Synchronized single electron emission from dynamical quantum dots

We study synchronized quantized charge pumping through several dynamical quantum dots (QDs) driven by a single time modulated gate signal. We show that the main obstacle for synchronization being the lack of uniformity can be overcome by operating the QDs in the decay cascade regime. We discuss the mechanism responsible for lifting the stringent uniformity requirements. This enhanced functionality of dynamical QDs might find applications in nanoelectronics and quantum metrology.Comment: 4 pages, 3 figures, submitted to AP

Community Structure in Time-Dependent, Multiscale, and Multiplex Networks

Network science is an interdisciplinary endeavor, with methods and applications drawn from across the natural, social, and information sciences. A prominent problem in network science is the algorithmic detection of tightly-connected groups of nodes known as communities. We developed a generalized framework of network quality functions that allowed us to study the community structure of arbitrary multislice networks, which are combinations of individual networks coupled through links that connect each node in one network slice to itself in other slices. This framework allows one to study community structure in a very general setting encompassing networks that evolve over time, have multiple types of links (multiplexity), and have multiple scales.Comment: 31 pages, 3 figures, 1 table. Includes main text and supporting material. This is the accepted version of the manuscript (the definitive version appeared in Science), with typographical corrections included her

Generation of energy selective excitations in quantum Hall edge states

We operate an on-demand source of single electrons in high perpendicular magnetic fields up to 30T, corresponding to a filling factor below 1/3. The device extracts and emits single charges at a tunable energy from and to a two-dimensional electron gas, brought into well defined integer and fractional quantum Hall (QH) states. It can therefore be used for sensitive electrical transport studies, e.g. of excitations and relaxation processes in QH edge states

Effect of correlations on network controllability

A dynamical system is controllable if by imposing appropriate external signals on a subset of its nodes, it can be driven from any initial state to any desired state in finite time. Here we study the impact of various network characteristics on the minimal number of driver nodes required to control a network. We find that clustering and modularity have no discernible impact, but the symmetries of the underlying matching problem can produce linear, quadratic or no dependence on degree correlation coefficients, depending on the nature of the underlying correlations. The results are supported by numerical simulations and help narrow the observed gap between the predicted and the observed number of driver nodes in real networks

Looking ‘beyond the factory gates’:towards more pluralist and radical approaches to intra-organizational trust research

The aim of this paper is to suggest new avenues for trust research by critiquing the extant literature on this topic. We analyze the most influential research on intra-organizational trust from the perspective of a classic industrial sociology framework from the 1970s – Alan Fox’s work on frames of reference and trust dynamics. Our analysis of intra-organizational trust studies leads us to three conclusions. Firstly, the large majority of intra-organizational trust research has strong unitarist underpinnings, which support a managerial agenda that is potentially detrimental to employees’ and (indeed managers’) long-term interests. Secondly, most of this research fails to explain how trust in organizations is embedded in societal and field level institutions, hence it would benefit from looking ‘beyond the factory gates’ for a more complete understanding of trust dynamics in organizations. In this connection, we argue that Fox’s pluralist and radical perspectives, which are under-represented in intra-organizational trust research, could provide new lines of inquiry by locating internal trust relations in a wider institutional context. Thirdly, Fox’s explanation of how low and high trust dynamics in organizations are embedded in wider society may help address the concerns about under-socialized, endogenous explanations and open the way for structure-agency analyses of building, maintaining and repairing intra-organizational trust

Modeling Abnormal Priming in Alzheimer's Patients with a Free Association Network

Alzheimer's Disease irremediably alters the proficiency of word search and retrieval processes even at its early stages. Such disruption can sometimes be paradoxical in specific language tasks, for example semantic priming. Here we focus in the striking side-effect of hyperpriming in Alzheimer's Disease patients, which has been well-established in the literature for a long time. Previous studies have evidenced that modern network theory can become a powerful complementary tool to gain insight in cognitive phenomena. Here, we first show that network modeling is an appropriate approach to account for semantic priming in normal subjects. Then we turn to priming in degraded cognition: hyperpriming can be readily understood in the scope of a progressive degradation of the semantic network structure. We compare our simulation results with previous empirical observations in diseased patients finding a qualitative agreement. The network approach presented here can be used to accommodate current theories about impaired cognition, and towards a better understanding of lexical organization in healthy and diseased patients

Local Difference Measures between Complex Networks for Dynamical System Model Evaluation

Acknowledgments We thank Reik V. Donner for inspiring suggestions that initialized the work presented herein. Jan H. Feldhoff is credited for providing us with the STARS simulation data and for his contributions to fruitful discussions. Comments by the anonymous reviewers are gratefully acknowledged as they led to substantial improvements of the manuscript.Peer reviewedPublisher PD

How teachers’ individual autonomy may hinder students’ academic progress and attainment: Professionalism in practice

This article reports a 3-year case study of a primary school in England, in which a recently appointed principal attempted to build ‘collegial professional autonomy’ (Nordic Journal of Studies in Educational Policy, 2, 2015, 20) within a push to improve students’ progress and attainment. The research examined the tensions between staff who embraced the principal's agenda for collegially agreed change, and whose students’ academic progress and performance improved over a 3-year consecutive period when measured in terms of students’ entry-level attainment and socio-economic factors, and staff who asserted their right to ‘individual professional autonomy’ and whose students’ academic progress and attainment declined. The research: (i) challenges claims that reform necessarily results in school cultures of compliancy, de-professionalisation and the technicisation of teaching; (ii) raises issues concerning the pedagogical leadership of principals in a devolved, ‘self-governing’ school system; and (iii) questions teachers’ entitlements to individual professional autonomy where this is associated with students’ continuing academic underperformance

Transient activation of dopaminergic neurons during development modulates visual responsiveness, locomotion and brain activity in a dopamine ontogeny model of schizophrenia

It has been observed that certain developmental environmental risk factors for schizophrenia when modeled in rodents alter the trajectory of dopaminergic development, leading to persistent behavioural changes in adults. This has recently been articulated as the "dopamine ontogeny hypothesis of schizophrenia". To test one aspect of this hypothesis, namely that transient dopaminergic effects during development modulate attention-like behavior and arousal in adults, we turned to a small-brain model, Drosophila melanogaster. By applying genetic tools allowing transient activation or silencing of dopaminergic neurons in the fly brain, we investigated whether a critical window exists during development when altered dopamine (DA) activity levels could lead to impairments in arousal states in adult animals. We found that increased activity in dopaminergic neurons in later stages of development significantly increased visual responsiveness and locomotion, especially in adult males. This misallocation of visual salience and hyperactivity mimicked the effect of acute methamphetamine feeding to adult flies, suggesting up-regulated DA signaling could result from developmental manipulations. Finally, brain recordings revealed significantly reduced gamma-band activity in adult animals exposed to the transient developmental insult. Together, these data support the idea that transient alterations in DA signaling during development can permanently alter behavior in adults, and that a reductionist model such as Drosophila can be used to investigate potential mechanisms underlying complex cognitive disorders such as schizophrenia