Reconstruction of Directed Networks from Consensus Dynamics

This paper addresses the problem of identifying the topology of an unknown, weighted, directed network running a consensus dynamics. We propose a methodology to reconstruct the network topology from the dynamic response when the system is stimulated by a wide-sense stationary noise of unknown power spectral density. The method is based on a node-knockout, or grounding, procedure wherein the grounded node broadcasts zero without being eliminated from the network. In this direction, we measure the empirical cross-power spectral densities of the outputs between every pair of nodes for both grounded and ungrounded consensus to reconstruct the unknown topology of the network. We also establish that in the special cases of undirected or purely unidirectional networks, the reconstruction does not need grounding. Finally, we extend our results to the case of a directed network assuming a general dynamics, and prove that the developed method can detect edges and their direction.Comment: 6 page

Fourier analysis of stationary time series in function space

We develop the basic building blocks of a frequency domain framework for drawing statistical inferences on the second-order structure of a stationary sequence of functional data. The key element in such a context is the spectral density operator, which generalises the notion of a spectral density matrix to the functional setting, and characterises the second-order dynamics of the process. Our main tool is the functional Discrete Fourier Transform (fDFT). We derive an asymptotic Gaussian representation of the fDFT, thus allowing the transformation of the original collection of dependent random functions into a collection of approximately independent complex-valued Gaussian random functions. Our results are then employed in order to construct estimators of the spectral density operator based on smoothed versions of the periodogram kernel, the functional generalisation of the periodogram matrix. The consistency and asymptotic law of these estimators are studied in detail. As immediate consequences, we obtain central limit theorems for the mean and the long-run covariance operator of a stationary functional time series. Our results do not depend on structural modelling assumptions, but only functional versions of classical cumulant mixing conditions, and are shown to be stable under discrete observation of the individual curves.Comment: Published in at http://dx.doi.org/10.1214/13-AOS1086 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Novel strategy to disrupt the nuclear pore barrier reversibly: Implications for nanomedicine

Several thousands of nuclear pore complexes (NPCs) perforate the nuclear envelope of each eukaryotic cell. These elaborate proteinaceous assemblies mediate all nucleocytoplasmic transport highly selectively through a central channel residing within a rigid and well-structured NPC scaffold. The selectivity of the NPCs is the major obstacle for non-viral gene therapy due to the prevention of exogenously applied therapeutic macromolecules from nuclear entry. Selectivity is attributed to highly dynamic and disordered Phenylalanine-Glycine rich proteins within the NPC central channel. The NPC scaffold poses an additional barrier-albeit ignored so far. We designed two distinct strategies to reversibly disrupt the NPC channel and scaffold in a separate fashion. Disruption of either is found to result in a significant increase of the NPC permeability and a combination of the two further intensifies the individual effects. The induced breakdown of the NPC permeability barrier may be exploited for gene therapeutic purposes

Addressing the shortage of pathologists in Africa: Creation of a MMed Programme in Pathology in Zambia

Background: With approximately one pathologist for one million people compared to ratios of approximately 1 to 25 000 in the United States and United Kingdom, there is a severe shortage of pathologists in much of Africa. The situation is particularly severe in Zambia, where, in 2009, the ratio was 1 to 1.4 million. Objective: To address this, a postgraduate Master of Medicine (MMed) training programme was launched in Lusaka in 2011. Methods: The process and most significant challenges and lessons learned were documented, as they may be of value to other countries facing similar challenges. Results: Since 2011, four Zambian pathologists have graduated, doubling the number of indigenous pathologists in the country. Currently 10 students are in training. The most significant problem was issues arising from the split responsibilities of the Ministries of Health and of Education and the most important lesson learned was the crucial need for broad local ownership and commitment. Conclusion: Successfully addressing the shortage of local pathologists by creating country-specific, postgraduate MMed training programmes, even in situations of restricted resources, is feasible. However, having access to and support from the shared resources, expertise and knowledge of a regional College of Pathologists would be a major advantage

Implications of the nuclear pore barrier for non-small cell lung cancer malignancy and therapy

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Establishing the College of Pathologists of East, Central and Southern Africa – The Regional East Central and Southern Africa College of Pathology

Issues: The scarcity of pathologists in sub-Saharan Africa is a well established fact that is attributable to few training programmes in the region; this is further compounded by the lack of harmonised curricula, training and exams within and without member countries. Description of the intervention: Through the Association of Pathologists of East, Central and Southern Africa, the College of Pathologists of East, Central and Southern Africa (COPECSA) was formed with the clear-cut goal of establishing a regional and internationally recognised college to support and inform good quality medical and laboratory practice by promoting leadership, mentorship and excellence in the safe practice of pathology through training, exams, accreditation, advocacy and professional development for health. Lessons learnt: Since its inception in 2010, COPECSA has conferred fellowships to 120 practising pathologists in the East, Central and Southern Africa in partnership with international organisations; the college has been awarded five competitive grants and conducted several quality improvement workshops. Recommendations: This paper describes the journey that COPECSA has made towards standardising the practice and training of pathology in the East Central and Southern Africa region