Temperature chaos in 3D Ising Spin Glasses is driven by rare events

Temperature chaos has often been reported in literature as a rare-event driven phenomenon. However, this fact has always been ignored in the data analysis, thus erasing the signal of the chaotic behavior (still rare in the sizes achieved) and leading to an overall picture of a weak and gradual phenomenon. On the contrary, our analysis relies on a large-deviations functional that allows to discuss the size dependencies. In addition, we had at our disposal unprecedentedly large configurations equilibrated at low temperatures, thanks to the Janus computer. According to our results, when temperature chaos occurs its effects are strong and can be felt even at short distances.Comment: 5 pages, 5 figure

Multidimensional analysis of nexus technologies II: dynamics of traditional and modern irrigation systems

From a technological perspective, irrigation is a dynamic field undergoing a shift from a horizontal expansion of the area equipped for irrigation (or “total irrigation market”) to a vertical transition of the technology mix in search of higher intensification and efficiency (more crop per drop). As a result, the “irrigation market” is currently experiencing a gradual transformation process from traditional flood irrigation towards more efficient pressurised irrigation technologies (sprinkler and drip). The results of this study suggest that these substitution dynamics will continue in the future, favouring the most recent and efficient technology, i.e. drip irrigation. A logistic projection of historical growth predicts drip to reach the highest growth rate among all technologies by 2035, and start a fast expansion over not only flood irrigated areas, but also sprinkler irrigated areas. The cost and size dynamics of irrigation projects are less clear given the extremely high context dependency and variability of some critical factors determining irrigation project costs, as well as the important differences across regions. Economies of scale also vary across regions, and are estimated to be higher for rehabilitation and modernization projects than for new development projects, with scale factors of 0.6 and 0.97 respectively. Regarding the learning effects, the limitations in data quality and completeness do not allow to derive clear quantitative and technology specific estimates of learning trends. Nevertheless, some positive learning is detected in rehabilitation projects since 1990 and certain cost reductions at the application technology level are reported by consulted irrigation technology experts. Focusing on the regions of interest for ISWEL case studies, South Asia may see a rapid expansion of drip irrigation through both private modernization initiatives at the small-medium scale and public large scale rehabilitation-modernization interventions on historical surface schemes. Thanks to the active local irrigation technology industry and off farm infrastructure stock, irrigation technology costs will remain lower than in other areas and could be subject for learning related cost reductions in the future. Meanwhile, projects in Africa may develop in the line of expanding the irrigation potential through mainly medium-large scale surface irrigation schemes. The costs of these new schemes are expected to be on the high edge of historical average ranges, due to the increasing complexity of suitable locations and thus of the systems offsetting the potential effects of economies of scale brought about by an increase in project size compared to the historical interventions. Meanwhile, sprinkler technology and particularly centre pivot seems to be a suitable option already expanding within the emerging commercial farming, due to the lower costs and the potential for technology sharing

The mechanosensitive channel Piezo1 cooperates with semaphorins to control neural crest migration

Cells are permanently exposed to a multitude of different kinds of signals: however, how cells respond to simultaneous extracellular signals within a complex in vivo environment is poorly understood. Here, we studied the role of the mechanosensitive ion channel Piezo1 on the migration of the neural crest, a multipotent embryonic cell population. We identify that Piezo1 is required for the migration of Xenopus cephalic neural crest. We show that loss of Piezo1 promotes focal adhesion turnover and cytoskeletal dynamics by controlling Rac1 activity, leading to increased speed of migration. Moreover, overactivation of Rac1, due to Piezo1 inhibition, counteracts cell migration inhibitory signals by Semaphorin 3A and Semaphorin 3F, generating aberrant neural crest invasion in vivo. Thus, we find that, for directional migration in vivo, neural crest cells require a tight regulation of Rac1, by semaphorins and Piezo1. We reveal here that a balance between a myriad of signals through Rac1 dictates cell migration in vivo, a mechanism that is likely to be conserved in other cell migration processes

Mechanosensitive ion channels in cell migration

Cellular processes are initiated and regulated by different stimuli, including mechanical forces. Cell membrane mechanosensors represent the first step towards the conversion of mechanical stimuli to a biochemical or electrical response. Mechanosensitive (MS) ion channels form a growing family of ion gating channels that respond to direct physical force or plasma membrane deformations. A number of calcium (Ca2+) permeable MS channels are known to regulate the initiation, direction, and persistence of cell migration during development and tumour progression. While the evidence that links individual MS ion channels to cell migration is growing, a unified analysis of the molecular mechanisms regulated downstream of MS ion channel activation is lacking. In this review, we describe the MS ion channel families known to regulate cell migration. We discuss the molecular mechanisms that act downstream of MS ion channels with an emphasis on Ca2+ mediated processes. Finally, we propose the future directions and impact of MS ion channel activity in the field of cell migration

Reprint of: Mechanosensitive ion channels in cell migration

Cellular processes are initiated and regulated by different stimuli, including mechanical forces. Cell membrane mechanosensors represent the first step towards the conversion of mechanical stimuli to a biochemical or electrical response. Mechanosensitive (MS) ion channels form a growing family of ion gating channels that respond to direct physical force or plasma membrane deformations. A number of calcium (Ca2+) permeable MS channels are known to regulate the initiation, direction, and persistence of cell migration during development and tumour progression. While the evidence that links individual MS ion channels to cell migration is growing, a unified analysis of the molecular mechanisms regulated downstream of MS ion channel activation is lacking. In this review, we describe the MS ion channel families known to regulate cell migration. We discuss the molecular mechanisms that act downstream of MS ion channels with an emphasis on Ca2+ mediated processes. Finally, we propose the future directions and impact of MS ion channel activity in the field of cell migration

A Scoping Review of the Demographic and Contextual Factors in Canada’s Educational Opportunity Gaps

Despite widespread discussion in the United States, up until now there has not been a review of the demographic and contextual factors associated with Canadian academic achievement. Using Arksey and O’Malley’s (2005) framework, a scoping review was conducted to answer two questions: What demographic and contextual factors are most commonly used in K–12 academic achievement studies in Canada? What, if any,research gaps exist? Fifty-four studies were identified for review. The results reveal 40 demographic or contextual factors, with socio-economic status (SES), gender, language factors, immigrant status, family structure, and Indigenous status being the most commonly studied. Race, religion, and LGBTQ+ identity were understudied factors. The authors recommend the adoption of “educational opportunity gap” as a consistentresearch term, identify understudied factors, and outline several research design considerations

Dynamical streams in the solar neighbourhood

The true nature of the Hyades and Sirius superclusters is still an open question. In this contribution, we confront Eggen's hypothesis that they are cluster remnants with the results of a kinematic analysis of more than 6000 K and M giants in the solar neighbourhood. This analysis includes new radial velocity data from a large survey performed with the Coravel spectrometer, complemented by Hipparcos parallaxes and Tycho-2 proper motions (Famaey et al. 2004). A maximum-likelihood method, based on a bayesian approach, has been applied to the data, in order to make full use of all the available data (including less precise parallaxes) and to derive the properties of the different kinematic subgroups. Two such subgroups can be identified with the Hyades and Sirius superclusters. Stars belonging to them span a very wide range of age, which is difficult to account for in Eggen's scenario. These groups are thus most probably "dynamical streams" related to the dynamical perturbation by spiral waves rather than to cluster remnants. In this scenario, the Hyades and Ursa Major clusters just happen to be in the Hyades and Sirius streams, which are purely dynamical features that have nothing to do with the remnants of more massive primordial clusters. This mechanism could be the key to understanding the presence of an old metal-rich population, and of many exoplanetary systems in our neighbourhood. Moreover, a strong spiral pattern seems to be needed in order to yield such prominent streams. Since spiral structure is usually baryonic, this would leave very little room for dark matter. This may be an indication that the era of the dark-matter paradigm explaining the dynamics of the Galaxy may come to an end, and is being superseded by modified gravity.Comment: 5 pages, 1 figure, to appear in The Three Dimensional Universe with GAIA, eds M. Perryman & C. Turo

Directional cell movements downstream of Gbx2 and Otx2 control the assembly of sensory placodes

Cranial placodes contribute to sensory structures including the inner ear, the lens and olfactory epithelium and the neurons of the cranial sensory ganglia. At neurula stages, placode precursors are interspersed in the ectoderm surrounding the anterior neural plate before segregating into distinct placodes by as yet unknown mechanisms. Here, we perform live imaging to follow placode progenitors as they aggregate to form the lens and otic placodes. We find that while placode progenitors move with the same speed as their non-placodal neighbours, they exhibit increased persistence and directionality and these properties are required to assemble morphological placodes. Furthermore, we demonstrate that these factors are components of the transcriptional networks that coordinate placode cell behaviour including their directional movements. Together with previous work, our results support a dual role for Otx and Gbx transcription factors in both the early patterning of the neural plate border and the later segregation of its derivatives into distinct placodes