Thermally multiplexed polymerase chain reaction

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.     

Maryam Mirzakhani

The article outlines the life and work of Maryam Mirzakhani — the first and the only female winner of the Fields Medal since its inception in 1936. Mirzakhani is an inspiration to young women around the world, to believe in their own abilities and pursue their academic dreams.     

The global middle class and school choice: a cosmopolitan sociology

In this paper we suggest the need for research which addresses school choice as a global phenomenon. That is, a form of choice which extends beyond local politics and policymaking. We consider here the educational choices and choice making contexts of a burgeoning, mobile, post-national middle class who operate on a global scale. We also sketch the educational market within which these choices are considered and realised but the main focus is on demand side issues. The paper seeks to open a space for further research, in which to ask some old and some new questions about social class and social reproduction through schooling, and to make the case for choice researchers to attend more carefully to choice in a framework of mobility, globalisation and related new kinds of social class identities and interests.     

A Case Study of Teacher Beliefs on Students' Beliefs about Multiple Representations

The mathematics education community, in its call for reform, underscores the importance of mathematics instruction emphasizing the use of multiple representations in the presentation of concepts. The focus of the study was how teacher beliefs affect their ability to implement a multiple representations curriculum. The novice instructor's attitude remained neutral while the experienced instructor's attitude remained somewhat positive. Of the eight students in the study, six of them showed a more positive attitude towards technology use and multiple representations by the end of the semester. The students increased their calculator use in both classes, particularly in the experienced teacher's class. Implications for further research were that teacher training is essential if reform curricula are to be properly implemented.