Characterizing different team sports using network analysis

Team sports are complex dynamic systems based on the frequent interaction of various players. Recently, social network analysis has been introduced to the study of sports dynamics in order to quantify the involvement of individual players in the interplay and to characterize the organizational processes used by teams. Nonetheless, only a limited set of team sports has been assessed to date, and the focus of most studies has been on the application of small sets of network metrics to a single sport. Our study aims at comparing the network patterns of different team sports in order to contribute to the understanding of their underlying nature. It considers three invasion games, namely professional matches from basketball, football and handball. By applying relevant centrality measures and minimum spanning trees a first comparison between the nature of interplay in various team sports is offered as well as a deeper understanding of the role of different tactical positions in each sport. The point guard in basketball, defensive midfielder in football and center in handball are identified as the most central tactical positions. Direct interplay is most balanced in football followed by basketball and handball. A visualization of the basic structure of interplay for each sport is achieved through minimum spanning trees

Investigation of a high angle grain boundary in Fe2.4wt.%Si BCC micropillars

Iron-silicon sheet steel is the most widely used material for the iron cores of electrical machines like generators, motors or transformers. Although already ubiquitous, the demand will nevertheless rise in the future since electro-mobility is spreading rapidly. For this reason, even small improvements of efficiency have a huge energy saving potential. Currently, hysteresis losses are one of the main limiting factors for efficiency, resulting from the movement of domain walls, which may be pinned by dislocations. Even though electrical sheet steel is generally used in a fully recrystallized state, it is the final stages of production involving cutting that introduce large plastic strains, and hence high local dislocation densities. These have been shown to cause significant loss in performance. The aim of this work is to understand the evolution of deformation structures on a fundamental basis taking grain boundaries, size effects and different strain-rates into account. To this end, single- and bi-crystalline-micropillars of 1, 2 und 4 µm in diameter were investigated. 158 micropillars were deformed in order to provide a statistically-relevant dataset. In addition, macroscopic single- and bi-crystal-samples with a diameter of 2.5 mm were deformed as a reference for the size effect. The considered grain boundary has an angle of about 50° and a very high geometrical transmission factor (m’=0.89). Regarding the strain-rate-sensitivity three different strain rates were used for the deformation of the micro-/macroscopic single- and bi-crystals, with strain rate jump tests additionally conducted for the single-crystals. To visualize the deformation structure, selected micropillars were lifted out of the sample, thinned to the middle and analyzed utilizing EBSD. For most micropillars a clear slip system could be determined. Regarding one orientation the active slip system changed from the single- to the bi-crystal, likely because the newly-activated slip system was better aligned relative to the slip system of the other half-crystal. The bi-crystal-micropillars showed a higher resolved shear stress despite direct slip transmission across the grain boundary. Furthermore, a pronounced strain-rate sensitivity and size effect was found

Die Sprache der Neuronen: Lernen, Gedächtnis und Vergessen

Unser Gehirn muss eine ungeheuer komplizierte Aufgabe erfüllen: Es muss einen kontinuierlichen Fluss an Sinnesinformationen verarbeiten und zur gleichen Zeit Erinnerungen, zum Teil für ein Leben lang, speichern und abrufen. Die Transmission von chemischen Botenstoffen zwischen Nervenzellen erfolgt dabei ebenso an den Synapsen wie das Generieren und Speichern neuer Informationscodes. Es muss bei hierbei immer ein Gleichgewicht hergestellt werden zwischen dem Abspeichern neuer Informationen und dem Erhalt vorhandenen Wissens. Welche Mechanismen und welche biochemischen Prozesse aber ermöglichen die Lern- und Gedächtnisvorgänge, was bedingt Vergessen? Die Fähigkeit, etwas zu lernen und im Gedächtnis zu behalten, ist über das Tierreich nicht gleich verteilt. Bei uns Menschen beispielsweise sind Effektivität und Kapazität von Lern- und Gedächtnisvorgängen besonders stark ausgeprägt und halten bis in das hohe Lebensalter hin an. Unsere diesbezüglichen Fähigkeiten sind neben unserer Sprache Grundlage und Voraussetzung unserer Kultur und unserer individuellen Persönlichkeit. Umgekehrt führt der Verlust des Gedächtnisses zum Verlust unserer Biographie und damit unsere Persönlichkeit sowie zum Verlust der Möglichkeit mit anderen Menschen interagieren zu können. Dem entsprechend ist das Thema Lernen und Gedächtnis eines der Hauptanliegen der Neurobiologie

The Effectiveness of Different Types of Sunscreen against UV Light on Escherichia coli

Ultraviolet (UV) light from the sun damages the DNA of our skin cells which could potentially lead to development of skin cancer (Mahroos, Yaar, Phillps, Bhawan, & Gilchrest, 2002). Sunscreen is used to protect our skin from this damage. The two most commonly used sunscreens are physical and chemical sunscreens. Physical sunscreens, also referred to as mineral sunscreens, work by sitting on top of your skin and reflecting UV light, whereas chemical sunscreens penetrate the skin and absorb UV light. There are many different brands of these sunscreens in the market. We hypothesized that the physical sunscreens would serve as better protection than the chemical sunscreens due to their high cost and natural ingredients. Brands that we used that represent physical sunscreens were Badger and Goddess Garden. Brands of chemical sunscreens were Aveeno, Hawaiian Tropic, and Up & Up Target Sports. All the sunscreens were creamy and had an SPF of 30. On average, the physical sunscreens were two times more expensive than chemical sunscreens. To test our hypothesis, we used the bacterium Escherichia coli (E. coli) as a model organism and exposed it to UV light while using the various sunscreens for protection. We then counted the survival rate of the E.coli colonies that were exposed. Our results demonstrated that there was no statistical significance in sunscreen protection. We concluded that physical sunscreens are not worth their price

Cortactin Contributes to Activity-Dependent Modulation of Spine Actin Dynamics and Spatial Memory Formation

Postsynaptic structures on excitatory neurons, dendritic spines, are actin-rich. It is well known that actin-binding proteins regulate actin dynamics and by this means orchestrate structural plasticity during the development of the brain, as well as synaptic plasticity mediating learning and memory processes. The actin-binding protein cortactin is localized to pre- and postsynaptic structures and translocates in a stimulus-dependent manner between spines and the dendritic compartment, thereby indicating a crucial role for synaptic plasticity and neuronal function. While it is known that cortactin directly binds F-actin, the Arp2/3 complex important for actin nucleation and branching as well as other factors involved in synaptic plasticity processes, its precise role in modulating actin remodeling in neurons needs to be deciphered. In this study, we characterized the general neuronal function of cortactin in knockout mice. Interestingly, we found that the loss of cortactin leads to deficits in hippocampus-dependent spatial memory formation. This impairment is correlated with a prominent dysregulation of functional and structural plasticity. Additional evidence shows impaired long-term potentiation in cortactin knockout mice together with a complete absence of structural spine plasticity. These phenotypes might at least in part be explained by alterations in the activity-dependent modulation of synaptic actin in cortactin-deficient neurons

Magnetic repeat station survey of Germany 1999/2000

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A New Approach to Measure Fundamental Microstructural Influences on the Magnetic Properties of Electrical Steel using a Miniaturized Single Sheet Tester

Magnetic properties of electrical steel are usually measured on Single Sheet Testers, Epstein frames or ring cores. Due to the geometric dimensions and measurement principles of these standardized setups, the fundamental microstructural influences on the magnetic behavior, e.g., deformation structures, crystal orientation or grain boundaries, are difficult to separate and quantify. In this paper, a miniaturized Single Sheet Tester is presented that allows the characterization of industrial steel sheets as well as from in size limited single, bi- and oligocrystals starting from samples with dimensions of 10x22 mm. Thereby, the measurement of global magnetic properties is coupled with microstructural analysis methods to allow the investigation of micro scale magnetic effects. An effect of grain orientation, grain boundaries and deformation structures has already been identified with the presented experimental setup. In addition, a correction function is introduced to allow quantitative comparisons between differently sized Single Sheet Testers. This approach is not limited to the presented Single Sheet Tester geometry, but applicable for the comparison of results of differently sized Single Sheet Testers. The results of the miniaturized Single Sheet Tester were validated on five industrial electrical steel grades. Furthermore, first results of differently oriented single crystals as well as measurements on grain-oriented electrical steel are shown to prove the additional value of the miniaturized Single Sheet Tester geometry

Deformation of micrometer and mm-sized Fe2.4wt.%Si single- and bi-crystals with a high angle grain boundary at room temperature

Plasticity in body-centred cubic (BCC) metals, including dislocation interactions at grain boundaries, is much less understood than in face-centred cubic (FCC) metals. At low temperatures additional resistance to dislocation motion due to the Peierls barrier becomes important, which increases the complexity of plasticity. Iron-silicon steel is an interesting, model BCC material since the evolution of the dislocation structure in specifically-oriented grains and at particular grain boundaries have far-reaching effects not only on the deformation behaviour but also on the magnetic properties, which are important in its final application as electrical steel. In this study, two different orientations of micropillars (1, 2, 4 microns in diameter) and macropillars (2500 microns) and their corresponding bi crystals are analysed after compression experiments with respect to the effect of size on strength and dislocation structures. Using different experimental methods, such as slip trace analysis, plane tilt analysis and cross-sectional EBSD, we show that direct slip transmission occurs, and different slip systems are active in the bi-crystals compared to their single-crystal counterparts. However, in spite of direct transmission and a very high transmission factor, dislocation pile-up at the grain boundary is also observed at early stages of deformation. Moreover, an effect of size scaling with the pillar size in single crystals and the grain size in bi-crystals is found, which is consistent with investigations elsewhere in FCC metals