Making history relevant: The case of computing

We investigate the motives to practice history, and the role that history could play for a scientific discipline. We consider these questions successively from three interrelated points of view: “history: why?” (§ 1), “history: for whom?” (§ 2), and “history: how?” (§ 3). Only the second of these sections is specific to the field of computing; the two other ones are more general, and could probably be applied to other fields as well. Needless to say, the responses that we propose are elements rather than definitive answers; the author also apologizes in advance if these reflections turn out to be nothing but platitudes: he was not trained as a historian, and it is very well possible that these three questions have already received more convincing answers elsewhere

Recursive Programming: A Clarification

We show that the block concept, as it was introduced in ALGOL 60, and two of the three main techniques introduced by E. W. Dijkstra in his seminal article Recursive Programming to implement it, the so-called "static links" and "display", have been partly misunderstood. These misunderstandings may have led to unnecessary restrictions in a number of later programming languages, for example PASCAL and C

Dissolving a half century old problem about the implementation of procedures

We investigate the semantics of the procedure concept, and of one of the main techniques introduced by E. W. Dijkstra in his article Recursive Programming to implement it, namely the "static link," sometimes also called "access link" or "lexical link." We show that a confusion about that technique persists, even in recent textbooks. Our analysis is meant to clarify the meaning of that technique, and of the procedure concept. Our main contribution is to propose a better characterization of the "static link."

On the Origin of Recursive Procedures

We investigate the origin of recursive procedures in imperative programming languages. We attempt to set the record straight, and to identify the trend that led to recursive procedures, by means of an analysis of the related concepts and of the most reliable available documents, as far as known to us. We show that not all of those who were involved in defining these concepts in these documents were fully aware of the implications of their proposals. Our aim is not primarily historical, but to contribute to a clarification of some of the concepts related to recursion. In particular, we demonstrate that recursive procedure declarations and recursive procedure activations are logically disjoint concepts

Directing neuronal cell fate in vitro: achievements and challenges

Human pluripotent stem cell (PSC) technology and direct somatic cell reprogramming have opened up a promising new avenue in the field of neuroscience. These recent advances allow researchers to obtain virtually any cell type found in the human brain, making it possible to produce and study functional neurons in laboratory conditions for both scientific and medical purposes. Although distinct approaches have shown to be successful in directing neuronal cell fate in vitro, their refinement and optimization, as well as the search for alternative approaches, remains necessary to help realize the full potential of the eventually derived neuronal populations. Furthermore, we are currently limited in the number of neuronal subtypes whose induction is fully established, and different cultivation protocols for each subtype exist, making it challenging to increase the reproducibility and decrease the variances that are observed between different protocols. In this review, we summarize the progress that has been made in generating various neuronal subtypes from PSCs and somatic cells, with special emphasis on chemically defined systems, transcription factor-mediated reprogramming and epigenetic-based approaches. We also discuss the efforts that are being made to increase the efficiency of current protocols and address the potential for the use of these cells in disease modelling, drug discovery and regenerative medicine

Increased 5-hydroxymethylation levels in the sub ventricular zone of the Alzheimer's brain

© 2016 The Authors. The subventricular zone (SVZ) is a site of neurogenesis in the aging brain, and epigenetic mechanisms have been implicated in regulating the "normal" distribution of new nerve cells into the existing cellular milieu. In a case-control study of human primary SVZ cultures and fixed tissue from the same individuals, we have found significant increases in DNA hydroxymethylation levels in the SVZ of Alzheimer's disease patients compared with nondiseased control subjects. We show that this increase in hydroxymethylation directly correlates to an increase in cellular proliferation in Alzheimer's disease precursor cells, which implicates the hydroxymethylation tag to a higher degree of cellular proliferation

Оцінювання за зашумленними спостереженнями невідомих даних лінійних еліптичних рівнянь, що допускають змішане варіаційне формулювання

Получен новый класс систем вариационных уравнений через решения которых выражаются минимаксные оценки значений функционалов от неизвестных правых частей линейных эллиптических уравнений 2-го порядка.Одержаний новий клас систем варіаційних рівнянь через розв'язки яких виражаються мінімаксні оцінки значень функционалів від невідомих правих частин лінійних еліптичних рівнянь 2-го порядку.We obtain a new class of systems of variational equations via whose solutions the minimax estimates of values of functionals from unknown right-hand sides of the second order linear elliptic equations are expressed

Epigenetic regulation of adult neural stem cells: implications for Alzheimer's disease.

Published onlineJournal ArticleResearch Support, Non-U.S. Gov'tReviewExperimental evidence has demonstrated that several aspects of adult neural stem cells (NSCs), including their quiescence, proliferation, fate specification and differentiation, are regulated by epigenetic mechanisms. These control the expression of specific sets of genes, often including those encoding for small non-coding RNAs, indicating a complex interplay between various epigenetic factors and cellular functions.Previous studies had indicated that in addition to the neuropathology in Alzheimer's disease (AD), plasticity-related changes are observed in brain areas with ongoing neurogenesis, like the hippocampus and subventricular zone. Given the role of stem cells e.g. in hippocampal functions like cognition, and given their potential for brain repair, we here review the epigenetic mechanisms relevant for NSCs and AD etiology. Understanding the molecular mechanisms involved in the epigenetic regulation of adult NSCs will advance our knowledge on the role of adult neurogenesis in degeneration and possibly regeneration in the AD brain.Internationale Stichting Alzheimer Onderzoek (ISAO)Netherlands Organization for Scientific Research (NWO)Maastricht University Medical Centre