Quasilinear first-order PDEs with hysteresis

AbstractThis paper deals with the Cauchy problem for a quasilinear first-order equation that includes a possibly discontinuous hysteresis operator F: ∂∂t[u+F(u)]+∂u∂x=fin R, for t>0. Existence of a weak solution is proved for F equal to a completed relay operator. In the case of f≡0, an entropy-type condition yields Lipschitz-continuous and monotone dependence on the initial data, hence uniqueness

On the evolution of ferromagnetic media

AbstractStarting from a microscopic model of ferromagnetism, information is deduced about the form of the macroscopic constitutive relationship between the fields H and M; this exhibits hysteresis and space interaction. Accordingly, the concepts of distributed and nondistributed hysteresis functionals are introduced. Constitutive relations of this type are coupled with Maxwell's equations for a distributed system, for both the quasistationary and the fast evolution cases. Several weak formulations in Sobolev spaces are introduced; existence results are proved by means of implicit time discretization, a priori estimates and compactness procedures for taking the limit in the hysteresis functional

Abundance of Rock Partridge (Alectoris graeca) in relation to the multi spatial structure of habitat and food availability.

In the Prealpi Giulie Natural Park the distribution and abundance of the Rock Partridge Alectoris graeca saxatilis have been studied in 5 sample areas using the play-back technique, and related to habitat availability (Vegetation Map of the park, 1:25.000) at different spatial scales. The UTM 1x1 kilometer regional grid has been used for a large scale approach, assigning the number of partridges counted to each quadrant. The mean geo-morphological aspects, the herbaceous and shrub vegetation characteristics (density, height, colour, etc), the abundance of insects (pitfall traps), and management applied on the area (pasture, mowing, etc) have also been measured for each quadrant. Buffer surfaces of 500 and 100 meters of radius from the detection-points of the animals have been used respectively as medium and small scale approaches and compared to randomly selected buffer areas. GIS analysis has been carried out to determine habitat coverage in each quadrant and buffer. Different parameters seem to describe properly the ecological requirements of this species in the study area. Its abundance was correlated at all scales to grasslands widely colonized by Genista radiata. This element, together with high herbaceous vegetation at large scales, could provide shelter from flying predators. At medium to small scales species-rich mesophile hay meadows seem to enhance the presence of Rock Partridges, locally providing a large stock of food resources and together with xeric grasslands representing the optimal mixture of habitats for this phasianid. In contrast pastures colonized by shrubs and trees (high density, large diameter) seem to have a negative effect on the species presence at large to small scales. This multiscale approach allows to detect more appropriately the ecological requirements of this animal

Determinanti e strategie del post-vendita

L'articolo prende spunto dalle evidenze emerse da una ricerca condotta sul tema dei processi post-vendita nel contesto delle imprese operanti in diversi settori di beni durevoli. In particolare, l'articolo, dopo aver messo in luce il ruolo dei servizi post-vendita nel processo di creazione di valore aziendale, presenta ed analizza le diverse possibili configurazioni strategiche che tali attivit\ue0 possono assumere

Gene expression response of the alga Fucus virsoides (Fucales, Ochrophyta) to glyphosate solution exposure

Fucus virsoides is an ecologically important canopy-forming brown algae endemic to the Adriatic Sea. Once widespread in marine coastal areas, this species underwent a rapid population decline and is now confined to small residual areas. Although the reasons behind this progressive disappearance are still a matter of debate, F. virsoides may suffer, like other macroalgae, from the potential toxic effects of glyphosate-based herbicides. Here, through a transcriptomic approach, we investigate the molecular basis of the high susceptibility of this species to glyphosate solution, previously observed at the morphological and eco-physiological levels. By simulating runoff event in a factorial experiment, we exposed F. virsoides to glyphosate (Roundup\uae 2.0), either alone or in association with nutrient enrichment, highlighting significant alterations of gene expression profiles that were already visible after three days of exposure. In particular, glyphosate exposure determined the near-complete expression shutdown of several genes involved in photosynthesis, protein synthesis and stress response molecular pathways. Curiously, these detrimental effects were partially mitigated by nutrient supplementation, which may explain the survival of relict population in confined areas with high nutrient inputs. Our results show that glyphosate impairs the expression of genes involved in photosynthesis and protein synthesis in F. virsoides

Relation between parasites, reproductive index and habitat change in Rock Partridge (Alectoris graeca) populations in the central Southern Alps.

Relation between parasites, reproductive index and habitat change in Rock Partridge (Alectoris graeca) populations in the central southern alps. FABRO C.1, VISINTIN A.1, FILACORDA S.1, FRANGIPANE DI REGALBONO A.2, ARTUSO I.3 1Department of Agriculture and Environmental Sciences \u2013 University of Udine 2Department of Experimental Veterinary Science- University of Padua 3Comprensorio Alpino N\ub01 Val Brembana Hunting district Within the hunting district of Val Brembana the presence of parasites along the intestinal tract in 60 individuals (32 adults and 22 juveniles, 6 indeterminate) has been studied and correlated to the reproductive indexes (R.I, measured on 3 and 6 years) of Rock Partridges Alectoris graeca saxatilis in 6 different sectors and the habitat change. Within these sectors the coverage (%) of several environmental classes in different sample areas has been identified through photo interpretation over a time interval of 25 years. In the whole area a high spread of the nematode Ascaridia was observed and high values of prevalence (P = 69.49%) and mean abundance (MA = 15.21) have been found, while the presence of genus Capillaria was low with MA = 0.17 and P = 13.56%. Heterakis was isolated in 33.90% of the Rock Partridges, with MA = 1.45. For Ascaridia and Heterakis the relationship between variance and mean abundance (s2/MA) was significantly greater than one (Ascarids = 48.94; Heterakis: 7.90) and the aggregation index k (s2 / (s2-MA) ) was very close to zero, proving that these parasites show a highly aggregated distribution within host populations. When analyzing separately the 2 age classes there seemed to be no significant difference in parasitic infection susceptibility between juveniles (P = 95.45%) and adults (P = 84.95%). Only MA and P of Heterakis in different sectors was negatively correlated to a change in reproductive success, both in short and medium term, while the sectors with the greatest MA of Ascaridia, both in short and medium term, showed the highest mean reproductive rates and the sectors with the highest k of Capillaria had the highest R.I. The presence of parasites and particularly the value of MA of Capillaria and the average total number of parasites seemed to increase with the decreasing of open areas (coverage) in the different sectors of the study area, as well as with the decreasing of this observed coverage throughout the 25 year period. A negative correlation between open areas and the s2/AM ratio was discovered to be very clear. The presence of open areas seemed to affect significantly the abundance of parasites that in turn seemed to only partially drive R.I changes. The research was supported by Comprensorio Alpino N\ub0 1 Val Brembana Hunting district

Parental Support during the COVID-19 Pandemic: Friend or Foe? A Moderation Analysis of the Association between Maternal Anxiety and Children’s Stress in Italian Dyads

There is evidence that parental psychological disorders in stressful situations increase the risk of disturbance in child development. This has been investigated in disasters but not in pandemics, which are sensibly different from other types of traumatic events. We investigated the relationship between mothers’ anxiety and their children’s (self-reported) stress and the boundary conditions of this association during the first full COVID-19 lockdown in Italy. During the COVID-19 pandemic, mothers might have increased their protective attitudes to secure and support their children; we tested whether the relationship between mothers’ anxiety and children’s stress was weaker (buffer effect) or stronger (over-protection effect) when perceived parental support was high. We measured mothers’ anxiety, children’s perceived parental support, and children’s stress in a sample of 414 8- to 11-year-old primary school children (229 females, Mage = 9.44) and 395 mothers (Mage = 42.84). Results supported the over-protection scenario and provided the first evidence for the “helicopter-parent effect” during the COVID-19 pandemic: mothers’ anxiety was positively associated with children’s stress only when perceived support was high. Our finding highlights the importance of educating parents (for example, via emotional training) to prevent the worst consequences of adverse events in children and promote their mental health

Stochastic model of hysteresis

The methods of the probability theory have been used in order to build up a new model of hysteresis. It turns out that the reversal points of the control parameter (e. g., the magnetic field) are Markov points which determine the stochastic evolution of the process. It has been shown that the branches of the hysteresis loop are converging to fixed limit curves when the number of cyclic back-and-forth variations of the control parameter between two consecutive reversal points is large enough. This convergence to limit curves gives a clear explanation of the accommodation process. The accommodated minor loops show the return-point memory property but this property is obviously absent in the case of non-accommodated minor loops which are not congruent and generally not closed. In contrast to the traditional Preisach model the reversal point susceptibilities are non-zero finite values. The stochastic model can provide a good approximation of the Raylaigh quadratic law when the external parameter varies between two sufficiently small values.Comment: 13 pages, 14 figure