physiological Mechanisms of Performance Enhancement with Sprint Interval Training Differ between the Upper and Lower Extremities in Humans JF - Frontiers in Physiology N2 - To elucidate the mechanisms underlying the differences in adaptation of arm and leg muscles to sprint training, over a period of 11 days 16 untrained men performed six sessions of 4–6 × 30-s all-out sprints (SIT) with the legs and arms, separately, with a 1-h interval of recovery. Limb-specific VO2peak, sprint performance (two 30-s Wingate tests with 4-min recovery), muscle efficiency and time-trial performance (TT, 5-min all-out) were assessed and biopsies from the m. vastus lateralis and m. triceps brachii taken before and after training. VO2peak and Wmax increased 3–11% after training, with a more pronounced change in the arms (P < 0.05). Gross efficiency improved for the arms (+8.8%, P < 0.05), but not the legs (−0.6%). Wingate peak and mean power outputs improved similarly for the arms and legs, as did TT performance. After training, VO2 during the two Wingate tests was increased by 52 and 6% for the arms and legs, respectively (P < 0.001). In the case of the arms, VO2 was higher during the first than second Wingate test (64 vs. 44%, P < 0.05). During the TT, relative exercise intensity, HR, VO2, VCO2, VE, and Vt were all lower during arm-cranking than leg-pedaling, and oxidation of fat was minimal, remaining so after training. Despite the higher relative intensity, fat oxidation was 70% greater during leg-pedaling (P = 0.017). The aerobic energy contribution in the legs was larger than for the arms during the Wingate tests, although VO2 for the arms was enhanced more by training, reducing the O2 deficit after SIT. The levels of muscle glycogen, as well as the myosin heavy chain composition were unchanged in both cases, while the activities of 3-hydroxyacyl-CoA-dehydrogenase and citrate synthase were elevated only in the legs and capillarization enhanced in both limbs. Multiple regression analysis demonstrated that the variables that predict TT performance differ for the arms and legs. The primary mechanism of adaptation to SIT by both the arms and legs is enhancement of aerobic energy production. However, with their higher proportion of fast muscle fibers, the arms exhibit greater plasticity. KW - high-intensity training KW - lower body KW - performance KW - triceps brachii KW - upper body Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-165257 VL - 7 IS - 426 ER - TY - JOUR A1 - Fischer, Rico A1 - Plessow, Franziska A1 - Kiesel, Andrea T1 - The effects of alerting signals in masked priming JF - Frontiers in Psychology N2 - Alerting signals often serve to reduce temporal uncertainty by predicting the time of stimulus onset. The resulting response time benefits have often been explained by facilitated translation of stimulus codes into response codes on the basis of established stimulus-response (S-R) links. In paradigms of masked S-R priming alerting signals also modulate response activation processes triggered by subliminally presented prime stimuli. In the present study we tested whether facilitation of visuo-motor translation processes due to alerting signals critically depends on established S-R links. Alerting signals resulted in significantly enhanced masked priming effects for masked prime stimuli that included and that did not include established S-R links fi.e., target vs. novel primes). Yet, the alerting-priming interaction was more pronounced for target than for novel primes. These results suggest that effects of alerting signals on masked priming are especially evident when S-R links between prime and target exist. At the same time, an alerting-priming interaction also for novel primes suggests that alerting signals also facilitate stimulus-response translation processes when masked prime stimuli provide action-trigger conditions in terms of programmed S-R links. KW - response selection KW - visual cortex KW - temporal predictability KW - stimuli KW - primes KW - target primes KW - simon task KW - automaticity KW - performance KW - perception KW - mechanism KW - novel primes KW - action-trigger KW - masked priming KW - accessory KW - alerting signal Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-122581 SN - 1664-1078 VL - 4 IS - 448 ER - TY - JOUR A1 - Kurrek, Matt M. A1 - Morgan, Pamela A1 - Howard, Steven A1 - Kranke, Peter A1 - Calhoun, Aaron A1 - Hui, Joshua A1 - Kiss, Alex T1 - Simulation as a New Tool to Establish Benchmark Outcome Measures in Obstetrics JF - PLoS ONE N2 - Background There are not enough clinical data from rare critical events to calculate statistics to decide if the management of actual events might be below what could reasonably be expected (i.e. was an outlier). Objectives In this project we used simulation to describe the distribution of management times as an approach to decide if the management of a simulated obstetrical crisis scenario could be considered an outlier. Design Twelve obstetrical teams managed 4 scenarios that were previously developed. Relevant outcome variables were defined by expert consensus. The distribution of the response times from the teams who performed the respective intervention was graphically displayed and median and quartiles calculated using rank order statistics. Results Only 7 of the 12 teams performed chest compressions during the arrest following the 'cannot intubate/cannot ventilate' scenario. All other outcome measures were performed by at least 11 of the 12 teams. Calculation of medians and quartiles with 95% CI was possible for all outcomes. Confidence intervals, given the small sample size, were large. Conclusion We demonstrated the use of simulation to calculate quantiles for management times of critical event. This approach could assist in deciding if a given performance could be considered normal and also point to aspects of care that seem to pose particular challenges as evidenced by a large number of teams not performing the expected maneuver. However sufficiently large sample sizes (i.e. from a national data base) will be required to calculate acceptable confidence intervals and to establish actual tolerance limits. KW - performance KW - anesthesiologists Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-151646 VL - 10 IS - 6 ER - TY - JOUR A1 - Nenadovic, Ana T1 - Performing Feminism, Autobiography, and Testimony. Feminist Rap in Latin America. JF - promptus - Würzburger Beiträge zur Romanistik N2 - This article focuses on selected Latin American female rap artists (Anita Tijoux, Rebeca Lane, and the duo Krudas Cubensi), and the way they perform feminism, autobiography and testimony through their lyrics and performances. The analysis concentrates on the synergies between the texts themselves, the official music videos shared on YouTube and the background music. It aims to demonstrate that only such a synergistic approach to rap allows a profound understanding of its particularities and its contributions to feminist discourses and spaces for feminist testimony in the current rise of both right-wing politics and feminist movements on the continent. KW - feminist rap KW - Latin America KW - performance KW - performativity KW - autobiography Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-221850 SN - 2364-6705 VL - 5 ER - TY - JOUR A1 - Matsusaka, Yohji A1 - Werner, Rudolf A. A1 - Arias-Loza, Paula A1 - Nose, Naoko A1 - Sasaki, Takanori A1 - Chen, Xinyu A1 - Lapa, Constantin A1 - Higuchi, Takahiro T1 - Performance Evaluation of a Preclinical SPECT Scanner with a Collimator Designed for Medium-Sized Animals JF - Molecular Imaging N2 - Background. Equipped with two stationary detectors, a large bore collimator for medium-sized animals has been recently introduced for dedicated preclinical single-photon emission computed tomography (SPECT) imaging. We aimed to evaluate the basic performance of the system using phantoms and healthy rabbits. Methods. A general-purpose medium-sized animal (GP-MSA) collimator with 135 mm bore diameter and thirty-three holes of 2.5 mm diameter was installed on an ultrahigh-resolution scanner equipped with two large stationary detectors (U-SPECT5-E/CT). The sensitivity and uniformity were investigated using a point source and a cylinder phantom containing 99mTc-pertechnetate, respectively. Uniformity (in %) was derived using volumes of interest (VOIs) on images of the cylinder phantom and calculated as , with lower values of % indicating superior performance. The spatial resolution and contrast-to-noise ratios (CNRs) were evaluated with images of a hot-rod Derenzo phantom using different activity concentrations. Feasibility of in vivo SPECT imaging was finally confirmed by rabbit imaging with the most commonly used clinical myocardial perfusion SPECT agent [99mTc]Tc-sestamibi (dynamic acquisition with a scan time of 5 min). Results. In the performance evaluation, a sensitivity of 790 cps/MBq, a spatial resolution with the hot-rod phantom of 2.5 mm, and a uniformity of 39.2% were achieved. The CNRs of the rod size 2.5 mm were 1.37, 1.24, 1.20, and 0.85 for activity concentration of 29.2, 1.0, 0.5, and 0.1 MBq/mL, respectively. Dynamic SPECT imaging in rabbits allowed to visualize most of the thorax and to generate time-activity curves of the left myocardial wall and ventricular cavity. Conclusion. Preclinical U-SPECT5-E/CT equipped with a large bore collimator demonstrated adequate sensitivity and resolution for in vivo rabbit imaging. Along with its unique features of SPECT molecular functional imaging is a superior collimator technology that is applicable to medium-sized animal models and thus may promote translational research for diagnostic purposes and development of novel therapeutics. KW - SPECT Scanner KW - medium-sized animals KW - performance Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-300713 VL - 2022 ER - TY - JOUR A1 - Asare-Kyei, Daniel A1 - Forkuor, Gerald A1 - Venus, Valentijn T1 - Modeling Flood Hazard Zones at the Sub-District Level with the Rational Model Integrated with GIS and Remote Sensing Approaches JF - Water N2 - Robust risk assessment requires accurate flood intensity area mapping to allow for the identification of populations and elements at risk. However, available flood maps in West Africa lack spatial variability while global datasets have resolutions too coarse to be relevant for local scale risk assessment. Consequently, local disaster managers are forced to use traditional methods such as watermarks on buildings and media reports to identify flood hazard areas. In this study, remote sensing and Geographic Information System (GIS) techniques were combined with hydrological and statistical models to delineate the spatial limits of flood hazard zones in selected communities in Ghana, Burkina Faso and Benin. The approach involves estimating peak runoff concentrations at different elevations and then applying statistical methods to develop a Flood Hazard Index (FHI). Results show that about half of the study areas fall into high intensity flood zones. Empirical validation using statistical confusion matrix and the principles of Participatory GIS show that flood hazard areas could be mapped at an accuracy ranging from 77% to 81%. This was supported with local expert knowledge which accurately classified 79% of communities deemed to be highly susceptible to flood hazard. The results will assist disaster managers to reduce the risk to flood disasters at the community level where risk outcomes are first materialized. KW - climate change KW - rational model KW - community KW - flood hazard index KW - West Africa KW - GIS KW - vulnerability KW - performance KW - impact KW - risk KW - mapping KW - runoff Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-151581 VL - 7 SP - 3531 EP - 3564 ER - TY - THES A1 - Kirsch, Artur T1 - Klinische Performance und Biokompatibilität der PUREMA® H-Dialysemembran T1 - Clinical performance and biocompatibility of the PUREMA® H dialysis membrane N2 - Im Rahmen einer randomisierten, prospektiven Cross-over-Studie wurden während der Hämodialyse an chronisch dialysepflichtigen Patienten standardisiert Parameter der Dialyseeffektivität und Biokompatibilität einer neuen, mittels einem Polyelektrolytadditiv modifizierten Dialysemembran, PUREMA® H, im Vergleich zu einer Kontrolldialysemembran, Helixone®, gemessen. Im Vergleich zur Kontrollmembran wies die PUREMA® H-Membran eine verbesserte Entfernung kleinmolekulargewichtiger Eiweiße incl. 2-Mikroglobulin und eine insbesondere für die Komplementaktivierung optimierte Biokompatibilität auf. N2 - In a prospective, randomized, cross-over study on maintenance dialysis patients, a new polyelectrolyte modified hemodialysis membrane, PUREMA® H, was compared to a control membrane, Helixone®, during haemodialysis. Parameters of dialysis efficacy and biocompatibility were measured in a standardized manner. Compared to control, PUREMA® H showed a significantly higher removal of low-molecular-weight proteins, including beta 2-microglobulin and an optimized biocompatibility particulary in regard to complement system activation. KW - Hämodialyse KW - Klinisches Experiment KW - Kontrollierte klinische Studie KW - Chronische Niereninsuffizienz KW - Biokompatibilität KW - Performance KW - Dialysatorleistung KW - terminale Niereninsuffizienz KW - haemodialysis KW - biocompatibility KW - dialysis membrane KW - end-stage renal disease KW - performance Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-34717 ER - TY - JOUR A1 - Kunz, Philipp A1 - Zinner, Christoph A1 - Holmberg, Hans-Christer A1 - Sperlich, Billy T1 - Intra- and post-match time-course of indicators related to perceived and performance fatigability and recovery in elite youth soccer players JF - Frontiers in Physiology N2 - PurposeOur aims were to examine (i) the internal load during simulated soccer match-play by elite youth players; and (ii) the time-course of subsequent recovery from perceived and performance fatigability. MethodsEleven male youth players (16 ± 1 years, 178 ± 7 cm, 67 ± 7 kg) participated in a 2 × 40-min simulated soccer match, completing 30 rounds (160 s each) with every round including multidirectional and linear sprinting (LS20m), jumping (CMJ) and running at different intensities. During each round, LS20m, CMJ, agility, heart rate (HR), oxygen uptake (VO2), energy expenditure (EE), substrate utilization and perceived exertion RPE were assessed. In addition, the blood level of lactate (Lac) was obtained after each of the five rounds. Creatine kinase (CK) concentration, maximal voluntary isometric knee extension and flexion, CMJ, number of skippings in 30 s, and subjective ratings on the Acute Recovery and Stress Scale (ARSS) were examined before and immediately, 24 and 48 h after the simulation. Results: During the game %HR\(_{peak}\) (p < 0.05, d = 1.08), %VO2\(_{peak}\) (p < 0.05; d = 0.68), Lac (p < 0.05, d = 2.59), RPE\(_{total}\) (p < 0.05, d = 4.59), and RPE\(_{legs}\) (p < 0.05, d = 4.45) all increased with time during both halves (all p < 0.05). Agility improved (p < 0.05, d = 0.70) over the time-course of the game, with no changes in LS20m (p ≥ 0.05, d = 0.34) or CMJ (p ≥ 0.05, d = 0.27). EE was similar during both halves (528 ± 58 vs. 514 ± 61 kcal; p = 0.60; d = 0.23), with 62% (second half: 65%) carbohydrate, 9% (9%) protein and 26% (27%) fat utilization. With respect to recovery, maximal voluntary knee extension (p ≥ 0.05, d = 0.50) and flexion force (p ≥ 0.05, d = 0.19), CMJ (p ≥ 0.05, d = 0.13), number of ground contacts (p ≥ 0.05, d = 0.57) and average contact time (p ≥ 0.05, d = 0.39) during 30-s of skipping remained unaltered 24 and 48 h after the game. Most ARSS dimensions of load (p < 0.05, d = 3.79) and recovery (p < 0.05, d = 3.22) returned to baseline levels after 24 h of recovery. Relative to baseline values, CK was elevated immediately and 24 h after (p < 0.05, d = 2.03) and normalized 48 h later. ConclusionIn youth soccer players the simulated match evoked considerable circulatory, metabolic and perceptual load, with an EE of 1042 ± 118 kcal. Among the indicators of perceived and performance fatigability examined, the level of CK and certain subjective ratings differed considerably immediately following or 24–48 h after a 2 × 40-min simulated soccer match in comparison to baseline. Accordingly, monitoring these variables may assist coaches in assessing a U17 player’s perceived and performance fatigability in connection with scheduling training following a soccer match. KW - soccer (football) KW - youth KW - match load KW - fatigue KW - intermittent exercise KW - performance Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-195657 SN - 1664-042X VL - 10 IS - 1383 ER - TY - THES A1 - Finkenberg, Frank T1 - Flipped Classroom im Physikunterricht T1 - Flipped Classroom in Physics Education N2 - In der Unterrichtsmethode Flipped Classroom sind schulische und häusliche Aktivitäten vertauscht. Instruktionale Elemente werden in online verfügbare Lernvideos ausgelagert, welche die Schüler als häusliche Vorbereitung ansehen. Im Unterricht stehen dann schülerzentrierte Tätigkeiten im Vordergrund, in denen die Schüler ihr Wissen anwenden und vertiefen können. Durch die Auslagerung von Inputphasen wandelt sich die Rolle des Lehrers vom Instructor zum Lernbegleiter. Die vorliegende quasi-experimentelle Studie im Pre-/Postdesign mit Kontrollgruppe untersuchte die Wirkungen des Flipped Classroom in Physikkursen der Oberstufe (Grundkursniveau) an zwei deutschen Gymnasien mit N = 151 Schülerinnen und Schülern. Acht Physikkurse der 11. Jahrgangsstufe nahmen an der Studie teil, die sich über einen Zeitraum von zwei Schuljahren erstreckte (2015/16 und 2016/17). Vier der fünf teilnehmenden Lehrkräfte unterrichteten sowohl einen Kontroll- als auch einen Treatmentkurs. Sämtliche Lernvideos wurden von den Lehrkräften selbst erstellt. Dabei integrierten sie reale Experimente, um dem Anspruch physikauthentischen Unterrichts gerecht zu werden. Die Forschungsfragen richteten sich sowohl auf die Leistung in einem Fachwissenstest als auch auf affektive Lernmerkmale wie die Motivation, das Interesse und das Selbstkonzept. Zusätzlich wurden die wahrgenommene Lehrerunterstützung und das Hausaufgabenverhalten untersucht. Die Anwendung von Flipped Classroom im Physikunterricht zeigte größtenteils positive Effekte. Die Schülerinnen und Schüler im Flipped Classroom hatten einen höheren kognitiven Lernzuwachs und ein besseres Selbstkonzept als ihre Mitschüler, die traditionell unterrichtet wurden. Das Leistungsniveau und das Geschlecht der Schülerinnen und Schüler hatten dabei keinen Einfluss auf diese Effekte. Während die Motivation, sich mit Physik zu beschäftigen, in der Kontrollgruppe sank, blieb sie in der Treatmentgruppe auf konstantem Niveau. Bei genauerem Blick zeigte sich, dass die Motivation bei Schülerinnen im Flipped Classroom anstieg, bei Schülerinnen im traditionellen Unterricht jedoch abnahm. Das Interesse am Unterrichtsfach Physik wurde in beiden Gruppen geringer. Sowohl die wahrgenommene Lehrerunterstützung als auch die Hausaufgabendauer blieben in beiden Gruppen zwischen Pre- und Posttest unverändert. Die Hausaufgabendisziplin war im Flipped Classroom jedoch deutlich höher, was zeigt, dass die Schülerinnen und Schüler eher bereit waren, sich instruktionale Lernvideos anzusehen als klassische Hausaufgaben zu bearbeiten. N2 - Flipped Classroom inverts traditional teaching methods by delivering direct instruction in online learning videos. The students watch the videos at home so that class time is freed up for student centered and collaborative activities that allow a deeper exploration of the con-tent. By outsourcing lectures, the role of the teacher shifts from instructing to coaching the students. The quasi-experimental pre/post-study with control group examined the effects of flipped classroom applied to basic physics courses at two German secondary schools with N = 151 students in a three-months-treatment. Eight 11th grade physics courses took part in the study that was conducted in the school years 2015/16 and 2016/17. Four of five teachers in-volved in the study taught both control and treatment courses. All videos were produced by the teachers and incorporated real experiments to ensure an authentic physics education experience. The research questions focused on the performance in a content knowledge test as well as non-cognitive attitudes such as motivation, interest and self-concept. In addition, perceived teacher support and homework habits were also evaluated. Applying flipped classroom in physics school education showed largely positive results. The students in flipped classroom had a higher gain in cognitive learning and a better self-concept than those in a traditional classroom setting. Physics aptitude as well as gender did not moderate these effects. Whereas the motivation to engage in physics declined in the control group, it remained unchanged in the treatment group. In particular, female students in flipped classroom developed a higher motivation to engage in physics than their female peers who lost motivation in the traditional classroom. The interest in physics as a school subject decreased in both groups. The perceived teacher support and the average length of homework stayed the same in both groups between pre- and post-test. However, the homework discipline was considerably higher in flipped classroom which showed that stu-dents were more likely to watch instructional videos than do traditional homework. KW - Physikunterricht KW - Lernvideos KW - active learning KW - Integriertes Lernen KW - Vergleichsstudie KW - Schüleraktivierung KW - explanatory videos KW - comparative study KW - performance KW - motivation KW - Lernerfolg KW - Kooperatives Lernen KW - E-Learning KW - Aktivierung KW - Motivation KW - Interesse Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-164146 ER - TY - THES A1 - Reeg, Johannes T1 - Empirical Studies of Contemporaneous Banking Research T1 - Empirische Studien aktueller Bankenforschung N2 - Banks perform important functions for the economy. Besides financial intermediation, banks provide information, liquidity, maturity- and risk-transformation (Fama, 1985). Banks ensure the transfer of liquidity from depositors to the most profitable investment projects. In addition, they perform important screening and monitoring services over investments hence contributing steadily to the efficient allocation of resources across the economy (Pathan and Faff, 2013). Since banks provide financial services all across the economy, this exposes banks (as opposed to non-banks) to systemic risk: the recent financial crisis revealed that banks can push economies into severe recessions. However, the crisis also revealed that certain bank types appear far more stable than others. For instance, cooperative banks performed better during the crisis than commercial banks. Different business models may reason these performance-differences: cooperative banks focus on relationship lending across their region, hence these banks suffered less from the collapse of the US housing market. Since cooperative banks performed better during the crisis than commercial banks, it is quite surprising that research concerning cooperative banks is highly underrepresented in the literature. For this reason, the following three studies aim to contribute to current literature by examining three independent contemporaneous research questions in the context of cooperative banks. Chapter 2 examines whether cooperative banks benefit from revenue diversification: Current banking literature reveals the recent trend in the overall banking industry that banks may opt for diversification by shifting their revenues to non-interest income. However, existing literature also shows that not every bank benefits from revenue diversification (Mercieca et al., 2007; Stiroh and Rumble, 2006; Goddard et al., 2008). Stiroh and Rumble (2006) find that large commercial banks (US Financial Holding Companies) perceive decreasing performance by shifting revenues towards non-interest income. Revenues from cooperative banks differ from those of commercial banks: commercial banks trade securities and derivatives, sell investment certificates and other trading assets. Concerning the lending business, commercial banks focus on providing loans for medium-sized and large companies rather than for small (private) customers. Cooperative banks rely on commission income (fees) from monetary transactions and selling insurances as a source of non-interest income. They generate most of their interest income by providing loans to small and medium-sized companies as well as to private customers in the region. These differences in revenues raise the question whether findings from Stiroh and Rumble (2006) apply to cooperative banks. For this reason, Chapter 2 evaluates a sample of German cooperative banks over the period 2005 to 2010 and aims to investigate the following research question: which cooperative banks benefit from revenue diversification? Results show that findings from Stiroh and Rumble (2006) do not apply to cooperative banks. Revenue concentration is positive related to risk-adjusted returns (indirect effect) for cooperative banks. At the same time, non-interest income is more profitable than interest income (direct effect). The evaluation of the underlying non-interest income share shows that banks who heavily focus on non-interest income benefit by shifting towards non-interest income. This finding arises due to the fact, that the positive direct effect dominates the negative indirect effect, leading in a positive (and significant) net effect. Furthermore, results reveal a negative net effect for banks who are heavily exposed to interest generating activities. This indicates that shifting to non-interest income decreases risk-adjusted returns for these banks. Consequently, these banks do better by focusing on the interest business. Overall, results show evidence that banks need time to build capabilities, expertise and experience before trading off return and risk efficiently with regard on revenue diversification. Chapter 3 deals with the relation between credit risk, liquidity risk, capital risk and bank efficiency: There has been rising competition in the European banking market due to technological development, deregulation and the introduction of the Euro as a common currency in recent decades. In order to remain competitive banks were forced to improve efficiency. That is, banks try to operate closer to a “best practice” production function in the sense that banks improve the input – output relation. The key question in this context is if banks improve efficiency at a cost of higher risk to compensate decreasing earnings. When it comes to bank risk, a large strand of literature discusses the issue of problem loans. Several studies identify that banks hold large shares of non-performing loans in their portfolio before becoming bankrupt (Barr and Siems, 1994; Demirgüc-Kunt, 1989). According to efficiency, studies show that the average bank generates low profits and incorporates high costs compared to the “best practice” production frontier (Fiordelisi et al., 2011; Williams, 2004). At first glance, these two issues do not seem related. However, Berger and DeYoung (1997) show that banks with poor management are less able to handle their costs (low cost-efficiency) as well as to monitor their debtors in an appropriate manner to ensure loan quality. The negative relationship between cost efficiency and non-performing loans leads to declining capital. Existing studies (e.g. Williams, 2004; Berger and DeYoung, 1997) show that banks with a low level of capital tend to engage in moral hazard behavior, which in turn can push these banks into bankruptcy. However, the business model of cooperative banks is based on the interests of its commonly local customers (the cooperative act: § 1 GenG). This may imply that the common perception of banks engaging in moral hazard behavior may not apply to cooperative banks. Since short-term shareholder interests (as a potential factor for moral hazard behavior) play no role for cooperative banks this may support this notion. Furthermore, liquidity has been widely neglected in the existing literature, since the common perception has been that access to additional liquid funds is not an issue. However, the recent financial crisis revealed that liquidity dried up for many banks due to increased mistrust in the banking sector. Besides investigating moral hazard behavior, using data from 2005 to 2010 this study moves beyond current literature by employing a measure for liquidity risk in order to evaluate how liquidity risk relates to efficiency and capital. Results mostly apply to current literature in this field since the empirical evaluation reveals that lower cost and profit-efficiency Granger-cause increases in credit risk. At the same time, results indicate that credit risk negatively Granger-causes cost and profit-efficiency, hence revealing a bi-directional relationship between these measures. However, most importantly, results also show a positive relationship between capital and credit risk, thus displaying that moral hazard behavior does not apply to cooperative banks. Especially the business model of cooperative banks, which is based on the interests of its commonly local customers (the cooperative act: § 1 GenG) may reason this finding. Contrary to Fiordelisi et al. (2011), results also show a negative relationship between capital and cost-efficiency, indicating that struggling cooperative banks focus on managing their cost-exposure in following periods. Concerning the employed liquidity risk measure, the authors find that banks who hold a high level of liquidity are less active in market related investments and hold high shares of equity capital. This outcome clearly reflects risk-preferences from the management of a bank. Chapter 4 examines governance structures of cooperative banks: The financial crisis of 2007/08 led to huge distortions in the banking market. The failure of Lehman Brothers was the beginning of government interventions in various countries all over the world in order to prevent domestic economies from even further disruptions. In the aftermath of the crisis, politicians and regulators identified governance deficiencies as one major factor that contributed to the crisis. Besides existing studies in the banking literature (e.g. Beltratti and Stulz, 2012; Diamond and Rajan, 2009; Erkens et al., 2012) an OECD study from 2009 supports this notion (Kirkpatrick, 2009). Public debates increased awareness for the need of appropriate governance mechanisms at that time. Consequently, politicians and regulators called for more financial expertise on bank boards. Accordingly, the Basel Committee on Banking Supervision states in principle 2 that “board members should remain qualified, individually and collectively, for their positions. They should understand their oversight and corporate governance role and be able to exercise sound, objective judgement about the affairs of the bank.” (BCBS, 2015). Taking these perceptions into consideration the prevailing question is whether financial experts on bank boards do really foster bank stability? This chapter aims to investigate this question by referring to the study from Minton et al. (2014). In their study, the authors investigate US commercial bank holding companies between the period 2003 and 2008. The authors find that financial experts on the board of US commercial bank holding companies promote pro-cyclical bank performance. Accordingly, the authors question regulators view of more financial experts on the board leading to more banking stability. However, Minton et al. (2014) do not examine whether their findings accrue due to financial experts who act in the interests of shareholders or due to the issue that financial experts may have a more risk-taking attitude (due to a better understanding of financial instruments) than other board members. Supposed that their findings accrue due to financial experts who act in the interests of shareholders. Then financial experts on the board of banks where short-term shareholder interests play no role (cooperative banks) may prove beneficial with regard on bank performance during the crisis as well as in normal times. This would mean that they use their skills and expertise to contribute sustainable growth to the bank. Contrary, if this study reveals pro-cyclical bank performance related to financial experts on the board of cooperative banks, this finding may be addressed solely to the risk-taking attitude of financial experts (since short-term shareholder interests play no role). For this reason, this chapter aims to identify the channel for the relation of financial experts and bank performance by examining the following research question: Do financial experts on the board promote pro-cyclical bank performance in a setting where short-term shareholder interests play no role? Results show that financial experts on the board of cooperative banks (data from 2006 to 2011) do not promote pro-cyclical bank performance. Contrary, results show evidence that financial experts on the board of cooperative banks appear to foster long-term bank stability. This suggests that regulators should consider ownership structure (and hence business model of banks) when imposing new regulatory constraints for financial experts on the bank board. N2 - Banken nehmen wichtige Funktionen innerhalb einer Volkswirtschaft wahr. Innerhalb ihrer Rolle als Finanzintermediär stellen sie Liquidität bereit und übernehmen elementare Aufgaben der Fristen- und Risikotransformation (Fama ,1985). Sie stellen sicher, dass die Liquidität der Depotinhaber den profitabelsten Investitionsprojekten zukommt. Darüber hinaus übernehmen Banken wichtige Prüfungs- und Überwachungsfunktionen über ihre Investitionsprojekte und sorgen damit für eine stetig effiziente Ressourcenallokation innerhalb einer Volkswirtschaft (Pathan and Faff, 2013). Da jedoch Banken ihre Finanzdienstleistungen der gesamten Volkswirtschaft zur Verfügung stellen, erzeugen sie damit auch (im Gegensatz zu Firmen) ein gewisses Systemrisiko: die Finanzkrise 2007 – 2008 hat gezeigt, dass Banken ganze Staaten in eine Rezession ziehen können. Gleichzeitig hat die Krise allerdings auch gezeigt, dass bestimmte Banktypen deutlich stabiler sind als andere. So sind beispielsweise die genossenschaftlichen Volks- und Raiffeisenbanken deutlich besser durch die Krise gekommen als nahezu alle Universalbanken. Genossenschaftsbanken existieren in allen größeren westlichen Volkswirtschaften und nehmen innerhalb dieser oft eine bedeutende Rolle ein. Aufgrund der einerseits hohen Bedeutung von Genossenschaftsbanken in den genannten Volkswirtschaften und der andererseits vergleichsweise geringen Beachtung in der Literatur, ist es das Ziel dieser Dissertation mit den folgenden drei empirischen Studien die bestehende Forschung der Genossenschaftsbanken voranzutreiben. Die drei empirischen Studien beschäftigen sich mit jeweils unabhängigen Forschungsfragen, die für den Bankensektor in jüngster Zeit von hoher Relevanz sind. Kapitel 2 beschäftigt sich mit der Frage, welche Genossenschaftsbanken von einer Einnahmendiversifikation profitieren können: bestehende Literatur offenbart den Trend innerhalb des Bankensektors, wonach Banken nach Diversifikation streben, indem sie ihre Einnahmen immer stärker im zinsunabhängigen Geschäft generieren. Jedoch zeigt sich in der Literatur ebenfalls, dass längst nicht alle Banken durch die Einnahmendiversifikation profitieren (Mercieca et al., 2007; Stiroh and Rumble, 2006; Goddard et al., 2008). Bei der Untersuchung von Genossenschaftsbanken ergibt sich folgendes Bild: es profitieren diejenigen Banken von einer weiteren Einnahmendiversifikation, welche bereits einen hohen Anteil ihrer Einnahmen durch das zinsunabhängige Geschäft generieren. Des Weiteren zeigt die Untersuchung einen negativen Nettoeffekt für diejenigen Banken, welche den Großteil ihrer Einnahmen durch das Zinsgeschäft generieren. Insgesamt deuten die Hinweise der empirischen Untersuchung darauf hin, dass Banken eine gewisse Zeit benötigen um entsprechende Expertise und Erfahrung aufzubauen damit eine Einnahmendiversifikation eine konkurrenzfähige risikoadjustierte Rendite erzeugt. Kapitel 3 beschäftigt sich mit der Beziehung zwischen dem Risiko, der Kapitalausstattung und der Effizienz einer Bank. Das Geschäftsmodell von Genossenschaftsbanken beruht auf der Förderung der Interessen der Mitglieder (§ 1 GenG). Das legt die Vermutung nahe, dass die in der Literatur weit verbreitete Ansicht des moralischen Risikoverhaltens nicht auf Genossenschaftsbanken zutrifft. Darüber hinaus könnten die besonderen Governance-Strukturen von Genossenschaftsbanken diese These stützen: kurzfristige Eigentümerinteressen als mögliche Ursache für moralisches Risikoverhalten spielen bei Genossenschaftsbanken keine Rolle. Die Ergebnisse der empirischen Untersuchung von Genossenschaftsbanken zeigen, dass eine niedrigere Kosten- und Gewinneffizienz zu einem höheren Kreditrisiko führt. Gleichzeitig bestätigen die Ergebnisse, dass ein negativer Zusammenhang zwischen dem Kreditrisiko von Banken und deren Kosten- und Gewinneffizienz besteht. Als zentraler Unterschied zu bestehenden Studien zeigt sich jedoch, dass ein positiver Zusammenhang zwischen der Eigenkapitalposition und dem Kreditrisiko besteht. Das bedeutet, dass moralisches Risikoverhalten („moral hazard“) bei Genossenschaftsbanken, wie bereits vermutet, nicht stattfindet. Insbesondere der Zweck der Genossenschaftsbanken (§ 1 GenG) und die damit einhergehenden besonderen Governance-Strukturen sind nach Ansicht der Autoren die wesentliche Begründung für diese Erkenntnis. Kapitel 4 widmet sich den Governance-Strukturen von Genossenschaftsbanken. Speziell wird in diesem Kapitel die Forschungsfrage behandelt, ob Finanzexperten im Aufsichtsrat von Genossenschaftsbanken zu einer prozyklischen Bankperformance führen. Dieser Zusammenhang wurde in der Studie von Minton, Taillard und Williamson (2014) bei kapitalmarktorientierten Banken aufgezeigt. Die Ergebnisse der Genossenschaftsbanken hingegen zeigen, dass Finanzexperten in den Aufsichtsräten von Genossenschaftsbanken im Zeitraum von 2006 bis 2011 keine prozyklische Bankperformance erzeugen. Im Gegenteil, die Ergebnisse weisen darauf hin, dass Finanzexperten in den Aufsichtsräten von Genossenschaftsbanken eine langfristige Stabilität der Banken gewährleisten. In der Konsequenz bedeutet das, dass Regulatoren die Eigentümerstrukturen (und damit das Geschäftsmodell) von Banken berücksichtigen sollten, wenn sie neue regulatorische Anforderungen hinsichtlich Finanzexperten in den Aufsichtsräten von Banken einführen. KW - cooperative diversification KW - Genossenschaftsbanken KW - performance KW - banksrevenue KW - risk KW - profitability KW - efficiency KW - Aufsichtsrat KW - Diversifikation KW - Risiko Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-153581 ER - TY - JOUR A1 - Hossfeld, Tobias A1 - Heegaard, Poul E. A1 - Kellerer, Wolfgang T1 - Comparing the scalability of communication networks and systems JF - IEEE Access N2 - Scalability is often mentioned in literature, but a stringent definition is missing. In particular, there is no general scalability assessment which clearly indicates whether a system scales or not or whether a system scales better than another. The key contribution of this article is the definition of a scalability index (SI) which quantifies if a system scales in comparison to another system, a hypothetical system, e.g., linear system, or the theoretically optimal system. The suggested SI generalizes different metrics from literature, which are specialized cases of our SI. The primary target of our scalability framework is, however, benchmarking of two systems, which does not require any reference system. The SI is demonstrated and evaluated for different use cases, that are (1) the performance of an IoT load balancer depending on the system load, (2) the availability of a communication system depending on the size and structure of the network, (3) scalability comparison of different location selection mechanisms in fog computing with respect to delays and energy consumption; (4) comparison of time-sensitive networking (TSN) mechanisms in terms of efficiency and utilization. Finally, we discuss how to use and how not to use the SI and give recommendations and guidelines in practice. To the best of our knowledge, this is the first work which provides a general SI for the comparison and benchmarking of systems, which is the primary target of our scalability analysis. KW - communication networks KW - performance KW - availability KW - scalability Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-349403 VL - 11 ER - TY - JOUR A1 - Zinner, Christoph A1 - Sperlich, Billy A1 - Wahl, Patrick A1 - Mester, Joachim T1 - Classification of selected cardiopulmonary variables of elite athletes of different age, gender, and disciplines during incremental exercise testing JF - SpringerPlus N2 - Incremental exercise testing is frequently used as a tool for evaluating determinants of endurance performance. The available reference values for the peak oxygen uptake \((VO_{2peak})\), % of \(VO_{2peak}\) , running speed at the lactate threshold \((v_{LT})\), running economy (RE), and maximal running speed \((v_{peak})\) for different age, gender, and disciplines are not sufficient for the elite athletic population. The key variables of 491 young athletes (age range 12–21 years; 250 males, 241 females) assessed during a running step test protocol \((2.4 m s^{−1} ; increase 0.4 m s^{−1} 5 min^{−1})\) were analysed in five subgroups, which were related to combat-, team-, endurance-, sprint- and power-, and racquet-related disciplines. Compared with female athletes, male athletes achieved a higher \(v_{peak}\) (P = 0.004). The body mass, lean body mass, height, abs. \(VO_{2peak} (ml min^{−1})\), rel. \(VO_{2peak} (ml kg^{−1} min^{−1})\), rel. \(VO_{2peak} (ml min^{−1} kg^{−0.75})\), and RE were higher in the male participants compared with the females (P < 0.01). The % of \(VO_2\) at \(v_{LT}\) was lower in the males compared with the females (P < 0.01). No differences between gender were detected for the \(v_{LT}\) (P = 0.17) and % of \(VO_2\) at \(v_{LT}\) (P = 0.42). This study is one of the first to provide a broad spectrum of data to classify nearly 500 elite athletes aged 12–21 years of both gender and different disciplines. KW - performance KW - data KW - competition KW - reference values Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-126275 VL - 4 IS - 544 ER - TY - THES A1 - Schnabel, Eva T1 - Alcohol and driving-related performance - A comprehensive meta-analysis focusing the significance of the non-significant T1 - Alkohol und fahrrelevante Leistungen - Eine umfassende Metaanalyse N2 - The present work reviews the experimental literature on the acute effects of alcohol on human behaviour related to driving performance. A meta-analysis was conducted which includes studies published between 1954 and 2007 in order to provide a comprehensive knowledge of the substance alcohol. 450 studies reporting 5,300 findings were selected from over 12,000 references after applying certain in- and exclusion criteria. Thus, the present meta-analysis comprises far more studies than reviews on alcohol up to now. In the selected studies, different performance tests were conducted which were relevant for driving. The classification system used in this work assigns these tests to eight categories. The main categories consist of several sub categories classifying the tasks more precisely. The main categories were: (1) visual functions, (2) attention (including vigilance), (3) divided attention, (4) en-/decoding (including information processing and memory), (5) reaction time (including simple reaction time and choice reaction time), (6) psychomotor skills, (7) tracking and (8) driving. In addition to the performance aspect, the classification system takes into account mood and social behaviour variables related to driving safety like tiredness or aggression. Following the evaluation method of vote-counting, the number of significant findings and the number of non-significant findings were summarised per blood alcohol concentration (BAC) group. Thereby, a quantitative estimation of the effects of alcohol depending on the BAC was established, the so-called impairment function, which shows the percentage of significantly impaired findings. In order to provide a general overview of alcohol effects on driving-related performance, a global impairment function was established by aggregating all performance findings. The function is nearly linear with about 30% significant findings at a BAC of 0.05% and 50% significant findings at a BAC of 0.08%. In addition, more specific impairment functions considering only the findings of the single behavioural categories were calculated. The results revealed that impairment depends not only on the BAC, but also clearly differs between most of the performance categories. Tracking and driving performance were most affected by alcohol with impairment beginning at very low BACs of 0.02%. Also psychomotor skills were considerably affected by rather low BACs. Impairment of visual functions and information processing occurred at BACs of 0.04% and increased substantially with higher BACs. Impairment in memory tests could be found with very low BACs of 0.02%, but varied depending on the kind of memory. Performance decrements in divided attention tests could also be found with very low BACs in some studies. Attention started to be impaired at 0.04% BAC, but – as in vigilance tasks – considerable impairment only occurred at higher BACs. Choice reaction time was affected at lower BACs than simple reaction time, which was – together with the critical flicker fusion frequency – the least sensitive parameter to the effects of alcohol. To conclude, most skills which are relevant for the safe operation of a vehicle are clearly impaired by BACs of 0.05%, with motor functions being more affected than cognitive functions and complex tasks more than simple tasks. Generally, the results provided no evidence of a threshold effect for alcohol. There was no driving-related performance category for which a sudden transition from unimpaired to impaired occurred at a particular BAC level. In addition, a comparison was made between the present meta-analysis and two reviews of Moskowitz (Moskowitz & Fiorentino, 2000; Moskowitz & Robinson, 1988). Moskowitz reported much lower BACs at which performance was impaired. The reasons for this discrepancy lies in a different way to review scientific findings. On the one hand, Moskowitz focused on significant findings when selecting studies and findings for his reviews. On the other hand, the evaluation method used by Moskowitz ignored non-significant findings and counted each study once at the lowest BAC for which impairment was found. Those non-significant findings are as important as the significant ones in order to determine thresholds of impairment. Therefore, in contrast to Moskowitz, the present work describes the effects of alcohol with functions considering also the non-significant findings. The significance of the non-significant is emphasized with respect to the selection procedure as well as to the evaluation method. N2 - Die vorliegende Arbeit gibt einen umfassenden Überblick experimenteller Studien, die die akute Wirkung von Alkohol auf fahrrelevante Leistungen untersuchen. Hierzu wurde eine Metaanalyse durchgeführt, in der Studien von 1954 bis 2007 berücksichtigt wurden. Aus über 12.000 Referenzen wurden 450 Studien mit insgesamt 5.300 Befunden nach vorher festgelegten Ein- und Ausschlusskriterien ausgewählt. So umfasst die vorliegende Metaanalyse weit mehr Studien als die bisherigen veröffentlichten Literaturüberlicke. In den ausgewählten Studien kamen verschiedene Leistungstests zur Anwendung, um die Effekte von Alkohol auf fahrrelevante Leistungen zu überprüfen. Diese Tests wurden in acht Kategorien klassifiziert: (1) visuelle Funktionen, (2) Aufmerksamkeit (einschließlich Vigilanz), (3) geteilte Aufmerksamkeit, (4) En-/ Dekodierung (einschließlich Informationsverarbeitung und Gedächtnis), (5) Reaktionszeit (einschließlich Einfachreaktionszeit und Wahlreaktionszeit), (6) psychomotorische Fähigkeiten, (7) Tracking und (8) Fahren. Neben den Leistungsaspekten berücksichtigt das in der vorliegenden Arbeit verwendete Klassifikationssystem auch andere für die Fahrleistung relevante Aspekte der beiden Bereiche subjektives Befinden und soziales Verhalten, wie beispielsweise Müdigkeit oder Aggressivität. Gemäß der Vote-counting-Methode wurde die Anzahl der signifikanten und nicht-signifikanten Befunde für verschiedene Blutalkoholkonzentrationsgruppen zusammengezählt. Daraus ergab sich eine quantitative Schätzung der Effekte von Alkohol in Abhängigkeit der Blutalkoholkonzentration (BAK), die sogenannte Beeinträchtigungsfunktion. Diese stellt den Prozentsatz an signifikanten Befunden, die eine Beeinträchtigung berichteten, dar. Um einen allgemeinen Überblick über Alkohol und die Effekte auf die Fahrleistung zu geben, wurde eine globale Beeinträchtigungsfunktion aufgestellt, in die alle Leistungsbefunde eingegangen sind. Diese Funktion ist nahezu linear mit etwa 30% signifikanten Befunden bei einer BAK von 0,05% und 50% signifikanten Befunde bei einer BAK von 0,08%. Darüber hinaus wurden spezifische Beeinträchtigungsfunktionen berechnet, in denen die jeweiligen Befunde der einzelnen Kategorien berücksichtigt wurden. Die Ergebnisse zeigten, dass die Beeinträchtigung nicht nur von der BAK abhängt, sondern auch von der geforderten Leistung. Tracking- und Fahrleistung waren dabei am stärksten betroffen. Hier zeigten sich bereits bei sehr geringen BAK von 0,02% Beeinträchtigungen. Auch psychomotorische Fähigkeiten wurden beträchtlich durch geringe BAK beeinträchtigt. Eine Beeinträchtigung der visuellen Funktionen und Informationsverarbeitung trat bei einer BAK von 0,04% auf und verstärkte sich deutlich mit höheren BAK. Eine Beeinträchtigung in Gedächtnistests konnte bei sehr geringen BAK von 0,02% gefunden werden, wobei diese in Abhängigkeit von der Art der Gedächtnistests variierte. Eine Abnahme der Leistung in Tests zu geteilter Aufmerksamkeit konnte in einigen Studien ebenfalls bei sehr geringen BAK gefunden werden. Eine Beeinträchtigung der Aufmerksamkeit trat bei einer BAK von 0,04% auf, aber erst bei höheren BAK kam es – wie bei Vigilanzaufgaben – zu erheblichen Beeinträchtigungen. Die Einfachreaktionszeit war zusammen mit der Flicker-Verschmelzungsfrequenz der am wenigsten sensitive Parameter für Alkoholeffekte. Zusammenfassend lässt sich sagen, dass die meisten Fertigkeiten, die für das sichere Führen eines Fahrzeugs relevant sind, ab einer BAK von 0,05% deutlich beeinträchtigt sind. Die motorischen Fertigkeiten sind dabei stärker betroffen als die kognitiven Funktionen, und komplexe Aufgaben stärker als einfache Aufgaben. Generell lieferten die Ergebnisse keinen Hinweis für einen Schwelleneffekt von Alkohol. Das heißt es gab keine fahrrelevante Leistungskategorie, bei der bei einer bestimmten BAK-Stufe ein plötzlicher Übergang von unbeeinträchtigt zu beeinträchtigt auftrat. Um Schwellen für ein Auftreten der Beeinträchtigung zu bestimmen, sind nicht-signifikante Befunde genauso wichtig wie signifikante. Die vorliegende Arbeit hebt die Bedeutung der Nichtsignifikanz sowohl für das Auswahlverfahren der Studien als auch für die Auswertungsmethode explizit hervor und beschreibt die Effekte von Alkohol durch Funktionen, die auch nicht-signifikante Befunde berücksichtigen. KW - Trunkenheit im Verkehr KW - Alkohol KW - Fahrerverhalten KW - Fahren KW - Leistung KW - Review KW - experimentelle Studien KW - Leistungstests KW - Metaanalyse KW - Alcohol KW - performance KW - driving KW - meta-analysis KW - review Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-69959 ER -