CROSS-DIFFUSION EFFECTS ON STATIONARY PATTERN FORMATION IN THE FITZHUGH-NAGUMO MODEL

We investigate the formation of stationary patterns in the FitzHugh-Nagumo reaction-diffusion system with linear cross-diffusion terms. We focus our analysis on the effects of cross-diffusion on the Turing mechanism. Linear stability analysis indicates that positive values of the inhibitor cross-diffusion enlarge the region in the parameter space where a Turing instability is excited. A sufficiently large cross-diffusion coefficient of the inhibitor removes the requirement imposed by the classical Turing mechanism that the inhibitor must diffuse faster than the activator. In an extended region of the parameter space a new phenomenon occurs, namely the existence of a double bifurcation threshold of the inhibitor/activator diffusivity ratio for the onset of patterning instabilities: for large values of inhibitor/activator diffusivity ratio, classical Turing patterns emerge where the two species are in-phase, while, for small values of the diffusion ratio, the analysis predicts the formation of out-of-phase spatial structures (named cross-Turing patterns). In addition, for increasingly large values of the inhibitor cross-diffusion, the upper and lower bifurcation thresholds merge, so that the instability develops independently on the value of the diffusion ratio, whose magnitude selects Turing or cross-Turing patterns. Finally, the pattern selection problem is addressed through a weakly nonlinear analysis

Learning to Buy Time. A Data-Driven Model For Avoiding Silence While Task-Related Information Cannot Yet Be Presented

Lopez Gambino MS. Learning to Buy Time. A Data-Driven Model For Avoiding Silence While Task-Related Information Cannot Yet Be Presented. In: Proceedings of 22nd Workshop on the Semantics and Pragmatics of Dialogue (Semdial 2018). 2018

Triggering of Toll-like receptors in the elderly. A pilot study relevant for vaccination

The impaired ability of the elderly to mount an efficient immune response after exposure to microbes or vaccines represents a major challenge in protection against pathogens in ageing. Recently studies have shown that stimulation of Toll-like receptors (TLRs), using stimulatory ligands, can enhance vaccine efficacy by a number of mechanisms, including the activation of innate immune cells and the consequent production of inflammatory cytokines

First data on microflora of loggerhead sea turtle (Caretta caretta) nests from the coastlines of Sicily

Caretta caretta is threatened by many dangers in the Mediterranean basin, but most are human-related. The purposes of this research were: (i) to investigate microflora in samples from six loggerhead sea turtle nests located on the Sicilian coast and (ii) to understand microbial diversity associated with nests, with particular attention to bacteria and fungi involved in failed hatchings. During the 2016 and 2018 summers, 456 eggs and seven dead hatchling from six nests were collected. We performed bacteriological and mycological analyses on 88 egg samples and seven dead hatchlings, allowing us to isolate: Fusarium spp. (80.6%), Aeromonas hydrophila (55.6%), Aspergillus spp. (27.2%) and Citrobacter freundii (9%). Two Fusarium species were identified by microscopy and were confirmed by PCR and internal transcribed spacer sequencing. Statistical analyses showed significant differences between nests and the presence/absence of microflora, whereas no significant differences were observed between eggs and nests. This is the first report that catalogues microflora from C. caretta nests/eggs in the Mediterranean Sea and provides key information on potential pathogens that may affect hatching success. Moreover, our results suggest the need for wider investigations over extensive areas to identify other microflora, and to better understand hatching failures and mortality related to microbial contamination in this important turtle species

The importance of the interactions between KIRs and HLA ligands in the development of human autoimmune and viral diseases

Killer immunoglobulin-like receptors (KIRs) regulate the activation of natural killer cells through their interaction with human leucocyte antigens (HLA). KIR and HLA loci are highly polymorphic, and certain KIR/HLA combinations have been found to protect against viral infections or to predispose to autoimmune disorders. In particular, some activating KIR profiles may be detrimental in autoimmune pathogenesis, and specific KIR genes may be particularly aggressive in the clearance of different microorganisms, protecting individuals in the control of a given pathogen. Here we reviewed a growing body of evidence purporting the influence of KIR polymorphism and KIR-HLA interaction in the development of the main human autoimmune and viral diseases

Vulnerability to alcohol operant-drinking behaviour: implications of environmental stim

Environmental stimuli, occurring early in life, shape the drinking trajectories and the psychopathological outcome of alcohol consumption in adult life. In particular, early perinatal procedures can permanently alter various patterns of drug use and behaviour in rat adulthood (Pryce CR, 2001). Early handling (EH) apparently is responsible for neurochemical and behavioural changes in adulthood, due to boosts in maternal care after daily reunion. It has been suggested that fostered maternal care, in the form of licking and grooming, is a key feature in determining neural changes and offspring fear responses and alter the reward/reinforcement pathway through epigenetic mechanisms that likely underlie remodeling in DA transmission (Francis, 2008, Francis et al., 2002). Such evidence is important, since fear together with stress, is thought to be related to vulnerability associated with drug abuse (Kreek and LaForge, 2007; Sinha and Li, 2007). Various studies on ethanol consumption and preference, showed less vulnerability to ethanol in adult male rats submitted to EH procedure (Ploj K, 2003). Based upon these findings, this study was aimed at examining the impact of brief early handling, 15-minute daily separations of litters from the dams during the first 2 weeks of life, on vulnerability to heavy drinking and dependence in adult male Wistar rats employed an operant self-administration procedure well known as a valid paradigm, highly predictive of drug-seeking and drug-taking behaviour in rats (Higgins et al., 1994). The operant-drinking behaviour protocol consisted of: 1) Training phase in which the animals learnt to self-administer EtOH 10% over 21 days; 2) Extinction phase during which reward delivery was suspended; 3) Deprivation period when ethanol self-administration was suspended for 7 days to achieve a forced abstinence; 4) Relapse phase, 7 days, to assess animal reinstatement for ethanol (Cacace, 2012). Our data revealed that EH procedure has a protective influence towards the onset and escalation of drug abuse, showing a reduction in addictive behaviour as displayed by a lower frequency of lever presses with respect to control group. These findings further corroborate the role of early life experiences on ethanol consumption in adulthood, highlighting that environmental influences may induce individual different responses to drug abuse

L'interpretazione strutturale del paesaggio

Il saggio si inserisce in un volume che presenta metodologia ed esiti di un esperienza di ricerca interdisciplinare svolta dal Centro Europeo di Documentazione sulla Pianificazione delle Aree Protette (CED-PPN) e della Scuola di Specializzazione in Beni Architettonici e Paesaggio del Politecnico di Torino per l’Ente Parco Nazionale Val Grande. Il capitolo rappresenta la sintesi interpretativa delle letture specialistiche, illustrando il processo per giungere all’individuazione di tipi di paesaggio ed esemplificando modalità di rappresentazione

Functional effect of grapevine 1-deoxy-D-xylulose 5-phosphate synthase substitution K284N on Muscat flavour formation

Grape berries of Muscat cultivars (Vitis vinifera L.) contain high levels of monoterpenols and exhibit a distinct aroma related to this composition of volatiles. A structural gene of the plastidial methyl-erythritol-phosphate (MEP) pathway, 1-deoxy-D-xylulose 5-phosphate synthase (VvDXS), was recently suggested as a candidate gene for this trait, having been co-localized with a major quantitative trait locus for linalool, nerol, and geraniol concentrations in berries. In addition, a structured association study discovered a putative causal single nucleotide polymorphism (SNP) responsible for the substitution of a lysine with an asparagine at position 284 of the VvDXS protein, and this SNP was significantly associated with Muscat-flavoured varieties. The significance of this nucleotide difference was investigated by comparing the monoterpene profiles with the expression of VvDXS alleles throughout berry development in Moscato Bianco, a cultivar heterozygous for the SNP mutation. Although correlation was detected between the VvDXS transcript profile and the accumulation of free monoterpenol odorants, the modulation of VvDXS expression during berry development appears to be independent of nucleotide variation in the coding sequence. In order to assess how the non-synonymous mutation may enhance Muscat flavour, an in vitro characterization of enzyme isoforms was performed followed by in vivo overexpression of each VvDXS allele in tobacco. The results showed that the amino acid non-neutral substitution influences the enzyme kinetics by increasing the catalytic efficiency and also dramatically affects monoterpene levels in transgenic lines. These findings confirm a functional effect of the VvDXS gene polymorphism and may pave the way for metabolic engineering of terpenoid contents in grapevine