A bootstrap approach to testing for an association between bursts in the neonatal EEG and changes in cerebral blood flow

In the EEG of normal premature neonates, the Tracé Discontinu pattern is common, consisting of bursts of relatively high amplitude activity, followed by periods of low amplitude. Little is known about the neurophysiology underlying these bursts.We therefore investigated if cerebral blood flow (CBFV), as measured by transcranial Doppler ultrasound varies with the bursts. We analysed 12 simultaneous recordings of CBFV and EEG from 8 neonates (gestational ages 25-32 weeks), recorded within the first two days after birth. The bursts in the EEG were identified semi-automatically by an experienced neonatal electroencephalographer (GB). The mean CBFV in each heart-beat was identified, and interpolated to achieve a uniform sampling rate. The ensemble of segments of mean CBFV, synchronized with the start of each burst was then obtained, and coherently averaged. Signals from some of the recordings showed an apparently consistent change in CBFV, whose statistical significance we then investigated.Due to the wide variation in responses between subjects, we investigated simple measures of 'consistency' of the CBFV responses within each recording, rather than any specific pattern of response. We thus tested the statistical significance of the mean-square difference between each response and their coherent average, using a bootstrap approach. In this, the results from the ensemble of signal segments synchronized with burst-onset are compared to those from random selections of signal-segments within each recording. Simulation studies confirmed the statistical robustness of the approach, and its sensitivity and flexibility.<br/

Blockchain Technology for Access and Authorization Management in the Internet of Things

The Internet of Things (IoT) continues to suffer from security issues, even after 20 years of technological evolution and continuing efforts. While the decentralization of the IoT seems to be a solution for improved resource management and scalability, most of the services remain centralized, exposing IoT systems to malicious attacks. As a result, this leads to functionality failures and endangers user and data integrity. Identity and Access Management (IAM) has the ability to provide defense against a great number of security threats. Additionally, blockchain is a technology which can natively support decentralization, as well as access and authorization management techniques, using the corresponding programmable logic and leveraging cryptographic mechanisms for privacy and security. Using standardized frameworks (e.g., Decentralized Identifiers and Verifiable Credentials), a blockchain-based access and authorization solution can present the basis for a uniform decentralized IAM framework for the IoT. To this end, this paper presents a proof-of-concept design and implementation of an IAM solution based on Solidity smart contracts, targeting two areas: firstly, supporting the fact that blockchain can seamlessly provide the basis for a decentralized IAM framework, while secondly (and most importantly) exploring the challenge of integrating within existing IoT systems, avoiding redesigning and redeveloping on behalf of IoT manufacturers

Microbial activities at the benthic boundary layer in the Aegean Sea

International audienceDuring the Aegean Sea component of the EU MTP-MATER project, benthic samples were acquired along a depth gradient from two continental margins in the Aegean Sea. Sampling was undertaken during spring and summer 1997 and the microbial metabolic activities measured (Vmax for aminopeptidase activity, 14C-glutamate respiration and assimilation) displayed seasonal variability even in deep-sea conditions. The metabolic rates encountered in the North Aegean (average depth 566±234 m), were approximately five-fold higher than in the deeper (1336±140 m) Southern part of the Aegean. The aminopeptidase rates, however, were the exception with higher values recorded in the more oligotrophic sediments of the Southern stations (1383±152 vs. 766±297 nmol MCA cm-2 h-1). A discrepancy in bacterial metabolism also appeared in the near bottom waters. In the Southern stations, 80% of the glutamate uptake was used for energy yielding processes and only 20% devoted to biomass production, while in the North Aegean, most of the used glutamate was incorporated into bacterial cells. During the early burial stages, bacterial mineralization rates estimated from 14C-glutamate respiration decreased drastically compared to the rates of biopolymer hydrolysis estimated by aminopeptidase assays. Thus, at the 2-cm depth layer, these rates were only 32 and up to 77% of the corresponding average values, respectively, in the superficial layer. Such a discrepancy between the evolution of these two metabolic activities is possibly due to the rapid removal of readily utilizable monomers in the surface deposits. The correlation between bacterial respiration and total organic carbon, or total organic nitrogen, is higher in the surficial sediment (0-2 and 2-4 cm) than in the underlying layer. Conversely, it is only at 4-cm depth layer that the hydrolysis rates appear correlated with organic carbon and nitrogen concentrations. This pattern confirms the drastic degradation of organic matter during the early burial stages

A proposed scoring system for assessing the severity of actinic keratosis on the head: actinic keratosis area and severity index

Background: Actinic keratosis (AK) severity is currently evaluated by subjective assessment of patients. Objectives: To develop and perform an initial pilot validation of a new easy-to-use quantitative tool for assessing AK severity on the head. Methods: The actinic keratosis area and severity index (AKASI) for the head was developed based on a review of other severity scoring systems in dermatology, in particular the psoriasis area and severity index (PASI). Initial validation was performed by 13 physicians assessing AK severity in 18 AK patients and two controls using a physician global assessment (PGA) and AKASI. To determine an AKASI score, the head was divided into four regions (scalp, forehead, left/right cheek ear, chin and nose). In each region, the percentage of the area affected by AKs was estimated, and the severities of three clinical signs of AK were assessed: distribution, erythema and thickness. Results: There was a strong correlation between AKASI and PGA scores (Pearson correlation coefficient: 0.86). AKASI was able to discriminate between different PGA categories: mean (SD) AKASI increased from 2.88 (1.18) for âlightâ to 5.33 (1.48) for âmoderateâ, 8.28 (1.89) for âsevereâ, and 8.73 (3.03) for âvery severeâ PGA classification. The coefficient of variation for AKASI scores was low and relatively constant across all PGA categories. Conclusions: Actinic keratosis area and severity index is proposed as a new quantitative tool for assessing AK severity on the head. It may be useful in the future evaluation of new AK treatments in clinical studies and the management of AK in daily practice