Dielectrophoretic manipulation of ribosomal RNA     

Giraud G  Pethig R  Schulze H  Henihan G  Terry JG  Menachery A  Ciani I  Corrigan D  Campbell CJ  Mount AR  Ghazal P  Walton AJ  Crain J  Bachmann TT 《Biomicrofluidics》2011,5(2):24116

The manipulation of ribosomal RNA (rRNA) extracted from E. coli cells by dielectrophoresis (DEP) has been demonstrated over the range of 3 kHz-50 MHz using interdigitated microelectrodes. Quantitative measurement using total internal reflection fluorescence microscopy of the time dependent collection indicated a positive DEP response characterized by a plateau between 3 kHz and 1 MHz followed by a decrease in response at higher frequencies. Negative DEP was observed above 9 MHz. The positive DEP response below 1 MHz is described by the Clausius-Mossotti model and corresponds to an induced dipole moment of 3300 D with a polarizability of 7.8×10(-32) F m(2). The negative DEP response above 9 MHz indicates that the rRNA molecules exhibit a net moment of -250 D, to give an effective permittivity value of 78.5 ε(0), close to that of the aqueous suspending medium, and a relatively small surface conductance value of ～0.1 nS. This suggests that our rRNA samples have a fairly open structure accessible to the surrounding water molecules, with counterions strongly bound to the charged phosphate groups in the rRNA backbone. These results are the first demonstration of DEP for fast capture and release of rRNA units, opening new opportunities for rRNA-based biosensing devices.  相似文献   

Ökonomie Olympischer Spiele     

Holger Preuss 《Sportwissenschaft》2004,34(3):377-379

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Licensing as a commercialisation strategy for new technology-based firms   总被引：1，自引：0，他引：1  

Holger Kollmer 《Research Policy》2004,33(8):1141-1151

We investigate licensing as a commercialisation strategy for new technology-based firms (NTBFs) in the biopharmaceutical industry using a combination of survey and database research methods. We found that most firms in our sample were not fully integrated regardless of their company age which is consistent with the picture of NTBFs as agents of technology transfer. Comparing fully and not-fully integrated firms we find differences in the use of licensing strategies. According to Ford and Ryan [Harvard Business Review 59 (1981) 117] fully integrated companies apply licensing for strategic reasons and for financially unattractive projects. Our results provide partial support for this theory.  相似文献   

Once good teaching,always good teaching? The differential stability of student perceptions of teaching quality     

Holger Gaertner  Martin Brunner 《Educational Assessment, Evaluation and Accountability》2018,30(2):159-182

In many countries, students are asked about their perceptions of teaching in order to make decisions about the further development of teaching practices on the basis of this feedback. The stability of this measurement of teaching quality is a prerequisite for the ability to generalize the results to other teaching situations. The present study aims to expand the extant empirical body of knowledge on the effects of situational factors on the stability of students’ perceptions of teaching quality. Therefore, we investigate whether the degree of stability is moderated by three situational factors: time between assessments, subjects taught by teachers, and students’ grade levels. To this end, we analyzed data from a web-based student feedback system. The study involved 497 teachers, each of whom conducted two student surveys. We examined the differential stability of student perceptions of 16 teaching constructs that were operationalized as latent correlations between aggregated student perceptions of the same teacher’s teaching. Testing metric invariance indicated that student ratings provided measures of teaching constructs that were invariant across time, subjects, and grade levels. Stability was moderated to some extent by grade level but not by subjects taught nor time spacing between surveys. The results provide evidence of the extent to which situational factors may affect the stability of student perceptions of teaching constructs. The generalizability of the students’ feedback results to other teaching situations is discussed.  相似文献   

Model-based testing with UML applied to a roaming algorithm for Bluetooth devices     

GRABOWSKI Jens  NEUKIRCHEN Helmut  PALS Holger 《Journal of Zhejiang University. Science. B》2004,(11)

INTRODUCTION The Unified Modeling Language (UML)(Eriksson, 2003) is a visual language supporting thedesign and development of complex object-orientedsystems. While UML models focus primarily on thedefinition of system structure and behavior, theyprovide only limited means for describing test ob-jectives and test procedures. Furthermore, thegrowing system complexity increases the need forsolid testing. Thus, in 2001, the Object Manage-ment Group issued a Request for Proposal (U…  相似文献   

Teachers' predictions and pupils' destinies: A West African survey   总被引：1，自引：0，他引：1  

Holger Daun 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1995,41(5):405-425

This article presents a case study of the primary schooling and post-primary careers of a group of West African pupils. Their school performance and later careers were studied in relation to a number of variables, some relating to the school itself, others to background factors. Among the most important of the former were the predictions made by teachers about the pupils' ability to succeed. While teachers' predictions tended to be fairly accurate, they also functioned to some extent as self-fulfilling prophecies. The study shows that socio-economic and cultural variables are as important as school variables in explaining variations in former pupils' geographical location and socio-economic position eight to nine years later. The study has implications in relation to the improvement of the quality of primary education, since out-of-school variables cannot be manipulated through educational policies alone.

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Zusammenfassung In dem vorliegenden Artikel werden Ergebnisse einer westafrikanischen Studie dargestellt, die sich mit dem Schulbesuch und mit der Laufbahn nach abgeschlossenem Schulbesuch beschäftigt. Die Ausbildung der Schüler in zwei senegalischen Dörfern und ihre Laufbahn nach der Ausbildung werden im Verhältnis zu gewissen Schulvariablen und Hintergrundsvariablen studiert. Unter den erstgenannten waren die Voraussagen der Lehrer über die Möglichkeit der Schüler, von einer Klasse in die nächste versetzt zu werden, wichtig. Die Annahmen der Lehrer waren ziemlich sicher, aber sie funktionierten auch in hohem Grade als selbsterfüllende Prognosen. Die Studie zeigt, daß sozioökonomische und kulturelle Variablen genauso aussagekräftig sind wie Schulvariablen, wenn man die Unterschiede in dem geographischen Wohnort und in der sozioökonomischen Position der früheren Schüler acht bis neun Jahre später erklären will. Das hat Implikationen für eine Menge Richtlinien und Vorschläge, die in den letzten Jahren im Hinblick auf die Verbessergung der Qualität der Schule vorgelegt wurden, weil sich die Variablen außerhalb der Schule durch rein bildungspolitische Maßnahmen nicht manipulieren lassen.

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Resumen Este artículo presenta los resultados de un estudio que se ocupa de la enseñanza primarla y de las carreras post-primarias en un grupo de alumnos de Africa Occidental. La formación que recibieron los alumnos en dos pueblos senegaleses y las carreras que hicieron después de la escuela se estudian en cuanto a determinadas variables; relacionadas con la escuela misma y con el medio. Una de las más importantes de la primera catgoría eran las predicciones que los maestros hacían sobre las posibilidades que tendrían los alumnos de pasar al grado superior. las suposiciones de los maestros eran bastante acertadas, pero también funcionaban, en bueno grado, como pronósticos que se cumplirían automáticamente. El estudio demuestra que las variables socioeconómicas y culturales son tan importantes como las variables escolares, si se quieren explicar, ocho u nueve años desputés, las diferencias en localizatión geográfica y posición socioeconómica de los antiguou alumnos. Esto tiene implicaciones en una cantidad de directivas y sugerencias que se presentaron en los ültimos años para mejorar la calidad de la enseñanza primaria, ya que las variables del entorno extra-escolar no pueden manipularse a través de meras medidas de política educacional.

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Résumé Cet article présente une étude de cas en Afrique Occidentale se rapportant à l'enseignement primaire et aux carrières post-primaires, le succès scolaire des élèves ainsi que leurs carrières sont examinés par rapport à des variables scolaires et des variables concernant le milieu de l'élève constituent les variables importantes. Ces prédictions sont pluôt exactes, mais dans une certaine mesure elles relèvent de la prédiction qui s'accomplit automatiquement. L'étude démontre que les variables socio-économiques et culturelles sont aussi importantes que les variables scolaires; elles expliques les variations les variations dans la localisation géographique ainsi que le statut socio-économique de l'élève entre huit ans et neuf ans plus tard. Ceci a des implications pour un grand nombre de suggestions soumises récemment pour améliorer la qualité de l'enseignement primaire primaire étant donné qu'il est impossible de modifier les variables extra-scolaires uniquement à travers la politique de l'éducation.

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The effect of pre-exercise carbohydrate feedings on the intensity that elicits maximal fat oxidation     

Juul Achten & Asker E Jeukendrup 《Journal of sports sciences》2013,31(12):1017-1025

The aim of the present study was to examine the effect of ingesting 75?g of glucose 45?min before the start of a graded exercise test to exhaustion on the determination of the intensity that elicits maximal fat oxidation (Fat_max). Eleven moderately trained individuals ( V?O_2max: 58.9±1.0?ml?·?kg^?1?·?min^?1; mean±s_x¯ ), who had fasted overnight, performed two graded exercise tests to exhaustion, one 45?min after ingesting a placebo drink and one 45?min after ingesting 75?g of carbohydrate in the form of glucose. The tests started at 95?W and the workload was increased by 35?W every 3?min. Gas exchange measures and heart rate were recorded throughout exercise. Fat oxidation rates were calculated using stoichiometric equations. Blood samples were collected at rest and at the end of each stage of the test. Maximal fat oxidation rates decreased from 0.46±0.06 to 0.33±0.06?g?·?min^?1 when carbohydrate was ingested before the start of exercise (P?<0.01). There was also a decrease in the intensity which elicited maximal fat oxidation (60.1±1.9% vs 52.0±3.4% V?O_2max) after carbohydrate ingestion (P?<0.05). Maximal power output was higher in the carbohydrate than in the placebo trial (346±12 vs 332±12?W) (P?<0.05). In conclusion, the ingestion of 75?g of carbohydrate 45?min before the onset of exercise decreased Fat_max by 14%, while the maximal rate of fat oxidation decreased by 28%.  相似文献   

Cognitively demanding learning materials with texts and instructional pictures: teachers’ diagnostic skills, pedagogical beliefs and motivation     

Nele McElvany  Sascha Schroeder  Jürgen Baumert  Wolfgang Schnotz  Holger Horz  Mark Ullrich 《European Journal of Psychology of Education - EJPE》2012,27(3):403-420

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Book review     

Jens Holger Lorenz  John P. Pace 《Educational Studies in Mathematics》1991,22(1):87-103

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Credibility and Economic Value in the Visual Arts     

Holger Bonus  Dieter Ronte 《Journal of Cultural Economics》1997,21(2):103-118

The paper states that the quality of visual arts cannot be measured objectively. An artist must be credible to the public in order to generate economic value. How is credibility and thus economic value generated on the market? To judge the quality of arts, it takes experts. They form a worldwide network relationship and apply cultural knowledge, a highly specific type of knowledge which requires lifelong learning. Cultural knowledge is only in part of a factual nature and includes subjective elements. Since the public cannot in general ascertain the quality of an artist's oeuvre directly, experts must themselves be credible to the public in order to lend credibility to a given oeuvre. It is shown that the process by which experts generate public credibility for a given oeuvre is path dependent, i.e., may by chance end up at inferior solutions.  相似文献