Evolutionary and demographic correlates of Pleistocene coastline changes in the Sicilian wall lizard Podarcis wagleriana

Aim Emergence of coastal lowlands during Pleistocene ice ages might have provided conditions for glacial expansions (demographic and spatial), rather than contraction, of coastal populations of temperate species. Here, we tested these predictions in the insular endemic Sicilian wall lizard Podarcis wagleriana. Location Sicily and neighbouring islands. Methods We sampled 179 individuals from 45 localities across the whole range of P. wagleriana. We investigated demographic and spatial variations through time using Bayesian coalescent models (Bayesian phylogeographic reconstruction, Extended Bayesian Skyline plots, Isolation‐with‐migration models) based on multilocus DNA sequence data. We used species distribution modelling to reconstruct present and past habitat suitability. Results We found two main lineages distributed in the east and west portions of the current species range and a third lineage restricted to a small area in the north of Sicily. Multiple lines of evidence from palaeogeographic (shorelines), palaeoclimatic (species distribution models), and multilocus genetic data (demographic and spatial Bayesian reconstructions) indicate that these lineages originated in distinct refugia, located in the north‐western and south‐eastern coastal lowlands, during Middle Pleistocene interglacial phases, and came into secondary contact following demographic and spatial expansions during the last glacial phase. Main conclusions This scenario of interglacial contraction and glacial expansion is in sharp contrast with patterns commonly observed in temperate species on the continent but parallels recent findings on other Mediterranean island endemics. Such a reverse expansion–contraction (EC) dynamic has been likely associated with glacial increases of climatically suitable coastal lowlands, suggesting this might be a general pattern in Mediterranean island species and also in other coastal regions strongly affected by glacial marine regressions during glacial episodes. This study provides explicit predictions and some methodological recommendations for testing the reverse EC model in other region and taxa

MV Power Grids Integration of a Resistive Fault Current Limiter Based on HTS-CCs

Due to the energy demand growth and distributed generation (DG) units penetration, a substantial increase of the rated short-circuit current of the electrical lines is expected. As a consequence, the electrical grid infrastructure needs to be extended or drastically renovated. In this context, resistive superconducting fault current limiters (RFCLs) based on high temperature superconducting coated conductors (HTS-CCs) represent a promising technology to limit the upgrading costs. Thanks to recent improvements on HTS-CCs performances, RFCLs are now close to commercial applications. However, as they are novel devices, their real impact on the electricity network remains an open issue. In particular, the subject of this research is to study the grid integration of the RFCL designed within the European project ECCOFLOW [1]. The device has been simulated in two applications in two different typologies of existing medium voltage grids: RFCL used as busbars coupler and RFCL used as transformer feeder. This contribution is the continuation of previous works [2], [3], where the effects of symmetrical and unsymmetrical short-circuits on inhomogeneous HTS-CCs have been extensively analyzed

Impact of the Normal Zone Propagations Velocity of High Temperature Superconducting Coated Conductors on Resistive Fault Current Limiters

The engineering critical current (Ic) of the high temperature superconducting coated conductors (HTS-CCs), today available on the market, is not a uniform parameter and varies significantly along the length of the conductors. Moreover, commercial HTS-CCs have a low normal zone propagation velocity (NZPV). This property, together with the Ic inhomogeneity, exposes the HTS-CCs to local thermal instabilities. A crucial challenge for the design of resistive fault current limiters (RFCLs) based on HTS-CCs is to avoid the thermal runaway of the conductors, and in this respect the enhancement of the NZPV is a promising solution. In the recent years, several methods have been proposed and many and various techniques are now available to enhance the NZPV. Whichever will be the best technical solution to improve NZPV of HTS-CCs, our aim is to quantify the impact the enhancement of NZPV will have on the design of RFCLs based on HTS-CCs. For this reason, we used numerical models to analyze the effects of the enhancement of NZPV on the limitation performance of a RFCL integrated in a medium voltage (MV) power grid. In this manuscript, we quantify the benefits the enhancement of the NZPV will have on the next generation of HTS-CC-based RFCLs for MV grid

Osteomalacia and Vitamin D Status: A Clinical Update 2020

Historically, rickets and osteomalacia have been synonymous with vitamin D deficiency dating back to the 17th century. The term osteomalacia, which literally means soft bone, was traditionally applied to characteristic radiologically or histologically documented skeletal disease and not just to clinical or biochemical abnormalities. Osteomalacia results from impaired mineralization of bone that can manifest in several types, which differ from one another by the relationships of osteoid (ie, unmineralized bone matrix) thickness both with osteoid surface and mineral apposition rate. Osteomalacia related to vitamin D deficiency evolves in three stages. The initial stage is characterized by normal serum levels of calcium and phosphate and elevated alkaline phosphatase, PTH, and 1,25-dihydroxyvitamin D [1,25(OH)2D]—the latter a consequence of increased PTH. In the second stage, serum calcium and often phosphate levels usually decline, and both serum PTH and alkaline phosphatase values increase further. However, serum 1,25(OH)2D returns to normal or low values depending on the concentration of its substrate, 25-hydroxyvitamin D (25OHD; the best available index of vitamin D nutrition) and the degree of PTH elevation. In the final stage, hypocalcemia and hypophosphatemia are invariably low with further exacerbation of secondary hyperparathyroidism. The exact,or even an approximate, prevalence of osteomalacia caused by vitamin D deficiency is difficult to estimate, most likely it is underrecognized or misdiagnosed as osteoporosis. Signs and symptoms include diffuse bone, muscle weakness, and characteristic fracture pattern, often referred to as pseudofractures, involving ribs, scapulae, pubic rami, proximal femurs, and codfish-type vertebrae. The goal of therapy of vitamin D-deficiency osteomalacia is to alleviate symptoms, promote fracture healing, restore bone strength, and improve quality of life while correcting biochemical abnormalities. There is a need for better understanding of the epidemiology of osteomalacia. Simplified tools validated by concurrent bone histology should be developed to help clinicians promptly diagnose osteomalacia

Impact of synchrophasor measurement types and uncertainties on the accuracy of distribution system linear state estimators

The paper aims at assessing the effects of combined voltage and/or current synchrophasor measurements, and their associated uncertainties, on the accuracy of state estimators adopted in distribution systems. Such an assessment is first carried out with respect to a generic transmission line with the purpose of determining the combination of voltage and/or current synchrophasor measurements that provides the best accuracy of the estimated quantities. A comprehensive analysis on the impact of different measurement uncertainties and operating conditions is included for this specific case. In order to derive general conclusions, the study is then extended to a distribution system composed of the IEEE 13-bus test feeder. For this case, we perform an a-posteriori assessment of the probability distributions of the estimation errors by using a discrete Kalman filter state estimator fed with noisy voltage and/or injected current synchrophasor measurements

Definition and assessment of reference values for PMU calibration in static and transient conditions

The calibration of Phasor Measurement Units (PMUs) consists of comparing Coordinated Universal Time (UTC) time-stamped phasors (synchrophasors) estimated by the PMU under test, against reference synchrophasors generated through a PMU calibrator. The IEEE Standard C37.118-2011 and its amendment (IEEE Std) describe compliance tests for static and dynamic conditions, and indicate the relative limits in terms of accuracy. In this context, the paper focuses on the definition and accuracy assessment of the reference synchrophasors in the test conditions dictated by the above IEEE Std. In the first part of the paper, we describe the characterization of a nonlinear least-squares (NL-LSQ) fitting algorithm used to determine the parameters of the reference synchrophasors. We analyse the uniqueness and robustness of the solution provided by the algorithm. We assess its accuracy within the whole range of static tests required by the IEEE Std. In the second part, we discuss the appropriateness of synchrophasor model to evaluate the PMU performance in step test conditions. We compare the proposed algorithm against two synchrophasor estimation algorithms. Finally, we propose a time domain process for the better evaluation of PMU performances in transient conditions

Protection Testing for Multiterminal High-Voltage dc Grid:Procedures and Procedures and Assessment

eAssessment The application of multiterminal (MT), high-voltage dc (HVdc) (MTdc) grid technology requires test procedures for the operation and implementation of the protection solutions. The test procedures are usually derived from experience and from extensive measurement data, which, at present, are still not widely available. Based on a hardware-inthe- loop (HIL) method, advanced dc protection testing strategies, utilizing existing experience for ac grids and requirements for MTdc grids, may overcome this gap

Architecture and characterization of a calibrator for PMUs operating in power distribution systems

In recent years, the Phasor Measurement Unit (PMU) technology is rapidly evolving towards the potential deployment also in power distribution systems (DSs). In general, this specific field of applications requires PMUs whose accuracy levels are beyond those required by the IEEE Std. C37.118. Additionally, there is the need to define the architecture of an associated calibration system capable to assess the metrological performances of these devices. In this paper, we first analyse the impact of the uncertainties (in term of phase and magnitude) introduced by arbitrary PMUs on a state estimation (SE) process performed on the IEEE 13-bus distribution test feeder. The outcomes of this analysis are used to infer the most stringent steady-state performances of PMUs for DSs monitoring and, consequently, to define the requirements and the hardware archi- tecture of a PMU calibrator presently developed at the Author’s laboratories. A preliminary metrological characterization of the proposed calibrator is presented in the paper

Constrained Spherical Deconvolution Tractography reveals a direct cerebello-ventro tegmental pathway in humans

Introduction. In addition to its role in motor control, reflex adaption and motor learning in the past years numerous studies demonstrated the role of the cerebellum in non-motor functions. Furthermore, lesional animal and neuroimaging in vivo human studies demonstrated connections of the cerebellum with brain regions involved in cognitive, emotional, motivation linguistic processing [1, 2]. Although, studies suggest the role of the cerebellum in neuropsychiatric disorders of the mesocorticolimbic structure (i.e. schizophrenia), at the present time the existence cerebello-ventro tegmental pathway has been demonstrated in only in rodents and only hypothesized in humans. Aim. The goal of this in vivo constrained spherical deconvolution (CSD) tractography study is the investigation on the presence of a direct cerebello-ventro tegmental pathway in the human brain. Material and Methods. We recruited 15 human subjects with no previous history of neurological or psychiatric disorders. The entire study was performed using a 3T Achieva Philips scanner; a SENSE 8 channels head coil, acquiring T1 weighted 3D TFE, DTI sequence; data were analyzed by using constrained spherical deconvolution techniques (CDS). Results. We demonstrated with CSD dentate-ventral midbrain connections. In particular, we found a direct route linking between the dentate nucleus and the ventro tegmental area. Conclusions. This study provides for the first time the existence of a human dentate nucleus connections with the ventro tegmental area, moreover the existence of this cerebello-midbrain pathway suggest that the cerebellum may be involved in the modulation of the mesocorticolimbic system and in related neuropsychiatric disorders such as the schizophrenia