Revision of the Cretaceous shark Protoxynotus (Chondrichthyes, Squaliformes) and early evolution of somniosid sharks

Due to the peculiar combination of dental features characteristic for different squaliform families, the position of the Late Cretaceous genera Protoxynotus and Paraphorosoides within Squaliformes has long been controversial. In this study, we revise these genera based on previously known fossil teeth and new dental material. The phylogenetic placement of Protoxynotus and Paraphorosoides among other extant and extinct squaliforms is discussed based on morphological characters combined with DNA sequence data of extant species. Our results suggest that Protoxynotus and Paraphorosoides should be included in the Somniosidae and that Paraphorosoides is a junior synonym of Protoxynotus. New dental material from the Campanian of Germany and the Maastrichtian of Austria enabled the description of a new species Protoxynotus mayrmelnhofi sp. nov. In addition, the evolution and origin of the characteristic squaliform tooth morphology are discussed, indicating that the elongated lower jaw teeth with erected cusp and distinct dignathic heterodonty of Protoxynotus represents a novel functional adaptation in its cutting-clutching type dentition among early squaliform sharks. Furthermore, the depositional environment of the tooth bearing horizons allows for an interpretation of the preferred habitat of this extinct dogfish shark, which exclusively occupied shelf environments of the Boreal- and northern Tethyan realms during the Late Cretaceous.publishedVersio

GUN: An Efficient Execution Strategy for Querying the Web of Data

International audienceLocal-As-View (LAV) mediators provide a uniform interface to a federation of heterogeneous data sources, attempting to execute queries against the federation. LAV mediators rely on query rewriters to translate mediator queries into equivalent queries on the federated data sources. The query rewriting problem in LAV mediators has shown to be NP-complete, and there may be an exponential number of rewritings, making unfeasible the execution or even generation of all the rewritings for some queries. The complexity of this problem can be particularly impacted when queries and data sources are described using SPARQL conjunctive queries, for which millions of rewritings could be generated. We aim at providing an efficient solution to the problem of executing LAV SPARQL query rewritings while the gathered answer is as complete as possible. We formulate the Result-Maximal k-Execution problem (ReMakE) as the problem of maximizing the query results obtained from the execution of only k rewritings. Additionally, a novel query execution strategy called GUN is proposed to solve the ReMakE problem. Our experimental evaluation demonstrates that GUN outperforms traditional techniques in terms of answer completeness and execution time

Pedagogies of critique : struggling with what and how to think

No abstract available

Teaching small animal reproduction via virtual patients

Virtual patients have become an interesting alternative in medical education. Due to increasing demands regarding theoretical and clinical teaching and to improve an interdisciplinary approach, a new blended learning concept including virtual patients was developed and implemented in the veterinary curriculum of the Freie Universität Berlin. In the presented project, three virtual patients from the field of canine reproduction were developed. They focus on pregnancy diagnosis with suspected luteal insufficiency, pyometra and benign prostatic hyperplasia, respectively. The results of an evaluation by veterinary students of the 7th semester showed a high acceptance of virtual patients in a blended learning reproduction module in the interdisciplinary lectures. Students especially preferred videos, such as video lectures, hands‐on videos and animations as well as a glossary for background information, to successfully and autonomously work on a virtual case. The content covered by the new modules that were developed in the context of this project is part of a spiral curriculum; they will be revised and enhanced during the clinical year

Comprehension as social and intellectual practice: Rebuilding curriculum in low socioeconomic and cultural minority schools

This article reframes the concept of comprehension as a social and intellectual practice. It reviews current approaches to reading instruction for linguistically and culturally diverse and low socioeconomic students, noting an emphasis on comprehension as autonomous skills. The Four Resources model (Freebody & Luke, 1990) is used to make the case for the integration of comprehension instruction with an emphasis on student cultural and community knowledge, and substantive intellectual and sociocultural content in elementary school curricula. Illustrations are drawn from research underway on the teaching of literacy in primary schools in low SES communities

ANAPSID: An Adaptive Query Processing Engine for SPARQL Endpoints

Abstract. Following the design rules of Linked Data, the number of available SPARQL endpoints that support remote query processing is quickly growing; however, because of the lack of adaptivity, query executions may frequently be unsuccessful. First, fixed plans identified following the traditional optimize-then-execute paradigm, may timeout as a consequence of endpoint availability. Sec-ond, because blocking operators are usually implemented, endpoint query en-gines are not able to incrementally produce results, and may become blocked if data sources stop sending data. We present ANAPSID, an adaptive query engine for SPARQL endpoints that adapts query execution schedulers to data availabil-ity and run-time conditions. ANAPSID provides physical SPARQL operators that detect when a source becomes blocked or data traffic is bursty, and opportunis-tically, the operators produce results as quickly as data arrives from the sources. Additionally, ANAPSID operators implement main memory replacement policies to move previously computed matches to secondary memory avoiding duplicates. We compared ANAPSID performance with respect to RDF stores and endpoints, and observed that ANAPSID speeds up execution time, in some cases, in more than one order of magnitude.

Schools, teachers and community: cultivating the conditions for engaged student learning

This paper reveals the nature of the actions, discussions and relationships which characterised teachers' and associated school personnel's efforts to engage poor and refugee students through a community garden located in a school in a low socio-economic urban area in south-east Queensland, Australia. These actions, discussions and relationships are described as both revealing and producing particular 'practice architectures' which help constitute conditions for practice-in this case, conditions for beneficial student learning. The paper draws upon interview data with teachers, other school staff and community members working in the school to reveal the interrelating actions, discussions and relationships involved in developing and using the garden for academic and non-academic purposes. By better understanding such interrelationships as practice architectures, the paper reveals how teachers and those in schooling settings learn to facilitate student learning practices that likely to assist some of the most marginalised students in schooling settings

Processing Regular Path Queries on Arbitrarily Distributed Data

Regular Path Queries (RPQs) are a type of graph query where answers are pairs of nodes connected by a sequence of edges matching a regular expression. We study the techniques to process such queries on a distributed graph of data. While many techniques assume the location of each data element (node or edge) is known, when the components of the distributed system are autonomous, the data will be arbitrarily distributed. As the different query processing strategies are equivalently costly in the worst case, we isolate query-dependent cost factors and present a method to choose between strategies, using new query cost estimation techniques. We evaluate our techniques using meaningful queries on biomedical data