Heuristic search for equivalence checking

Equivalence checking plays a crucial role in formal verification since it is a natural relation for expressing the matching of a system implementation against its specification. In this paper, we present an efficient procedure, based on heuristic search, for checking well-known bisimulation equivalences for concurrent systems specified through process algebras. The method tries to improve, with respect to other solutions, both the memory occupation and the time required for proving the equivalence of systems. A prototype has been developed to evaluate the approach on several examples of concurrent system specifications

A role for startups in unleashing the disruptive power of social media

As social media attract increasing attention from executives and find varied applications in different industries, research on the subject has been investigating the antecedents, moderators, mediators and outcomes of social media adoption, as well as impacts on the organizational and individual level. However, relatively little attention has been paid to the discussion of the new sources of social media innovation-i.e., the upstream originators of social media solutions. Such innovations of a possibly disruptive nature often originate from startups, which can constitute a significant driver for social media development and can influence the adopting incumbents' behaviors. This study aims at shedding first light on social media-based solutions developed and delivered by startups. By surveying the Crunchbase database, we identified 724 funded social media startups, which were further classified into six categories, namely: (i) social network; (ii) social commerce; (iii) social recruitment; (iv) social management; (v) social loyalty and advocacy; (vi) contact management. Our findings show how the large majority of startups deliver social network solutions to incumbents, followed by social media management applications. The findings also shed light on emerging approaches to value generation and open innovation from social media related to and driven by startups

Thermal performance of mortars based on different binders and containing a novel sustainable Phase Change Material (PCM)

Increasing concerns about climate change and global warming bring about technical steps for the development of several energy-efficient technologies. Since the building sector is one of the largest energy users for cooling and heating necessities, the incorporation of a proper energy-efficient material into the building envelopes could be an interesting solution for saving energy. Phase change material (PCM)-based thermal energy storage (TES) seems suitable to provide efficient energy redistribution. This is possible because the PCM is able to store and release its latent heat during the phase change processes that occurs according to the environmental temperature. The purpose of this paper was the characterization of the thermal properties of a composite PCM (i.e., Lecce stone/poly-ethylene glycol, previously developed) incorporated into mortar compositions based on different binders (i.e., hydraulic lime and cement). The study was carried out using an experimental set up through which it was possible to simulate the different seasons of the years. It was observed that the addition of PCM in mortars leads to a decrease of the maximum temperatures and increase of the minimum temperatures. Furthermore, the results shown a reduction of the heating and cooling needs, thus confirming the capability of this material to save energy

A novel SEMA3G mutation in two siblings affected by syndromic GnRH deficiency

Introduction: Gonadotropin-releasing hormone (GnRH) deficiency causes hypogonadotropic hypogonadism (HH), a rare genetic disorder that impairs sexual reproduction. HH can be due to defective GnRH-secreting neuron development or function and may be associated with other clinical signs in overlapping genetic syndromes. With most of the cases being idiopathic, genetics underlying HH is still largely unknown. Objective: To assess the contribution of mutated Semaphorin 3G (SEMA3G) gene in the onset of a syndromic form of HH, characterized by intellectual disabilities and facial dysmorphic features. Method: By combining homozygosity mapping with exome sequencing, we identified a novel variant in SEMA3G gene. We then applied mouse as a model organism to examine SEMA3G expression and its functional requirement in vivo. Further, we applied homology modelling in silico and cell culture assays in vitro to validate the pathogenicity of the identified gene variant. Results: We found that: SEMA3G is expressed along the migratory route of GnRH neurons and in the developing pituitary; SEMA3G affects GnRH neuron development, but is redundant in the adult hypothalamic-pituitary-gonadal axis; mutated SEMA3G alters binding properties in silico and in vitro to its PlexinAs receptors and attenuates its effect on the migration of immortalized GnRH neurons. Conclusion: In silico, in vitro and in vivo models revealed that SEMA3G regulates GnRH neuron migration and that its mutation affecting receptor selectivity may be responsible for the HH-related defects

LGR4 deficiency results in delayed puberty through impaired Wnt/beta-catenin signaling

The initiation of puberty is driven by an upsurge in hypothalamic gonadotropin-releasing hormone (GnRH) secretion. In turn, GnRH secretion upsurge depends on the development of a complex GnRH neuroendocrine network during embryonic life. Although delayed puberty (DP) affects up to 2% of the population, is highly heritable, and is associated with adverse health outcomes, the genes underlying DP remain largely unknown. We aimed to discover regulators by whole-exome sequencing of 160 individuals of 67 multigenerational families in our large, accurately phenotyped DP cohort. LGR4 was the only gene remaining after analysis that was significantly enriched for potentially pathogenic, rare variants in 6 probands, Expression analysis identified specific Lgr4 expression at the site of GnRH neuron development. LGR4 mutant proteins showed impaired Wnt/beta-catenin signaling, owing to defective protein expression, trafficking, and degradation. Mice deficient in Lgr4 had significantly delayed onset of puberty and fewer GnRH neurons compared with WT, whereas lgr4 knockdown in zebrafish embryos prevented formation and migration of GnRH neurons. Further, genetic lineage tracing showed strong Lgr4-mediated Wnt/beta-catenin signaling pathway activation during GnRH neuron development. In conclusion, our results show that LGR4 deficiency impairs Wnt/beta-catenin signaling with observed defects in GnRH neuron development, resulting in a DP phenotype.Peer reviewe

Phase Change Materials for Energy Efficiency in Buildings and Their Use in Mortars

The construction industry is responsible for consuming large amounts of energy. The development of new materials with the purpose of increasing the thermal efficiency of buildings is, therefore, becoming, imperative. Thus, during the last decades, integration of Phase Change Materials (PCMs) into buildings has gained interest. Such materials can reduce the temperature variations, leading to an improvement in human comfort and decreasing at the same time the energy consumption of buildings, due to their capability to absorb and release energy from/in the environment. In the present paper, recent experimental studies dealing with mortars or concrete-containing PCMs, used as passive building systems, have been examined. This review is mainly aimed at providing information on the currently investigated materials and the employed methodologies for their manufacture, as well as at summarizing the results achieved so far on this subject

GreASE: A Tool for Efficient "Nonequivalence" Checking

Equivalence checking plays a crucial role in formal verification to ensure the correctness of concurrent systems. However, this method cannot be scaled as easily with the increasing complexity of systems due to the state explosion problem. This article presents an efficient procedure, based on heuristic search, for checking Milner's strong and weak equivalence; to achieve higher efficiency, we actually search for a difference between two processes to be discovered as soon as possible, thus the heuristics aims to find a counterexample, even if not the minimum one, to prove nonequivalence. The presented algorithm builds the system state graph on-the-fly, during the checking, and the heuristics promotes the construction of the more promising subgraph. The heuristic function is syntax based, but the approach can be applied to different specification languages such as CCS, LOTOS, and CSP, provided that the language semantics is based on the concept of transition. The algorithm to explore the search space of the problem is based on a greedy technique; GreASE (Greedy Algorithm for System Equivalence), the tool supporting the approach, is used to evaluate the achieved reduction of both state-space size and time with respect to other verification environments