915 research outputs found
Causal Consistency for Reversible Multiparty Protocols
In programming models with a reversible semantics, computational steps can be
undone. This paper addresses the integration of reversible semantics into
process languages for communication-centric systems equipped with behavioral
types. In prior work, we introduced a monitors-as-memories approach to
seamlessly integrate reversible semantics into a process model in which
concurrency is governed by session types (a class of behavioral types),
covering binary (two-party) protocols with synchronous communication. The
applicability and expressiveness of the binary setting, however, is limited.
Here we extend our approach, and use it to define reversible semantics for an
expressive process model that accounts for multiparty (n-party) protocols,
asynchronous communication, decoupled rollbacks, and abstraction passing. As
main result, we prove that our reversible semantics for multiparty protocols is
causally-consistent. A key technical ingredient in our developments is an
alternative reversible semantics with atomic rollbacks, which is conceptually
simple and is shown to characterize decoupled rollbacks.Comment: Extended, revised version of a PPDP'17 paper
(https://doi.org/10.1145/3131851.3131864
Cyberbullying, K-12 Public Schools, and the 1st Amendment
The first amendment protected studentsâ first amendment rights in K-12 public schools; however, state antibullying legislation required school officials to discipline students for bullying and, in most states, cyberbullying as well. An increasing number of students had access to mobile devices at home and during the school day. School officials had the responsibility to protect students from instances of bullying and cyberbullying; however, school officials did not fully understand the extent of their authority to discipline students for acts of bullying that occurred online, off school grounds. Despite the existence of state antibullying laws in all fifty states, contradictory appellate court decisions in cases involving cyberbullying and K-12 public schools made it difficult for school administrators to understand their authority. Appellate courts utilized a Tinker test when determining the outcomes of cases involving cyberbullying and K-12 public schools. The Tinker test was derived from the Supreme Court decision in Tinker vs. Des Moines Independent Community School District (1969), in which the Supreme Court overturned the suspension of students that wore armbands to protest the Vietnam War. There were two prongs of the Tinker test: (1) whether the instance of cyberbullying caused a substantial interference in the school, and (2) whether or not a substantial interference could be reasonably forecasted.
The purpose of this public policy dissertation was to provide state legislators and school administrators with an in-depth review of state antibullying laws as well as greater insight into how the appellate courts interpreted the extent and limitations of First Amendment in K-12 public schools.
This public policy dissertation compared state antibullying legislation in all 50 states in the United States and reviews all appellate court decisions involving K-12 public schools and cyberbullying. Each stateâs legislation was reviewed between October 31, 2016, and December 31, 2016, to determine (1) if there was an antibullying law in effect, (2) if cyberbullying was included in the legislation, (3) if bullying was defined as a one-time event, (4) if school officials were given the authority to discipline students for off-campus behavior, (5) if schools were required to implement an antibullying policy, (6) if the substantial interference or substantial disruption language from Tinker was included in the antibullying legislation, (7) if there was a school sanction for bullying, (8) if there was a criminal sanction for face-to-face bullying, and (9) if there was a criminal sanction for cyberbullying. Each appellate court decision involving K-12 public schools and cyberbullying was reviewed to determine how the Tinker test was applied in each case
Wearable Platform for Automatic Recognition of Parkinson Disease by Muscular Implication Monitoring
The need for diagnostic tools for the characterization of progressive movement disorders - as the Parkinson Disease (PD) - aiming to early detect and monitor the pathology is getting more and more impelling. The parallel request of wearable and wireless solutions, for the real-time monitoring in a non-controlled environment, has led to the implementation of a Quantitative Gait Analysis platform for the extraction of muscular implications features in ordinary motor action, such as gait. The here proposed platform is used for the quantification of PD symptoms. Addressing the wearable trend, the proposed architecture is able to define the real-time modulation of the muscular indexes by using 8 EMG wireless nodes positioned on lower limbs. The implemented system âtranslatesâ the acquisition in a 1-bit signal, exploiting a dynamic thresholding algorithm. The resulting 1-bit signals are used both to define muscular indexes both to drastically reduce the amount of data to be analyzed, preserving at the same time the muscular information. The overall architecture has been fully implemented on Altera Cyclone V FPGA. The system has been tested on 4 subjects: 2 affected by PD and 2 healthy subjects (control group). The experimental results highlight the validity of the proposed solution in Disease recognition and the outcomes match the clinical literature results
Reversibility in session-based concurrency: A fresh look
Much research has studied foundations for correct and reliable communication-centric software systems. A salient approach to correctness uses verification based on session types to enforce structured communications; a recent approach to reliability uses reversible actions as a way of reacting to unanticipated events or failures. In this paper, we develop a simple observation: the semantic machinery required to define asynchronous (queue-based), monitored communications can also support reversible protocols. We propose a framework of session communication in which monitors support reversibility of (untyped) processes. Main novelty in our approach are session types with present and past, which allow us to streamline the semantics of reversible actions. We prove that reversibility in our framework is causally consistent, and define ways of using monitors to control reversible actions.
Keyword
Bridging Causal Reversibility and Time Reversibility: A Stochastic Process Algebraic Approach
Causal reversibility blends reversibility and causality for concurrent
systems. It indicates that an action can be undone provided that all of its
consequences have been undone already, thus making it possible to bring the
system back to a past consistent state. Time reversibility is instead
considered in the field of stochastic processes, mostly for efficient analysis
purposes. A performance model based on a continuous-time Markov chain is time
reversible if its stochastic behavior remains the same when the direction of
time is reversed. We bridge these two theories of reversibility by showing the
conditions under which causal reversibility and time reversibility are both
ensured by construction. This is done in the setting of a stochastic process
calculus, which is then equipped with a variant of stochastic bisimilarity
accounting for both forward and backward directions
Formulazione semplificata per il calcolo in forma chiusa del diagramma Momento-Curvatura di una sezione circolare cava in CA (in Italian)
Per unâanalisi di vulnerabilitĂ di un ponte a travata Ăš possibile assumere che la curva di capacitĂ della struttura sia
approssimabile con la curva di capacitĂ della pila critica. Il comportamento della pila critica puĂČ essere, in generale,
influenzato da vari meccanismi quali la flessione, il taglio, gli effetti del secondâordine, lo sfilamento delle barre
longitudinali o la loro instabilizzazione. Il comportamento flessionale Ăš noto se si conosce il diagramma MomentoCurvatura della sezione dâincastro e la lunghezza di cerniera plastica. Considerando che gli altri meccanismi
possono essere valutati con formulazioni approssimate lâaspetto chiave del problema Ăš il diagramma MomentoCurvatura. Dopo aver valutato la sezione circolare piena in lavori precedenti, nella presente memoria si propone
una procedura per valutare il diagramma Momento-Curvatura di una sezione circolare cava in C.A. definendo la
posizione di alcuni suoi punti caratteristici. Per ognuno di questi si propone una soluzione adimensionale in forma
chiusa che dipende da quattro parametri anchâessi adimensionali: rapporto tra raggio del foro e raggio esterno,
rapporto di sforzo normale, rapporto meccanico di armatura longitudinale, rapporto volumetrico di staffatura.
Lâidea di base Ăš quella di avere buone indicazioni sulle prestazioni dei materiali (snervamento, salto del copriferro,
collasso, etc) basandosi su pochi parametri di input
Simplified closed-form solution for the determination of the moment-curvature response of a circular RC section
A seismic vulnerability analysis of a multi-span simply supported bridge is often based on the seismic response of the most critical pier. This response is influenced by different collapse modes (flexural, shear, second order effects, lap-splice of longitudinal bars or their buckling). Among these the flexural behaviour is important and it's known if the equivalent plastic hinge length and the Moment-Curvature law of the fixed end are given. This paper provides a closed-form dimensionless solution to obtain a 5 point Moment-Curvature diagram for circular RC section. The solution is based only on three parameters: dimensionless axial force, mechanical percentage of longitudinal reinforcement, geometrical percentage of transversal reinforcement. A numerical example is presented to test the solution comparing it with a FEM analysis
Multi-model assessment of the late-winter extra-tropical response to El Niño and La Nñna
El NiËno-Southern Oscillation (ENSO) is a natural phenomenon
in the tropical Pacific and the dominant mode of
climate variability on interannual timescales. The first term,
El NiËno, refers to a recurring warming of the tropical Pacific
Ocean (every 2-7 years), while the opposite phase, an anomalous
cooling, is called La NiËna. These variations in sea surface
temperature (SST) are accompanied by changes in the tropical
atmospheric circulation (Southern Oscillation), thus making
ENSO a coupled phenomenon involving ocean-atmosphere
interactions. Furthermore, ENSO can affect climate in regions
far from the tropical Pacific, producing a cascade of global
impacts through so-called âteleconnectionsâ. Understanding
the extra-tropical impacts of ENSO is important to improve
seasonal forecasts, for which it represents the most important
source of predictability.
In the North Atlantic-European (NAE) sector, the ENSO
teleconnection is still controversial in several aspects. A first
cornerstone was set in a review by Bršonnimann (2007) [1],
who concluded that a robust, âcanonicalâ ENSO signal exists
over the NAE region in late winter (January to March, JFM):
a dipole in sea-level pressure (SLP) with centers over the midlatitude
and high-latitude North Atlantic. While Bršonnimann
described this pattern as âclose to symmetricâ for El NiËno
and La NiËna, recent studies deliver contradictory results, with
some reporting a symmetric signal (e.g. [2] [3] [4]) and others
claiming asymmetry (e.g. [5] [6] [7]). The actual linearity of
the ENSO-NAE teleconnection thus remains unresolved, and
addressing this issue is the primary objective of this study.
We will also investigate another key aspect of the ENSONAE
teleconnection that is nothing but settled: the dynamical
mechanism leading to the âcanonicalâ SLP dipole.
The underlying idea of this study is to use idealized
experiments with atmospheric models forced by symmetric
anomalous SST patterns representing El NiËno and La NiËna
to diagnose symmetries and asymmetries in the extra-tropical
response. A multi-model approach is used, as the experiments
analyzed here are run with the same protocol using three stateof-
the-art models. We aim not only at diagnosing asymmetries
in the extra-tropical ENSO-related SLP signal, but also at
understanding their cause by examining all the steps involved
in the atmospheric response, starting from the tropical Pacific
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