The Design of Graphical Process Modeling Languages: from Free Composition to Modular Construction

Un Process Modeling Language (PML) grafico \ue8 un linguaggio specializzato per la modellazione di sistemi software in termini di processi. Tale linguaggio \ue8 detto grafico perch\ue8 la rappresentazione principale dei modelli consiste in diagrammi ottenuti combinando costrutti grafici e componenti precedentemente definiti. Un Process-Aware Information System (PAIS) \ue8 un sistema software guidato da modelli di processi con lo scopo di coordinare e supportare gli agenti nello svolgimento delle loro attivit\ue0. Tale sistema \ue8 responsabile della gestione simulatanea di diverse istanze di processo e del bilanciamento delle risorse disponibili. Un PML \ue8 l'interfaccia principale di un PAIS ed un aspetto fondamentale della sua progettazione, poich\ue8 \ue8 utilizzato da utenti finali, consulenti, e sviluppatori al fine di comprendere, implementare ed eseguire processi complessi. L'utilizzo di tecnologie PAIS pu\uf2 essere considerevolmente limitato dalle carenze di un PML nel descrivere casi complessi. Lo scopo principale della tesi \ue8 migliorare la progettazione di PML grafici al fine di costruire PAIS pi\uf9 efficaci. Tale obiettivo \ue8 perseguito attraverso tre percorsi interconnessi: per prima cosa, i PMLs esistenti e la loro teoria sottostante sono stati analizzati al fine di individuare pregi e difetti; successivamente, una tecnica di verifica molto diffusa in questo campo \ue8 stata consolidata ed estesa con una nuova tecnica per la correzione automatica di processi. Infine, una diversa soluzione per il design di PMLs \ue8 stata esplorata attraverso la definizione di un nuovo linguaggio, chiamato NestFlow, che migliora la modularit\ue0 e la comprensibilit\ue0 attraverso l'adozione di un approccio strutturato alla modellazione di processi. Un approccio modulare \ue8 possible solo se gli aspetti legati ai dati sono accettati come aspetto primario nel design di un PML. NestFlow cerca di semplificare l'attivit\ue0 di modellazione fornendo un insieme integrato di costrutti di control-flow e data-flow, promuovendo i secondi come aspetti principali nella modellazione di processi.A graphical Process Modeling Language (PML) is a language tailored for modeling software systems by means of process models. It is said to be graphical because the primary representation of models are diagrams obtained combining visual constructs and previously defined components. Graphical PMLs are interesting as they open the design space to new geometric representations of complex interrelated aspects like concurrency and interaction. A Process-Aware Information System (PAIS) is a software system driven by explicit process models with the aim to coordinate and support agents in performing their activities. It is responsible for managing several process model instances at the same time balancing the available resources. A PML is the primary interface of a PAIS and a main concern in its design, because it is used by end-users, consultants, and developers for understanding, implementing and enacting complex processes. The adoption of PAIS technology may be severely limited by the weakness of PMLs in describing complex use cases. The overall aim of this thesis is to improve the design of graphical PMLs in order to engineer more effective PAISs. This goal is pursued following three intertwined paths: firstly, mainstream PMLs and their theoretical foundations are analyzed for exposing their features and limits; secondly, a widespread PML verification method is consolidated and then extended with a novel technique for automating process correction; finally, an alternative PML design solution is explored through a proof-of-concept language, called NestFlow, that improves both modularity and comprehensibility by providing a more structured modeling approach. A modular approach is only possible if data-flow dependencies are accepted as a main concern in PML design. NestFlow tries to ease the modeling activity by providing a comprehensive set of tightly integrated control-flow and data-flow constructs, promoting the latter as first-class citizens in process modeling

On the use of generic types for smart contracts

This paper shows that generic types (generics) are useful for writing more abstract and more general smart contracts, but this comes with some security risks, reporting a concrete security issue found while using generics for writing smart contracts that implement shared entities for the Hotmoka blockchain. That issue can be used to steal the remuneration of validator nodes. This paper proposes a patch based on appropriate code rewriting. Namely, smart contracts are pieces of code that are deployed and executed in the context of a blockchain infrastructure in order to automatically enforce some effects when particular events occur. The writing of smart contracts is a complex and critical activity that can benefit from the use of high-level features of programming languages, and generics is one of them. In many programming languages, such as Java, generics are implemented by erasure, i.e. replaced by their upper bound type during compilation into bytecode. This is safe at source level, since the compiler takes care of checking that types are correct, before erasure. However, the erased types of the generated bytecode are consequently weaker. In a permissionless blockchain, where every user can call the bytecode of smart contracts installed by other users, these weaker types pose a risk of attack

Tracking social provenance in chains of retweets

In the era of massive sharing of information, the term social provenance is used to denote the ownership, source or origin of a piece of information which has been propagated through social media. Tracking the provenance of information is becoming increasingly important as social platforms acquire more relevance as source of news. In this scenario, Twitter is considered one of the most important social networks for information sharing and dissemination which can be accelerated through the use of retweets and quotes. However, the Twitter API does not provide a complete tracking of the retweet chains, since only the connection between a retweet and the original post is stored, while all the intermediate connections are lost. This can limit the ability to track the diffusion of information as well as the estimation of the importance of specific users, who can rapidly become influencers, in the news dissemination. This paper proposes an innovative approach for rebuilding the possible chains of retweets and also providing an estimation of the contributions given by each user in the information spread. For this purpose, we define the concept of Provenance Constraint Network and a modified version of the Path Consistency Algorithm. An application of the proposed technique to a real-world dataset is presented at the end of the paper

Resistencia a la compresión de un mortero cemento - arena adicionando 10% y 20% de mucílago de nopal

El presente proyecto de investigación está enfocado en determinar la resistencia de un mortero partiendo desde su fabricación, utilizando material natural mucilago de nopal en su elaboración adicionándolo en un 10% y 20%. Este proyecto es experimental, teniendo en cuenta que el material mucílago de nopal fue extraído de manera acuosa, cortando en rebanadas que se pusieron a remojar en agua en una cantidad recomendable de 7 días; dicha sustancia fue adicionada a la mezcla patrón de un mortero; también se fabricaron morteros patrón sin adición, con el fin de llevar a cabo la realización de cuadros comparativos de las resistencias obtenidas. En esta investigación, se determinaron los componentes químicos del mucílago de nopal, se determinaron fluideces para que se puedan tener resultados equivalentemente comparativos. Se elaboraron 27 probetas de mortero (9 patrón, 9 experimental con 10% de adición y 9 con 20% de adición), y posteriormente se determinaron las resistencias. Se determinó que las adiciones de 10% y 20% de mucílago de nopal tienden a disminuir la resistencia a la compresión de morteros a los 28 días con respecto a un mortero patrón, siendo expresadas éstas disminuciones en porcentajes de 11.02% y 5.60%, respectivamente. Las disminuciones se debieron a la presencia de componentes químicos un tanto dañinos del mucílago de nopal, entre ellos el sodio, que tiende a deteriorar el mortero con el transcurrir del tiempo, y la presencia de potasio, que tiende a dañar al mortero, ya que actúa de manera brusca con el agua y/o humedad y esta hace que no se pueda hidratar de manera adecuada; por otra parte el pH de 4.18 (ácido) también fue responsable de esta disminución.Tesi

Untargeted Metabolomics Analysis of the Orchid Species Oncidium sotoanum Reveals the Presence of Rare Bioactive C-Diglycosylated Chrysin Derivatives

Plants are valuable sources of secondary metabolites with pharmaceutical properties, but only a small proportion of plant life has been actively exploited for medicinal purposes to date. Underexplored plant species are therefore likely to contain novel bioactive compounds. In this study, we investigated the content of secondary metabolites in the flowers, leaves and pseudobulbs of the orchid Oncidium sotoanum using an untargeted metabolomics approach. We observed the strong accumulation of C-diglycosylated chrysin derivatives, which are rarely found in nature. Further characterization revealed evidence of antioxidant activity (FRAP and DPPH assays) and potential activity against neurodegenerative disorders (MAO-B inhibition assay) depending on the specific molecular structure of the metabolites. Natural product bioprospecting in underexplored plant species based on untargeted metabolomics can therefore help to identify novel chemical structures with diverse pharmaceutical properties

'Less is more': validation with Rasch analysis of five short-forms for the Brain Injury Rehabilitation Trust Personality Questionnaires (BIRT-PQs).

Background: Previous analyses demonstrated a lack of unidimensionality, item redundancy, and substantial administrative burden for the Brain Injury Rehabilitation Trust Personality Questionnaires (BIRT-PQs). Objective: To use Rasch Analysis to calibrate five short-forms of the BIRT-PQs, satisfying the Rasch model requirements. Methods: BIRT-PQs data from 154 patients with severe Acquired Brain Injury (s-ABI) and their caregivers (total sample = 308) underwent Rasch analysis to examine their internal construct validity and reliability according to the Rasch model. Results: The base Rasch analyses did not show sufficient internal construct validity according to the Rasch model for all five BIRT-PQs. After rescoring 18 items, and deleting 75 of 150 items, adequate internal construct validity was achieved for all five BIRT-PQs short forms (model chi-square p-values ranging from 0.0053 to 0.6675), with reliability values compatible with individual measurements. Conclusions: After extensive modifications, including a 48% reduction of the item load, we obtained five short forms of the BIRT-PQs satisfying the strict measurement requirements of the Rasch model. The ordinal-to-interval measurement conversion tables allow measuring on the same metric the perception of the neurobehavioral disability for both patients with s-ABI and their caregivers

Resistencia a la compresión de un mortero cemento - arena adicionando 10% y 20% de mucílago de nopal

TesisEl presente proyecto de investigación está enfocado en determinar la resistencia de un mortero partiendo desde su fabricación, utilizando material natural mucilago de nopal en su elaboración adicionándolo en un 10% y 20%. Este proyecto es experimental, teniendo en cuenta que el material mucílago de nopal fue extraído de manera acuosa, cortando en rebanadas que se pusieron a remojar en agua en una cantidad recomendable de 7 días; dicha sustancia fue adicionada a la mezcla patrón de un mortero; también se fabricaron morteros patrón sin adición, con el fin de llevar a cabo la realización de cuadros comparativos de las resistencias obtenidas. En esta investigación, se determinaron los componentes químicos del mucílago de nopal, se determinaron fluideces para que se puedan tener resultados equivalentemente comparativos. Se elaboraron 27 probetas de mortero (9 patrón, 9 experimental con 10% de adición y 9 con 20% de adición), y posteriormente se determinaron las resistencias. Se determinó que las adiciones de 10% y 20% de mucílago de nopal tienden a disminuir la resistencia a la compresión de morteros a los 28 días con respecto a un mortero patrón, siendo expresadas éstas disminuciones en porcentajes de 11.02% y 5.60%, respectivamente. Las disminuciones se debieron a la presencia de componentes químicos un tanto dañinos del mucílago de nopal, entre ellos el sodio, que tiende a deteriorar el mortero con el transcurrir del tiempo, y la presencia de potasio, que tiende a dañar al mortero, ya que actúa de manera brusca con el agua y/o humedad y esta hace que no se pueda hidratar de manera adecuada; por otra parte el pH de 4.18 (ácido) también fue responsable de esta disminución

A Blockchain-based Solution to Fake Check-ins in Location-Based Social Networks

Location-Based Social Networks (LBSNs) are an emerging kind of social network in which users can share their position with others and talk about visited places, providing comments and recommendations. Some LBSNs encourage the voluntary submission of place reviews by offering to users some sort of reward for this activity. However, soon or later this possibility has lead to fraudulent behaviours, in which attackers try to perform fake check-ins in order to increase the obtained rewards without actually visiting any place. Several different solutions have been proposed for distinguishing between real and fake check-ins with a certain degree of confidence. In this paper, we propose an alternative solution based on the use of the emerging blockchain technology, where a decentralized service can provide reliable presence claims for users