Coarsened Lattice Spatial Disorder in the Thermodynamic Limit

In this Rapid Research Note the application of recently introduced [Physica A 277 (2000) 157] entropic measure S_Delta of spatial disorder for systems of finite-sized objects is presented. In the thermodynamic limit the critical behaviour of coarsened lattice model of random two-phase systems is illustrated for certain grain size distributions (GSDs) and chosen parameters. Also the changes of spatial disorder, quantified by S_Delta, between the limit GSDs clearly show that the topological equivalence of the two phases is broken.Comment: 3 pages, 1 figur

Coulomb gap in a model with finite charge transfer energy

The Coulomb gap in a donor-acceptor model with finite charge transfer energy $\Delta$ describing the electronic system on the dielectric side of the metal-insulator transition is investigated by means of computer simulations on two- and three-dimensional finite samples with a random distribution of equal amounts of donor and acceptor sites. Rigorous relations reflecting the symmetry of the model presented with respect to the exchange of donors and acceptors are derived. In the immediate neighborhood of the Fermi energy $\mu$ the the density of one-electron excitations $g(\epsilon)$ is determined solely by finite size effects and $g(\epsilon)$ further away from $\mu$ is described by an asymmetric power law with a non-universal exponent, depending on the parameter $\Delta$.Comment: 10 pages, 6 figures, submitted to Phys. Rev.

Non-ergodic effects in the Coulomb glass: specific heat

We present a numerical method for the investigation of non-ergodic effects in the Coulomb glass. For that, an almost complete set of low-energy many-particle states is obtained by a new algorithm. The dynamics of the sample is mapped to the graph formed by the relevant transitions between these states, that means by transitions with rates larger than the inverse of the duration of the measurement. The formation of isolated clusters in the graph indicates non-ergodicity. We analyze the connectivity of this graph in dependence on temperature, duration of measurement, degree of disorder, and dimensionality, studying how non-ergodicity is reflected in the specific heat.Comment: Submited Phys. Rev.

Universal Crossover between Efros-Shklovskii and Mott Variable-Range-Hopping Regimes

A universal scaling function, describing the crossover between the Mott and the Efros-Shklovskii hopping regimes, is derived, using the percolation picture of transport in strongly localized systems. This function is agrees very well with experimental data. Quantitative comparison with experiment allows for the possible determination of the role played by polarons in the transport.Comment: 7 pages + 1 figure, Revte

Erfolgsfaktor Kundenbindung in Zeiten des liberalisierten Wettbewerbs: Vorschlag zur praktischen Umsetzung bei Energieversorgungsunternehmen

Gem¨aß dem Prinzip des homo oeconomicus wird versucht ein bestimmtes Ziel mit einemm¨oglichst geringen Einsatz von Mitteln zu erreichen. Da Menschen jedoch nur ¨uberbeschr¨ankte kognitive F¨ahigkeiten verf¨ugen, entwickelte Simon das Modell der ”boundedrationality“. Darin wird festgelegt, dass Menschen nur nach der ersten zufriedenstellendenL¨osung suchen. Auch werden zur Entscheidungsfindung h¨aufig kognitive Skripts verwendet.Zus¨atzlich wurde festgestellt, dass Menschen in bestimmten Situationen risikoscheuund in anderen Situation risikofreudig reagieren. Dies belegt, dass bei der Kundenbindungdavon ausgegangen werden muss, dass Kunden meistens nicht rational handeln.Vielmehr werden die Konsumenten von verschiedenen Motiven und Emotionen geleitet.Daher ist es wichtig zu verstehen, wie Emotionen aktiviert werden k¨onnen. Besonders f¨urhomogene G¨uter, wie Strom, ist es notwendig das Angebot ¨uber eine emotionale Konditionierungin der Werbung f¨ur den Kunden unterscheidbar zu machen. All dies muss beieiner erfolgreichen Kundenbindung ber¨ucksichtigt werden. Um diese zu erreichen, kannauf verschiedene Instrumente zur¨uckgegriffen werden. Eine Grundvoraussetzung ist, beimKunden Zufriedenheit zu schaffen. Zus¨atzlich ist es notwendig, ein gutes Beschwerdemanagementsystemzu haben, um unzufriedene Kunden wieder von dem Unternehmen¨uberzeugen zu k¨onnen. Die Wahl des Instrumentes f¨ur die Kundenbindung ist auch vomGrad des Involvements des Konsumenten abh¨angig. Ziel sollte es immer sein, Commitmentbeim Kunden herbeizuf¨uhren. Typische Instrumente sind Bonusprogramme, wiebeispielsweise Kundenkarten, bei denen die Treue des Kunden belohnt wird. Besonderswichtig sind Maßnahmen zur Kundenbindung f¨ur den Energiemarkt, da hier ein starkerVerdr¨angungswettbewerb herrscht. Daher ist es notwendig, das Dienstleistungsangebot zuerweitern und die Darstellung des Unternehmens in der ¨Offentlichkeit zu verbessern. Esist jedoch zu beachten, dass es nicht n¨otig ist jeden Kunden zu binden. Dies ist abh¨angigvom Kundenwert. Hierzu kann z.B. ein Kundendeckungsbeitrag berechnet werden

Density of States, Relaxation Dynamics, and Hopping Conductivity of Disordered Many-Electron Systems with Long-Range Correlation

We investigate the Coulomb glass as a model for the low-temperature behavior of polyanilines. It comprises many localized electrons subject to long-range Coulomb interaction in a random potential. Electron transfer takes place via hopping. We present Monte-Carlo results for the single-particle density of states. Hopping occurs between the many-particle states and is described by a rate equation which can be solved exactly yielding the relaxation dynamics and the conductivity

Effects of balance training on balance performance in youth: role of training difficulty

Background!#!Cross-sectional studies have shown that balance performance can be challenged by the level of task difficulty (e.g., varying stance conditions, sensory manipulations). However, it remains unclear whether the application of different levels of task difficulty during balance training (BT) leads to altered adaptations in balance performance. Thus, we examined the effects of BT conducted under a high versus a low level of task difficulty on balance performance.!##!Methods!#!Forty male adolescents were randomly assigned to a BT program using a low (BT-low: n = 20; age: 12.4 ± 2.0 yrs) or a high (BT-high: n = 20; age: 12.5 ± 2.5 yrs) level of balance task difficulty. Both groups trained for 7 weeks (2 sessions/week, 30-35 min each). Pre- and post-training assessments included measures of static (one-legged stance [OLS] time), dynamic (10-m gait velocity), and proactive (Y-Balance Test [YBT] reach distance, Functional Reach Test [FRT]; Timed-Up-and-Go Test [TUG]) balance.!##!Results!#!Significant main effects of Test (i.e., pre- to post-test improvements) were observed for all but one balance measure (i.e., 10-m gait velocity). Additionally, a Test x Group interaction was detected for the FRT in favor of the BT-high group (Δ + 8%, p < 0.001, d = 0.35). Further, tendencies toward significant Test x Group interactions were found for the YBT anterior reach (in favor of BT-high: Δ + 9%, p < 0.001, d = 0.60) and for the OLS with eyes opened and on firm surface (in favor of BT-low: Δ + 31%, p = 0.003, d = 0.67).!##!Conclusions!#!Following 7 weeks of BT, enhancements in measures of static, dynamic, and proactive balance were observed in the BT-high and BT-low groups. However, BT-high appears to be more effective for increasing measures of proactive balance, whereas BT-low seems to be more effective for improving proxies of static balance.!##!Trial registration!#!Current Controlled Trials ISRCTN83638708  (Retrospectively registered 19th June, 2020)

Validity and Reliability of an Electronic Contact Mat for Drop Jump Assessment in Physically Active Adults

The aim of the present study was to investigate the concurrent validity and the test–retest reliability of an electronic contact mat for drop jump assessment in physically active adults. Seventy-nine young, physically active adults participated in the validity study, and 49 subjects were recruited for the reliability study. The motor task required subjects to perform two-legged drop jumps using drop heights of 24, 43, and 62 cm as well as one-legged drop jumps with the left and right leg using a drop height of 24 cm. Ground contact times were simultaneously quantified with an electronic contact mat, a force plate (i.e., gold standard), and a light-barrier system (another criterion device). Concurrent validity was assessed using intraclass correlation coefficient (ICC), systematic bias, limits of agreement, and linear regression analysis. Test–retest reliability (one week apart) was determined by calculating the ICC, the standard error of measurement (SEM), the coefficient of variation (CV), and Lin´s concordance correlation coefficient (рc). Further, we determined the minimal detectable change (MDC95%). Irrespective of drop height and jump condition, good agreements between testing devices (ICC ≥ 0.95) were shown. Compared to the force plate (−0.6 to 3.1 ms) but not to the light-barrier system (31.4 to 41.7 ms), the contact mat showed low systematic bias values. In terms of test–retest reliability, our analyses showed that the measuring devices are in agreement (ICC: 0.70–0.92; SEM: 8.5–18.4 ms; CV: 3.6–6.4%). Depending on the measurement device, drop height, and jump condition, a MDC95% value ranging from 23.6 to 50.9 ms represents the minimum amount of change needed to identify practical relevant effects in repeated measurements of drop jump performance. Our findings indicate that the electronic contact mat is a valid and reliable testing device for drop jump assessment from different drop heights in young physically active adults