On the six-dimensional origin of the AGT correspondence

We argue that the six-dimensional (2,0) superconformal theory defined on M \times C, with M being a four-manifold and C a Riemann surface, can be twisted in a way that makes it topological on M and holomorphic on C. Assuming the existence of such a twisted theory, we show that its chiral algebra contains a W-algebra when M = R^4, possibly in the presence of a codimension-two defect operator supported on R^2 \times C \subset M \times C. We expect this structure to survive the \Omega-deformation.Comment: References added. 14 page

Steady-state levels of imported tRNAs in Chlamydomonas mitochondria are correlated with both cytosolic and mitochondrial codon usages

The mitochondrial genome of Chlamydomonas reinhardtii only encodes three expressed tRNA genes, thus most mitochondrial tRNAs are likely imported. The sharing of tRNAs between chloroplasts and mitochondria has been speculated in this organism. We first demonstrate that no plastidial tRNA is present in mitochondria and that the mitochondrial translation mainly relies on the import of nucleus-encoded tRNA species. Then, using northern analysis, we show that the extent of mitochondrial localization for the 49 tRNA isoacceptor families encoded by the C. reinhardtii nuclear genome is highly variable. Until now the reasons for such variability were unknown. By comparing cytosolic and mitochondrial codon usage with the sub-cellular distribution of tRNAs, we provide unprecedented evidence that the steady-state level of a mitochondrial tRNA is linked not only to the frequency of the cognate codon in mitochondria but also to its frequency in the cytosol, then allowing optimal mitochondrial translation

Generalized Toda Theory from Six Dimensions and the Conifold

Recently, a physical derivation of the Alday-Gaiotto-Tachikawa correspondence has been put forward. A crucial role is played by the complex Chern-Simons theory arising in the 3d-3d correspondence, whose boundary modes lead to Toda theory on a Riemann surface. We explore several features of this derivation and subsequently argue that it can be extended to a generalization of the AGT correspondence. The latter involves codimension two defects in six dimensions that wrap the Riemann surface. We use a purely geometrical description of these defects and find that the generalized AGT setup can be modeled in a pole region using generalized conifolds. Furthermore, we argue that the ordinary conifold clarifies several features of the derivation of the original AGT correspondence.Comment: 27+2 pages, 3 figure

Unitarity Bounds in AdS_3 Higher Spin Gravity

We study SL(N,R) Chern-Simons gauge theories in three dimensions. The choice of the embedding of SL(2,R) in SL(N,R), together with asymptotic boundary conditions, defines a theory of higher spin gravity. Each inequivalent embedding leads to a different asymptotic symmetry group, which we map to an OPE structure at the boundary. A simple inspection of these algebras indicates that only the W_N algebra constructed using the principal embedding could admit a unitary representation for large values of the central charge.Comment: 1+23 pages, Version 3 Appendix B revise

Opioid use is associated with increased out-of-hospital cardiac arrest risk among 40,000-cases across two countries

AIMS: Opioid use has substantially increased in the last decade and is associated with overdose mortality, but also with increased mortality from cardiovascular causes. This finding may partly reflect an association between opioids and out‐of‐hospital cardiac arrest (OHCA). Therefore, we aimed to investigate OHCA‐risk of opioids in the community. METHODS: We conducted 2 population‐based case–control studies separately in the Netherlands (2009–2018) and Denmark (2001–2015). Cases were individuals who experienced OHCA of presumed cardiac cause. Each case was matched with up to 5 non‐OHCA‐controls according to age, sex and OHCA‐date. Conditional logistic regression analysis was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: We included 5473 OHCA‐cases matched with 21 866 non‐OHCA‐controls in the Netherlands, and 35 017 OHCA‐cases matched with 175 085 non‐OHCA‐controls in Denmark. We found that use of opioids (the Netherlands: cases: 5.4%, controls: 1.8%; Denmark: cases: 11.9%, controls: 4.4%) was associated with increased OHCA‐risk in both regions (the Netherlands: OR 2.1 [95% CI 1.8–2.5]; Denmark: OR 1.8 [95% CI 1.5–2.1]). The association was observed in both sexes, and in individuals with cardiovascular disease (the Netherlands: OR 1.8 [95% CI 1.5–2.1]; Denmark: OR 1.6 [95% CI 1.5–1.7]) or without (the Netherlands: OR 3.4 [95% CI: 2.4–4.8], P (interaction) < .0001; Denmark: OR 2.3 [95% CI: 2.0–2.5], P (interaction) < .0001). CONCLUSION: Use of opioids is associated with increased OHCA‐risk in both sexes, independently of concomitant cardiovascular disease. These findings should be considered when evaluating the harms and benefits of treatment with opioids

Imaging the kidney using magnetic resonance techniques: structure to function

Purpose of review Magnetic resonance imaging (MRI) offers the possibility to non-invasively assess both the structure and function of the kidney in a single MR scan session. This review summarises recent advancements in functional renal MRI techniques, with a particular focus on their clinical relevance. Recent findings A number of MRI techniques have been developed that provide non-invasive measures of relevance to the pathophysiology of kidney disease. Diffusion-weighted imaging (DWI) has been used in chronic kidney disease (CKD) and renal transplantation, and appears promising as a measure of renal impairment and fibrosis. Longitudinal relaxation time (T1) mapping has been utilised in cardiac MRI to measure fibrosis and oedema; recent work suggests its potential for assessment of the kidney. Blood oxygen level dependent (BOLD) MRI to measure renal oxygenation has been extensively studied, but a number of other factors affect results making it hard to draw definite conclusions as to its utility as an independent measure. Phase contrast and arterial spin labelling (ASL) can measure renal artery blood flow and renal perfusion respectively without exogenous contrast, in contrast to dynamic contrast enhanced (DCE) studies. Current data on clinical use of such functional renal MR measures is largely restricted to cross-sectional studies. Summary Renal MRI has seen significant recent interest and advances. Current evidence demonstrates its potential, and next steps include wider evaluation of its clinical application

Is adhesion superficial? Silicon wafers as a model system to study van der Waals interactions

Adhesion is a key issue for researchers of various fields, it is therefore of uppermost importance to understand the parameters that are involved. Commonly, only surface parameters are employed to determine the adhesive forces between materials. Yet, van der Waals forces act not only between atoms in the vicinity of the surface, but also between atoms in the bulk material. In this review, we describe the principles of van der Waals interactions and outline experimental and theoretical studies investigating the influence of the subsurface material on adhesion. In addition, we present a collection of data indicating that silicon wafers with native oxide layers are a good model substrate to study van der Waals interactions with coated materials

Use of antihypertensive agents and the risk of out-of-hospital cardiac arrest: A case control study

Background: Sudden cardiac arrest (SCA) is a complex multifactorial condition and is commonly caused by ventricular tachycardia/fibrillation (VT/VF). Some antihypertensive agents such as thiazides are associated with increased risk of SCA. Objectives: The aim of this study was to assess the association between different antihypertensive agents and the occurrence of out-of-hospital cardiac arrest (OHCA), taking into account their potential impact on serum potassium levels. Methods: Cases were drawn from the Amsterdam Resuscitation Studies (ARREST) registry and controls from the PHARMO database. This study was performed using 1948 cases who had OHCA with electrocardiogram (ECG)-documented VT/VF for the first time. These cases were matched by age, sex, and OHCA date (index date) to 8347 controls. From this dataset, we included only patients who were current users of antihypertensive agents (the index date fell between start date and end date of prescription + 10%). Antihypertensive therapies were classified according to their potential impact on serum potassium levels to therapies with neutral effect, therapies inducing hypokalemia, therapies inducing hyperkalemia, and therapies with unknown effect. Logistic regression analysis was used to study the association between use of antihypertensive agents and occurrence of OHCA and to control for confounding. Results: We included 1192 cases and 3303 controls who were current users of antihypertensive agents in our analysis. The risk of OHCA was significantly increased with users of antihypertensive therapies inducing hypokalemia (adjusted OR 1.48, 95%CI (1.12- 1.94)) and with users of antihypertensive therapies with unknown effect (adjusted OR 1.42, 95%CI (1.13-1.77)) versus users of antihypertensive therapies with neutral effect. There was no difference in OHCA risk between users of antihypertensive therapies inducing hyperkalemia versus users of antihypertensive therapies with neutral effect (adjusted OR 1.13, 95%CI (0.89-1.43)). Conclusions: The risk of OHCA is significantly increased in patients who were current users of antihypertensive therapies inducing hypokalemia and antihypertensive therapies with unknown effect on serum potassium levels

Holographic Charged Fluid with Anomalous Current at Finite Cutoff Surface in Einstein-Maxwell Gravity

The holographic charged fluid with anomalous current in Einstein-Maxwell gravity has been generalized from the infinite boundary to the finite cutoff surface by using the gravity/fluid correspondence. After perturbing the boosted Reissner-Nordstrom (RN)-AdS black brane solution of the Einstein-Maxwell gravity with the Chern-Simons term, we obtain the first order perturbative gravitational and Maxwell solutions, and calculate the stress tensor and charged current of the dual fluid at finite cutoff surfaces which contains undetermined parameters after demanding regularity condition at the future horizon. We adopt the Dirichlet boundary condition and impose the Landau frame to fix these parameters, finally obtain the dependence of transport coefficients in the dual stress tensor and charged current on the arbitrary radical cutoff $r_c$. We find that the dual fluid is not conformal, but it has vanishing bulk viscosity, and the shear viscosity to entropy density ratio is universally $1/4\pi$. Other transport coefficients of the dual current turns out to be cutoff-dependent. In particular, the chiral vortical conductivity expressed in terms of thermodynamic quantities takes the same form as that of the dual fluid at the asymptotic AdS boundary, and the chiral magnetic conductivity receives a cutoff-dependent correction which vanishes at the infinite boundary.Comment: 19 pages, v2: references added, v3: typos corrected, v5: typos corrected, version accepted for publication in JHE