DNA-library assembly programmed by on-demand nano-liter droplets from a custom microfluidic chip     

Uwe Tangen  Gabriel Antonio S. Minero  Abhishek Sharma  Patrick F. Wagler  Rafael Cohen  Ofir Raz  Tzipy Marx  Tuval Ben-Yehezkel  John S. McCaskill 《Biomicrofluidics》2015,9(4)

Nanoscale synthetic biology can benefit from programmable nanoliter-scale processing of DNA in microfluidic chips if they are interfaced effectively to biochemical arrays such as microwell plates. Whereas active microvalve chips require complex fabrication and operation, we show here how a passive and readily fabricated microchip can be employed for customizable nanoliter scale pipetting and reaction control involving DNA. This recently developed passive microfluidic device, supporting nanoliter scale combinatorial droplet generation and mixing, is here used to generate a DNA test library with one member per droplet exported to addressed locations on microwell plates. Standard DNA assembly techniques, such as Gibson assembly, compatible with isothermal on-chip operation, are employed and checked using off-chip PCR and assembly PCR. The control of output droplet sequences and mixing performance was verified using dyes and fluorescently labeled DNA solutions, both on-chip and in external capillary channels. Gel electrophoresis of products and DNA sequencing were employed to further verify controlled combination and functional enzymatic assembly. The scalability of the results to larger DNA libraries is also addressed by combinatorial input expansion using sequential injection plugs from a multiwell plate. Hence, the paper establishes a proof of principle of the production of functional combinatorial mixtures at the nanoliter scale for one sequence per well DNA libraries.  相似文献   

Who Benefits From a Foundational Logic Course? Effects on Undergraduate Course Performance     

Rafael Quintana  Christian Schunn 《Journal of research on educational effectiveness》2019,12(2):191-214

Being able to understand and evaluate arguments in different modalities and in different disciplines is thought to be a key component of students’ academic success in college. However, many students do not receive explicit instruction in the basic concepts and rules of argumentation. Using a difference-in-differences approach with a multicohort longitudinal data set of almost 15,000 undergraduates beginning in health and science, technology, engineering, and mathematics (STEM)-related fields at a research university, we examined changes in relative performance of students after enrolling in an introductory logic course. We find that students improved their grade point average (GPA) after taking the course, especially if they begin college with low academic achievement (Cohen’s d?=?0.18). Our results are consistent with the idea that acquiring foundational skills, in particular general skills in argumentation, prepares STEM students for future learning.  相似文献   

信息伦理学的本体论基础   总被引：5，自引：0，他引：5  

瑞菲尔&#;凯普偌  平爱 《上海师范大学学报(哲学社会科学版)》2006,35(5):24-35

文章首先对信息伦理学的悠久历史作了简单回顾。信息伦理学起源于米歇尔·佛科特(Michel FoucauIt)所分析的希腊语概念“自由演说”或言论自由。关于信息伦理学的最新概念尤其与20世纪随着计算机技术和因特网的发展而出现的各种问题密切相关,它包括大众媒体、图书馆学、信息科学以及商业等领域的伦理问题。从广义上说,信息伦理学概念涉及所有可能现象的数字重建,从而导致与数字本体论相关的种种问题。作者根据海德格尔关于本体论与形而上学关系的观点,认为本体论与“存在”本身有关,它不仅仅与形而上学讨论的主题即生物的生存有关。本文将海德格尔的理论和乔治·斯宾赛·布朗(George Spencer Brown)、高特路·甫瑞(Gottlob Frege)、尼克拉斯·鲁曼(Niklas Luhmann)等学者的学说相提并论,同时加以比较。用佛科特的专业术语来说,本体论是形而上学的尴尬困境。从本体论的角度探讨信息伦理学的基础,其首要目的是质疑数字本体论的形而上学的奢望。数字本体论被认为是当今对“存在”的普遍理解。作者把人类存在作为一种与万物存在即“无标记空间”相关的伦理关系加以分析,在此基础上探讨一些数字技术的挑战,并着重分析数字代理人的道德状况。作者据理论证,信息伦理学不仅仅涉及与佛劳瑞德(Floridi)所提到的“信息领域”相关的伦理问题。文章将这种观点与佛劳瑞德提出的关于信息伦理学基础以及数码代理人道德状态的论点进行对比分析。文章认为,简化论者把人体作为数字数据的观点忽视了数字本体论的局限性,抛弃了伦理定位的基础。最后,文章探讨了同“数字分隔”相关的问题以及信息伦理学跨文化的方方面面,并提出了长期和短期的研究设想。  相似文献   

Contributing factors to long‐term citation count in marine and freshwater biology articles          下载免费PDF全文

Joshua R. Nash  Rafael J. Araújo  Geoffrey S. Shideler 《Learned Publishing》2018,31(2):131-139

Researchers have investigated factors thought to affect the total number of citations in various academic disciplines, and some general trends have emerged. However, there are still limited data for many fields, including aquatic sciences. Using papers published in 2003–2005 (n = 785), we investigated marine and freshwater biology articles to identify factors that may contribute to the probability of citation and for cumulative citation counts over 10 years. We found no relationships with probability of citation; however, we found evidence that for those that were cited at least once, cumulative citations were related to several factors. Articles cited by books received more citations than those never cited by books, which we hypothesized to be indicative of the impact an article may have in the field. We also found that articles first cited within 2 years of publication received more cumulative citations than those first cited after 2 years. We found no evidence that self‐citation (as the first citation) had a significant effect on total citations. Our findings were compared with previous studies in other disciplines, and it was found that aquatic science citation patterns are comparable to fields in science and technology but less so to humanities and social sciences.  相似文献   

Cognitive-operative model of intelligent learning systems behavior     

Ana Lilia Laureano-Cruces  Javier Ramírez-Rodríguez  Martha Mora-Torres  Fernando de Arriaga  Rafael Escarela-Pérez 《Interactive Learning Environments》2013,21(1):11-38

In this paper behavior during the teaching–learning process is modeled by means of a fuzzy cognitive map. The elements used to model such behavior are part of a generic didactic model, which emphasizes the use of cognitive and operative strategies as part of the student–tutor interaction. Examples of possible initial scenarios for the teaching–learning process are developed, along with the results provided by the model.  相似文献   

The effect of a structured story reading intervention,story retelling and higher order thinking for English language and literacy acquisition     

Ana M. Cruz de Quirós  Rafael Lara‐Alecio  Fuhui Tong  Beverly J. Irby 《Journal of Research in Reading》2012,35(1):87-113

The purpose of this study was to investigate the effectiveness of structured story reading intervention, Story reTelling and higher order thinking for English Language and Literacy Acquisition (STELLA), delivered to 38 Hispanic English language learners (ELL) placed in an enhanced transitional bilingual programme over 2 years from first to second grade as compared with 34 control students placed in a typical practice transitional bilingual programme during the same time period. Both treatment and comparison ELL students' retellings of two stories in Spanish and English were measured by five story elements. Findings were that (a) students receiving intervention outperformed their comparison peers in all five story elements in English and Spanish of both stories; (b) students showed stronger ability in their native language in four of five story elements; and (c) students performed at a higher level in the narrative‐informational story than a narrative story in both languages. Educational implications are discussed.  相似文献   

Early School-leaving in Spain: evolution,intensity and determinants     

Enrique Fernández-Macías  José-Ignacio Antón  Francisco-Javier Braña  Rafael Muñoz De Bustillo 《European Journal of Education》2013,48(1):150-164

Spain has one of the highest levels of early school leaving and educational failure of the European Union. The purpose of this paper is to analyse the anatomy of early school leaving in Spain and its characteristics. In order to do so, in the first part we discuss the measurement problems related with this concept and the evolution of drop-out rates in Spain. We argue that the published figures of early school leaving slightly underestimate the phenomenon, and discuss the impact of the increase in immigration rates on the level of educational failure and its very unequal distribution in terms of gender. In a second part, using data from the Labour Force Surveys of 2000 and 2007, we explore the factors behind educational failure by means of a logistic regression. The results of this model confirm the explanatory power of social reproduction hypotheses, but also show that there are important aspects of the patterns and recent evolution of early school leaving which cannot be explained by a single theoretical approach.  相似文献   

El papel de la memoria de trabajo en la adquisición lectora en niños de habla castellana     

Conrado Navalón  Manuel Ato  Rafael Rabadán 《Infancia y Aprendizaje》2013,36(45):85-105

Resumen

En este trabajo se abordan cuestiones básicas relativas a la manipulación y retención de la información en la Memoria de Trabajo y su vinculación con la adquisición lectora desde la perspectiva de los modelos interactivos de procesamiento de la información. Se plantean cuatro experimentos aplicados a niños de nivel lector alto y bajo de primero, tercero y quinto de EGB, respectivamente. Los resultados indican que sólo existen diferencias significativas entre grupos de distinto nivel lector en aquellas tareas con mayor implicaión de componentes funcionales, mientras que las diferencias más importantes entre cursos se dan entre primero y tercero, tanto para componentes estructurales como funcionales.  相似文献   

Ethical Challenges of the Information Society in the 21st Century     

Rafael Capurro 《International Information and Library Review》2013,45(3-4):257-276

The paper deals with theoretical and practical challenges of the information society in the 21st century. In the first part an overview of past and current activities in the field of information ethics at UNESCO is provided (Virtual Forum, Second International Congress on Information Ethics, Observatory on the information Society). The second part presents a historical interpretation of the development of modern information society with the emerging networked world society with its characteristics of interactivity and decentralization. The diversity of moral norms and traditions within this global medium gives rise to the question concerning an Internet-morality as a challenge to ethical thinking. The third part deals with the question of our identity within the framework of a digital ontology. The concepts of “net” and “information” are analysed. A future information ethics is based on a digital ontology. Living in the information age is considered from the point of view of both an ethical imperative and the art of living.  相似文献   

Effects of adding a weekly eccentric-overload training session on strength and athletic performance in team-handball players     

Rafael Sabido  Javier Botella  Angel Navarro  Julio Tous-Fajardo 《European Journal of Sport Science》2017,17(5):530-538

To investigate the influence of adding a weekly eccentric-overload training (EOT) session in several athletic performance’s tests, 18 team-handball players were assigned either to an EOT (n?=?11) or a Control (n?=?7) group. Both groups continued to perform the same habitual strength training, but the EOT group added one session/week during a 7-week training programme consisting of four sets of eight repetitions for the bilateral half-squat and unilateral lunge exercises. The test battery included handball throwing velocity, maximum dynamic strength (1RM), countermovement jump (CMJ), 20?m sprint, triple hop for distance, and eccentric/concentric power in both the half-squat and lunge exercises. Data were analysed using magnitude-based inferences. Both groups improved their 1RM in the half squat, 20?m sprint time, and CMJ performance to a similar extent, but the EOT group showed a beneficial effect for both right [(42/58/0), possibly positive] and left [(99/1/0), very likely positive] triple hop for distance performance. In addition, the EOT group showed greater power output improvements in both eccentric and concentric phases of the half-squat (difference in percent of change ranging from 6.5% to 22.0%) and lunge exercises (difference in per cent of change ranging from 13.1% to 24.9%). Nevertheless, no group showed changes in handball throwing velocity. Selected variables related to team-handball performance (i.e. functional jumping performance, power output) can be improved by adding a single EOT session per week, highlighting the usefulness of this low-volume/high-intensity training when aiming at optimizing dynamic athletic performance.  相似文献