Regularity of the optimal sets for some spectral functionals

In this paper we study the regularity of the optimal sets for the shape optimization problem min{λ1(Ω)+⋯+λk(Ω) : Ω⊂Rd open, |Ω|=1}, where λ1(·) , … , λk(·) denote the eigenvalues of the Dirichlet Laplacian and | · | the d-dimensional Lebesgue measure. We prove that the topological boundary of a minimizer Ωk∗ is composed of a relatively open regular part which is locally a graph of a C∞ function and a closed singular part, which is empty if d< d∗, contains at most a finite number of isolated points if d= d∗ and has Hausdorff dimension smaller than (d- d∗) if d> d∗, where the natural number d∗∈ [ 5 , 7 ] is the smallest dimension at which minimizing one-phase free boundaries admit singularities. To achieve our goal, as an auxiliary result, we shall extend for the first time the known regularity theory for the one-phase free boundary problem to the vector-valued case

Procedura di confronto tra AEP, INRIM e PTB per la taratura della macchina di taratura di forza per confronto da 5 MN del Laboratorio AEP.

During the period from March to June 2015, a comparison between the primary force standard machine of the Istituto Nazionale di Ricerca Metrologica (INRiM) in Turin and Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig (Germy) and the 5 MN calibration force machine for comparison of the accredited calibration Laboratory of AEP Transducers di Cognento (MO), has been carried out. The comparison, carried out according the calibration guide EURAMET cg-4, Version 2.0, following the Traceability Path A, has been used to perform the calibration of the calibration force machines

Perturbations of the optical properties of mineral dust particles by mixing with black carbon: A numerical simulation study

Field observations show that individual aerosol particles are a complex mixture of a wide variety of species, reflecting different sources and physico-chemical transformations. The impacts of individual aerosol morphology and mixing characteristics on the Earth system are not yet fully understood. Here we present a sensitivity study on climate-relevant aerosols optical properties to various approximations. Based on aerosol samples collected in various geographical locations, we have observationally constrained size, morphology and mixing, and accordingly simulated, using the discrete dipole approximation model (DDSCAT), optical properties of three aerosols types: (1) bare black carbon (BC) aggregates, (2) bare mineral dust, and (3) an internal mixture of a BC aggregate laying on top of a mineral dust particle, also referred to as polluted dust. DDSCAT predicts optical properties and their spectral dependence consistently with observations for all the studied cases. Predicted values of mass absorption, scattering and extinction coefficients (MAC, MSC, MEC) for bare BC show a weak dependence on the BC aggregate size, while the asymmetry parameter (g) shows the opposite behavior. The simulated optical properties of bare mineral dust present a large variability depending on the modeled dust shape, confirming the limited range of applicability of spheroids over different types and size of mineral dust aerosols, in agreement with previous modeling studies. The polluted dust cases show a strong decrease in MAC values with the increase in dust particle size (for the same BC size) and an increase of the single scattering albedo (SSA). Furthermore, particles with a radius between 180 and 300 nm are characterized by a decrease in SSA values compared to bare dust, in agreement with field observations. This paper demonstrates that observationally constrained DDSCAT simulations allow one to better understand the variability of the measured aerosol optical properties in ambient air and to define benchmark biases due to different approximations in aerosol parametrization

Mathematical modelling and numerical bifurcation analysis of inbreeding and interdisciplinarity dynamics in academia

We address a mathematical model to approximate in a coarse qualitative the interaction between inbreeding-lobbying and interdisciplinarity in academia and perform a one and two-parameter numerical bifurcation analysis to analyse its dynamics. Disciplinary diversity is a necessary condition for the development of interdisciplinarity, which is being recognized today as the key to establish a vibrant academic environment with bigger potential for breakthroughs/innovation in research and technology. However, the interaction of several factors including institutional policies, and behavioural attitudes put significant barriers on advancing interdisciplinarity. A “cognitive rigidity” may rise due to reactive academic lobby behaviours favouring inbreeding. The proposed model consists of four coupled non-linear Ordinary Differential Equations simulating the interaction between certain types of academic behaviour and the rate of knowledge advancement which is related to the level of disciplinary diversity. The effect of a control policy that inhibits inbreeding-lobbying is also investigated. The numerical bifurcation analysis reveals a rich nonlinear behaviour including multistability, sustained oscillations, limit points of limit cycles, homoclinic bifurcations as well as codimension-two bifurcations and in particular Bogdanov–Takens and Bautin bifurcations

Correlazioni tra le velocit\ue0 ultrasoniche e le caratteristiche petrografiche in ceramiche archeologiche: un primo approccio metodologico

L\u2019analisi delle velocit\ue0 degli ultrasuoni permette di investigare i caratteri tessiturali e strutturali e di individuare la presenza di eventuali difetti localizzati all\u2019interno del campione. La loro diffusione negli studi archeometrici \ue8 legata alla non distruttivit\ue0 e alla possibilit\ue0 di fornire risultati accurati in tempo reale. In questo lavoro sono state effettuate numerose analisi petrografiche in sezione sottile e misure di velocit\ue0 di propagazione degli ultrasuoni su reperti ceramici di interesse archeologico. In particolare sono stati selezionati ed analizzati ceramiche preistoriche ed anfore da trasporto del V-IV sec. a.C., caratterizzati da differente granulometria, composizione e struttura. Da questo primo approccio \ue8 stato possibile evidenziare che il parametro petrografico che influenza maggiormente la velocit\ue0 degli ultrasuoni \ue8 la forma e la disposizione spaziale dei pori, e la dimensione media degli inclusi, mentre correlazioni poco significative si ottengono prendendo in considerazione la percentuale e il tipo di inerte presente nell\u2019impasto ceramico

Dose-dependent positive-to-negative shift of litter effects on seedling growth: a modelling study on 35 plant litter types

Modelling the inter-relationships between litter accumulation and plant–soil feedback is a major challenge to predict natural and agricultural ecosystem dynamics. At increasing levels of undecomposed plant litter, seedling growth tends to show a multi-faceted response trend, characterised by a peak of positive stimulation at lower dosage followed by inhibition at higher dosage. In this study, a new logistic model was developed to describe such trend and disentangle substrate-specific positive and negative effects of plant litter. The model was tested on 35 litter types applied to the common phytometer Lepidium sativum; all litter types were collected in Mediterranean shrublands of Campania region (southern Italy). Model fitting resulted to be generally higher relative to the widely used linear log response model, although in only half of the cases it also gave more parsimonious results in terms of minimising information loss. Positive and negative effects of plant litter resulted to be uncorrelated, showing that the overall trend is probably the result of the combined action of separate factors rather than the effect of a single factor behaving differently at the different doses. The results of this work provide new tools to finely tune the optimal doses in experiments on hormesis and litter phytotoxicity, through the identification of the most suited doses to centre the range of nearly linear response to litter concentration. A wide screening is also presented on the phytotoxicity profiles of a number of spontaneous plant species widely distributed in the Mediterranean area

Robot-mediated therapy for paretic upper limb of chronic patients following neurological injury

Objective: To evaluate the effectiveness of robot-mediated therapy targeted at the motor recovery of the upper limb in chronic patients following neurological injury

Upper Limb Spasticity Reduction Following Active Training: A Robot-Mediated Study In Patients With Chronic Hemiparesis

sion of the arm. A 3-month follow-up was performed. Results: Statistically significant improvements were found in both groups after treatment. Some differences were found in elbow motor improvement between the 2 groups. Conclusion: Comparison between groups confirms that active movement training does not result in increased hypertonia, but results in spasticity reduction in antagonist muscles by activating the reciprocal inhibition mechanism. Furthermore, robot-mediated therapy contributes to a decrease in motor impairment of the upper limbs in subjects with chronic hemiparesis, resulting in a reduction in shoulder pain

Fungal endophytes affect plant response to leaf litter with contrasting chemical traits

Abstract Plant litter decomposition is a crucial process of nutrient cycling within ecosystems. However, many studies have shown that, apart from its several beneficial effects, organic matter decomposition can be disadvantageous to seed germination, seedling growth, and physiological activity of plants. Litter decomposition was reported to affect both plants and their associated soil microbial communities. The aim of this work was to test the relationships between seed-associated endophytic fungi on the either positive or negative plant's response to different litter types. Leaf material of four species was collected and used in a decomposition experiment inside a growth chamber for 120 days. The plant growth experiment was set in a greenhouse using Trifolium repens and Triticum durum with and without their associated endophytic fungi in the presence of the different litter species at two decay levels (fresh litter and after 120 days of decomposition). Results demonstrated that fresh litter exerted a strong inhibition effect on the plant total biomass when compared to decomposed litter. Moreover, seed-associated endophytic fungi enhanced the inhibitory effect of litter in the observed experimental conditions. The removal of seed-associated endophytic fungi improved the capacity of tested plants to resist to litter inhibitory effect