Neural synchrony in cortical networks : history, concept and current status

Following the discovery of context-dependent synchronization of oscillatory neuronal responses in the visual system, the role of neural synchrony in cortical networks has been expanded to provide a general mechanism for the coordination of distributed neural activity patterns. In the current paper, we present an update of the status of this hypothesis through summarizing recent results from our laboratory that suggest important new insights regarding the mechanisms, function and relevance of this phenomenon. In the first part, we present recent results derived from animal experiments and mathematical simulations that provide novel explanations and mechanisms for zero and nero-zero phase lag synchronization. In the second part, we shall discuss the role of neural synchrony for expectancy during perceptual organization and its role in conscious experience. This will be followed by evidence that indicates that in addition to supporting conscious cognition, neural synchrony is abnormal in major brain disorders, such as schizophrenia and autism spectrum disorders. We conclude this paper with suggestions for further research as well as with critical issues that need to be addressed in future studies

Neural synchrony in cortical networks : history, concept and current status

Following the discovery of context-dependent synchronization of oscillatory neuronal responses in the visual system, the role of neural synchrony in cortical networks has been expanded to provide a general mechanism for the coordination of distributed neural activity patterns. In the current paper, we present an update of the status of this hypothesis through summarizing recent results from our laboratory that suggest important new insights regarding the mechanisms, function and relevance of this phenomenon. In the first part, we present recent results derived from animal experiments and mathematical simulations that provide novel explanations and mechanisms for zero and nero-zero phase lag synchronization. In the second part, we shall discuss the role of neural synchrony for expectancy during perceptual organization and its role in conscious experience. This will be followed by evidence that indicates that in addition to supporting conscious cognition, neural synchrony is abnormal in major brain disorders, such as schizophrenia and autism spectrum disorders. We conclude this paper with suggestions for further research as well as with critical issues that need to be addressed in future studies

Quantum gravitational onset of Starobinsky inflation in a closed universe

Recent cosmic microwave background observations favor low-energy-scale inflationary models in a closed universe. However, the onset of inflation in such models for a closed universe is known to be severely problematic. In particular, such a universe recollapses within a few Planck seconds and encounters a big crunch singularity when initial conditions are given in the Planck regime. We show that this problem of the onset of inflation in low-energy-scale inflationary models can be successfully overcome in a quantum-gravitational framework where the big bang/big crunch singularities are resolved and a nonsingular cyclic evolution exists prior to inflation. As an example, we consider a model in loop quantum cosmology and demonstrate that the successful onset of low-energy-scale inflation in a closed universe is possible for the Starobinsky inflationary model starting from a variety of initial conditions where it is impossible in the classical theory. For comparison, we also investigate the onset of inflation in the φ2 inflationary model under highly unfavorable conditions and find similar results. Our numerical investigation including the phase-space analysis shows that the preinflationary phase with quantum gravity effects is composed of nonidentical cycles of bounces and recollapses resulting in a hysteresis-like phenomenon, which plays an important role in creating suitable conditions for inflation to occur after some number of nonsingular cycles. Our analysis shows that the tension in the classical theory amounting to the unsuitability of closed Friedmann-Lemaître-Robertson-Walker universes with respect to the onset of low-energy-scale inflation can be successfully resolved in loop quantum cosmology

Lensing in the Darkness: A Bayesian Analysis of 22 Chandra Sources at z≳6z \gtrsim 6 Shows No Evidence of Lensing

More than $200$ quasars have been detected so far at $z > 6$, with only one showing clear signs of strong gravitational lensing. Some studies call for a missing population of lensed high-$z$ quasars, but their existence is still in doubt. A large fraction of high-$z$ quasars being lensed would have a significant effect on the shape of the intrinsic quasar luminosity function (QLF). Here, we perform the first systematic search for lensed X-ray-detected quasars at $z \gtrsim 6$ employing a Bayesian analysis, with the code BAYMAX, to look for morphological evidence of multiple images that may escape a visual inspection. We analyzed a sample of 22 quasars at $z > 5.8$ imaged by the Chandra X-ray observatory and found none with statistically significant multiple images. In the sub-sample of the 8 sources with photon counts $>20$ we exclude multiple images with separations $r>1''$ and count ratios $f>0.4$, or with separations as small as $0.''7$ and $f>0.7$ at $95\%$ confidence level. Comparing this non-detection with predictions from theoretical models suggesting a high and a low lensed fraction, we placed upper limits on the bright-end slope, $\beta$, of the QLF. Using only the sub-sample with 8 sources, we obtain, in the high-lensing model, a limit $\beta < 3.38$. Assuming no multiple source is present in the full sample of 22 sources, we obtain $\beta < 2.89$ and $\beta < 3.53$ in the high and low lensing models, respectively. These constraints strongly disfavor steep QLF shapes previously proposed in the literature.Comment: Accepted for publication in MNRAS. This is the final version of the manuscript. 10 pages, 5 figure

Life &amp; Legacy:A Window into Jewish Life Across the Islamic World

Through stunning images, maps and insightful commentary, this book offers a glimpse into the diversity, historical legacy, and rich culture of Jewish communities within the Muslim world. From the growing Jewish community of Dubai to ancient synagogues and shrines, these photographs capture the beauty and complexity of Jewish life around North Africa, the Middle East, and Central Asia. Above all, this photographic book serves as a reminder of the enduring spirit of the Jewish people and the diversity of lived experiences within Islamic societies.This volume presents thematically organized contemporary images of both Jewish life and Jewish heritage from across the Middle Eastern and North Africa. Interspersed throughout the images are an assortment of short essays written by scholars and University of Groningen students to contextualize the presented images

Statistical constraints on climate model parameters using a scalable cloud-based inference framework

Atmospheric aerosols influence the Earth’s climate, primarily by affecting cloud formation and scattering visible radiation. However, aerosol-related physical processes in climate simulations are highly uncertain. Constraining these processes could help improve model-based climate predictions. We propose a scalable statistical framework for constraining the parameters of expensive climate models by comparing model outputs with observations. Using the C3.AI Suite, a cloud computing platform, we use a perturbed parameter ensemble of the UKESM1 climate model to efficiently train a surrogate model. A method for estimating a data-driven model discrepancy term is described. The strict bounds method is applied to quantify parametric uncertainty in a principled way. We demonstrate the scalability of this framework with 2 weeks’ worth of simulated aerosol optical depth data over the South Atlantic and Central African region, written from the model every 3 hr and matched in time to twice-daily MODIS satellite observations. When constraining the model using real satellite observations, we establish constraints on combinations of two model parameters using much higher time-resolution outputs from the climate model than previous studies. This result suggests that within the limits imposed by an imperfect climate model, potentially very powerful constraints may be achieved when our framework is scaled to the analysis of more observations and for longer time periods

Which eligible households get grants? Demographic correlates of receipt in South Africa

Since Apartheid, the South African government transformed and expanded the social grants system to improve the well-being of its vulnerable populations. Despite increased efforts, a sub-section of the grant-eligible population is not reached. Too little is known about the factors that contribute to grant receipt, especially for the household as a whole. This article examines the household and community characteristics associated with grant receipt among poor households in KwaZulu-Natal. We add to previous work by assessing grant receipt at the household level, examining receipt of the two major grants and analysing correlates in a multivariate framework. While associations with grant receipt are complex and varied, we find higher grant receipt (especially the Child Support Grant) among more disadvantaged households. We also find that characteristics across multiple domains are needed to best distinguish household grant receipt. We discuss theoretical implications for models of grant receipt and practical implications for improving grant access

Peripheral myelin protein-22 (PMP22) modulates alpha 6 integrin expression in the human endometrium

<p>Abstract</p> <p>Background</p> <p>PMP22, a member of the GAS3 family of tetraspan proteins, is associated with a variety of neurological diseases. Previous studies have shown that PMP22 is expressed in proliferative endometrium, but its function within this tissue is poorly understood. In this study, we first characterized the expression of PMP22 in the human menstrual cycle and began to characterize its function in the endometrium.</p> <p>Methods</p> <p>Using a combination of immunohistochemistry and quantitative PCR, we characterized the expression of PMP22 in both proliferative and secretory endometrium. Differences in PMP22 expression between proliferative and secretory endometrium were determined using a Mann-Whitney U test. In order to investigate the influence of PMP22 on α6 integrin expression, cells were created that ectopically overexpressed PMP22 or expressed a siRNA to inhibit its expression. These cells were analyzed for changes in integrins and binding to extracellular matrices.</p> <p>Results</p> <p>In this study, we show that PMP22 expression is higher in proliferative phase than secretory phase. Functionally, we have begun to characterize the functional significance of this expression. Previous studies have suggested a link between PMP22 and α6 integrin, and therefore we asked whether PMP22 could associate or potentially modulate the expression of α6 integrin. Expression of both PMP22 and α6 integrin were detectable in endometrial epithelial and stromal cells, and we show that both proteins can associate and colocalize with each other. To understand if PMP22 directly altered the expression of a6 integrin, we examined cell lines with modulated levels of the protein. Overexpression of PMP22 was sufficient to increase α6 integrin surface expression with a concominant increase in binding to the extracellular matrix laminin, while a reduction in PMP22 suppressed α6 integrin surface expression.</p> <p>Conclusion</p> <p>These findings suggest a physiologic role for PMP22 on the expression of α6 integrin. We predict that this may be important for the maintainence of endometrial integrity and to the disease biology associated with altered levels of α6 integrin expression in the endometrium.</p