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Results achieved by the authors in the course of research activity on continuum mechanics and electrodynamics (CME) during the past twenty years are illustrated, revised and discussed. Adoption of a geometric approach leads to renewal of concepts and methods of classical CME and to formulation in Euclid (3+1)D ambient spacetime wherein innovation, clarity and depth of a geometric treatment naturally emerge. The dissemination of novel concepts and methods in CME is not delayable, with critical revisitation of problematic notions, analyses and results still currently on the scene. Material frame indifference, equilibrium in a reference configuration, extremality principles in Dynamics, finite elasticity, chain decomposition of finite strain in elasto-thermo-plasticity, variance of electro-magnetic induction laws under frame changes, action on electric charges moving in a magnetic field, are under the spotlight of innovation and advancement. Fostering basic knowledge of Differential Geometry and application of geometric notions and methods contribute effective tools in formulating meaningful rules, amending misstatements and dimming debates based on vague affirmations. [ABSTRACT FROM AUTHOR]

In Continuum Mechanics a widely cited formula, due to Nanson (Mess Math 7:182–185, 1878), contributes the relation between the product of area and unit normal vectors relevant to corresponding surfaces in two configurations of a 3D body. A geometric treatment provides equivalent expressions of Nanson formula by direct elaborations on Euler–Jacobi volume change formula. Meaning and limits of Nanson formula are underlined. In the literature this formula has been improperly assumed to be expedient for attempts of imposing equilibrium in a reference shape of the body. A critical revision shows recourse to scaling and parallel transport of surface and bulk forces is impassable in assessing alleged referential equilibrium. A variational formulation of evolutive equilibrium in spacetime is developed and finite step elastic problems guided by control algorithms in computational procedures are illustrated. Step-by-step iterative methods of solution of nonlinear structural problems and simple counterexamples should help in convincing referential equilibria are not conceivable in Nonlinear Continuum Mechanics. [ABSTRACT FROM AUTHOR]

Studying the cis–trans isomerization process in crocin (CR), one of the few water-soluble carotenoids extracted from saffron, is important to better understand the physiological role of cis-carotenoids in vivo and their potential as antioxidants in therapeutic applications. For that, cis–trans isomerization of both methanol- and water-dissolved CR was induced by light or thermally generated singlet oxygen (1O2). The kinetics of molecular concentrations were monitored by both high-performance liquid chromatography (HPLC) and non-destructive spectrophotometric methods. These last made it possible to simultaneously follow the cis–trans isomerization, the possible bleaching of compounds and the amount of thermally generated 1O2. Our results were in accordance with a comprehensive model where the cis–trans isomerization occurs as relaxation from the triplet state of all-trans- or 13-cis-CR, whatever is the way to populate the CR triplet state, either by photon or 1O2 energy transfer. The process is much more (1.9 to 10-fold) efficient from cis to trans than vice versa. In H2O, a 1O2-induced bleaching effect on the starting CR was not negligible. However, the CR "flip-flop" isomerization reaction could still occur, suggesting that this process can represent an efficient mechanism for quenching of reactive oxygen species (ROS) in vivo, with a limited need of carotenoid regeneration. [ABSTRACT FROM AUTHOR]

Background: To evaluate the neuroprotective effect of the topical ocular administration of fluoxetine (FLX) in a mouse model of acute retinal damage. Methods: Ocular ischemia/reperfusion (I/R) injury in C57BL/6J mice was used to elicit retinal damage. Mice were divided into three groups: control group, I/R group, and I/R group treated with topical FLX. A pattern electroretinogram (PERG) was used as a sensitive measure of retinal ganglion cell (RGC) function. Finally, we analyzed the retinal mRNA expression of inflammatory markers (IL-6, TNF-α, Iba-1, IL-1β, and S100β) through Digital Droplet PCR. Results: PERG amplitude values were significantly (p < 0.05) higher in the I/R-FLX group compared to the I/R group, whereas PERG latency values were significantly (p < 0.05) reduced in I/R-FLX-treated mice compared to the I/R group. Retinal inflammatory markers increased significantly (p < 0.05) after I/R injury. FLX treatment was able to significantly (p < 0.05) attenuate the expression of inflammatory markers after I/R damage. Conclusions: Topical treatment with FLX was effective in counteracting the damage of RGCs and preserving retinal function. Moreover, FLX treatment attenuates the production of pro-inflammatory molecules elicited by retinal I/R damage. Further studies need to be performed to support the use of FLX as neuroprotective agent in retinal degenerative diseases. [ABSTRACT FROM AUTHOR]

The virtual power principle (VPP) of continuum mechanics states a celebrated variational equality between external and internal virtual powers for any virtual velocity field conforming with linear kinematic constraints. The topic is here addressed to investigate how the original ideas born in the early XIX century are modelled by modern formulations based on Functional Analysis and Differential Geometry. These notions are able to provide an effective mathematical context for proving existence of Lagrange multipliers associated with the constraint of rigidity on velocity fields. The VPP stands as privileged tool for giving to stress fields a consistent definition based on duality with conforming virtual stretching fields. By complementarity, the VPP generates a variational condition for integrability of stretching fields, with self-equilibrated stresses as test fields. Progress is got by the formulation of the rate virtual power principle (RVPP) by time derivation of the VPP along the motion, with internal virtual power integrated per unit mass. The basic distinction between spatial and material fields according to the geometric paradigm is prompted to replace the one previously adopted in the literature. The need for a non-redundant implicit formulation of the rigidity constraint is emphasised to contrast degeneracy. This logical demand avoids proliferation of multipliers, in the spirit of Ockham's Razor, a celebrated philosophical motto with multiform applications. The shining mathematical theory set out by Leonhard Euler, Jean-Baptiste Le Rond d'Alembert, Joseph Louis Lagrange, and Augustin Cauchy is in this respect a point of optimality. A geometric rate theory of elasticity meets the call for no-dissipation in push-closed elastic cycles, with non need of any finite strain elastic energy functional, thus leading to a proper statement of rate equilibrium problems, basilar for computational formulations and for investigations about instability phenomena and post-critical behaviours. [ABSTRACT FROM AUTHOR]

The use of light for therapeutic purposes dates back to ancient Egypt, where the sun itself was an innovative source, probably used for the first time to heal skin diseases. Since then, technical innovation and advancement in medical sciences have produced newer and more sophisticated solutions for light-emitting sources and their applications in medicine. Starting from a brief historical introduction, the concept of innovation in light sources is discussed and analysed, first from a technical point of view and then in the light of their fitness to improve existing therapeutic protocols or propose new ones. If it is true that a “pure” technical advancement is a good reason for innovation, only a sub-system of those advancements is innovative for phototherapy. To illustrate this concept, the most representative examples of innovative light sources are presented and discussed, both from a technical point of view and from the perspective of their diffusion and applications in the clinical field. [ABSTRACT FROM AUTHOR]

Background: Ascaris lumbricoides and Ascaris suum are the most common soil-transmitted helminths of humans and pigs, respectively. The zoonotic potential of A. suum has been a matter of debate for decades. This study was aimed to present a case of human ascariasis caused by A. suum in southern Italy.Case Presentation: A 75-year-old man presented to the department of surgery in Avellino (southern Italy) complaining of abdominal pain and vomiting. Physical examination revealed bloating and abdominal tenderness. A computed tomography scan showed air-fluid levels and small bowel distension. During exploratory laparotomy a small bowel volvulus with mesenteritis was evident and surprisingly an intraluminal worm was detected. The worm was removed with a small enterotomy and identified as an adult female of A. suum based on morphological and molecular analysis. Faecal examination revealed the presence of unfertilized Ascaris eggs with an intensity of 16 eggs per gram (EPG) of faeces. The patient was treated with mebendanzole 100 mg twice a day for 3 days. The post-operative course was regular with re-alimentation after 3 days and discharge after 12 days.Conclusions: This report shows as A. suum can function as a relevant agent of human zoonosis. Therefore, in patients with bowel obstruction with no evident aetiology a helminthic infestation should be considered for an accurate diagnosis, especially in patients living in rural areas. [ABSTRACT FROM AUTHOR]

After European Medicines Agency (EMA) approval, national pricing and reimbursement procedures are necessary to guarantee access to drugs, based on the willingness to pay and the recognition of therapeutic value. These can result in delays in drug availability for patients, even for those with important unfmet needs for whom it may be necessary and ethical to ensure access. The objective of this study was to evaluate the use of ruxolitinib for patients with graft-versus-host disease (GvHD) after EMA approval at the University Hospital of Catania. We analysed data about the use of ruxolitinib in patients with GvHD, describing their basic characteristics, their outcomes and the cost of the treatment. In the reference period, 24 ruxolitinib treatments were started according to the Summary of Product Characteristic. The average treatment duration was 10 months. Twenty patients showed a response, maintained over time, with no adverse reactions. The total expenditure amounts to EUR 963,424. The use of ruxolitinib in a real population confirms its role in an important therapeutic need. The quantification of costs requires a reflection on the sustainability of early access to medicines authorised by the EMA for serious diseases and in the absence of therapeutic alternatives. [ABSTRACT FROM AUTHOR]

Nonlocal elasticity is addressed in the context of geometrically linearised structural models with linear and symmetric constitutive relations between dual fields, with physical interpretation of stress and elastic strain. The theory applies equally well to formulations as integral convolutions with an averaging symmetric kernel and to those involving an elastic potential depending on local gradients. According to the original strain-driven nonlocal elastic model, input and output of the stiffness operator are, respectively, the elastic strain field and the stress field. The swapped correspondence is assumed in the recently proposed stress-driven nonlocal elastic model, with input and output of the compliance operator, respectively, given by the stress field and the elastic strain field. Two distinct nonlocal elasticity models, not the inverse of one another, may thus be considered. The strain-driven model leads to nonlocal elastostatic problems which may not admit solution due to conflicting requirements imposed on the stress field by constitutive law and equilibrium. To overcome this obstruction, several modifications of the original scheme have been proposed, including mixtures of local/nonlocal elastic laws and compensation of boundary effects. On the other hand, the stress-driven model leads to nonlocal elastostatic problems which are consistent and well-posed. Two iterative methods of solution, respectively, for stress-driven and mixture strain-driven models, are here contributed and analysed. The relevant algorithms require only solutions of standard local elastostatic problems. Fixed points of the algorithms are shown to be coincident with solutions of the pertinent nonlocal elastostatic problem. It is also proven that, for statically determinate structural models, the iterative method pertaining to the nonlocal stress-driven model converges to the solution just at the first step. For statically indeterminate ones, the computations reveal that convergence is asymptotic but very fast. Clamped-free and clamped-supported nano-beams are investigated as standard examples in order to provide evidence of the theoretical results and to test and show performance of the iterative procedures. [ABSTRACT FROM AUTHOR]

Uveal melanoma (UM) represents the most frequent primary tumor of the eye. Despite the development of new drugs and screening programs, the prognosis of patients with UM remains poor and no effective prognostic biomarkers are yet able to identify high-risk patients. Therefore, in the present study, microRNA (miRNA or miR) expression data, contained in the TCGA UM (UVM) database, were analyzed in order to identify a set of miRNAs with prognostic significance to be used as biomarkers in clinical practice. Patients were stratified into 2 groups, including tumor stage (high-grade vs. low-grade) and status (deceased vs. alive); differential analyses of miRNA expression among these groups were performed. A total of 20 deregulated miRNAs for each group were identified. In total 7 miRNAs were common between the groups. The majority of common miRNAs belonged to the miR-506-514 cluster, known to be involved in UM development. The prognostic value of the 20 selected miRNAs related to tumor stage was assessed. The deregulation of 12 miRNAs (6 upregulated and 6 downregulated) was associated with a worse prognosis of patients with UM. Subsequently, miRCancerdb and microRNA Data Integration Portal bioinformatics tools were used to identify a set of genes associated with the 20 miRNAs and to establish their interaction levels. By this approach, 53 different negatively and positively associated genes were identified. Finally, DIANA-mirPath prediction pathway and Gene Ontology enrichment analyses were performed on the lists of genes previously generated to establish their functional involvement in biological processes and molecular pathways. All the miRNAs and genes were involved in molecular pathways usually altered in cancer, including the mitogen-activated protein kinase (MAPK) pathway. Overall, the findings of the presents study demonstrated that the miRNAs of the miR-506-514 cluster, hsa-miR-592 and hsa-miR-199a-5p were the most deregulated miRNAs in patients with high-grade disease compared to those with low-grade disease and were strictly related to the overall survival (OS) of the patients. However, further in vitro and translational approaches are required to validate these preliminary findings. [ABSTRACT FROM AUTHOR]

Abstract This study aims to detect the variability of riparian vegetation by means of in-situ measurements of the Leaf Area Index (LAI) and its retrieval from Landsat 8 satellite images in a Mediterranean stream ('Cammarota', Puglia region, Southern Italy) characterized by the presence of intact and destroyed check dams. Fifty-three transects were measured using a Plant Canopy Analyzer and a broad range of LAI values (0.26–5.71) was observed. Lower values were found in Cammarota reaches with damaged or destroyed check dams that led to active erosive processes, whereas higher LAI values were detected in the reaches with greater geomorphological stability. These results were confirmed by the analysis of a nearby stream ('Vallone della Madonna') with intact check dams and sound riparian vegetation which produced a higher range (4.08–5.93) of LAI values. The LAI values of riparian vegetation in both streams were compared with those found in more homogeneous types of vegetation (wheat field and deciduous forest) in the surrounding areas, which were used as control plots. Landsat 8 satellite images relating to the same period of field activity were also analyzed, and the performance of three equations for deriving LAI values from the corrected Normalized Difference Vegetation Index (NDVI) was evaluated. The Lambert-Beer equation gave the best statistical performance for predicting LAI within the reaches of the Cammarota stream with a denser vegetation, as well as in the Vallone della Madonna stream and deciduous forest. The significant variability of the observed LAI values in the Cammarota reach subject to initial erosive processes, was not detected by any of the equations applied. Graphical abstract Unlabelled Image Highlights • Leaf Area Index of riparian vegetation is variable based on erosive processes. • Check dams have important effects on riparian vegetation. • Leaf Area Index values of riparian vegetation can be similar to forest areas. • Landsat 8 satellite images represent Leaf Area Index values with some limitations. • The Lambert-Beer equation gave the best statistical performance. [ABSTRACT FROM AUTHOR]

Abstract The near-wake flow field downstream of a square-back car model is analyzed to investigate on the combined effect of horizontal and vertical deflectors. Aerodynamic coefficients and near-wake velocity fields are presented for a range of deflectors size and slant angles, for Reynolds number Re ≈ 250,000 based on free stream velocity and model height. Mean velocity fields and turbulence quantities are shown to shed light onto the interactions taking place within the wake. The underlying rationale is to couple a decrease of the wake extent along the vertical direction, achieved by reducing the size of the top separated region, to a simultaneous reduction of the fluctuations in the horizontal plane induced by the lateral longitudinal vortices. Vertical deflectors height is reported to play a key role in this scenario markedly affecting the resulting drag and lift coefficients. Analysis of velocity fields points out the existence of an optimal vertical spoiler size, in the presented set-up equal to 2/3 of model height, which features the overall best performance compared to other tested configurations. The beneficial effect of combined spoilers is found to be more relevant when horizontal and vertical deflectors feature a moderate (20°) slant angle with respect to free stream direction. Highlights • Particle Image Velocimetry measurements of the near wake of a square-back model with deflectors. • Near-wake data is correlated to aerodynamic coefficients measurements. • Combination of horizontal and vertical deflectors of different sizes and at different angles are analyzed. • An optimal combination of deflectors size and angle is identified. [ABSTRACT FROM AUTHOR]

[Display omitted] • Plunging water jets issuing horizontally in air from different orifices are studied. • Asymmetry is observed in both circular and rectangular jets. • For circular jets, better mixing performances are observed at low Reynolds numbers. • For rectangular jets, better mixing ability is observed for high Reynolds numbers. • Shear layer instabilities are investigated. In the present work we study the topology, mixing properties, turbulence quantities, dependence on the outlet geometry of a sharp-edged orifice plunging jet which first issues horizontally in air and then plunges in a water pool. The investigated orifices shapes are circular and rectangular. Data are acquired at different Reynolds numbers in the range 11000–25000, based on the orifice diameter (equal to 2 cm) and on the average exit velocity, as derived from flow rate measurements. Velocity fields in vertical and horizontal planes are measured using planar time-resolved Particle Image Velocimetry. Results show a clear asymmetry of the cross-velocity profiles both in circular and rectangular cases, with the latter that revealed a shape which is Reynolds number dependent. Axial velocity decays, potential core lengths and spreading rates highlight an opposite trend between the two jet geometries, thus suggesting a higher mixing for the lowest Reynolds number circular jet and the highest rectangular one. Plunging angle shows a dependency on Reynolds number. Moreover, it seems to play a role in the evolution of the upper and lower side of the jet due to the onset of a co-flow. Ambient mass entrainment points out the different interactions of the two plunging jets with the ambient flow: in circular case, it entrains fluid from the surroundings, from horizontal to vertical planes in streamwise direction, while in rectangular one it ejects flow from vertical to horizontal planes. Finally, Strouhal numbers are derived for main vortices frequencies along jet centerline, other than upper and lower sides. [ABSTRACT FROM AUTHOR]

Isoflavones are a group of (poly)phenols, also defined as phytoestrogens, with chemical structures comparable with estrogen, that exert weak estrogenic effects. These phytochemical compounds have been targeted for their proven antioxidant and protective effects. Recognizing the increasing prevalence of cardiovascular diseases (CVD), there is a growing interest in understanding the potential cardiovascular benefits associated with these phytochemical compounds. Gut microbiota may play a key role in mediating the effects of isoflavones on vascular and endothelial functions, as it is directly implicated in isoflavones metabolism. The findings from randomized clinical trials indicate that isoflavone supplementation may exert putative effects on vascular biomarkers among healthy individuals, but not among patients affected by cardiometabolic disorders. These results might be explained by the enzymatic transformation to which isoflavones are subjected by the gut microbiota, suggesting that a diverse composition of the microbiota may determine the diverse bioavailability of these compounds. Specifically, the conversion of isoflavones in equol—a microbiota-derived metabolite—seems to differ between individuals. Further studies are needed to clarify the intricate molecular mechanisms behind these contrasting results. [ABSTRACT FROM AUTHOR]

Nonlocal elasticity is addressed in terms of integral convolutions for structural models of any dimension, that is bars, beams, plates, shells and 3D continua. A characteristic feature of the treatment is the recourse to the theory of generalised functions (distributions) to provide a unified presentation of previous proposals. Local-nonlocal mixtures are also included in the analysis. Boundary effects of convolutions on bounded domains are investigated, and analytical evaluations are provided in the general case. Methods for compensation of boundary effects are compared and discussed with a comprehensive treatment. Estimates of limit behaviours for extreme values of the nonlocal parameter are shown to give helpful information on model properties, allowing for new comments on previous proposals. Strain-driven and stress-driven models are shown to emerge by swapping the mechanical role of input and output fields in the constitutive convolution, with stress-driven elastic model leading to well-posed problems. Computations of stress-driven nonlocal one-dimensional elastic models are performed to exemplify the theoretical results. [ABSTRACT FROM AUTHOR]

The general role of control windows is investigated by an assessment of the fundamentals of continuum dynamics in the spacetime context. The momentum rate of change of a continuous body is evaluated with reference to a control window travelling in the spacetime trajectory manifold. The resulting formula involves the rate of change of the momentum in the control window and the rate of outflow of the momentum across the control window boundary. An effective tool for investigating challenging dynamical problems is thus available, and some interesting examples, taken from early and recent contributions, are illustrated. Among these, motions of chains falling under the action of gravity, object of several investigations in the past two centuries, are revisited. Around the middle of the nineteenth century, the problem was inserted as a daring task in the Mathematical Tripos at Cambridge. The choice of a special control window, named the skeleton, in motion with the solid case, provides the proper methodology for the formulation of solid-fluid interaction problems, with applications to turbines, jets, rockets and sprinklers. As a further significant application of travelling control windows, a variational formulation of conservation of mass is developed and shown to yield the notion of mass flow vector field, with applications in problems of fluid flow through a porous solid. [ABSTRACT FROM AUTHOR]

The aim of this study is to model potential changes in land use and evaluate their effects on sediment load in a Mediterranean watershed, the Carapelle, in Southern Italy. For this purpose, a set of Landsat Thematic Mapper (TM) images were processed to generate three different land use maps for 1987, 2002, and 2011. The images were corrected for geometric distortion and atmospheric interference before performing an unsupervised classification and decision expert system post classification. The land use maps for 1987 and 2002, derived from the Landsat TM processing, were analyzed using a Land Change Modeler (LCM) module to identify transitions from the first land cover type to the second. The transitions were modeled using a multi-layer perceptron (MLP) neural network to create transition potential maps, which provide the controls for subsequent dynamic land use change predictions. The model produced a predicted land use map for 2011 using Markov Chain analysis, which was validated with the actual 2011 land use map. Consequently, a land use scenario (S1) for 2035 and 2050 was predicted, taking into account the current constraints and management options. LCM was further used to define two additional scenarios (S2 and S3) both for 2035 and 2050 based on different land management options. Finally, the Annual Agricultural Non-Point Source Pollution Model (AnnAGNPS) was used to estimate the effect of the predicted land use changes on sediment load after model calibration, using a five-year dataset registered at the Ordona monitoring station. The land use change analysis revealed low transformations from 1987 to 2011. Equally, land use changes were low for the base scenario (S1) so moderate variations in sediment load were estimated. The changes in land use were more significant for the additional scenarios (S2 and S3) and consequently the model estimations underwent major variations, with a significant reduction of soil erosion. The associated utilization of land use change analysis and AnnAGNPS modeling demonstrates how land use management options can be adopted to reduce potential watershed sediment load. [ABSTRACT FROM AUTHOR]

There are, in each branch of science, statements which, expressed in ambiguous or even incorrect but seemingly friendly manner, were repeated for a long time and eventually became diffusely accepted. Objectivity of physical fields and of their time rates and frame indifference of constitutive relations are among such notions. A geometric reflection on the description of frame changes as spacetime automorphisms, on induced push-pull transformations and on proper physico-mathematical definitions of material, spatial and spacetime tensor fields and of their time-derivatives along the motion, is here carried out with the aim of pointing out essential notions and of unveiling false claims. Theoretical and computational aspects of nonlinear continuum mechanics, and especially those pertaining to constitutive relations, involving material fields and their time rates, gain decisive conceptual and operative improvement from a proper geometric treatment. Outcomes of the geometric analysis are frame covariance of spacetime velocity, material stretching and material spin. A univocal and frame-covariant tool for evaluation of time rates of material fields is provided by the Lie derivative along the motion. The postulate of frame covariance of material fields is assessed to be a natural physical requirement which cannot interfere with the formulation of constitutive laws, with claims of the contrary stemming from an improper imposition of equality in place of equivalence. [ABSTRACT FROM AUTHOR]

Nonlocal integral constitutive laws, for application to nano-beams, are investigated in a general setting. Both purely nonlocal and mixture models involving convolutions with averaging kernels are taken into account. Evidence of boundary effects is enlightened by theoretical analysis and numerical computations. Proposed compensation procedures are analyzed, relevant new results are evidenced and confirmed by computations. The strain-driven model and related local-nonlocal mixtures are addressed, with singular phenomena foreseen and numerically quantified. Effectiveness of the recently proposed stress-driven nonlocal elastic model is discussed and illustrated by description of a general solution procedure for nonlocal elastic beams. Comparisons between strain-driven models, stress-driven models and local/nonlocal mixtures are considered from theoretical and computational perspectives. Examples of statically determinate and indeterminate beams are elaborated to show that an effective simulation of scale effects in nano-structures, ensuring existence and uniqueness of solution for any data, is provided by the stress-driven model. [ABSTRACT FROM AUTHOR]

In the strain-driven model of nonlocal elasticity proposed by Eringen , the elastic strain is defined by a Fredholm integral equation in which the stress is the output of a convolution between the local response to an elastic strain and a smoothing kernel dependent on a nonlocal parameter. In the wake of this proposal, size effects in nano-beams were investigated in literature by adopting a differential formulation considered to be equivalent to the integral one. Recent improvements have however revealed that equivalence requires also the fulfilment of constitutive boundary conditions. Moreover, this strain-driven nonlocal elastic problem has been shown to be ill-posed, being conflicting with equilibrium requirements. A stress-driven integral constitutive law provides the natural way to get well-posed nonlocal elastic problems for application to nano-structures. The new integral constitutive law is formulated with explicit reference to plane and straight nano-beams according to the standard Bernoulli - Euler structural model. The solution procedure based on the stress-driven nonlocal law is described and adopted for the solution of a simple statically indeterminate scheme, thus showing effectiveness of the new model for the structural design of nano-devices. [ABSTRACT FROM AUTHOR]

The dynamical interaction between solids and fluids is a subject of paramount importance in Mechanics with a wide range of applications to engineering problems. It is, however, still a challenging topic of theoretical investigation. With a view to case studies of dynamical behaviour of rockets, turbines, jets and sprinklers, we develop here a treatment that, in the full respect of the principle of conservation of mass and under suitable simplifying assumptions, leads to evaluate the thrusting force exerted by the fluid on the solid. The goal is reached by applying the Euler-d'Alembert law of continuum dynamics to the trajectory of a skeleton whose motion is an extension of the one of the solid. It is shown that the formulation in the context of continuum mechanics is essential to get a full understanding of the dynamical problem and for grasping the meaning and range of validity of the results. This is a distinctive feature from treatments in literature where particles or control windows with variable mass are considered. The statement of the von Buquoy-Meshchersky law as a governing principle in the dynamics of particles with variable mass, in substitution of Newton's second law, is critically addressed. Under the assumption of low mass and high momentum time rate, the formula for the thrusting force is validated as a simplified expression fulfilling Galilei's principle of relativity. [ABSTRACT FROM AUTHOR]

A debated issue, in applications of Eringen 's nonlocal model of elasticity to nanobeams, is the paradox concerning the solution of simple beam problems, such as the cantilever under end-point loading. In the adopted nonlocal model, the bending field is expressed as convolution of elastic curvature with a smoothing kernel. The inversion of the nonlocal elastic law leads to solution of a Fredholm integral equation of the first kind. It is here shown that this problem admits a unique solution or no solution at all, depending on whether the bending field fulfils constitutive boundary conditions or not. Paradoxical results found in solving nonlocal elastostatic problems of simple beams are shown to stem from incompatibility between the constitutive boundary conditions and equilibrium conditions imposed on the bending field. The conclusion is that existence of a solution of nonlocal beam elastostatic problems is an exception, the rule being non-existence for problems of applicative interest. Numerical evaluations reported in the literature hide or shadow this conclusion since nodal forces expressing the elastic response are not checked against equilibrium under the prescribed data. The cantilever problem is investigated as case study and analytically solved to exemplify the matter. [ABSTRACT FROM AUTHOR]

The kinematics of generalized continua is investigated and key points concerning the definition of overall tangent strain measure are put into evidence. It is shown that classical measures adopted in the literature for micromorphic continua do not obey a constraint qualification requirement, to be fulfilled for well-posedness in optimization theory, and are therefore termed redundant. Redundancy of continua with latent microstructure and of constrained Cosserat continua is also assessed. A simplest, non-redundant, kinematic model of micromorphic continua, is proposed by dropping the microcurvature field. The equilibrium conditions and the related variational linear elastostatic problem are formulated and briefly discussed. The simplest model involves a reduced number of state variables and of elastic constitutive coefficients, when compared with other models of micromorphic continua, being still capable of enriching the Cauchy continuum model in a significant way. [ABSTRACT FROM AUTHOR]

A scaled-model of a horizontal axis tidal current turbine (HATCT) is tested in the CNR-INM Circulating Water Channel. The experiments are designed to establish in the first place the performances of the turbine at different working settings. The second goal is to investigate the hydrodynamics generated by the turbine in the near wake using the Particle Image Velocimetry (PIV) technique. For this purpose, velocity measurements are performed in a longitudinal plane and phase-locked to the rotor angle in order to resolve the wake structure at different working regimes. The analysis of the axial and radial velocity fields reveals the flow features of the slipstream, as well as its expansion and dependence on the turbine operating parameters. Analysis of the non-diagonal terms of the Reynolds stress tensor provides insight into the onset of tip vortex pairing and of vortex instabilities. Furthermore the separate contributions of transport, production and dissipation to the turbulent kinetic energy in the wake field are discussed in detail. The vortex unsteadiness is captured and correlated with the evolution of the kinetic energy transport and production terms. Understanding these phenomenologies is an important step to develop computational tools able to estimate the radiated noise or the potential impact of turbulence on performances of further rotors placed in the wake, as in an array of tidal turbines. • Topology of rotor wake is revealed via in-phase Particle Image Velocimetry (PIV). • Slipstream expansion is largest at maximum power coefficient. • Production and transport of turbulent kinetic energy are dominant in tip vortices. • Dissipation and viscous effects are negligible in the near wake. • Vorticity skewness is a probe into the spatial fluctuations of the tip vortex. [ABSTRACT FROM AUTHOR]

In this work, a turbulent backward-facing step flow at Reynolds number ReH = 17 520, laden with rod-like particles, is investigated by means of particle image velocimetry. Particle loadings tested are within 0.02% and 0.05% volume fractions; thus, the suspensions may be considered as dilute. The high spatial resolution allows the identification of fiber orientation within the flow, so that mutual interactions between phases can be investigated by considering flow modifications and phenomena related to preferential concentration and orientation of fibers. Fibers' concentration data show a moderate trend to accumulate at the channel centreline, whereas orientation data display a strong preferential orientation of fibers. Specifically, the local fibers' orientation is correlated to the flow field in terms of mean flow direction and plane of maximum shear. The occurrence of a symmetrical orientation profile with respect to the channel centre-line is reported as well as the tendency to recover such profile downstream of the step. [ABSTRACT FROM AUTHOR]

Elasticity is the prototype of constitutive models in Continuum Mechanics. In the nonlinear range, the elastic model claims for a geometrically consistent physico-mathematical formulation providing also the logical premise for linearized approximations. A theoretic framework is envisaged here with the aim of contributing a conceptually clear, physically consistent, and computationally convenient formulation. A reasoning about the physics of the model, from a geometric point of view, leads to conceive constitutive relations as instantaneous incremental responses to a finite set of tensorial state variables and to their time rates along the space-time motion. Integrability of the tangent elastic compliance, existence of an elastic stress potential, and conservativeness of the elastic response, under the conservation of mass, are given a brand new treatment. Finite elastic strains have no physical interpretation in the new rate theory, and referential local placements are appealed to, just as loci for operations of linear calculus. Frame invariance is assessed with a consistent geometric treatment, and the clear distinction between the new notion and the property of isotropy is pointed out, thus overcoming the improper statement of material frame indifference. Extension of the theory to elasto-visco-plastic constitutive models is briefly addressed. Basic computational steps are described to illustrate feasibility and convenience of calculations according to the new theory of elasticity. [ABSTRACT FROM AUTHOR]

In solving problems of geometrically nonlinear structural mechanics, a prominent role is played by formulation of rate equilibrium conditions. In the computational machinery, the evaluation of the stiffness operator provides the trial incremental displacement field as fixed point of an iterative algorithm. The issue is investigated by a new geometric approach to continuum mechanics. Kinematics is described by the motion along a trajectory manifold embedded in the affine four-dimensional space-time. Variational conditions of equilibrium and rate equilibrium are formulated in terms of natural time rates of stress and stretching. The rate elastostatic problem is formulated in the full nonlinear context by adopting a newly contributed rate-elastic constitutive model. The geometric stiffness and forcing operators are expressed in terms of an arbitrary linear spatial connection. It is shown that the adoption of a Levi- Civita connection provides a linear expression of the geometric stiffness involving a curvature term. For bodies in motion in the flat Euclid space with parallel transport by translation, a symmetric expression of the geometric stiffness is obtained, thus extending the standard formula to bodies of any dimensionality. [ABSTRACT FROM AUTHOR]

Abstract: The need for a proper geometric approach to constitutive theory in non-linear continuum mechanics (NLCM) is witnessed by lasting debates about basic questions concerning time-invariance, integrability, conservativeness and frame invariance. Our aim is to bring geometry to play a central role in theoretical and computational issues of NLCM. This demand is imposed by the present state of art, dominated by a mainly algebraic approach which, being a modified heritage of the linearized theory, is inadequate to manage concepts and methods in a non-linear framework. A proper definition of spatial and material fields and the statement of the ensuing covariance paradigm, provide a firm foundation to the theory of constitutive behavior in NLCM. The notion of constitutive frame invariance (CFI) is introduced as geometric correction to the formulation of material frame indifference (MFI). Standard models of constitutive behavior are critically discussed and compared with the ones consistent with the new approach. The outcome is a physically testable theory which eventually results in new effective computation tools for structural engineers. [Copyright &y& Elsevier]

The Lie time-derivative of the material metric tensor field along the motion is the proper mathematical definition of the physical notion of strain rate or stretching. Its expression, as symmetric part of the velocity gradient in Euclid space, is provided by a celebrated formula conceived by the genius of Leonhard Euler around the middle of the eighteenth century and since then reproduced in articles, books and treatises on continuum mechanics. We present here a formulation, in the proper geometric context of the four-dimensional space-time manifold endowed with an arbitrary linear connection and referring to a material body of arbitrary dimensionality. The expression involves the material time-derivative of the metric field and torsion-form and gradient of the velocity field, according to the connection induced on the trajectory. As an application, the expressions of the G ram matrix of the stretching in natural and in normalized (or engineering) reference systems induced by orthogonal polar coordinates are provided. [ABSTRACT FROM AUTHOR]

We introduce a probabilistic version of the well-known Rand Index (RI) for measuring the similarity between two partitions, called Probabilistic Rand Index (PRI), in which agreements and disagreements at the object-pair level are weighted according to the probability of their occurring by chance. We then cast consensus clustering as an optimization problem of the PRI value between a target partition and a set of given partitions, experimenting with a simple and very efficient stochastic optimization algorithm. Remarkable performance gains over input partitions as well as over existing related methods are demonstrated through a range of applications, including a new use of consensus clustering to improve subtopic retrieval. [ABSTRACT FROM PUBLISHER]

Abstract: Torsion and shear stress fields of a Saint-Venant beam and the relative location of shear and twist centres are investigated for sections of any degree of connectedness. The sliding-torsional compliance tensor of a Timoshenko beam is evaluated by an energy equivalence with Saint-Venant theory. Accordingly, the mutual sliding-torsional term is shown to depend linearly on the relative position of shear and twist centres and the standard definition of shear centre in a Timoshenko beam is found to be coincident with Saint-Venant twist centre. Coincidence of shear and twist centres is assessed for sections with vanishing Poisson ratio and for open, closed and multi-cell thin-walled cross sections. The eigenvalues of the shear factors tensor and the torsion factor are shown to be greater than unity, with the principal directions of shearing and bending compliances non necessarily coincident for non-symmetric cross sections. Numerical examples are developed to provide evidences of the location of the centres and of the principal shearing directions, for non-symmetric L-shaped cross sections with various thickness ratios. [Copyright &y& Elsevier]

Abstract: The theory of constitutive behavior, with explicit reference to hypo-elastic materials, is addressed with a geometric approach which, following physical arguments, leads to a covariant formulation. The essential role played by a careful distinction between spatial vectors, material-based spatial vectors and material vectors is emphasized. Definite answers to debated issues, such as the proper definition of stress rate, the formulation of integrability conditions, the fulfilment of material frame-indifference, and the task of evaluating the stress state evolution, are given. Simple shear and extension of a specimen of a hypo-elastic material are investigated as applications of the theory. Improper statements and unsound physical responses of hypo-elastic materials are overcome by the covariant theory, thus restoring the proper role to this constitutive model, for both theoretical and computational purposes. [Copyright &y& Elsevier]

Purpose: To perform colorimetric characterization of 2 blue light–filtering intraocular lens (IOL) models and an IOL that filters ultraviolet–violet (UV–v) light and compare the charactizations with those of a standard UV light–filtering IOL and the human crystalline lens at various ages. Setting: Department of Clinical Physiopathology, University of Florence, and National Institute of Applied Optics, CNR, Florence, Italy. Design: Experimental study. Methods: Three IOLs of each model with different dioptric powers (16.0, 21.0, and 26.0 diopters) were analyzed. The colorimetric coordinates of the IOLs were calculated by measuring their transmission spectra using a microspectroscopy technique. Subsequently, a parameter (ΔE) that was proportional to the perceived color differences was defined. The results of the IOLs and of the human crystalline lens at different ages (4, 22, 41, 53, and 72 years; values taken from the literature) were compared. The colorimetric analysis was performed using Commission Internationale de l’Éclairage standards. Results: The maximum ΔE value was with the standard UV light–filtering IOL at any crystalline lens age and was greatest with a 72-year-old human lens. The minimum ΔE value was obtained for both blue light–filtering IOLs with middle-aged human lenses. Conclusions: None of the analyzed IOLs had the same colorimetric performance of the human crystalline lens. The 2 blue light–filtering IOLs best reproduced yellowing of the human lens at 40 to 50 years of age. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. [ABSTRACT FROM AUTHOR]

Abstract: The algorithmic, or consistent, tangent stiffness was introduced to improve the asymptotic convergence rate of the iterative correction algorithm for the evolutive analysis of elastoplastic structures. The original approach is based on a formulation of the elastoplastic law in terms of a plastic multiplier with an analysis which, in general, requires an operator inversion. A geometric description of the method, based on hypersurface theory, is proposed here to provide a clear picture of the algorithmic properties. An estimate of the tangent stiffness associated with finite step elastoplastic and elastoviscoplastic constitutive models is given. It is based on the properties of the projection operator on the elastic domain and avoids operator inversions retaining the beneficial properties of the original one. [Copyright &y& Elsevier]

The First Principle of Continuum Thermodynamics is formulated as a variational condition whose test fields are piecewise constant virtual temperatures. Lagrange multipliers theorem is applied to relax the constraint of piecewise constancy of test fields. This provides the existence of square summable vector fields of heat flow through the body fulfilling a virtual thermal work principle, analogous to the virtual work principle in Mechanics. The issue of compatibility of thermal gradients is dealt with and expressed by the complementary variational condition. Primal, complementary and mixed variational inequalities leading to computational methods in heat-conduction boundary-value problems are briefly discussed. [ABSTRACT FROM AUTHOR]

The theory of continuous dynamical systems is developed with an intrinsic geometric approach based on the action principle formulated in the velocity-time manifold. By endowing the finite dimensional Riemannian ambient manifold with a connection, an induced connection is naturally defined in the infinite dimensional configuration manifold of maps. The motion is shown to be governed, in the Banach configuration manifold, by a generalized Lagrange law and, in the ambient manifold, by a generalized Euler law which is independent of the Banach topology of the configuration manifold. Extended versions of Euler–Poincaré law, Euler classical laws and d’Alembert law are also derived as special cases. Stress fields in the body are introduced as Lagrange’s multipliers of the rigidity constraint on virtual velocities, dual to the Lie derivative of the metric. No special assumptions are made so that any constitutive behaviors can be modeled. [ABSTRACT FROM AUTHOR]

Abstract: The dynamics of Lagrangian systems is formulated with a differential geometric approach and according to a new paradigm of the calculus of variations. Discontinuities in the trajectory, non-potential force systems and linear constraints are taken into account with a coordinate-free treatment. The law of dynamics, characterizing the trajectory in a general non-linear configuration manifold, is expressed in terms of a variational principle and of differential and jump conditions. By endowing the configuration manifold with a connection, the general law is shown to be tensorial in the velocity of virtual flows and to depend on the torsion of the connection. This result provides a general expression of the EULER–LAGRANGE operator. POINCARÉ and LAGRANGE forms of the law are recovered as special cases corresponding, respectively, to the connection induced by natural and mobile reference frames. For free motions, the geodesic property of the trajectory is directly inferred by adopting the LEVI-CIVITA connection induced by the kinetic energy. [Copyright &y& Elsevier]

A new statement of Maupertuis principle of extremal action is contributed on the basis of a constrained action principle in the velocity phase-space in which the condition of energy conservation is imposed on virtual velocities. Dynamical systems governed by time-dependent Lagrangians on nonlinear configuration manifolds and subject to the action of time-dependent forces are considered. In time-independent systems, and in particular in conservative systems, the constrained action principle specializes to a formulation of the original Maupertuis least action principle in which however conservation of energy along the trajectory is a natural consequence of the variational principle and not an a priori assumption as in classical statements. [Copyright &y& Elsevier]

The effect of three windshield shapes on the aerodynamic performance of a racing-type motorcycle is investigated experimentally via global wind-tunnel force balance measurement and detailed local wake analysis by Particle Image Velocimetry. Results are compared to two driver's stances as well as to a baseline case. Results are dependent mainly on the windshield length as coupled to the driver positioning. Full-size windshield is characterized by a quite uniform wake structure and reduced level of velocity fluctuations and turbulence and is associated to improved stability, in spite of a relative increase of drag. When the additional safety and driver's protection from weather conditions are considered, the use of a full-size windshield appears an effective solution for commercial motorcycles. • Aerodynamics of a racing motorcycle is analyzed by force measurements and PIV. • A range of windshield lengths and rider stances is investigated. • Full-size windshield features uniform wake structure and reduced velocity fluctuations. [ABSTRACT FROM AUTHOR]

Abstract: The theory of material inhomogeneities, according to Noll’s approach, is revisited in detail and its interpretations in the recent literature on material anelastic behaviors, growth and phase transition phenomena are critically discussed. [Copyright &y& Elsevier]

An implication rule Q→ R is a statement of the form “for all objects in the database, if an object has the attribute–value pairs Q then it has also the attribute–value pairs R.” This simple type of rule is theoretically interesting, because it supports reasoning, similar to functional dependencies in database theory, and it may be of practical significance because the size of the set of implication rules that hold in a relation can remain substantially high even when mining real data and considering only most general covers; i.e., covers containing rules with unredundant right and left sizes. Motivated by these observations, we focus on the extraction of short-rule covers, which cannot be efficiently mined by standard rule miners. We present an algorithm driven by “negative examples” (i.e., satisfy Q but not R) to prune the rule-candidate lattice associated with each “positive example” (i.e., satisfies both Q and R). The algorithm scales up quite well with respect to the number of objects and it is particularly suitable for databases with attributes described by large domains. Furthermore, a perfect hash function ensures extraction of short-rule covers even from databases containing a large number of attributes. [ABSTRACT FROM AUTHOR]

Examines methods for automatic query expansion from top retrieved documents that make use of various functions for scoring expansion terms within a classical reweighting scheme. Comparison of several retrieval feedback methods; Description of an approach to combining the results produced by multiple term-scoring functions; Effect of query length on retrieval feedback performance.

Presents an approach to document ranking that addresses the word mismatch problem by exploiting interdocument similarity information. Limitations of hierarchical clustering-based ranking; View of document ranking as a representation transformation in a conceptual space; Introduction of concept lattice-based ranking.

Glaucoma is a heterogeneous group of chronic neurodegenerative disorders characterized by a relatively selective, progressive damage to the retinal ganglion cells (RGCs) and their axons, which leads to axon loss and visual field alterations. To date, many studies have shown the role of various elements, mainly metals, in maintaining the balance of prooxidative and antioxidative processes, regulation of fluid and ion flow through cell membranes of the ocular tissues. Based on the earlier and current research results, their relationship with the development and progression of glaucoma seems obvious and is increasingly appreciated. In this review, we aimed to summarize the current evidence on the role of trace elements in the pathogenesis and prevention of glaucomatous diseases. Special attention is also paid to the genetic background associated with glaucoma-related abnormalities of physiological processes that regulate or involve the ions of elements considered as trace elements necessary for the functioning of the cells. [ABSTRACT FROM AUTHOR]

In this paper we consider two related types of data dependencies that can hold in a relation: conjunctive implication rules between attribute-value pairs, and functional dependencies. We present a conceptual clustering approach that can be used, with some small modifications, for inferring a cover for both types of dependencies. The approach consists of two steps. First, a particular clustered representation of the relation, called concept (or Galois) lattice, is built. Then, a cover is extracted from the lattice built in the earlier step. Our main emphasis is on the second step. We study the computational complexity of the proposed approach and present an experimental comparison with other methods that confirms its validity. The results of the experiments show that our algorithm for extracting implication rules from concept lattices clearly outperforms an earlier algorithm, and suggest that the overall lattice-based approach to inferring functional dependencies from relations can be seen as an alternative to traditional methods. [ABSTRACT FROM AUTHOR]

The present study aims investigating experimentally wing/blade geometries in which the leading edge is modified by the presence of artificial bumps, following examples in nature ("biomimetics"). Specifically, the tubercles observed in humpback whales are considered with a special focus on easy manufacturing and performance improvements, trying to overcome the observed lift coefficient reduction before stall in comparison with a standard wing. To this end, different tubercle geometries are tested, by measuring overall forces acting on the wings and by deriving detailed velocity fields using particle image velocimetry. Measurements indicate performance improvements for all trailing edge tubercle geometries here tested. In addition, the detailed analysis of mechanisms underlying the improvement of performances suggests that a triangular shape of the leading edge combines the advantages of easy manufacturing and improvements of pre-stall behaviour. So far, a simple mathematical model, describing tubercles as delta wings, is presented and verified by experimental data. The objective of the present work is focusing on the basic fluid-mechanics phenomena involved, to show that beneficial effects of tubercles are present even when tubercle details are simplified, in order to couple performance improvement and ease of assembly. [ABSTRACT FROM AUTHOR]

In recent decades, technological advancements in sensors have generated increasing interest in remote sensing data for the study of vegetation features. Image pixel resolution can affect data analysis and results. This study evaluated the potential of three satellite images of differing resolution (Landsat 8, 30 m; Sentinel-2, 10 m; and Pleiades 1A, 2 m) in assessing the Leaf Area Index (LAI) of riparian vegetation in two Mediterranean streams, and in both a winter wheat field and a deciduous forest used to compare the accuracy of the results. In this study, three different retrieval methods—the Caraux-Garson, the Lambert-Beer, and the Campbell and Norman equations—are used to estimate LAI from the Normalized Difference Vegetation Index (NDVI). To validate sensor data, LAI values were measured in the field using the LAI 2200 Plant Canopy Analyzer. The statistical indices showed a better performance for Pleiades 1A and Landsat 8 images, the former particularly in sites characterized by high canopy closure, such as deciduous forests, or in areas with stable riparian vegetation, the latter where stable reaches of riparian vegetation cover are almost absent or very homogenous, as in winter wheat fields. Sentinel-2 images provided more accurate results in terms of the range of LAI values. Considering the different types of satellite imagery, the Lambert-Beer equation generally performed best in estimating LAI from the NDVI, especially in areas that are geomorphologically stable or have a denser vegetation cover, such as deciduous forests. [ABSTRACT FROM AUTHOR]

To investigate the role of P2X7 receptor to preserve retinal ganglion cells (RGCs) structure and function in a genetic mouse model (DBA/2J mouse) of age-related glaucomatous neurodegeneration. Chronic treatment with P2X7 receptor antagonist eye drops was carried out in order to assess RGCs function and density by pattern electroretinogram (PERG) and RBPMS immunostaining, respectively. Further, microglia activation was assessed in flat-mounted retina by using Iba-1 immunostaining. Untreated glaucomatous eyes displayed significant microglia activation, alteration of PERG signal, and RGCs loss. In the P2X7 receptor antagonist-treated eyes, the PERG signal was significantly (p < 0.05) improved compared to controls, along with a significant (p < 0.05) reduction in terms of retinal microglial activation, and remarkable preservation of RGCs density. Altogether, these findings demonstrated that topical treatment with a P2X7 receptor antagonist has a neuroprotective effect on RGCs in glaucomatous mice, suggesting an appealing pharmacological approach to prevent retinal degenerative damage in optic neuropathy. [ABSTRACT FROM AUTHOR]