¿Qué pintan un motor y una botella en el cálculo integral? Curso corto de didáctica

Se pretende crear un marco de resolución de problemas que sea motivador para los alumnos del último año de Bachillerato o del primer año de estudios en la Universidad, y para ello se presentan cuatro problemas reales, cuya solución requiere establecer el concepto de integral definida, y uno histórico, que fue propuesto y resuelto por Arquímedes. Asimismo, en el desarrollo del curso se verá la importancia del uso de herramientas didácticas, tales como el generador de volúmenes de revolución, que se construirá en el propio curso, y el ordenador, cuyo uso será absolutamente necesario para resolver los problemas planteados. En suma, además de promover adaptaciones curriculares adecuadas, se fijan estos tres objetivos fundamentales: Cómo se crea un marco de resolución de problemas y cómo se integran herramientas didácticas apropiadas.

[1H,15N] N.M.R. Kinetic Studies of Reactions of cis- and trans-[PtCl2(15NH3)(c-C6H1115NH2)] with Guanosine 5'-Monophosphate

cis-[PtCl2(15NH3)(c-C6H11NH2)] is an active metabolite of the oral platinum(IV) anticancer drug cis,trans,cis-[PtCl2(CH3CO2)2(NH2)(c-C6H11NH2)]. Since it is likely that guanine bases on DNA are targets for this drug, we have analysed the kinetics of reaction of this platinum(II) metabolite with guanosine 5′-monophosphate (5′-GMP) at 310 K, pH 7, using [1H, 15N] n.m.r. methods. Reactions of the trans isomer are reported for comparison. The reactions proceed via aquated intermediates, and, for the cis isomer, the rates of aquation and substitution of H2O by 5′-GMP are 2-5 times faster trans to the amine ligand (c-C6H11NH2) compared to trans to NH3 for both the first and second steps. For the trans complex, the first aquation step is c. 3 times faster than for the cis complex, as expected from the higher trans influence of Cl¯, whereas the rate of the second aquation step (trans to N7 of 5′-GMP) is comparable to that trans to NH3. These findings have implications for the courses of reactions with DNA.

High electric current density-induced interfacial reactions in micro ball grid array (μBGA) solder joints

The effect of a high electric current density on the interfacial reactions of micro ball grid array solder joints was studied at room temperature and at 150 °C. Four types of phenomena were reported. Along with electromigration-induced interfacial intermetallic compound (IMC) formation, dissolution at the Cu under bump metallization (UBM)/bond pad was also noticed. With a detailed investigation, it was found that the narrow and thin metallization at the component side produced “Joule heating” due to its higher resistance, which in turn was responsible for the rapid dissolution of the Cu UBM/bond pad near to the Cu trace. During an “electromigration test” of a solder joint, the heat generation due to Joule heating and the heat dissipation from the package should be considered carefully. When the heat dissipation fails to compete with the Joule heating, the solder joint melts and molten solder accelerates the interfacial reactions in the solder joint. The presence of a liquid phase was demonstrated from microstructural evidence of solder joints after different current stressing (ranging from 0.3 to 2 A) as well as an in situ observation. Electromigration-induced liquid state diffusion of Cu was found to be responsible for the higher growth rate of the IMC on the anode side.

Risikowahrnehmung und psychologische Reaktionen in öffentlichen Krisensituationen am Beispiel von Terrorattentaten / Risk perception and psychological reactions in public crisis situations using the example of terror attacks

The reactions to the 9/11 terror attacks were immense in the western population. In the current review, the impact of terror attacks is presented with surveys, clinical interviews, and scientific polls, which were identified in a comprehensive literature search. Results show that the fear of further terror attacks is comparatively overestimated in the population and is associated with numerous psychological consequences and reactions. The overestimation of the probability of further terror attacks is related among other reasons to its unique features and its strong representation in the media. Several independent studies proved that the number of stress symptoms and psychiatric diagnoses is associated with a high risk perception in relation to terror attacks. This was not only the case for victims of terror attacks, but also for people indirectly exposed to the terror attacks. In addition, there is evidence that the number of the stress symptoms correlate with the duration of TV consumption of new findings about terror attempts. Methodologically, there is a critical lack of more in-depth analyses to explain the development of risk perceptions and its influence on mental and physical health. Because of the international importance and cross-cultural differences, an international standardization of research is desirable. [In German] Die Reaktionen auf die Terrorattentate vom 9. September 2001 in New York waren in der westlichen Bevölkerung immens. In der vorliegenden Übersichtsarbeit werden die Auswirkungen von Terrorattentaten durch Einbeziehung bevölkerungsrepräsentativer Untersuchungen, Surveys, klinischer Interviews und Einstellungsbefragungen dargestellt, die über eine deskriptive Literaturrecherche ermittelt wurden. Als Ergebnis des Reviews zeigt sich, dass die Angst vor weiteren Terrorattentaten in der Bevölkerung vergleichsweise hoch und mit zahlreichen psychologischen Folgen und Reaktionen assoziiert ist. Die Einschätzung der Auftretenswahrscheinlichkeit eines Terrorattentats hängt unter anderem mit den besonderen Charakteristika und der hohen medialen Präsenz des Themas zusammen. Die Anzahl der Stresssymptome bis hin zu psychiatrischen Diagnosen erwies sich in mehreren unabhängigen Untersuchungen mit einer hohen Risikowahrnehmung assoziiert. Dies ließ sich nicht nur bei den Opfern von Terrorattentaten, sondern auch bei indirekt Betroffenen zeigen. Darüber hinaus gibt es mehrfache Belege dafür, dass die Anzahl der Stresssymptome mit der Dauer des TV-Konsums über Neuigkeiten zu Terrorattentaten zusammenhing. Als methodische Kritik ist an den gegenwärtigen Untersuchungsszenarien einzuwenden, dass es derzeit keine tiefer gehenden Analysen zur Entwicklung der Risikowahrnehmung und zu ihrem Einfluss auf die Gesundheit gibt. Aufgrund der internationalen Bedeutung des Themas und der interkulturellen Unterschiede im Umgang mit Krisensituationen ist eine internationale Standardisierung von Untersuchungszugängen wünschenswert.

The missing link between information and action: hastenings and delays as universal reactions to performance feedback

This chapter focuses on what the key decision makers in organizations decide after having received information on the current state of the organizational performance. Because of strong attributions to success and failure, it is impossible to predict in advance which concrete actions will occur. We can however find out what kinds of actions are decided upon by means of an organizational learning model that focuses on the hastenings and delays after performance feedback. As an illustration, the responses to performance signals by trainers and club owners in Dutch soccer clubs are analyzed.

A Quantitative Investigation of Selected Reactions in the Fibrinolytic Cascade

Previous work has shown that thrombin activatable fibrinolysis inhibitor (TAFI) was unable to prolong lysis of purified clots in the presence of Lys-plasminogen (Lys-Pg), indicating a possible mechanism for fibrinolysis to circumvent prolongation mediated by activated TAFI (TAFIa). Therefore, the effects of TAFIa on Lys-Pg activation and Lys-plasmin (Lys-Pn) inhibition by antiplasmin (AP) were quantitatively investigated using a fluorescently labeled recombinant Pg mutant which does not produce active Pn. High molecular weight fibrin degradation products (HMW-FDPs), a soluble fibrin surrogate that models Pn modified fibrin, treated with TAFIa decreased the catalytic efficiency (kcat/Km) of 5IAF-Glu-Pg cleavage by 417-fold and of 5IAF-Lys-Pg cleavage by 55-fold. A previously devised intact clot system was used to measure the apparent second order rate constant (k2) for Pn inhibition by AP over time. While TAFIa was able to abolish the protection associated with Pn modified fibrin in clots formed with Glu-Pg, it was not able to abolish the protection in clots formed with Lys-Pg. However, TAFIa was still able to prolong the lysis of clots formed with Lys-Pg. TAFIa prolongs clot lysis by removing the positive feedback loop for Pn generation. The effect of TAFIa modification of the HMW-FDPs on the rate of tissue type plasminogen activator (tPA) inhibition by plasminogen activator inhibitor type 1 (PAI-1) was investigated using a previously devised end point assay. HMW-FDPs decreased the k2 for tPA inhibition rate by 3-fold. Thus, HMW-FDPs protect tPA from PAI-1. TAFIa treatment of the HMW-FDPs resulted in no change in protection. Vitronectin also did not appreciably affect tPA inhibition by PAI-1. Pg, in conjunction with HMW-FDPs, decreased the k2 for tPA inhibition by 30-fold. Hence, Pg, when bound to HMW-FDPs, protects tPA by an additional 10-fold. TAFIa treatment of the HMW-FDPs completely removed this additional protection provided by Pg. In conclusion, an additional mechanism was identified whereby TAFIa can prolong clot lysis by increasing the rate of tPA inhibition by PAI-1 by eliminating the protective effects of Pn-modified fibrin and Pg. Because TAFIa can suppress Lys-Pg activation but cannot attenuate Lys-Pn inhibition by AP, the Glu- to Lys-Pg/Pn conversion is able to act as a fibrinolytic switch to ultimately lyse the clot.

Judging Time Intevals using a model of perceptuo-motor control

Estimating a time interval and temporally coordinating movements in space are fundamental skills, but the relationships between these different forms of timing, and the neural processes that they incur, are not well understood. While different theories have been proposed to account for time perception, time estimation, and the temporal patterns of coordination, there are no general mechanisms which unify these various timing skills. This study considers whether a model of perceptuo-motor timing, the tau(GUIDE), can also describe how certain judgements of elapsed time are made. To evaluate this, an equation for determining interval estimates was derived from the tau(GUIDE) model and tested in a task where participants had to throw a ball and estimate when it would hit the floor. The results showed that in accordance with the model, very accurate judgements could be made without vision (mean timing error -19.24 msec), and the model was a good predictor of skilled participants' estimate timing. It was concluded that since the tau(GUIDE) principle provides temporal information in a generic form, it could be a unitary process that links different forms of timing.