Thermally multiplexed polymerase chain reaction     

Christopher R. Phaneuf  Nikita Pak  D. Curtis Saunders  Gregory L. Holst  Joav Birjiniuk  Nikita Nagpal  Stephen Culpepper  Emily Popler  Andi L. Shane  Robert Jerris  Craig R. Forest 《Biomicrofluidics》2015,9(4)

Amplification of multiple unique genetic targets using the polymerase chain reaction (PCR) is commonly required in molecular biology laboratories. Such reactions are typically performed either serially or by multiplex PCR. Serial reactions are time consuming, and multiplex PCR, while powerful and widely used, can be prone to amplification bias, PCR drift, and primer-primer interactions. We present a new thermocycling method, termed thermal multiplexing, in which a single heat source is uniformly distributed and selectively modulated for independent temperature control of an array of PCR reactions. Thermal multiplexing allows amplification of multiple targets simultaneously—each reaction segregated and performed at optimal conditions. We demonstrate the method using a microfluidic system consisting of an infrared laser thermocycler, a polymer microchip featuring 1 μl, oil-encapsulated reactions, and closed-loop pulse-width modulation control. Heat transfer modeling is used to characterize thermal performance limitations of the system. We validate the model and perform two reactions simultaneously with widely varying annealing temperatures (48 °C and 68 °C), demonstrating excellent amplification. In addition, to demonstrate microfluidic infrared PCR using clinical specimens, we successfully amplified and detected both influenza A and B from human nasopharyngeal swabs. Thermal multiplexing is scalable and applicable to challenges such as pathogen detection where patients presenting non-specific symptoms need to be efficiently screened across a viral or bacterial panel.  相似文献   

Kinematic,kinetic and EMG analysis of four front crawl flip turn techniques     

Suzana Matheus Pereira  Caroline Ruschel  Marcel Hubert  Leandro Machado  Helio Roesler  Ricardo Jorge Fernandes 《Journal of sports sciences》2015,33(19):2006-2015

This study aimed to analyse the kinematic, kinetic and electromyographic characteristics of four front crawl flip turn technique variants. The variants distinguished from each other by differences in body position (i.e. dorsal, lateral, ventral) during rolling, wall support, pushing and gliding phases. Seventeen highly trained swimmers (17.9 ± 3.2 years old) participated in interventional sessions and performed three trials of each variant, being monitored with a 3-D video system, a force platform and an electromyography (EMG) system. Studied variables: rolling time and distance, wall support time, push-off time, peak force and horizontal impulse at wall support and push-off, centre of mass horizontal velocity at the end of the push-off, gliding time, centre of mass depth, distance, average and final velocity during gliding, total turn time and electrical activity of Gastrocnemius Medialis, Tibialis Anterior, Biceps Femoris and Vastus Lateralis muscles. Depending on the variant, total turn time ranged from 2.37 ± 0.32 to 2.43 ± 0.33 s, push-off force from 1.86 ± 0.33 to 1.92 ± 0.26 BW and centre of mass velocity during gliding from 1.78 ± 0.21 to 1.94 ± 0.22 m · s^?1. The variants were not distinguishable in terms of kinematical, kinetic and EMG parameters during the rolling, wall support, pushing and gliding phases.  相似文献   

Undisclosed Flexibility in Computing and Reporting Structural Equation Models in Communication Science     

Christopher Scott Seaman  Rene Weber 《Communication methods and measures》2015,9(4):208-232

The use of structural equation modeling (SEM) in communication research has become increasingly popular in recent years, with SEM being commonly used as the primary method of data analysis in studies published within the field’s journals. However, despite its widespread use, there are persistent misapplications of SEM in published empirical studies in the communication sciences. Of these types of misuse, the most troubling are those related to the exploitation of flexibilities in data collection and analysis. Given the number of decisions that must be made when analyzing and reporting structural equation models, decisions which often remain undisclosed, the potential for researchers to exploit flexibilities in SEM research is high. To assess the extent of this problem, as well as the more longstanding types of misuse (i.e., omission of information and disclosed “bad practice”) identified by prior studies, we undertake a methodical review of studies employing structural equation modeling within major journals in the field of communication between the years 2007 and 2011. Articles were coded on the characteristics of the sample, characteristics of the model tested, as well as for various potential problems that we defined a priori. The most serious issues are identified, and recommendations for future standards in SEM research are suggested.  相似文献   

The evolving reference desk: A case study     

Christopher Ross Bowron  Joseph E. Weber 《The Journal of Academic Librarianship》2019,45(5):102057

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Direct and Indirect Effects of Involvement on Hostile Media Perceptions in the Context of the Refugee Crisis in Germany and Switzerland     

Dorothee Arlt  Caroline Dalmus  Julia Metag 《Mass Communication and Society》2019,22(2):171-195

This article examines hostile media perceptions (HMPs) by building on recent trends in hostile media research. Our study considers the effects of people’s cognitive as well as their affective involvement on HMPs. As the media landscape has changed fundamentally since HMPs were initially identified, the role of social media is explored more profoundly. In addition, this article not only examines the direct effects of involvement and communication activities but tests for indirect effects of involvement mediated through media use and interpersonal discussions. Using data simultaneously collected from two online surveys conducted in Germany and the German-speaking part of Switzerland, the findings strengthen previous evidence that affective involvement is a stronger predictor of HMPs than cognitive involvement. In contrast, media use and interpersonal discussions had only marginal direct effects. The study provides initial evidence for the indirect effects of involvement mediated through exposure to online user comments and interpersonal discussions.  相似文献   

Individual Differences in Childhood Behavior Disorders Associated With Epigenetic Modulation of the Cortisol Receptor Gene          下载免费PDF全文

Mark R. Dadds  Caroline Moul  David J. Hawes  Antonio Mendoza Diaz  John Brennan 《Child development》2015,86(5):1311-1320

Behavioral/emotional difficulties in children are the first sign of mental health problems. These problems are however, heterogeneous. A domain that may identify homogenous subgroups is hypothalamic–pituitary–adrenal function. This study tested whether epigenetic regulation of glucocorticoid receptor gene could explain the co‐occurrence of anxiety problems in children with behavior problems. Four‐ to 16‐year‐old clinically referred children (N = 241) were measured for psychiatric symptoms, methylation of target CpG sites in blood or saliva, and morning cortisol levels in those who gave blood. Increased methylation of promoter 1F CpG sites was associated with higher vulnerability to co‐occurring internalizing symptoms and morning cortisol. The results support increasing optimism that epigenetic regulation of key neuroendocrine systems might help explain hitherto unfathomable individual differences in susceptibility to psychiatric symptom profiles.  相似文献   

Children's literacy interest and its relation to parents’ literacy‐promoting practices          下载免费PDF全文

Laura E. Hume  Christopher J. Lonigan  Jessica D. McQueen 《Journal of Research in Reading》2015,38(2):172-193

This study examined how children's literacy interests related to parent literacy‐promoting practices across time. Using a sample of 909 preschool‐age children and the newly developed Child Activities Preference Checklist, literacy interest appeared to be a complex construct, not easily captured by a single measure. In a subsample of 230 children with longitudinal data, parent literacy practices and child literacy interests related concurrently and across time. Parent literacy practices were more stable than child literacy interests, with children's literacy interest continuing to develop over the preschool year. Parent practices of exposing children to literacy and teaching them literacy concepts appeared to be distinct constructs. Exposure to literacy was especially important in the growth of literacy interests and the hypothesis that exposure has a negative effect on children with little initial interest was not fully supported.  相似文献   

Genetic and Environmental Etiologies of the Longitudinal Relations Between Prereading Skills and Reading          下载免费PDF全文

Micaela E. Christopher  Jacqueline Hulslander  Brian Byrne  Stefan Samuelsson  Janice M. Keenan  Bruce Pennington  John C. DeFries  Sally J. Wadsworth  Erik Willcutt  Richard K. Olson 《Child development》2015,86(2):342-361

The present study explored the environmental and genetic etiologies of the longitudinal relations between prereading skills and reading and spelling. Twin pairs (n = 489) were assessed before kindergarten (M = 4.9 years), post‐first grade (M = 7.4 years), and post‐fourth grade (M = 10.4 years). Genetic influences on five prereading skills (print knowledge, rapid naming, phonological awareness, vocabulary, and verbal memory) were primarily responsible for relations with word reading and spelling. However, relations with post‐fourth‐grade reading comprehension were due to both genetic and shared environmental influences. Genetic and shared environmental influences that were common among the prereading variables covaried with reading and spelling, as did genetic influences unique to verbal memory (only post‐fourth‐grade comprehension), print knowledge, and rapid naming.  相似文献   

Exploring Shifts in Middle School Learners’ Modeling Activity While Generating Drawings,Animations, and Computational Simulations of Molecular Diffusion   总被引：1，自引：1，他引：0  

Michelle H. Wilkerson-Jerde  Brian E. Gravel  Christopher A. Macrander 《Journal of Science Education and Technology》2015,24(2-3):396-415

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Technology integration coursework and finding meaning in pre-service teachers’ reflective practice     

Royce Kimmons  Brant G. Miller  Julie Amador  Christopher David Desjardins  Cassidy Hall 《Educational technology research and development : ETR & D》2015,63(6):809-829

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