NMR Time Reversal Experiments in Highly Polarised Liquid 3He-4He Mixtures

Long-range magnetic interactions in highly magnetised liquids (laser-polarised 3He-4He dilute mixtures at 1 K in our experiment) introduce a significant non-linear and non-local contribution to the evolution of nuclear magnetisation that leads to instabilities during free precession. We recently demonstrated that a multi-echo NMR sequence, based on the magic sandwich pulse scheme developed for solid-state NMR, can be used to stabilise the magnetisation against the effect of distant dipolar fields. Here, we report investigations of echo attenuation in an applied field gradient that show the potential of this NMR sequence for spin diffusion measurements at high magnetisation densities.Comment: Accepted for publication in the Journal of Low Temperature Physic

You made him be alive: Children’s perceptions of animacy in a humanoid robot

Social robots are becoming more sophisticated; in many cases they offer complex, autonomous interactions, responsive behaviors, and biomimetic appearances. These features may have significant impact on how people perceive and engage with robots; young children may be particularly influenced due to their developing ideas of agency. Young children are considered to hold naive beliefs of animacy and a tendency to mis-categorise moving objects as being alive but, with development, children can demonstrate a biological understanding of animacy. We experimentally explore the impact of children’s age and a humanoid’s movement on children’s perceptions of its animacy. Our humanoid’s behavior varied in apparent autonomy, from motionless, to manually operated, to covertly operated. Across conditions, younger children rated the robot as being significantly more person-like than older children did. We further found an interaction effect: younger children classified the robot as significantly more machine-like if they observed direct operation in contrast observing the motionless or apparently autonomous robot. Our findings replicate field results, supporting the modal model of the developmental trajectory for children’s understanding of animacy. We outline a program of research to both deepen the theoretical understanding of children’s animacy beliefs and develop robotic characters appropriate across key stages of child development

Empirical evidence of the impact of lesson study on: students’ achievement, teachers’ professional learning and on institutional and system evolution

In this article we review the evidence of the impact of lesson study on student learning, teacher development, teaching materials, curriculum, professional learning and system enhancement. We argue for lesson study to be treated holistically as a vehicle for development and improvement at classroom, school and system levels rather than as a curricular or pedagogical intervention. We illustrate the need for this approach to evaluating lesson study through a complex case exemplar which used Research Lesson Study (a form of lesson study popular in the UK and Europe) to develop learning, teaching, curriculum and local improvement capacity across schools initially involved in a two-year mathematics curriculum development project that later evolved into three self-sustaining, voluntary lesson study school hubs in London. We discuss resulting changes in culture, practice, belief, expectation and student learning. We argue as a result for greater policy level understanding of this expanded conception of lesson study as a vehicle in classroom, school and system transformation.Both projects described received funding from the Greater London Authorit

Implementing a new mathematics curriculum in England: district Research Lesson Study as a driver for student learning, teacher learning and professional dialogue.

Against a backdrop of a transformation in teacher professional development and learning and state school organisation in England this century, this chapter describes a project which harnessed six cycles of Research Lesson Study at school and district level over two years to tailor the implementation of a new statutory curriculum in England to address the professional development needs of teachers and classroom learning needs of London students. It also reports the findings of research carried out during the project into how these teachers learned and developed this new curricular expertise and practice- knowledge through lesson study dialogues that supported student learning. It concludes by proposing future directions for teacher professional learning research and practice

Cross-Dimensional Mapping of Number, Length and Brightness by Preschool Children

Human adults in diverse cultures, children, infants, and non-human primates relate number to space, but it is not clear whether this ability reflects a specific and privileged number-space mapping. To investigate this possibility, we tested preschool children in matching tasks where the dimensions of number and length were mapped both to one another and to a third dimension, brightness. Children detected variation on all three dimensions, and they reliably performed mappings between number and length, and partially between brightness and length, but not between number and brightness. Moreover, children showed reliably better mapping of number onto the dimension of length than onto the dimension of brightness. These findings suggest that number establishes a privileged mapping with the dimension of length, and that other dimensions, including brightness, can be mapped onto length, although less efficiently. Children's adeptness at number-length mappings suggests that these two dimensions are intuitively related by the end of the preschool years

On the equivalence between the Scheduled Relaxation Jacobi method and Richardson's non-stationary method

The Scheduled Relaxation Jacobi (SRJ) method is an extension of the classical Jacobi iterative method to solve linear systems of equations (Au=b) associated with elliptic problems. It inherits its robustness and accelerates its convergence rate computing a set of P relaxation factors that result from a minimization problem. In a typical SRJ scheme, the former set of factors is employed in cycles of M consecutive iterations until a prescribed tolerance is reached. We present the analytic form for the optimal set of relaxation factors for the case in which all of them are strictly different, and find that the resulting algorithm is equivalent to a non-stationary generalized Richardson's method where the matrix of the system of equations is preconditioned multiplying it by D=diag(A). Our method to estimate the weights has the advantage that the explicit computation of the maximum and minimum eigenvalues of the matrix A (or the corresponding iteration matrix of the underlying weighted Jacobi scheme) is replaced by the (much easier) calculation of the maximum and minimum frequencies derived from a von Neumann analysis of the continuous elliptic operator. This set of weights is also the optimal one for the general problem, resulting in the fastest convergence of all possible SRJ schemes for a given grid structure. The amplification factor of the method can be found analytically and allows for the exact estimation of the number of iterations needed to achieve a desired tolerance. We also show that with the set of weights computed for the optimal SRJ scheme for a fixed cycle size it is possible to estimate numerically the optimal value of the parameter ω in the Successive Overrelaxation (SOR) method in some cases. Finally, we demonstrate with practical examples that our method also works very well for Poisson-like problems in which a high-order discretization of the Laplacian operator is employed (e.g., a 9- or 17-points discretization). This is of interest since the former discretizations do not yield consistently ordered A matrices and, hence, the theory of Young cannot be used to predict the optimal value of the SOR parameter. Furthermore, the optimal SRJ schemes deduced here are advantageous over existing SOR implementations for high-order discretizations of the Laplacian operator in as much as they do not need to resort to multi-coloring schemes for their parallel implementation

Professional Trajectories of the University Teachers in Russia: Request for Individualization

В статье анализируются особенности профессиональных стратегий профессорско-преподавательского состава (ППС) и научных сотрудников (НС) в российских университетах, а также сложившиеся подходы к их профессиональному развитию и мотивации. Рассмотрены составляющие профессиональной стратегии преподавателя высшей школы: мобильность, институциональные условия выбора карьерной траектории; желаемое и реальное соотношение методического / преподавательского, научного и административного видов работ. Обосновано, что российские преподаватели и научные сотрудники ориентированы на работу в своем вузе и регионе, мобильность носит горизонтальный характер. Значимыми мотивами переезда для работы в вузе являются карьерный рост (повышение по должности / занятие административной позиции) и повышение заработной платы в 2 раза. Существует запрос на увеличение доли научной работы в отдельных типах вузов. Отмечена необходимость учета индивидуальных запросов ППС на новые компетенции и треки профессионального развития со стороны руководства вузов. Обсуждается необходимость выделения треков, соответствующих основным видам деятельности – наука, преподавание и практическая / административная деятельность. Сделаны выводы о необходимости построения системы поддержки развития профессиональных стратегий ППС на уровне всей страны и внедрения такой системы с учетом особенностей и ресурсов каждого конкретного вуза. Материал подготовлен по итогам проведения исследования «Профессиональные стратегии преподавателей высшей школы в современной России» в рамках проекта «Зеркальные лаборатории НИУ ВШЭ».The article examines the peculiarities of professional strategies of the faculty and researchers in Russian universities, as well as the established approaches to their professional development and motivation. The components of the professional strategy of higher education teachers are considered, including mobility, institutional conditions for career trajectory choices, and the desired and actual balance between methodological/teaching, research, and administrative work. It is argued that Russian teachers and researchers are oriented towards working in their own university and region, with mobility being predominantly horizontal. Significant motives for relocation to work in a university include career advancement (promotion/occupying an administrative position) and a doubling of salary. There is a demand for increasing the share of research work in certain types of universities. The need to consider individual faculty requests for new competencies and professional development tracks by university management is emphasized. The article discusses the necessity of identifying tracks corresponding to the main types of activities - research, teaching, and practical/ administrative work. Conclusions are drawn regarding the need to establish a system to support the development of professional strategies for faculty at the national level and to implement such a system, taking into account the specific characteristics and resources of each university. The material was prepared as a result of the research project “Professional Strategies of Higher Education Teachers in Modern Russia” within the framework of the “Mirror Laboratories of HSE University”

Impact of High Mathematics Education on the Number Sense

In adult number processing two mechanisms are commonly used: approximate estimation of quantity and exact calculation. While the former relies on the approximate number sense (ANS) which we share with animals and preverbal infants, the latter has been proposed to rely on an exact number system (ENS) which develops later in life following the acquisition of symbolic number knowledge. The current study investigated the influence of high level math education on the ANS and the ENS. Our results showed that the precision of non-symbolic quantity representation was not significantly altered by high level math education. However, performance in a symbolic number comparison task as well as the ability to map accurately between symbolic and non-symbolic quantities was significantly better the higher mathematics achievement. Our findings suggest that high level math education in adults shows little influence on their ANS, but it seems to be associated with a better anchored ENS and better mapping abilities between ENS and ANS