Non-Parametric Approximations for Anisotropy Estimation in Two-dimensional Differentiable Gaussian Random Fields

Spatially referenced data often have autocovariance functions with elliptical isolevel contours, a property known as geometric anisotropy. The anisotropy parameters include the tilt of the ellipse (orientation angle) with respect to a reference axis and the aspect ratio of the principal correlation lengths. Since these parameters are unknown a priori, sample estimates are needed to define suitable spatial models for the interpolation of incomplete data. The distribution of the anisotropy statistics is determined by a non-Gaussian sampling joint probability density. By means of analytical calculations, we derive an explicit expression for the joint probability density function of the anisotropy statistics for Gaussian, stationary and differentiable random fields. Based on this expression, we obtain an approximate joint density which we use to formulate a statistical test for isotropy. The approximate joint density is independent of the autocovariance function and provides conservative probability and confidence regions for the anisotropy parameters. We validate the theoretical analysis by means of simulations using synthetic data, and we illustrate the detection of anisotropy changes with a case study involving background radiation exposure data. The approximate joint density provides (i) a stand-alone approximate estimate of the anisotropy statistics distribution (ii) informed initial values for maximum likelihood estimation, and (iii) a useful prior for Bayesian anisotropy inference.Comment: 39 pages; 8 figure

Effect of the COVID-19 pandemic on surgery for indeterminate thyroid nodules (THYCOVID): a retrospective, international, multicentre, cross-sectional study

Background Since its outbreak in early 2020, the COVID-19 pandemic has diverted resources from non-urgent and elective procedures, leading to diagnosis and treatment delays, with an increased number of neoplasms at advanced stages worldwide. The aims of this study were to quantify the reduction in surgical activity for indeterminate thyroid nodules during the COVID-19 pandemic; and to evaluate whether delays in surgery led to an increased occurrence of aggressive tumours.Methods In this retrospective, international, cross-sectional study, centres were invited to participate in June 22, 2022; each centre joining the study was asked to provide data from medical records on all surgical thyroidectomies consecutively performed from Jan 1, 2019, to Dec 31, 2021. Patients with indeterminate thyroid nodules were divided into three groups according to when they underwent surgery: from Jan 1, 2019, to Feb 29, 2020 (global prepandemic phase), from March 1, 2020, to May 31, 2021 (pandemic escalation phase), and from June 1 to Dec 31, 2021 (pandemic decrease phase). The main outcomes were, for each phase, the number of surgeries for indeterminate thyroid nodules, and in patients with a postoperative diagnosis of thyroid cancers, the occurrence of tumours larger than 10 mm, extrathyroidal extension, lymph node metastases, vascular invasion, distant metastases, and tumours at high risk of structural disease recurrence. Univariate analysis was used to compare the probability of aggressive thyroid features between the first and third study phases. The study was registered on ClinicalTrials.gov, NCT05178186.Findings Data from 157 centres (n=49 countries) on 87 467 patients who underwent surgery for benign and malignant thyroid disease were collected, of whom 22 974 patients (18 052 [78 center dot 6%] female patients and 4922 [21 center dot 4%] male patients) received surgery for indeterminate thyroid nodules. We observed a significant reduction in surgery for indeterminate thyroid nodules during the pandemic escalation phase (median monthly surgeries per centre, 1 center dot 4 [IQR 0 center dot 6-3 center dot 4]) compared with the prepandemic phase (2 center dot 0 [0 center dot 9-3 center dot 7]; p<0 center dot 0001) and pandemic decrease phase (2 center dot 3 [1 center dot 0-5 center dot 0]; p<0 center dot 0001). Compared with the prepandemic phase, in the pandemic decrease phase we observed an increased occurrence of thyroid tumours larger than 10 mm (2554 [69 center dot 0%] of 3704 vs 1515 [71 center dot 5%] of 2119; OR 1 center dot 1 [95% CI 1 center dot 0-1 center dot 3]; p=0 center dot 042), lymph node metastases (343 [9 center dot 3%] vs 264 [12 center dot 5%]; OR 1 center dot 4 [1 center dot 2-1 center dot 7]; p=0 center dot 0001), and tumours at high risk of structural disease recurrence (203 [5 center dot 7%] of 3584 vs 155 [7 center dot 7%] of 2006; OR 1 center dot 4 [1 center dot 1-1 center dot 7]; p=0 center dot 0039).Interpretation Our study suggests that the reduction in surgical activity for indeterminate thyroid nodules during the COVID-19 pandemic period could have led to an increased occurrence of aggressive thyroid tumours. However, other compelling hypotheses, including increased selection of patients with aggressive malignancies during this period, should be considered. We suggest that surgery for indeterminate thyroid nodules should no longer be postponed even in future instances of pandemic escalation.Funding None.Copyright (c) 2023 Published by Elsevier Ltd. All rights reserved

A linear gradient sequential injection chromatography method exploiting programmable fluidics for the determination of three methylxanthines

This work describes a novel sequential injection chromatography (SIC)method combined with linear gradient elution for the separation and determination of three main methylxanthines (theobromine, theophylline and caffeine)using a short C18 monolithic column. The method utilizes a hybrid manifold which exploits zone fluidics for solution manipulation and programmable fluidics for the implementation of a two-solvent linear gradient elution protocol. This approach offers a high degree of automation and enables faster separation of the three target methylxanthines with respect to isocratic elution as well as better chromatographic efficiency. The limits of detection of the three methylxanthines ranged from 0.18 to 0.45 μmol L−1, the instrumental repeatability (at the 10 μmol L−1 level of the target compounds, n = 6)was ≤2% and the separation time was 3.3 min. The SIC method was validated and applied to the analysis of coffee, chocolate and tea samples. © 2019 Elsevier B.V

An electronic system for simulation of neural networks with a micro- second real time constraint

Neural networks implemented in hardware can perform pattern recognition very quickly, and as such have been used to advantage in the triggering systems of certain high energy physics experiments. Typically, time constants of the order of a few microseconds are required. We present a new system, MAHARADJA, for evaluating MLP and RBF neural network paradigms in real time. The system is tested on a possible ATLAS muon triggering application suggested by the Tel Aviv ATLAS group, consisting of a 4-8-8-4 MLP which must be evaluated in 10 microseconds. The inputs to the net are dx/dz, x(z=0), dy/dz, and y(z=0), whereas the outputs give pt, tan(phi), sin(theta), and q, the charge. With a 10 MHz clock, MAHARADJA calculates the result in 6.8 microseconds; at 20 MHz, which is readily attainable, this would be reduced to only 3.4 microseconds. The system can also handle RBF networks with 3 different distance metrics (Euclidean, Manhattan and Mahalanobis), and can simulate any MLP of 10 hidden layers or less. The electronic implementation is with FPGAs, which can be optimized for a specific neural network because the number of processing elements can be modified. (3 refs)

What Physical Layer Security Can Do for 6G Security

While existing security protocols were designed with a focus on the core network, the enhancement of the security of the B5G access network becomes of critical importance. Despite the strengthening of 5G security protocols with respect to LTE, there are still open issues that have not been fully addressed. This work is articulated around the premise that rethinking the security design bottom up, starting at the physical layer, is not only viable in 6G but importantly, arises as an efficient way to overcome security hurdles in novel use cases, notably massive machine type communications (mMTC), ultra reliable low latency communications (URLLC) and autonomous cyberphysical systems. Unlike existing review papers that treat physical layer security orthogonally to cryptography, we will try to provide a few insights of underlying connections. Discussing many practical issues, we will present a comprehensive review of the state-of the-art in i) secret key generation from shared randomness, ii) the wiretap channels and fundamental limits, iii) authentication of devices using physical unclonable functions (PUFs), localization and multi-factor authentication, and, iv) jamming attacks at the physical layer. We finally conclude with the proposers' aspirations for the 6G security landscape, in the hyper-connectivity and semantic communications era

Lazaroid U-74389G for cardioplegia-related ischemia–reperfusion injury: an experimental study

Background The adverse effects of myocardial ischemia and reperfusion during cardiopulmonary bypass (CPB) have been thoroughly described. Lazaroid U-74389G, a 21 aminosteroid, has been shown to attenuate ischemia and reperfusion injury and improve recovery in a variety of experimental models. Methods Sixteen male swine were randomly divided in two groups. All animals underwent 45 min of ischemic cardioplegic arrest, with U-74389G addition to the standard cardioplegic solution, whereas controls underwent the same procedure without U-74389G. Creatine kinase-MB isoenzyme (CK-MB) and cardiac troponin T levels were measured immediately before CPB (time point 0), during the ischemic period (time point 1) and 30 (time point 2), 60 (time point 3), and 120 (time point 4) min after reperfusion. Myocardial biopsies were obtained at time points 0 and 4. Results CK-MB levels (in U/L) at time points 0-4 were 205 (186-235) versus 219 (196-269; P = 0.72), 215 (167-248) versus 253 (193-339; P = 0.23), 234 (198-255) versus 338 (249-441; P = 0.02), 244 (217-272) versus 354 (269-496; P = 0.01), and 285 (230-321) versus 439 (432-530; P < 0.01) in lazaroid-treated animals versus controls, respectively. Cardiac troponin T levels (in ng/L) at time points 0-4 were 58 (26-287) versus 237 (26-395; P = 0.72), 129 (61-405) versus 265 (145-525; P = 0.23), 261 (123-467) versus 474 (427-1604; P = 0.04), 417 (204-750) versus 841 (584-1818; P = 0.11), and 643 (353-1259) versus 1600 (1378-2313; P < 0.01), respectively. Necrosis grades at time point 4 were 0.0 (0.0-1.0) versus 1.5 (1.0-2.0; P < 0.01) in lazaroid-treated animals versus controls, respectively. Conclusions The present study, in addition to reconfirming the well-described adverse effects of CPB, demonstrates the efficacy of the newer generation lazaroid U-74389G in alleviating these effects. © 2016 Elsevier Inc

Overexpression of γ-tubulin in non-small cell lung cancer.

We and others have previously shown that increased expression and altered compartmentalization of γ-tubulin may contribute to tumorigenesis and tumor progression (J. Cell Physiol. 2009;223:519-529; Cancer Biol. Ther. 2010;9:66-76). Here we have determined by immunohistochemistry the localization and cellular distribution of γ-tubulin in clinical tissue samples from 109 non-small cell lung cancer (NSCLC) cases. The expression and distribution of γ-tubulin protein and transcripts was also determined in the NSCLC tumor cell lines NCI-H460 (HTB-177) and NCI-H69 (HTB-119) by immunocytochemistry, quantitative immunoblotting and reverse transcription quantitative real-time PCR (RT-qPCR). Polyclonal and monoclonal anti-peptide antibodies recognizing epitopes in the C- or N-terminal domains of γ-tubulins and human gene-specific primers for γ-tubulins 1 (TUBG1) and 2 (TUBG2) were used. In non-neoplastic cells of the airway epithelium in situ, γ-tubulin exhibited predominantly apical surface and pericentriolar localizations. In contrast, markedly increased, albeit heterogeneous and variously prominent γ-tubulin immunoreactivity was detected in clinical tumor specimens and in the NCI-H460 and NCI-H69 cell lines, where tumor cells exhibited overlapping multi-punctate and diffuse patterns of localization. Co-expression of γ-tubulin and Ki-67 (MIB-1) was detected in a population of proliferating tumor cells. A statistically significant increase of γ-tubulin expression was found in Stage III compared to lesser stage tumors (p<0.001 v. Stages I/II) regardless of histological subtype or grade. By quantitative immunoblotting NCI-H460 and NCI-H69 cells expressed higher levels of γ-tubulin protein compared to small airway epithelial cells (SAEC). In both tumor cell lines increase in TUBG1 and TUBG2 transcripts was detected by RT-qPCR. Our results reveal for the first time an increased expression of γ-tubulin in lung cancer

Acute impact of active and passive electronic cigarette smoking on serum cotinine and lung function

Context: Electronic cigarettes (e-cigarettes) are becoming increasingly popular yet their effects on health remain unknown. Objective: To conduct the first comprehensive and standardized assessment of the acute impact of active and passive e-cigarette smoking on serum cotinine and lung function, as compared to active and passive tobacco cigarette smoking. Materials and methods: Fifteen smokers (>= 15 cigarettes/day; seven females; eight males) and 15 never-smokers (seven females; eight males) completed this repeated-measures controlled study. Smokers underwent a control session, an active tobacco cigarette (their favorite brand) smoking session and an active e-cigarette smoking session. Never-smokers underwent a control session, a passive tobacco cigarette smoking session and a passive e-cigarette smoking session. Serum cotinine, lung function, exhaled carbon monoxide and nitric oxide were assessed. The level of significance was set at p 0.001) effects on serum cotinine levels after active (60.6 +/- 34.3 versus 61.3 +/- 36.6 ng/ml) and passive (2.4 +/- 0.9 versus 2.6 +/- 0.6 ng/ml) smoking. Neither a brief session of active e-cigarette smoking (indicative: 3% reduction in FEV1/FVC) nor a 1 h passive e-cigarette smoking (indicative: 2.3% reduction in FEV1/FVC) significantly affected the lung function (p>0.001). In contrast, active (indicative: 7.2% reduction in FEV1/FVC; p<0.001) but not passive (indicative: 3.4% reduction in FEV1/FVC; p=0.005) tobacco cigarette smoking undermined lung function. Conclusion: Regarding short-term usage, the studied e-cigarettes generate smaller changes in lung function but similar nicotinergic impact to tobacco cigarettes. Future research should target the health effects of long-term e-cigarette usage, including the effects of nicotine dosage