High-intracavity-power thin-disk laser for the alignment of molecules

We propose a novel approach for strong alignment of gas-phase molecules for experiments at arbitrary repetition rates. A high-intracavity-power continuous-wave laser will provide the necessary ac electric field of $\!10^{10}$- $10^{11}~\text{W}/\text{cm}^2$. We demonstrate thin-disk lasers based on Yb:YAG and Yb:Lu$_2$O$_3$ in a linear high-finesse resonator providing intracavity power levels in excess of 100~kW at pump power levels on the order of 50~W. The multi-longitudinal-mode operation of this laser avoids spatial-hole burning even in a linear standing-wave resonator. The system will be scaled up as in-vacuum system to allow for the generation of fields of $10^{11}~\text{W}/\text{cm}^2$. This system will be directly applicable for experiments at modern X-ray light sources, such as synchrotrons or free-electron lasers, which operate at various very high repetition rates. This would allow to record molecular movies through temporally resolved diffractive imaging of fixed-in-space molecules, as well as the spectroscopic investigation of combined X-ray-NIR strong-field effects of atomic and molecular systems

El análisis de datos cualitativos como proceso de clasificación

El artículo describe detalladamente el procedimiento referido a la Investiga sobre las teorías implícitas de maestros de la escuela primaria sobre-ción debilidad aritmética de niños y discute las consecuencias de los hallazgos para la formación de maestros. Utiliza dos ejemplos adicionales de estudios sobre profesores (problemas de disciplina en el aula; control por el profesor y aprendizaje auto-regulado). También se contempla un intento de generalizar la relevancia del enfoque descrito.___________________________________ This article describes In detail the procedure to take in relation to the research on the implicit theories of Primary education teachers about the arithmetical weakness of children and discusses the consequences of the findings for the training of teachers. The paper uses two additional examples of studies about teachers (discipline problems in the classroom, teacher control and the selfregulated learning), as well as attempt to generalise the relevance of this approach

Psychological models in teacher training

Die Psychologie hat in der Aus- und Weiterbildung von Lehrern wichtige Funktionen. Lehrern werden psychologische Kenntnisse und Handlungsregeln vermittelt; die Ausbildung wird nach psychologischen Modellen des Lehrens und Lernens konzipiert. Von einer Analyse problematischer Elemente in der Beziehung von Psychologie und Lehrerbildung aus werden Wissensvermittlung und Fertigkeitstraining als personzentrierte Modelle, Fallstudien und Methodentraining als situationszentrierte Modelle der Übertragung psychologischer Ansätze auf Verfahren der Lehrerbildung skizziert. Aus der Kritik an einseitiger Anwendung solcher Modelle werden eine handlungstheoretische Orientierung der Lehrerbildung abgeleitet und ihre wichtigsten Merkmale (Orientierung am Alltagshandeln des Lehrers, Berücksichtigung mehrerer Handlungsebenen und des Entscheidungsdrucks in pädagogischen Situationen) beschrieben. (DIPF/Orig.)Psychology has important functions in the pre- and in-service training of teachers. It includes courses about different areas of psychology, and the training is organized according to psychological models of teaching and learning. Starting from an analysis of problematic elements in the relation of psychology to teacher training, acquiring knowledge and specific skills are outlined as typical examples for person-centered approaches, case studies and instruction about teaching methods as situation-centered approaches in teacher training. After a critical discussion of these models the article proposes an action-theoretical orientation for teacher training, and describes main characteristics of this approach (i. e. taking into account the implicit psychology of teachers, different levels of action, and elements of coping processes)

INTERACTION OF IMPLICIT THEORIES AND ORIENTATION STYLE IN TEACHER PRACTICUM

The classroom practicum for student teachers is evaluated controversely both by educational researches and by student teachers. We suggested that student teachers' differing evaluations are due to interpersonal differences: according to their own experiences as pupils and to their uncertainty vs. certainty orientation student teachers developed implicit theories of teaching, which determine their actual practicum experiences. Interviews with 18 student teachers selected on the basis oftheir orientation style were analyzed using a combination of qualitative and quantitative methods. The results show a clear interaction of central components of their implicit theories of teaching and their orientation style. Consequences for the organization of teacher practica are outlined.La práctica en el aula es evaluada de un modo controvertido tanto por parte de los investigadores en educación como de los futuros profesores. Nuestra hipótesis es que las diferentes evaluaciones del profesor en formación son debidas a diferencias interpersonales: según sus propias experiencias como alumno; su orientación hacia la certidumbre o la incertidumbre, los futuros profesores desarrollan teorías implícitas de enseñanza que determinan el tipo de experiencia que sacarán de la propia práctica. Con este fin se analizaron -usando una combinación de métodos cuantitativos y cualitativos- 18 entrevistas con estudiantes de Pedagogía seleccionados sobre la base de su estilo de orientación. Los resultados muestran una clara interacción entre los componentes centrales de sus teorías implícitas acerca de la enseñanza y sus estilos de orientación. Se deducen, como conclusión, algunas consecuencias para la organización de la práctica

Yellow laser performance of Dy3+^{3+} in co-doped Dy,Tb:LiLuF4_4

We present laser results obtained from a Dy$^{3+}$-Tb$^{3+}$ co-doped LiLuF$_{4}$ crystal, pumped by a blue emitting InGaN laser diode, aiming for the generation of a compact 578 nm source. We exploit the yellow Dy$^{3+}$ transition $^{4}$F$_{9/2}$ $\Longrightarrow$ $^{6}$H$_{13/2}$ to generate yellow laser emission. The lifetime of the lower laser level is quenched via energy transfer to co-doped Tb$^{3+}$ ions in the fluoride crystal. We report the growth technique, spectroscopic study and room temperature continuous wave (cw) laser results in a hemispherical cavity at 574 nm and with a highly reflective output coupler at 578 nm. A yellow laser at 578 nm is very relevant for metrological applications, in particular for pumping of the forbidden $^{1}$S$_{0} \Longrightarrow ^{3}$P$_{0}$ Ytterbium clock transition, which is recommended as a secondary representation of the second in the international system (SI) of units. This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.39.006628. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Comment: 8 pages, 5 figure

Teacher-pupil Systems in teaching-leanring-research

Lehr-Lern-Forschung beschäftigt sich traditionell mit den kognitiven Prozessen schulischen Lernens. Parallel dazu besteht ein Forschungszweig, der die sozialen Bezüge unterrichtlichen Geschehens untersucht. Im vorliegenden Beitrag wird die Notwendigkeit einer Verknüpfung kognitiver und sozialer Variablen betont. Auf dem Hintergrund systemtheoretischer Annahmen werden anhand von Beispielen aus der Unterrichtsforschung Überlegungen angestellt, wie sich die Vernetzung der Variablen möglicherweise auswirkt und wie die Methodologie solcher Untersuchungen aussehen müßte.Teaching-learning-research is preoccupied with cognitive processes of learning in classrooms. Social relations in schools are investigated separately. This paper concentrates on the necessity to connect cognitive and social-emotional variables. Based on a Systems approach suggestions are discussed concerning the effects of a network conception of variables in educational research and its methodological implications

Efficient visible laser emission of GaN laser diode pumped Pr-doped fluoride scheelite crystals.

In the present work we report on the growth, spectroscopy and laser results of diode pumped Pr-doped LiYF4, LiLuF4 and LiGdF4 fluoride, scheelite-type structure crystals. We measured the polarisation dependent absorption and emission properties as well as the decay time of the P-3(0) level. Exploiting the P-3(2) absorption around 444 nm, we obtained efficient laser emission under GaN laser diode pumping on several transitions from the green to the near infrared wavelength range. (C) 2008 Optical Society of Americ

Lactate dehydrogenase from the hyperthermophilic bacterium Thermotoga maritima: the crystal structure at 2.1 å resolution reveals strategies for intrinsic protein stabilization

AbstractBackground: L(+)-Lactate dehydrogenase (LDH) catalyzes the last step in anaerobic glycolysis, the conversion of pyruvate to lactate, with the concomitant oxidation of NADH. Extensive physicochemical and structural investigations of LDHs from both mesophilic and thermophilic organisms have been undertaken in order to study the temperature adaptation of proteins. In this study we aimed to determine the high-resolution structure of LDH from the hyperthermophilic bacterium Thermotoga maritima (TmLDH), the most thermostable LDH to be isolated so far. It was hoped that the structure of TmLDH would serve as a model system to reveal strategies of protein stabilization at temperatures near the boiling point of water.Results: The crystal structure of the extremely thermostable TmLDH has been determined at 2.1 å resolution as a quaternary complex with the cofactor NADH, the allosteric activator fructose-1,6-bisphosphate, and the substrate analog oxamate. The structure of TmLDH was solved by Patterson search methods using a homology-based model as a search probe. The native tetramer shows perfect 222 symmetry. Structural comparisons with five LDHs from mesophilic and moderately thermophilic organisms and with other ultrastable enzymes from T. maritima reveal possible strategies of protein thermostabilization.Conclusions: Structural analysis of TmLDH and comparison of the enzyme to moderately thermophilic and mesophilic homologs reveals a strong conservation of both the three-dimensional fold and the catalytic mechanism. Going from lower to higher physiological temperatures a variety of structural differences can be observed: an increased number of intrasubunit ion pairs; a decrease of the ratio of hydrophobic to charged surface area, mainly caused by an increased number of arginine and glutamate sidechains on the protein surface; an increased secondary structure content including an additional unique ‘thermohelix’ (αT) in TmLDH; more tightly bound intersubunit contacts mainly based on hydrophobic interactions; and a decrease in both the number and the total volume of internal cavities. Similar strategies for thermal adaptation can be observed in other enzymes from T. maritima

Plasmodium knowlesi infection in a returning German traveller from Thailand: a case report on an emerging malaria pathogen in a popular low-risk travel destination

Background: Thailand is a major destination for German travellers with more than 760,000 arrivals in 2015. At the same time, malaria is a concern in travel recommendations with regard to this destination. The World Malaria Report of 2016 mentions only P. falciparum and P. vivax as prevalent species for Thailand, however, P. knowlesi infections have been occasionally reported in Thailand. In German travellers, only five cases of P. knowlesi infections have been reported to date. Case presentation: A 45-year-old German male tourist travelled to Thailand from 25 December 2016 to 13 January 2017. On 14 January he developed fever with no other symptoms, and presented on 17 January at the Division for Tropical Medicine and Infectious Diseases in Munich, Germany. Malaria was diagnosed, primarily based on a single parasite in the thin smear microscopy, while commercial rapid diagnostic testing remained negative. Only the result of a differential PCR assay revealed P. knowlesi infection. Conclusions: P. knowlesi has to be considered in travellers returning from Thailand. Cases may present with an extremely low parasitaemia. This is in contrast to the assumption that P. knowlesi was likely to cause high parasitaemia due to its short replication cycle