Maths Living in Social Arenas, From Practice to Foundations

Maths comes to life in human interaction. This has consequences for the mathematics itself. This paper discusses how this ``coming to life\u27\u27 of mathematics in different social arenas influences the foundations of maths. We will argue that this influence is profound, to the extent that it is hard to upkeep the idea that there is or should be one foundation on which all mathematics can be built

High performance photonic reservoir computer based on a coherently driven passive cavity

Reservoir computing is a recent bio-inspired approach for processing time-dependent signals. It has enabled a breakthrough in analog information processing, with several experiments, both electronic and optical, demonstrating state-of-the-art performances for hard tasks such as speech recognition, time series prediction and nonlinear channel equalization. A proof-of-principle experiment using a linear optical circuit on a photonic chip to process digital signals was recently reported. Here we present a photonic implementation of a reservoir computer based on a coherently driven passive fiber cavity processing analog signals. Our experiment has error rate as low or lower than previous experiments on a wide variety of tasks, and also has lower power consumption. Furthermore, the analytical model describing our experiment is also of interest, as it constitutes a very simple high performance reservoir computer algorithm. The present experiment, given its good performances, low energy consumption and conceptual simplicity, confirms the great potential of photonic reservoir computing for information processing applications ranging from artificial intelligence to telecommunicationsComment: non

Cannabis en cannabinoïden : van onkruid tot designerdrugs

Het gebruik van cannabis als recreatieve of medicinale drug heeft een lange geschiedenis. Sinds de tweede helft van de vorige eeuw krijgt men inzicht in de werking van het „endocannabinoïdensysteem” (ECS) en sindsdien ontstonden er in onderzoekslaboratoria honderden synthetische cannabinoïden (SC’s). Deze SC’s worden sinds het begin van deze eeuw teruggevonden in producten die (vaak nog legaal) verkocht worden als designerdrugs voor recreatieve doeleinden. De farmacokinetische en -dynamische verschillen van SC’s ten opzichte van natuurlijke cannabis, de moeilijke opspoorbaarheid ervan en de creativiteit van producenten en marketeers stellen zowel de arts, het laboratorium als de wetgever voor bijzondere uitdagingen

Mimetic desire in autism spectrum disorder

International audienceMimetic desire (MD), the spontaneous propensity to pursue goals that others pursue, is a case of social influence that is believed to shape preferences. Autism spectrum disorder (ASD) is defined by both atypical interests and altered social interaction. We investigated whether MD is lower in adults with ASD compared to typically developed adults and whether MD correlates with social anhedonia and social judgment, two aspects of atypical social functioning in autism. Contrary to our hypotheses, MD was similarly present in both ASD and control groups. Anhedonia and social judgment differed between the ASD and control groups but did not correlate with MD. These results extend previous findings by suggesting that basic mechanisms of social influence are preserved in autism. The finding of intact MD in ASD stands against the intuitive idea that atypical interests stem from reduced social influence and indirectly favors the possibility that special interests might be selected for their intrinsic properties

LSD1-mediated enhancer silencing attenuates retinoic acid signalling during pancreatic endocrine cell development.

Developmental progression depends on temporally defined changes in gene expression mediated by transient exposure of lineage intermediates to signals in the progenitor niche. To determine whether cell-intrinsic epigenetic mechanisms contribute to signal-induced transcriptional responses, here we manipulate the signalling environment and activity of the histone demethylase LSD1 during differentiation of hESC-gut tube intermediates into pancreatic endocrine cells. We identify a transient requirement for LSD1 in endocrine cell differentiation spanning a short time-window early in pancreas development, a phenotype we reproduced in mice. Examination of enhancer and transcriptome landscapes revealed that LSD1 silences transiently active retinoic acid (RA)-induced enhancers and their target genes. Furthermore, prolonged RA exposure phenocopies LSD1 inhibition, suggesting that LSD1 regulates endocrine cell differentiation by limiting the duration of RA signalling. Our findings identify LSD1-mediated enhancer silencing as a cell-intrinsic epigenetic feedback mechanism by which the duration of the transcriptional response to a developmental signal is limited

Too little, too late: reduced visual span and speed characterize pure alexia

Whether normal word reading includes a stage of visual processing selectively dedicated to word or letter recognition is highly debated. Characterizing pure alexia, a seemingly selective disorder of reading, has been central to this debate. Two main theories claim either that 1) Pure alexia is caused by damage to a reading specific brain region in the left fusiform gyrus or 2) Pure alexia results from a general visual impairment that may particularly affect simultaneous processing of multiple items. We tested these competing theories in 4 patients with pure alexia using sensitive psychophysical measures and mathematical modeling. Recognition of single letters and digits in the central visual field was impaired in all patients. Visual apprehension span was also reduced for both letters and digits in all patients. The only cortical region lesioned across all 4 patients was the left fusiform gyrus, indicating that this region subserves a function broader than letter or word identification. We suggest that a seemingly pure disorder of reading can arise due to a general reduction of visual speed and span, and explain why this has a disproportionate impact on word reading while recognition of other visual stimuli are less obviously affected

A Network of microRNAs Acts to Promote Cell Cycle Exit and Differentiation of Human Pancreatic Endocrine Cells.

Pancreatic endocrine cell differentiation is orchestrated by the action of transcription factors that operate in a gene regulatory network to activate endocrine lineage genes and repress lineage-inappropriate genes. MicroRNAs (miRNAs) are important modulators of gene expression, yet their role in endocrine cell differentiation has not been systematically explored. Here we characterize miRNA-regulatory networks active in human endocrine cell differentiation by combining small RNA sequencing, miRNA over-expression, and network modeling approaches. Our analysis identified Let-7g, Let-7a, miR-200a, miR-127, and miR-375 as endocrine-enriched miRNAs that drive endocrine cell differentiation-associated gene expression changes. These miRNAs are predicted to target different transcription factors, which converge on genes involved in cell cycle regulation. When expressed in human embryonic stem cell-derived pancreatic progenitors, these miRNAs induce cell cycle exit and promote endocrine cell differentiation. Our study delineates the role of miRNAs in human endocrine cell differentiation and identifies miRNAs that could facilitate endocrine cell reprogramming