Quantum Extremal Islands Made Easy, Part I: Entanglement on the Brane

Recent progress in our understanding of the black hole information paradox has lead to a new prescription for calculating entanglement entropies, which involves special subsystems in regions where gravity is dynamical, called \textit{quantum extremal islands}. We present a simple holographic framework where the emergence of quantum extremal islands can be understood in terms of the standard Ryu-Takayanagi prescription, used for calculating entanglement entropies in the boundary theory. Our setup describes a $d$-dimensional boundary CFT coupled to a ($d$-1)-dimensional defect, which are dual to global AdS${}_{d+1}$ containing a codimension-one brane. Through the Randall-Sundrum mechanism, graviton modes become localized at the brane, and in a certain parameter regime, an effective description of the brane is given by Einstein gravity on an AdS${}_d$ background coupled to two copies of the boundary CFT. Within this effective description, the standard RT formula implies the existence of quantum extremal islands in the gravitating region, whenever the RT surface crosses the brane. This indicates that islands are a universal feature of effective theories of gravity and need not be tied to the presence of black holes

Mechanistic Understanding and Three‐Dimensional Tuning of Fluid Imbibition in Silica‐Coated Cotton Linter Paper Sheets

Paper‐based microfluidic devices are used in point of care diagnostic, sensor technology or lab‐on‐a‐chip devices. Although a number of studies has been reported, only relatively few paper‐based diagnostic tools are available on the market. A remaining challenge is the mechanistic understanding and precise design of capillary flow in paper. Here, silica coatings are applied to control paper wettability, fiber swelling, and thus fluid transport in all three dimensions of a paper sheet via a simple dip‐coating and post‐treatment process. By adjusting the three‐dimensional silica coating distribution, a three‐dimensional asymmetric wettability gradient within the paper sheet is obtained which controls the fluid distribution and imbibition. The correlation between silica coating amount and silica distribution with the resulting fluid behavior is systematically elaborated by analyzing the interaction between fiber and fluid as well as the fiber swelling by applying confocal microscopy. Three different silica‐amount dependent fluid distribution states are demonstrated. These new insights into the mechanism of fluid imbibition using simple silica coatings enable the specific design of different imbibition mechanisms and thus the adjustment of the microfluidic properties in paper‐based microfluidic devices with control over all three spatial dimensions of a paper sheet in one fabrication step

Quantum Extremal Islands Made Easy, Part II: Black Holes on the Brane

We discuss holographic models of extremal and non-extremal black holes in contact with a bath in d dimensions, based on a brane world model introduced in arXiv:2006.04851. The main benefit of our setup is that it allows for a high degree of analytic control as compared to previous work in higher dimensions. We show that the appearance of quantum extremal islands in those models is a consequence of the well-understood phase transition of RT surfaces, and does not make any direct reference to ensemble averaging. For non-extremal black holes the appearance of quantum extremal islands has the right behaviour to avoid the information paradox in any dimension. We further show that for these models the calculation of the full Page curve is possible in any dimension. The calculation reduces to numerically solving two ODEs. In the case of extremal black holes in higher dimensions, we find no quantum extremal islands for a wide range of parameters. In two dimensions, our results agree with arXiv:1910.11077 at leading order; however a finite UV cutoff introduced by the brane results in subleading corrections. For example, these corrections result in the quantum extremal surfaces moving further outward from the horizon, and shifting the Page transition to a slightly earlier time

Mechanistic Understanding and Three-Dimensional Tuning of Fluid Imbibition in Silica-Coated Cotton Linter Paper Sheets: Public Data

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Reorganization of inter-chromosomal interactions in the 2q37-deletion syndrome

Chromosomes occupy distinct interphase territories in the three-dimensional nucleus. However, how these chromosome territories are arranged relative to one another is poorly understood. Here, we investigated the inter-chromosomal interactions between chromosomes 2q, 12, and 17 in human mesenchymal stem cells (MSCs) and MSC-derived cell types by DNA-FISH We compared our findings in normal karyotypes with a three-generation family harboring a 2q37-deletion syndrome, featuring a heterozygous partial deletion of histone deacetylase 4 (HDAC4) on chr2q37. In normal karyotypes, we detected stable, recurring arrangements and interactions between the three chromosomal territories with a tissue-specific interaction bias at certain loci. These inter-chromosomal interactions were confirmed by Hi-C. Interestingly, the disease-related HDAC4 deletion resulted in displaced inter-chromosomal arrangements and altered interactions between the deletion-affected chromosome 2 and chromosome 12 and/or 17 in 2q37-deletion syndrome patients. Our findings provide evidence for a direct link between a structural chromosomal aberration and altered interphase architecture that results in a nuclear configuration, supporting a possible molecular pathogenesis

Autosomal-dominant hypertension with type E brachydactyly is caused by rearrangement on the short arm of chromosome 12

We are studying a Turkish family with autosomal-dominant hypertension and brachydactyly; affected persons die of stroke before 50 years of age. With interphase fluorescence in situ hybridization, we found a chromosome 12p deletion, reinsertion, and inversion in affected persons. This finding suggested that the hypertension could be caused by one or more of 3 genes, the ATP-dependent potassium channel Kir6.1, its regulator the sulfonyl urea receptor SUR2, and the phosphodiesterase PDE3A. We further studied 6 affected and 4 nonaffected persons. Buttocks biopsies were done, small vessels were tested on a myograph, and mRNA was extracted. We performed forearm blood flow studies with intrabrachial artery diazoxide, isoproterenol, and milrinone infusions. Systemic pharmacological testing was done with intravenous diazoxide, nitroprusside, and isoproterenol. PDE3A mRNA was high in vessels from 3 affected subjects, but not high in 3 others. The vessels responded similarly to forskolin, with or without glibenclamide, and to cromakalim. However, there was a suggestion that the dilatation after milrinone might be exaggerated. The forearm infusion studies showed no differences in the responses to diazoxide, isoproterenol, or milrinone. Systemically, affected persons showed a greater blood pressure response to diazoxide and nitroprusside, and a greater heart rate response to isoproterenol than nonaffected persons. The results shed doubt on Kir6.1 and SUR2. The differences in PDE3A expression and responses may be the result of hypertension rather than the cause. Although our 3 candidate genes are no longer likely, the rearrangement we describe greatly enhances the perspectives of this project

Saúde e segurança no ambiente rural: uma análise das condições de trabalho em um setor de ordenha Health and safety at rural environment: an analysis of work conditions in a milking sector

A saúde e a segurança no trabalho são fatores preponderantes em todos os setores produtivos, assim como no agronegócio e, especificamente, na cadeia produtiva do leite. Neste artigo, apresentam-se os resultados de uma análise das condições do ambiente de trabalho de um setor de ordenha de leite localizado na região Sudoeste do Estado da Bahia. Buscou-se identificar os riscos ocupacionais (físicos, químicos, biológicos, ergonômicos e de acidentes), bem como aspectos relativos à higiene do alimento. A pesquisa consistiu de um estudo de caso, com características qualitativas e exploratórias, tendo por finalidade descrever a situação encontrada no setor, confrontando-a com as legislações vigentes. Foram diagnosticados, predominantemente, riscos ergonômicos e de acidentes, além de irregularidades nas condições higiênico-sanitárias, que podem constituir riscos biológicos. Não foram constatados riscos químicos ou físicos no setor. Os resultados apontam para a necessidade de melhoria no setor, que vão desde mudanças estruturais, questões organizacionais, como o oferecimento de treinamentos sobre procedimentos operacionais e em saúde e segurança no trabalho.<br>The health and safety at work are important and might be considered as essential and relevant for all productive sectors, including agribusiness, specifically in the milk chain production. This paper presents the results of an environment work conditions analysis in a milking sector at southwest region of Bahia State. The study aimed to identify the occupational risks (physical, chemical, biological, ergonomic and accidents), as well as aspects related to food hygiene. The research consisted in a case study with qualitative and exploratory characteristics, aiming to observe and report the real conditions identified in the work environment and comparing with the current legislation. It was diagnosed predominantly ergonomic and accident risks, as well as irregular sanitary conditions that can result in biological risks. It was not found chemical or physical risks in the sector. Facing the results, it was proposed some recommendations involving issues related to organizational conditions, by offering training on operational procedures and health and safety at work