306 research outputs found

    Influence of electromagnetic interferences on the gravimetric sensitivity of surface acoustic waveguides

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    Surface acoustic waveguides are increasing in interest for (bio)chemical detection. The surface mass modification leads to measurable changes in the propagation properties of the waveguide. Among a wide variety of waveguides, Love mode has been investigated because of its high gravimetric sensitivity. The acoustic signal launched and detected in the waveguide by electrical transducers is accompanied by an electromagnetic wave; the interaction of the two signals, easily enhanced by the open structure of the sensor, creates interference patterns in the transfer function of the sensor. The influence of these interferences on the gravimetric sensitivity is presented, whereby the structure of the entire sensor is modelled. We show that electromagnetic interferences generate an error in the experimental value of the sensitivity. This error is different for the open and the closed loop configurations of the sensor. The theoretical approach is completed by the experimentation of an actual Love mode sensor operated under liquid in open loop configuration. The experiment indicates that the interaction depends on the frequency and the mass modifications.Comment: 28 pages, 8 figure

    Simultaneous surface acoustic wave and surface plasmon resonance measurements: electrodeposition and biological interactions monitoring

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    We present results from an instrument combining surface acoustic wave (SAW) propagation and surface plasmon resonance (SPR) measurements. The objective is to use two independent methods, the former based on adsorbed mass change measurements and the latter on surface dielectric properties variations, to identify physical properties of protein layers, and more specifically their water content. We display mass sensitivity calibration curves using electrodeposition of copper leading to a sensitivity in liquid of 150±15\pm15 cm2/gcm^2/g for the Love mode device used here, and the application to monitoring biological processes. The extraction of protein layer thickness and protein to water content ratio is also presented for S-layer proteins under investigation. We obtain respectively 4.7±\pm0.7 nm and 75±\pm15%.Comment: 13 pages, 4 figure

    Supporting and Retaining Early Career Mathematics Teachers Using an Online Community of Practice

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    This study reports on efforts over several years to design and implement a yearlong intervention intended to support secondary mathematics teachers in their early years of teaching. The intervention is designed to retain early career mathematics teachers in the professions by engaging them in the development of meaningful professional relationships with a school-based mentors, and by creating an online community of practice for support with other professionals. The intervention itself consists of early career teachers and their mentors participating in monthly professional learning activities such as online meetings, videoconferencing panels with experts, and collaborative reading and discussing timely, purposeful, and relevant content. The intervention is designed to not over burden the participants and to be feasible for national implementation with little to no funding. This article presents the purpose, design, and implementations of the intervention, as well as a discussion of challenges faced and potential next steps and future directions for similar work

    Identification of the novel KI polyomavirus in paranasal and lung tissues

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    KI is a novel polyomavirus identified in the respiratory secretions of children with acute respiratory symptoms. Whether this reflects a causal role of the virus in the human respiratory disease remains to be established. To investigate the presence of KIV in the respiratory tissue, we examined 20 fresh lung cancer specimens and surrounding normal tissue along with one paranasal and one lung biopsy from two transplanted children. KIV-VP1 gene was detected in 9/20 lung cancer patients and 2/2 transplanted patients. However, amplification of the sequence coding for the C-terminal part of the early region of KIV performed on the 11 positive cases was successful only in two malignant lung tissues, one surrounding normal tissue, and 1/2 biopsies tested. Phylogenetic analysis performed on the early region of KIV (including the four Italian isolates), BKV and JCV revealed the presence of three distinct clades. Within the KIV clade two sub-clades were observed. A sub-clade A containing the four Italian strains, and a sub-clade B comprising the Swedish and Australian isolates. Interestingly, the two Italian strains identified in normal tissue clustered together, whereas those detected in malignant tissue fell outside this cluster. In vitro studies are needed to investigate the transforming potential of KIV strains. J. Med. Virol. 81:558-561,2009. (C) 2009 Wiley-Liss, Inc

    Herbert Simon's decision-making approach: Investigation of cognitive processes in experts

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    This is a post print version of the article. The official published can be obtained from the links below - PsycINFO Database Record (c) 2010 APA, all rights reserved.Herbert Simon's research endeavor aimed to understand the processes that participate in human decision making. However, despite his effort to investigate this question, his work did not have the impact in the “decision making” community that it had in other fields. His rejection of the assumption of perfect rationality, made in mainstream economics, led him to develop the concept of bounded rationality. Simon's approach also emphasized the limitations of the cognitive system, the change of processes due to expertise, and the direct empirical study of cognitive processes involved in decision making. In this article, we argue that his subsequent research program in problem solving and expertise offered critical tools for studying decision-making processes that took into account his original notion of bounded rationality. Unfortunately, these tools were ignored by the main research paradigms in decision making, such as Tversky and Kahneman's biased rationality approach (also known as the heuristics and biases approach) and the ecological approach advanced by Gigerenzer and others. We make a proposal of how to integrate Simon's approach with the main current approaches to decision making. We argue that this would lead to better models of decision making that are more generalizable, have higher ecological validity, include specification of cognitive processes, and provide a better understanding of the interaction between the characteristics of the cognitive system and the contingencies of the environment

    Accounting for expert performance: the devil is in the details

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    The deliberate practice view has generated a great deal of scientific and popular interest in expert performance. At the same time, empirical evidence now indicates that deliberate practice, while certainly important, is not as important as Ericsson and colleagues have argued it is. In particular, we (Hambrick, Oswald, Altmann, Meinz, Gobet, & Campitelli, 2014) found that individual differences in accumulated amount of deliberate practice accounted for about one-third of the reliable variance in performance in chess and music, leaving the majority of the reliable variance unexplained and potentially explainable by other factors. Ericsson's (2014) defense of the deliberate practice view, though vigorous, is undercut by contradictions, oversights, and errors in his arguments and criticisms, several of which we describe here. We reiterate that the task now is to develop and rigorously test falsifiable theories of expert performance that take into account as many potentially relevant constructs as possible

    THE DESIGN AND IMPLEMENTATION OF AN INTERVENTION TO SUPPORT AND RETAIN EARLY CAREER MATHEMATICS TEACHERS

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    This study reports on efforts over several years to design and implement a yearlong intervention intended to support secondary mathematics teachers in their early years of teaching. The intervention is designed to support these teachers’ development of meaningful professional relationships with a school-based mentor and to create an online community of practice for support with other professionals. The intervention itself consists of early career teachers and their mentors participating in monthly professional development sessions such as online meetings, Zoom panels with experts, and collaboratively reading and discussing timely, purposeful, and relevant content. The intervention is designed to not over burden the participants and to be feasible for national implementation with little funding. The goal of the intervention is to try to retain secondary mathematics teachers in the profession by providing them with meaningful and targeted support Half of all teachers leave the profession within the first five years, and this rate is highest for mathematics positions in high poverty schools (Fantilli & McDougall, 2009; Goldring et al., 2014). Furthermore, half of all current teachers in the U.S. retiring in the next five years (Foster, 2010), enrollment in teacher preparation programs declining, and teacher turnover is costing America $7.3 billion annually (National Math + Science Initiative, 2013), which represents a crisis for public education in the U.S. These conditions lead to classrooms staffed with underprepared/unqualified teachers, which profoundly affects the mathematical preparation of students in high school, college, and beyond. Experts agree that addressing the mathematics-teaching crisis meaningfully will require building a more cohesive system of teacher preparation, support, and development (Mehta, TheisenHomer, Braslow, & Lopatin 2015). The purpose of this study is to report on the design and implementation of a cost effective, easily replicable intervention for early career secondary mathematics teachers with the goal of positively impacting teacher retention. We also present lessons learned over two years of implementing the intervention and provide suggestions for future research

    Recurrent Endometrial Cancer: Which Is the Best Treatment? Systematic Review of the Literature

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    Background: Endometrial cancer is the most common gynaecological tumour in developed countries. The overall rate of relapse has remained unchanged in recent decades. Recurrences occur in approximately 20% of endometrioid and 50% of non-endometrioid cases. The aim of this systematic review is to compare different therapeutic strategies in the treatment of endometrial cancer recurrence to evaluate their prognostic and curative effects based on site and type of recurrence. Methods: This systematic review of literature was conducted in accordance with the PRISMA guidelines. The study protocol was registered on PROSPERO (CRD42020154042). PubMed, Embase, Chocrane and Cinahl databases were searched from January 1995 to September 2021. Five retrospective studies were selected. Results: A total of 3571 studies were included in the initial search. Applying the screening criteria, 299 articles were considered eligible for full-text reading, of which, after applying the exclusion criteria, 4 studies were selected for the final analysis and included in the systematic review. No studies were included for a quantitative analysis. We divided the results according to the location of the recurrence: locoregional recurrence, abdominal recurrence and extra abdominal recurrence. Conclusion: the treatment of choice should be assessed according to the relapse location and to the presence of single or multiple lesions. A crucial role in the decision-making algorithm is also the type of adjuvant treatment received at the time of the first diagnosis

    Effective connectivity reveals strategy differences in an expert calculator

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    Mathematical reasoning is a core component of cognition and the study of experts defines the upper limits of human cognitive abilities, which is why we are fascinated by peak performers, such as chess masters and mental calculators. Here, we investigated the neural bases of calendrical skills, i.e. the ability to rapidly identify the weekday of a particular date, in a gifted mental calculator who does not fall in the autistic spectrum, using functional MRI. Graph-based mapping of effective connectivity, but not univariate analysis, revealed distinct anatomical location of “cortical hubs” supporting the processing of well-practiced close dates and less-practiced remote dates: the former engaged predominantly occipital and medial temporal areas, whereas the latter were associated mainly with prefrontal, orbitofrontal and anterior cingulate connectivity. These results point to the effect of extensive practice on the development of expertise and long term working memory, and demonstrate the role of frontal networks in supporting performance on less practiced calculations, which incur additional processing demands. Through the example of calendrical skills, our results demonstrate that the ability to perform complex calculations is initially supported by extensive attentional and strategic resources, which, as expertise develops, are gradually replaced by access to long term working memory for familiar material
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