Diagnostic of the ability to conduct scientific investigations in University

Der Erwerb von Experimentierkompetenz stellt ein wichtiges Ziel der universitären Ausbildung im Fach Physik dar. Dennoch wird bei Untersuchungen zum Lernerfolg im Physikstudium gerade dieser Aspekt vernachlässigt. Dies liegt insbesondere daran, dass eine valide Erfassung von Experimentierkompetenz bisher nur eingeschränkt gelungen ist. Das Ziel der vorliegenden Arbeit ist die Entwicklung eines Instruments zur validen Erfassung von Experimentierkompetenz. Im Rahmen der Arbeit wurde ein Modell zur Experimentierkompetenz entwickelt. Darauf aufbauend wurden Ansätze zur Diagnostik von Experimentierkompetenz analysiert und bzgl. der Testgüte beurteilt. Aus dieser Analyse wurden Anforderungen an ein Testinstrument zur reliablen und objektiven, vor allem aber validen Erfassung von Experimentierkompetenz abgeleitet. Mittels einer Fachinhaltsanalyse von N=10 deutschsprachigen Praktika wurde inhaltliche Validität und Generalisierbarkeit auf deutschsprachige Praktika im Bereich Optik sichergestellt. Mit einer Think Aloud Studie mit N=16 Probanden wurde geprüft, inwieweit die kognitiven Prozesse der Probanden durch die Auswertung des Laborhefts (Produkt) bzw. die zeitaufwändigere Auswertung des Vorgehens beim Experimentieren mittels Videoanalyse (Prozess) valide abgebildet werden können. Aus den Erkenntnissen wurde ein ökonomisches und valides Auswerteverfahren zur Beurteilung von Experimentierkompetenz entwickelt. In einer Feldstudie mit N=58 Studierenden wurde die strukturelle- und externe Validität untersucht. Dabei konnte eine ausreichende Reliabilitäten bzw. interne Konsistenz, auch für einzelne Subskalen nachgewiesen werden. Zudem konnten erste Hinweise auf eine Unabhängigkeit der Teildimensionen der Experimentierkompetenz gewonnen werden. Eine ausreichende Untersuchung zur externen- und prädiktiven Validität konnte im Rahmen der Arbeit nicht umgesetzt werden

The effect of anode potential on current production from complex substrates in bioelectrochemical systems: a case study with glucose

Anode potential can affect the degradation pathway of complex substrates in bioelectrochemical systems (BESs), thereby influencing current production and coulombic efficiency. However, the intricacies behind this interplay are poorly understood. This study used glucose as a model substrate to comprehensively investigate the effect of different anode potentials (− 150 mV, 0 mV and + 200 mV) on the relationship between current production, the electrogenic pathway and the abundance of the electrogenic microorganisms involved in batch mode fed BESs. Current production in glucose-acclimatized reactors was a function of the abundance of Geobacteraceae and of the availability of acetate and formate produced by glucose degradation. Current production was increased by high anode potentials during acclimation (0 mV and + 200 mV), likely due to more Geobacteraceae developing. However, this effect was much weaker than a stimulus from an artificial high acetate supply: acetate was the rate-limiting intermediate in these systems. The supply of acetate could not be influenced by anode potential; altering the flow regime, batch time and management of the upstream fermentation processes may be a greater engineering tool in BES. However, these findings suggest that if high current production is the focus, it will be extremely difficult to achieve success with complex waste streams such as domestic wastewater

Gender differences in the implementation of cardiovascular prevention measures after an acute coronary event

Objective To compare gender-related lifestyle changes and risk factor management after hospitalisation for a coronary event or revascularisation intervention in Europe. Method The EUROASPIRE III survey was carried out in 22 European countries in 2006-2007. Consecutive patients having had a coronary event or revascularisation before the age of 80 were identified. A total of 8966 patients (25.3% women) were interviewed and underwent clinical and biochemical tests at least 6 months after hospital admission. Trends in cardiovascular risk management were assessed on the basis of the 1994-1995, 1999-2000 and 2006-2007 EUROASPIRE surveys. Results Female survey participants were generally older and had a lower educational level than male participants (p<0.0001). The prevalences of obesity (p<0.0001), high blood pressure (BP) (p=0.001), elevated low-density lipoprotein (LDL)-cholesterol (p<0.0001) and diabetes (p<0.0001) were significantly higher in women than in men, whereas current smoking (p<0.0001) was significantly more common in men. The use of antihypertensive and antidiabetic drugs (but not that of other drugs) was more common in women than in men. However, BP (p<0.0001), LDL-cholesterol (p<0.0001) and HbA1c (p<0.0001) targets were less often achieved in women than in men. Between 1994 and 2007, cholesterol control improved less in women than in men (interaction: p=0.009), whereas trends in BP control (p=0.32) and glycaemia (p=0.36) were similar for both genders. Conclusion The EUROASPIRE III results show that despite similarities in medication exposure, women are less likely than men to achieve BP, LDL-cholesterol and HbA1c targets after a coronary event. This gap did not appear to narrow between 1994 and 2007

Kondo screening cloud in the single-impurity Anderson model: A density matrix renormalization group study

A magnetic moment in a metal or in a quantum dot is, at low temperatures, screened by the conduction electrons through the mechanism of the Kondo effect. This gives rise to spin-spin correlations between the magnetic moment and the conduction electrons, which can have a substantial spatial extension. We study this phenomenon, the so-called Kondo cloud, by means of the density matrix renormalization group method for the case of the single-impurity Anderson model. We focus on the question whether the Kondo screening length, typically assumed to be proportional to the inverse Kondo temperature, can be extracted from the spin-spin correlations. For several mechanisms -- the gate potential and a magnetic field -- which destroy the Kondo effect, we investigate the behavior of the screening cloud induced by these perturbations.Comment: updated some data, minor change

Determination of the Relationship between the Energy Content of Municipal Wastewater and Its Chemical Oxygen Demand

Quantitatively evaluating progress toward energy neutral, or even energy positive, wastewater treatment necessitates reliable data on the intrinsic energy content of the wastewater. It has long been assumed that the amount of energy in wastewater is directly related to its chemical oxygen demand (COD), but the convoluted method for measuring the wastewater energy content has meant that a reliable, statistically robust relationship between COD and energy has never been drawn. In this research, we used a new drying method and analyzed a set of 107 municipal wastewater samples, with a range of COD values from 16.4 to 1151 mg/L. The results revealed a strong correlation between COD and energy content of 16.1 kJ/g of COD (p < 0.001). Reliable predictions of a wastewater’s energy content can now be made on the basis of the COD measurement alone