DNA-Computing – ein funktionales Modell im laborpraktischen Experiment

Zusammenfassung.   Im Zentrum der Betrachtungen zum DNA-Computing steht die Frage nach den Chancen und Grenzen dieses neuen Berechnungsmodells, nachdem in den letzten Jahren eine rasante Entwicklung auf das Thema aufmerksam machte. Neben beachtlichen theoretischen Untersuchungen zum “Rechnen im Reagenzglas” werden auch laborpraktische Implementierungen favorisiert. An der TU Dresden wurde in interdisziplin?rer Arbeit ein Integer-Rucksackproblem mittels eines DNA-Algorithmus im Labor gel?st und dabei eine Vielzahl molekularbiologischer Operationen analysiert. Mit Hilfe dieses Satzes von Operationen gelang eine universelle und labornahe Modellierung des DNA-Computing. Hierbei angewandte Techniken und Methoden werden vorgestellt und bewertet. Die Beschreibung des DNA-Algorithmus zeigt, wie sich Einzeloperationen vorteilhaft zu Operationsfolgen zusammensetzen lassen und gemeinsam mit einer geeigneten DNA-Kodierung der Eingangsdaten zur L?sung des Problems im Labor führen. Erstmalig wurden hierbei natürliche Zahlen verarbeitet. Die Arbeitsgemeinschaft DNA-Computing Dresden konzentriert sich auf Aufgabenstellungen, die formale Modelle des DNA-Computing mit überzeugenden Laborimplementierungen verbinden. Eingegangen am 14. Februar 2000 / Angenommen am 26. Oktober 2000     

Strategy selection for cognitive skill acquisition depends on task demands and working memory capacity

The involvement of working memory capacity (WMC) in ruled-based cognitive skill acquisition is well-established, but the duration of its involvement and its role in learning strategy selection are less certain. Participants (N = 610) learned four logic rules, their corresponding symbols, or logic gates, and the appropriate input–output combinations in three-gate circuit patterns. Participants practiced 120 repetitions of each rule (480 total gates) over the course of 10 training blocks. Memory load varied between subjects. The confluence of task demands and individual differences in WMC (N = 518) dramatically affected speed–accuracy tradeoffs and strategic use of a computerized help function. Cluster analysis revealed five distinct groups of participants based on the combination of response accuracy, latency, and help use. Some groups with moderate to high mean WMC acquired the task with predictable performance patterns. Other groups, prevalently under a memory load and with low mean WMC, failed to learn or overused help.     

灵感交锋 触摸流行之潮——记“巴黎家居装饰博览会和巴黎国际家具博览会”

在法国人的眼里,家的地位仅次于家庭,家代表的是居住环境而家庭则代表的是家人的和睦。MAISON＆OBJET——巴黎家居装饰博览会和巴黎国际家具博览会正是独一无二的表达家这个概念的平台,MAISON＆OBJET以及它的联展令观众既能欣赏实用又独特的家居设计产品,     

Administering Spatial and Cognitive Instruments In-class and On-line: Are These Equivalent?

Standardized, well-established paper-and-pencil tests, which measure spatial abilities or which measure reasoning abilities, have long been found to be predictive of success in the STEM (science, technology, engineering, and mathematics) fields. Instructors can use these tests for prediction of success and to inform instruction. A comparative administration of spatial visualization and cognitive reasoning tests, between in-class (proctored paper and pencil) and on-line (unproctored Internet) (N = 457), was used to investigate and to determine whether the differing instrument formats yielded equal measures of spatial ability and reasoning ability in large first-semester general chemistry sections. Although some gender differences were found, findings suggest that some differences across administration formats, but that on-line administration had similar properties of predicting chemistry performance as the in-class version. Therefore, on-line administration is a viable option for instructors to consider especially when dealing with large classes.     

Taste quality and extinction of a conditioned taste aversion in rats

Rats (Rattus norvegicus) that received a taste cue (saccharin, saline, quinine, or sucrose) paired with a lithium chloride (LiCl) injection displayed a robust decrease in consumption of that taste, relative to controls that had the taste unpaired with LiCl. Consumption of the paired taste increased with each nonreinforced presentation (i.e., extinction). After asymptotic extinction, rats that had had a 0.1% saccharin cue paired with LiCl consumed less of the saccharin solution than did controls. A similar data pattern was observed with a 10% sucrose solution. These results are consistent with the view that some aspect of the excitatory CS-US association remains after extinction. On the other hand, rats that had a bitter (0.005% or 0.001% quinine) or salty (1% or 0.5% saline) solution paired with LiCl drank similar amounts of the fluid as controls after asymptotic extinction treatment. Together, these experiments suggest that a taste that is either sweet or preferred is required in order to demonstrate the chronic decrease in fluid consumption after extinction treatment. The data suggest that the conditioning experience prevents the later development of a preference for the sweet taste, rather than there being a retained aversion that suppresses fluid consumption.