Customizing BPMN Diagrams Using Timelines

BPMN (Business Process Model and Notation) is widely used standard modeling technique for representing Business Processes by using diagrams, but lacks in some aspects. Representing execution-dependent and time-dependent decisions in BPMN Diagrams may be a daunting challenge [Carlo Combi et al., 2017]. In many cases such constraints are omitted in order to preserve the simplicity and the readability of the process model. However, for purposes such as compliance checking, process mining, and verification, formalizing such constraints could be very useful. In this paper, we propose a novel approach for annotating BPMN Diagrams with Temporal Synchronization Rules borrowed from the timeline-based planning field. We discuss the expressivity of the proposed approach and show that it is able to capture a lot of complex temporally-related constraints without affecting the structure of BPMN diagrams. Finally, we provide a mapping from annotated BPMN diagrams to timeline-based planning problems that allows one to take advantage of the last twenty years of theoretical and practical developments in the field

Molecular regulation of dendritic spine shape and function.

Dendritic spines are discrete membrane protrusions from dendritic shafts where the large majority of excitatory synapses are located. Their highly heterogeneous morphology is thought to be the morphological basis for synaptic plasticity. Electron microscopy and time-lapse imaging studies have suggested that the shape and number of spines can change after long-term potentiation (LTP), although there is no evidence that morphological changes are necessary for LTP induction and maintenance. An increasing number of proteins have been found to be morphogens for dendritic spines and provide new insights into the molecular mechanisms regulating spine formation and morphology

V5116 Sgr, an Eclipsing Supersoft Post-Outburst Nova?

V5116 Sgr (Nova Sgr 2005 No. 2), discovered on 2005 July 4, was observed with XMM-Newton in March 2007, 20 months after the optical outburst. The X-ray spectrum shows that the nova had evolved to a pure supersoft X-ray source, with no significant emission at energies above 1 keV. The X-ray light-curve shows abrupt decreases and increases of the flux by a factor ~8. It is consistent with a periodicity of 2.97 h, the orbital period suggested by Dobrotka et al. (2007), although the observation lasted just a little more than a whole period. We estimate the distance to V5116 Sgr to be 11+/-3 kpc. A simple blackbody model does not fit correctly the EPIC spectra, with reduced chi^2>4. In contrast, ONe rich white dwarf atmosphere models provide a good fit, with nH=1.3(+/-0.1)e21 cm^-2, T=6.1(+/-0.1)e5 K, and L=3.9(+/-0.8)e37(D/10kpc)^2 erg/s (during the high-flux periods). This is consistent with residual hydrogen burning in the white dwarf envelope. The white dwarf atmosphere temperature is the same both in the low and the high flux periods, ruling out an intrinsic variation of the X-ray source as the origin of the flux changes. We speculate that the X-ray light-curve may result from a partial coverage by an asymmetric accretion disk in a high inclination system.Comment: 2 figures, emulateapj, to appear in ApJ

Interval-based temporal functional dependencies: specification and verification

In the temporal database literature, every fact stored in a database may beequipped with two temporal dimensions: the valid time, which describes the time whenthe fact is true in the modeled reality, and the transaction time, which describes the timewhen the fact is current in the database and can be retrieved. Temporal functional dependencies(TFDs) add valid time to classical functional dependencies (FDs) in order to expressdatabase integrity constraints over the flow of time. Currently, proposals dealing with TFDsadopt a point-based approach, where tuples hold at specific time points, to express integrityconstraints such as \u201cfor each month, the salary of an employee depends only on his role\u201d. Tothe best of our knowledge, there are no proposals dealing with interval-based temporal functionaldependencies (ITFDs), where the associated valid time is represented by an intervaland there is the need of representing both point-based and interval-based data dependencies.In this paper, we propose ITFDs based on Allen\u2019s interval relations and discuss theirexpressive power with respect to other TFDs proposed in the literature: ITFDs allow us toexpress interval-based data dependencies, which cannot be expressed through the existingpoint-based TFDs. ITFDs allow one to express constraints such as \u201cemployees starting towork the same day with the same role get the same salary\u201d or \u201cemployees with a given roleworking on a project cannot start to work with the same role on another project that willend before the first one\u201d. Furthermore, we propose new algorithms based on B-trees to efficientlyverify the satisfaction of ITFDs in a temporal database. These algorithms guaranteethat, starting from a relation satisfying a set of ITFDs, the updated relation still satisfies thegiven ITFDs

Conditioning the information in asset pricing

This thesis analyzes different theoretical and empirical aspects related to the use of the information in asset pricing. As a main innovation I extend the asset pricing literature proposing a new highly flexible technique for the estimation of the markets subjective distribution of future returns. Applying this technique to different problems I answer to some long-lasting puzzles present in literature. The contribution of this project to the literature is two-fold: first, in line with the new findings of Ross (2015) but from a fully different prospective I propose a new technique to estimate the market's subjective distribution of future returns using, jointly, stock and options data. Second, after studying the theoretical reason behind the superiority of the proposed technique, I use it for different empirical applications

Contingent Convertible Bonds in Financial Networks

We study the role of contingent convertible bonds (CoCos) in a network of interconnected banks. We first confirm the phase transitions documented by Acemoglu et al. (2015) in absence of CoCos, thus revealing that the structure of the interbank network is of fundamental importance for the effectiveness of CoCos as a financial stability enhancing mechanism. Furthermore, we show that in the presence of a moderate financial shock lightly interconnected financial networks are more robust than highly interconnected networks, and can possibly be the optimal choice for both CoCos issuers and buyers. Finally our results show that, under some network structures, the presence of CoCos can increase (and not reduce) financial fragility, because of the occurring of unneeded triggers and consequential suboptimal conversions that damage CoCos investors.Comment: 38 pages, 8 figure

Contingent convertible bonds in financial networks

We study the role of contingent convertible bonds (CoCos) in a complex network of interconnected banks. By studying the system’s phase transitions, we reveal that the structure of the interbank network is of fundamental importance for the effectiveness of CoCos as a financial stability enhancing mechanism. Our results show that, under some network structures, the presence of CoCos can increase (and not reduce) financial fragility, because of the occurring of unneeded triggers and consequential suboptimal conversions that damage CoCos investors. We also demonstrate that, in the presence of a moderate financial shock, lightly interconnected financial networks are more robust than highly interconnected networks. This makes them a potentially optimal choice for both CoCos issuers and buyers

Free-carrier screening of polarization fields in wurtzite GaN/InGaN laser structures

The free-carrier screening of macroscopic polarization fields in wurtzite GaN/InGaN quantum wells lasers is investigated via a self-consistent tight-binding approach. We show that the high carrier concentrations found experimentally in nitride laser structures effectively screen the built-in spontaneous and piezoelectric polarization fields, thus inducing a ``field-free'' band profile. Our results explain some heretofore puzzling experimental data on nitride lasers, such as the unusually high lasing excitation thresholds and emission blue-shifts for increasing excitation levels.Comment: RevTeX 4 pages, 4 figure

Discovering Evolving Temporal Information: Theory and Application to Clinical Databases

Functional dependencies (FDs) allow us to represent database constraints, corresponding to requirements as \u201cpatients having the same symptoms undergo the same medical tests.\u201d Some research eforts have focused on extending such dependencies to consider also temporal constraints such as \u201cpatients having the same symptoms undergo in the next period the same medical tests.\u201d Temporal functional dependencies are able to represent such kind of temporal constraints in relational databases. Another extension for FDs allows one to represent approximate functional dependencies (AFDs), as \u201cpatients with the same symptoms generally undergo the same medical tests.\u201d It enables data to deviate from the defned constraints according to a user-defned percentage. Approximate temporal functional dependencies (ATFDs) merge the concepts of temporal functional dependency and of approximate functional dependency. Among the diferent kinds of ATFD, the Approximate Pure Temporally Evolving Functional Dependencies (APE-FDs for short) allow one to detect patterns on the evolution of data in the database and to discover dependencies as \u201cFor most patients with the same initial diagnosis, the same medical test is prescribed after the occurrence of same symptom.\u201d Mining ATFDs from large databases may be computationally expensive. In this paper, we focus on APE-FDs and prove that, unfortunately, verifying a single APE-FD over a given database instance is in general NP-complete. In order to cope with this problem, we propose a framework for mining complex APE-FDs in real-world data collections. In the framework, we designed and applied sound and advanced model-checking techniques. To prove the feasibility of our proposal, we used real-world databases from two medical domains (namely, psychiatry and pharmacovigilance) and tested the running prototype we developed on such databases