Lerndialoge von Kindern in einem jahrgangsgemischten Anfangsunterricht Mathematik

Innerhalb der Mathematikdidaktik haben sich seit geraumer Zeit bestimmte Grundüberzeugungen dazu herausgestellt, wie Kinder Mathematik lernen. Dazu gehört die Sicht auf das Kind als Konstrukteur seines Wissens, das sich die Lerninhalte aktiv-entdeckend aneignet, genau so wie die Auffassung vom Lernen als eine soziokulturell geprägte Tätigkeit. Aus diesen beiden grundlegenden Überzeugzungen leiten sich Vorstellungen von einer veränderten Unterrichtskultur ab, die sich beispielsweise auf die Lehrerrolle, auf den Umgang mit Fehlern und auch auf die im Unterricht praktizierte Aufgabenkultur beziehen. Wenn diese drei Grundfesten mathematischer Bildungsprozesse berücksichtigt werden, ist wohl immer guter Mathematikunterricht möglich. Mit der Jahrgangsmischung soll an diesen Grundfesten nicht gerüttelt werden, vielmehr tritt sie als schulisches Merkmal hinzu. Sie bildet quasi eine besondere Hintergrundfolie für die in der Schule stattfindenden Lernprozesse. Mit meiner Untersuchung gehe ich daher nicht der Frage nach, ob und inwiefern Kinder in der Jahrgangsmischung besser als in herkömmlichen homogenen Klassenverbänden Mathematik lernen können. Stattdessen richte ich den Blick darauf, welche besonderen Chancen sich in einer jahrgangsgemischten Zusammensetzung im Hinblick auf das Lernen von Mathematik ergeben können

Achievable data rates on simultaneously connected bluetooth low energy devices

Bluetooth Low Energy (BLE) has been optimized for low power and targets low data rate applications. However, there are applications where several peripherals are simultaneously connected to a central device, with the requirement of achieving moderate data rates for each connection. Available hardware and software stacks place limitations on the number of simultaneous connections as well as on the achievable data rates. This paper presents measurement results for different scenarios. On the central device side the explored options cover tablets based on Android and iOS as well as dongles that can be connected through a USB port. On the peripheral side several selected hardware set-ups (chips and modules) are measured and compared. Analysis of captured packets provides insight into why the reached data rates are often significantly lower than theoretically expected

Simultaneously connecting devices through bluetooth smart

Modern data loggers record and store large amounts of data from many different types of sensors. This enables their use in various applications to capture different measurands. However wireless access to the recorded data opens countless possibilities for novel and innovative applications, for example in the health monitoring of humans or livestock. In many of these applications a central device connects simultaneously to several data loggers. This paper discusses the experiences made during the design, implementation and test of an energy efficient wireless interface to a data logger. The implemented system serves as an application example for Bluetooth Smart. It allows a user to monitor ongoing measurements of several data loggers through a smartphone. Additionally the recorded data of several loggers can be simultaneously uploaded to a central gateway. The available Bluetooth Smart chips and software stacks place limitations on usable bandwidth as well as on the number of simultaneous connections. Although most modern smartphones include hardware for Bluetooth Smart, implementations differ widely across platforms, thus creating additional effort for the app programmer. This paper presents measurement results and introduces the implemented approaches to optimize these parameters

Pituitary duplication and nasopharyngeal teratoma in a newborn: CT, MRI, US and correlative histopathological findings

The computed tomography and MRI imaging findings in a case of pituitary duplication and epipharyngeal teratoma are described in a newborn baby girl with respiratory difficulties. Associated skull base and central nervous system malformations are presented. Teratoma diagnosis was confirmed by histology. The embryological pathogenesis is discusse

Work function of few layer graphene covered nickel thin films measured with Kelvin probe force microscopy

Few layer graphene and graphite are simultaneously grown on a similar to 100 nm thick polycrystalline nickel film. The work function of few layer graphene/Ni is found to be 4.15 eV with a variation of 50 meV by local measurements with Kelvin probe force microscopy. This value is lower than the work function of free standing graphene due to peculiar electronic structure resulting from metal 3d-carbon 2p(pi) hybridization. (C) 2016 AIP Publishing LLC

Shortcomings of cuffed paediatric tracheal tubes†

Background. The goal of this investigation was to evaluate adequacy of the design of readily available paediatric cuffed tracheal tubes (CPTT). Methods. In 15 series of cuffed (11) and uncuffed (four) paediatric tracheal tubes (ID: 2.5-7.0 mm) from four different manufacturers the following dimensions were measured: outer diameter of the tube, position and largest diameter of the tube cuff inflated at 20 cm H2O and position of depth markings and compared with age‐related dimensions. Results. Outer diameters for tubes with similar IDs varied markedly between manufacturers and between cuffed and uncuffed tracheal tubes from the same manufacturer. Cuff diameters at 20 cm H2O cuff pressure and cross‐sectional cuff area at 20 cm H2O cuff pressure did not always cover maximal internal age‐related tracheal diameters and cross‐sectional areas. Placing the tube tip in the mid‐trachea, the cuffs of cuffed tubes with ID 3.0, 4.0, or 5.0 mm would become positioned within the larynx. If the cuffs were placed 1 cm below the cricoid level, many of the tube tips would be dangerously deep within the trachea. Only five of the 11 cuffed tubes had a depth marking. In many of these tubes the distances from depth marking to tube tip were greater than the age‐related minimal tracheal length. Conclusion. Most cuffed paediatric tracheal tubes are poorly designed, in particular the smaller sizes. A better design of cuffed tubes with a short high‐volume, low‐pressure cuff, cuff‐free subglottic space and adequately placed depth markings are urgently needed. Br J Anaesth 2004; 92: 78-8

Pediatric Epstein-Barr Virus Carriers With or Without Tonsillar Enlargement May Substantially Contribute to Spreading of the Virus

Background. Human-to-human transmission of the persistent infection establishing Epstein-Barr virus (EBV) occurs via saliva. Tonsils act as important portal of entry and exit of EBV. The contagiousness of pediatric EBV carriers and the role played by tonsillar enlargement (TE) are not known. Methods. We compared EBV shedding in mouthwash samples from pediatric EBV carriers with or without TE to that in mouthwash samples from pediatric patients with infectious mononucleosis (IM), the symptomatic form of primary infection if delayed after the age of 5 years. EBV DNA was quantified by polymerase chain reaction, and contagiousness was assessed using the cord lymphocyte transformation assay. Results. EBV carriers with TE shed EBV DNA at an almost similar frequency (although in lower amounts) as pediatric patients with acute IM but more frequently (P ! .001) and in higher amounts (Pp.038) than EBV carriers without TE. EBV DNA levels in mouthwash samples from EBV carriers with TE mirrored levels in tonsils and gradually declined after tonsillectomy. Almost half of the mouthwash samples from pediatric EBV carriers contained infectious EBV. Conclusions. Pediatric EBV carriers-in particular, those with TE-may considerably contribute to the spreading of EBV in industrialized countrie

Pediatric epstein-barr virus carriers with or without tonsillar enlargement may substantially contribute to spreading of the virus

BACKGROUND: Human-to-human transmission of the persistent infection establishing Epstein-Barr virus (EBV) occurs via saliva. Tonsils act as important portal of entry and exit of EBV. The contagiousness of pediatric EBV carriers and the role played by tonsillar enlargement (TE) are not known. METHODS: We compared EBV shedding in mouthwash samples from pediatric EBV carriers with or without TE to that in mouthwash samples from pediatric patients with infectious mononucleosis (IM), the symptomatic form of primary infection if delayed after the age of 5 years. EBV DNA was quantified by polymerase chain reaction, and contagiousness was assessed using the cord lymphocyte transformation assay. RESULTS: EBV carriers with TE shed EBV DNA at an almost similar frequency (although in lower amounts) as pediatric patients with acute IM but more frequently (P <.001) and in higher amounts (P = .038) than EBV carriers without TE. EBV DNA levels in mouthwash samples from EBV carriers with TE mirrored levels in tonsils and gradually declined after tonsillectomy. Almost half of the mouthwash samples from pediatric EBV carriers contained infectious EBV. CONCLUSIONS: Pediatric EBV carriers--in particular, those with TE-may considerably contribute to the spreading of EBV in industrialized countries

Combined SIMS-SPM Instrument For High Sensitivity And High Resolution Elemental 3D Analysis

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 - August 2, 201