240 research outputs found
Causal holographic information does not satisfy the linearized quantum focusing condition
The Hubeny-Rangamani causal holographic information (CHI) defined by a region
of a holographic quantum field theory (QFT) is a modern version of the idea
that the area of event horizons might be related to an entropy. Here the event
horizon lives in a dual gravitational bulk theory with Newton's constant
, and the relation involves a factor of . The fact
that CHI is bounded below by the von Neumann entropy suggests that CHI is
coarse-grained. Its properties could thus differ markedly from those of . In
particular, recent results imply that when holographic QFTs are
perturbatively coupled to -dimensional gravity, the combined system
satisfies the so-called quantum focusing condition (QFC) at leading order in
the new gravitational coupling when the QFT entropy is taken to be that
of von Neumann. However, by studying states dual to spherical bulk (anti--de
Sitter) Schwarschild black holes in the conformal frame for which the boundary
is a -dimensional de Sitter space, we find the QFC defined by CHI is
violated even when perturbing about a Killing horizon and using a single null
congruence. Since it is known that a generalized second law (GSL) holds in this
context, our work demonstrates that the QFC is not required in order for an
entropy, or an entropy-like quantity, to satisfy such a GSL.Comment: 12 pages, 3 figures; v2: modifications to address referee comment
Anomalous hydrodynamics with triangular point group in 2 + 1 dimensions
We present a theory of hydrodynamics for a vector U(1) charge in 2+1
dimensions, whose rotational symmetry is broken to the point group of an
equilateral triangle. We show that it is possible for this U(1) to have a
chiral anomaly. The hydrodynamic consequence of this anomaly is the
introduction of a ballistic contribution to the dispersion relation for the
hydrodynamic modes. We simulate classical Markov chains and find compelling
numerical evidence for the anomalous hydrodynamic universality class.
Generalizations of our theory to other symmetry groups are also discussed
Continuous Dependence on the Initial Data in the Kadison Transitivity Theorem and GNS Construction
We consider how the outputs of the Kadison transitivity theorem and
Gelfand-Naimark-Segal construction may be obtained in families when the initial
data are varied. More precisely, for the Kadison transitivity theorem, we prove
that for any nonzero irreducible representation of a
-algebra and , there exists a continuous
function such that for all , where is the set
of pairs of -tuples such that the components of are linearly
independent. Versions of this result where maps into the self-adjoint or
unitary elements of are also presented. Regarding the
Gelfand-Naimark-Segal construction, we prove that given a topological
-algebra fiber bundle , one may construct a
topological fiber bundle whose fiber
over is the space of pure states of (with the norm
topology), as well as bundles and whose fibers and
over are the GNS
Hilbert space and closed left ideal, respectively, corresponding to .
When is a smooth fiber bundle, we show that
and are also smooth fiber bundles; this involves proving
that the group of -automorphisms of a -algebra is a Banach-Lie group.
In service of these results, we review the geometry of the topology and pure
state space. A simple non-interacting quantum spin system is provided as an
example
Flow of (higher) Berry curvature and bulk-boundary correspondence in parametrized quantum systems
This paper is concerned with the physics of parametrized gapped quantum
many-body systems, which can be viewed as a generalization of conventional
topological phases of matter. In such systems, rather than considering a single
Hamiltonian, one considers a family of Hamiltonians that depend continuously on
some parameters. After discussing the notion of phases of parametrized systems,
we formulate a bulk-boundary correspondence for an important bulk quantity, the
Kapustin-Spodyneiko higher Berry curvature, first in one spatial dimension and
then in arbitrary dimension. This clarifies the physical interpretation of the
higher Berry curvature, which in one spatial dimension is a flow of (ordinary)
Berry curvature. In d dimensions, the higher Berry curvature is a flow of
(d-1)-dimensional higher Berry curvature. Based on this, we discuss
one-dimensional systems that pump Chern number to/from spatial boundaries,
resulting in anomalous boundary modes featuring isolated Weyl points. In higher
dimensions, there are pumps of the analogous quantized invariants obtained by
integrating the higher Berry curvature. We also discuss the consequences for
parametrized systems of Kitaev's proposal that invertible phases are classified
by a generalized cohomology theory, and emphasize the role of the suspension
isomorphism in generating new examples of parametrized systems from known
invertible phases. Finally, we present a pair of general quantum pumping
constructions, based on physical pictures introduced by Kitaev, which take as
input a d-dimensional parametrized system, and produce new (d+1)-dimensional
parametrized systems. These constructions are useful for generating examples,
and we conjecture that one of the constructions realizes the suspension
isomorphism in a generalized cohomology theory of invertible phases.Comment: 35 pages, 11 figures. v2: references adde
Tetraphenylethylene-based glycoclusters with aggregation-induced emission (AIE) properties as high-affinity ligands of bacterial lectins
International audienceTetraphenylethylene (TPE) is fluorescent through aggregation induced emission (AIE) in water. Herein, TPE was used as the core of glycoclusters that target the bacterial lectins LecA and LecB of Pseudomonas aeruginosa. Synthesis of these TPE-based glycoclusters was accomplished by using azide-alkyne "click" chemistry. The AIE properties of the resulting glycoclusters could be readily verified, but imaging could not be pursued due to the overlap of the fluorescence signals from cells and bacteria. Nonetheless, the glycoclusters displayed nanomolar affinities toward LecA and LecB. Further evaluation in a cell-based anti-adhesive assay highlighted a limited decrease in adhesion (20%) for the fucosylated glycocluster. This confirmed that these TPE-based glycoclusters are indeed LecA and LecB high-affinity ligands. Nevertheless, the hypotheses involving their application in imaging or anti-adhesive therapy could not be verified
Differences in the functional brain architecture of sustained attention and working memory in youth and adults
Sustained attention (SA) and working memory (WM) are critical processes, but the brain networks supporting these abilities in development are unknown. We characterized the functional brain architecture of SA and WM in 9- to 11-year-old children and adults. First, we found that adult network predictors of SA generalized to predict individual differences and fluctuations in SA in youth. A WM model predicted WM performance both across and within children—and captured individual differences in later recognition memory—but underperformed in youth relative to adults. We next characterized functional connections differentially related to SA and WM in youth compared to adults. Results revealed 2 network configurations: a dominant architecture predicting performance in both age groups and a secondary architecture, more prominent for WM than SA, predicting performance in each age group differently. Thus, functional connectivity (FC) predicts SA and WM in youth, with networks predicting WM performance differing more between youths and adults than those predicting SA
Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis
BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London
Alternative Ii-independent antigen-processing pathway in leukemic blasts involves TAP-dependent peptide loading of HLA class II complexes
During HLA class II synthesis in antigen-presenting cells, the invariant chain (Ii) not only stabilizes HLA class II complexes in the endoplasmic reticulum, but also mediates their transport to specialized lysosomal antigen-loading compartments termed MIICs. This study explores an alternative HLA class II presentation pathway in leukemic blasts that involves proteasome and transporter associated with antigen processing (TAP)-dependent peptide loading. Although HLA-DR did associate with Ii, Ii silencing in the human class II-associated invariant chain peptide (CLIP)-negative KG-1 myeloid leukemic cell line did not affect total and plasma membrane expression levels of HLA-DR, as determined by western blotting and flow cytometry. Since HLA-DR expression does require peptide binding, we examined the role of endogenous antigen-processing machinery in HLA-DR presentation by CLIP− leukemic blasts. The suppression of proteasome and TAP function using various inhibitors resulted in decreased HLA-DR levels in both CLIP− KG-1 and ME-1 blasts. Simultaneous inhibition of TAP and Ii completely down-modulated the expression of HLA-DR, demonstrating that together these molecules form the key mediators of HLA class II antigen presentation in leukemic blasts. By the use of a proteasome- and TAP-dependent pathway for HLA class II antigen presentation, CLIP− leukemic blasts might be able to present a broad range of endogenous leukemia-associated peptides via HLA class II to activate leukemia-specific CD4+ T cells
A Randomized Trial Examining the Effects of Parent Engagement on Early Language and Literacy: The Getting Ready Intervention
Language and literacy skills established during early childhood are critical for later school success. Parental engagement with children has been linked to a number of adaptive characteristics in preschoolers including language and literacy development, and family-school collaboration is an important contributor to school readiness. This study reports the results of a randomized trial of a parent engagement intervention designed to facilitate school readiness among disadvantaged preschool children, with a particular focus on language and literacy development. Participants included 217 children, 211 parents, and 29 Head Start teachers in 21 schools. Statistically significant differences in favor of the treatment group were observed between treatment and control participants in the rate of change over 2 academic years on teacher reports of children’s language use (d = 1.11), reading (d = 1.25), and writing skills (d = .93). Significant intervention effects on children’s direct measures of expressive language were identified for a subgroup of cases where there were concerns about a child’s development upon entry into preschool. Additionally, other child and family moderators revealed specific variables that influenced the treatment’s effects
Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study
Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world.
Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231.
Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001).
Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication
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