Insulin sensitivity indices: Fasting versus glucose-stimulated ýndices in pediatric non-alcoholic fatty liver disease

OBJECTIVE: We aimed to compare insulin sensitivity indices, fasting vs glucose stimulated, in children and adolescents with non-alcoholic fatty liver disease. PATIENTS AND METHODS: Two hundredeleven obese children with median age of 11.24 ± 2.65 years were evaluated. After initial clinical and anthropometric examination, B-mode ultrasonography (USG) was performed and all subjects underwent Oral Glucose Tolerance Test (OGTT). Quantitative insulin sensitivity check index (QUICKI), homeostatic model assessment for insulin resistance (Homa-IR), the insulinogenic index (IGI), the Matsuda index, and the oral glucose insulin sensitivity (OGIS) model were used to determine peripheral insulin sensitivity. RESULTS: 59.24% (68 boys, 57 girls) of obese children had NALFD. The prevalence of FLD in obese adolescents was significantly higher than in prepubertal children (65.8% vs. 51.5%). Fasting glucose, insulin, Homa-IR, QUICKI, and OGIS and Matsuda were significantly different between subjects with and without NALFD. Insulin and glucose indices were not found to be significantly different in the prepubertal group, whereas Homa-IR, QUICKI, Matsuda, and OGIS were significantly different in the pubertal group. Age, waist circumference, and OUICKI were found to be risk factors associated with the presence of NALFD in the logistic-regression analysis. CONCLUSIONS: Age, waist circumference, and OUICKI were found to be risk factors associated with NALFD. As the value of QUICKI decreases, the probability of having steatosis increases. Although OGTT results gave the information about the glucose tolerance of a subject, indices derived from OGTT were not found to be superior to the traditional surrogates such as Homa-IR or QUICKI

Link Performance of Multiple Reconfigurable Intelligent Surfaces and Direct Path in General Fading

We analyze the performance of a single-input single-output wireless link that is aided by multiple reconfigurable intelligent surfaces (RISs) – in terms of outage probability, average symbol error probability and ergodic capacity, for which we derive analytical expressions in closed form. In particular, we consider a realistic system model, where the direct path may not be blocked and for which channels corresponding to different RISs are assumed to be independent but not identical and follow the generic $\kappa-\mu$ fading distribution, which can be reduced to a number of fading scenarios (namely Rayleigh, Rice, Nakagami-m, and one-sided Gaussian). This enables the evaluation of the system performance when adopting any combination of these special cases or the generic $\kappa-\mu$ distribution for both hops of the multiple distributed RISs. The direct path is modeled by Rayleigh fading assuming no line-of-sight between the source and the destination. We verify the accuracy of the adopted approach by means of Monte Carlo simulations and conduct a performance analysis that demonstrates the significant improvement in the system performance due to the usage of the RISs. Especially, we show that increasing the number of reflecting elements equipped on the RISs and placing the RISs closer to either communication endpoints improve the performance considerably.acceptedVersionPeer reviewe

Ergodic Capacity Analysis of RIS-Aided Systems with Spatially Correlated Channels

This paper investigates the ergodic capacity of reflecting intelligent surface (RIS)-aided single-input single-output communication systems with spatially correlated Rayleigh-fading channels. The ergodic capacity for such systems does not admit an exact closed-form expression. Therefore, we consider two alternative fading distributions to approximate the systems' statistical characterization to enable the derivation of closed-form expressions for the ergodic capacity. We further simplify the ergodic capacity by proposing novel and unified approximations in the form of a weighted sum of logarithmic functions with optimized coefficients. We validate the effectiveness and the high accuracy of the adopted schemes and the proposed approximations through numerical results. Performance analysis to study the impact of several system parameters on the ergodic capacity is also conducted. Deploying an RIS to the communication system can significantly increase the ergodic capacity which increases even further with increasing the number of reflecting elements equipped on the RIS, and this effect is best seen when the direct path is weak.acceptedVersionPeer reviewe

Tight Logarithmic Approximations and Bounds for Generic Capacity Integrals and Their Applications to Statistical Analysis of Wireless Systems

We present tight yet tractable approximations and bounds for the ergodic capacity of any communication system in the form of a weighted sum of logarithmic functions, with the focus on the Nakagami and lognormal distributions that represent key building blocks for more complicated systems. A minimax optimization technique is developed to derive their coefficients resulting in uniform absolute or relative error. These approximations and bounds constitute a powerful tool for the statistical performance analysis as they enable the evaluation of the ergodic capacity of various communication systems that experience small-scale fading together with the lognormal shadowing effect and allow for simplifying the complicated integrals encountered when evaluating the ergodic capacity in different communication scenarios. Simple and tight closed-form solutions for the ergodic capacity of many classic and timely application examples are derived using the logarithmic approximations. The high accuracy of the proposed approximations is verified by numerical comparisons with existing approximations and with those obtained directly from numerical integration methods.publishedVersionPeer reviewe

Generalized Karagiannidis–Lioumpas Approximations and Bounds to the Gaussian Q-Function with Optimized Coefficients

We develop extremely tight novel approximations, lower bounds and upper bounds for the Gaussian Q-function and offer multiple alternatives for the coefficient sets thereof, which are optimized in terms of the four most relevant criteria: minimax absolute/relative error and total absolute/relative error. To minimize error maximum, we modify the classic Remez algorithm to comply with the challenging nonlinearity that pertains to the proposed expression for approximations and bounds. On the other hand, we minimize the total error numerically using the quasi-Newton algorithm. The proposed approximations and bounds are so well matching to the actual Q-function that they can be regarded as virtually exact in many applications since absolute and relative errors of 10-9 and 10-5, respectively, are reached with only ten terms. The significant advance in accuracy is shown by numerical comparisons with key reference cases.publishedVersionPeer reviewe

Multiple sclerosis in Finland 2018-Data from the national register

Objectives Finland is a high-risk multiple sclerosis (MS) region, but a national MS register has not existed until 2014. In this paper, we present the Finnish MS register variables and data collected by 31 December 2018. Materials and Methods Numbers and data counts of MS patients in the register (ICD-10 code G35) are presented. The disease types and proportion of patients receiving disease-modifying treatments (DMTs) were analysed in five hospital districts with most complete data sets. MS prevalence in Finland was estimated using administrative hospital discharge data as an additional resource. Results There were a total of 8722 MS patients in the Finnish MS register by 31 December 2018 (71.5% females). Mean age at MS diagnosis was 38.7 years and peak prevalence was at age 50-54 years. Disease course was relapsing remitting (RRMS) in 66.7%, secondary progressive (SPMS) in 13.5%, and primary progressive (PPMS) in 7.9% of the 5365 MS patients in the selected districts with most complete data. A total of 66.0% of RRMS patients, 19.6% of SPMS patients and 9.9% of PPMS patients were receiving DMTs. By combining MS register data with databases of those hospitals that had not joined the register, the nationwide prevalence estimate was between 10 and 11 thousand patients (corresponding to crude prevalence 180-200/100 000). Conclusions The Finnish MS register is currently used in 15/21 Finnish hospital districts. By register integration into the electronic patient files, the coverage of the register has increased to approximately 80% of the estimated Finnish MS population.Peer reviewe

HybridDeepRx: Deep Learning Receiver for High-EVM Signals

In this paper, we propose a machine learning (ML) based physical layer receiver solution for demodulating OFDM signals that are subject to a high level of nonlinear distortion. Specifically, a novel deep learning based convolutional neural network receiver is devised, containing layers in both time- and frequency domains, allowing to demodulate and decode the transmitted bits reliably despite the high error vector magnitude (EVM) in the transmit signal. Extensive set of numerical results is provided, in the context of 5G NR uplink incorporating also measured terminal power amplifier characteristics. The obtained results show that the proposed receiver system is able to clearly outperform classical linear receivers as well as existing ML receiver approaches, especially when the EVM is high in comparison with modulation order. The proposed ML receiver can thus facilitate pushing the terminal power amplifier (PA) systems deeper into saturation, and thereon improve the terminal power-efficiency, radiated power and network coverage.Comment: To be presented in the 2021 IEEE International Symposium on Personal, Indoor and Mobile Radio Communication

Performance analysis of Multi-Phase cooperative NOMA systems under passive eavesdropping

A key feature of the non-orthogonal multiple access (NOMA) technique is that users with better channel conditions have prior knowledge about the information of other weak users. Given this prior knowledge, the idea that a strong user can serve as a relay node for other weak users in order to improve their performance, is known as cooperative NOMA. In this paper, we study the physical layer security of such a cooperative NOMA system. In order to reduce the complexity of the analytical process, the considered system in this paper has three users, in which the performance of the weaker users are enhanced by the stronger users. Given that there is an eavesdropper in the system that can hear all the transmissions, we study the secrecy performance of all the users. More specifically, we make an attempt to derive the ergodic secrecy capacity (ESC) and secrecy outage probability (SOP) of all the users. Due to the intractable nature of the exact analysis for the weak users, we provide the closed form expressions of the ESC and SOP for these users at the high SNR regime, while providing the exact analysis for the strongest user. Targeting on the optimality, we further reveal that better secrecy performance of the system is achievable through an appropriate power control mechanism. Finally, based on the analytical methodology of the three-user cooperative system, we provide insightful observations on the performance (in terms of ESC and SOP) of a multi-phase cooperative NOMA system with N users at the high SNR regime. Through rigorous numerical simulations, we verify the correctness of our analytical derivations under different practical scenarios while providing evidence of achieving optimal secrecy performance with the proposed power control scheme.acceptedVersionPeer reviewe

Gut microbiota develop towards an adult profile in a sex-specific manner during puberty

Accumulating evidence indicates that gut microbiota may regulate sex-hormone levels in the host, with effects on reproductive health. Very little is known about the development of intestinal microbiota during puberty in humans. To assess the connection between pubertal timing and fecal microbiota, and to assess how fecal microbiota develop during puberty in comparison with adult microbiota, we utilized a Finnish allergy-prevention-trial cohort (Flora). Data collected at 13-year follow-up were compared with adult data from a different Finnish cohort. Among the 13-year-old participants we collected questionnaire information, growth data from school-health-system records and fecal samples from 148 participants. Reference adult fecal samples were received from the Health and Early Life Microbiota (HELMi) cohort (n=840). Fecal microbiota were analyzed using 16S rRNA gene amplicon sequencing; the data were correlated with pubertal timing and compared with data on adult microbiota. Probiotic intervention in the allergy-prevention-trial cohort was considered as a confounding factor only. The main outcome was composition of the microbiota in relation to pubertal timing (time to/from peak growth velocity) in both sexes separately, and similarity to adult microbiota. In girls, fecal microbiota became more adult-like with pubertal progression (p= 0.009). No such development was observed in boys (p = 0.9). Both sexes showed a trend towards increasing relative abundance of estrogen-metabolizing Clostridia and decreasing Bacteroidia with pubertal development, but this was statistically significant in girls only (p = 0.03). In girls, pubertal timing was associated positively with exposure to cephalosporins prior to the age of 10. Our data support the hypothesis that gut microbiota, particularly members of Ruminococcaceae, may affect pubertal timing, possibly via regulating host sex-hormone levels.Peer reviewe