1,062 research outputs found
Causality and replication in concurrent processes
The replication operator was introduced by Milner for obtaining a simplified description of recursive processes. The standard interleaving semantics denotes the replication of a process P, written !P, a shorthand for its unbound parallel composition, operationally equivalent to the process P | P | …, with P repeated as many times as needed. Albeit the replication mechanism has become increasingly popular, investigations on its causal semantics has been scarce. In fact, the correspondence between replication and unbound parallelism makes it difficult to recover basic properties usually associated with these semantics, such as the so-called concurrency diamond. In this paper we consider the interleaving semantics for the operator proposed by Sangiorgi and Walker, and we show how to refine it in order to capture causality. Furthermore, we prove it coincident with the standard causal semantics for recursive process studied in the literature, for processes defined by means of constant invocations
Synthetic aggregates for the production of innovative low impact porous layers for urban pavements
According to the latest estimates, 40% of urban areas are covered by pavements. One of the most remarkable effects on the urban environment is the increase in impermeable surfaces which leads to problems related to water infiltration into the ground and the increase in wash-off volumes. The use of permeable and porous layers in urban applications for cycle lanes, footpaths and parking areas is growing in interest, increasing the potential for control and management of urban runoff. In this paper, a physical and mechanical characterization is proposed of an innovative mixture, prepared with a polymeric transparent binder for semi-porous layers with reduced contribution to the urban heat island effect. Two versions of this mixture are compared, one with just virgin and the one with artificial synthetic aggregates, produced through the alkali-activation of waste basalt powder. Results show suitable properties for both materials if compared to porous asphalt concretes in traditional pavements. Furthermore, the application of synthetic aggregates seems to be a viable solution for the production of innovative and eco-friendly mixtures, allowing the recycling of waste materials
Assessment of construction and demolition waste materials for sublayers of low traffic rural roads
The need for exploiting massive amounts of natural raw materials for constructing
pavements of roads as a key element for development of infrastructures in modern
age, together with enormous production amounts of wastes related to civil engineering activities
as biggest portion of solid waste generated all over the world, have highlighted the
importance of utilizing recycled aggregates of these materials in road pavement layers. The
key factor in this quest, is to evaluate load-bearing abilities of various kinds of waste aggregates.
Aggregates of reclaimed asphalt, pre-stressed or normal concrete, masonry and demolition
waste (CDW) exhibit different behavior under loading after compaction. The ideal
situation would be to achieve the densest compacted and durable layer in order to get the
highest durability, comparing to traditional road materials. In this study, aggregates from
four types of recycled materials are being subjected to study for unbound and cemented pavement
layers. Initial laboratory evaluations of size and composition are followed by constructing
a field on a subgrade with high non-homogenous surface. Vibrating elastic modulus (Evib)
for these materials were determined by Continuous Compaction Control (CCC) Oscillating
Rollers. It is observed that, despite the weaknesses arisen from weak components such as
masonry and elongated tiles, the stabilized distribution of the particle size can accelerate
reaching to final compaction of unbound aggregates with roller passing. This process could be
repeated with more or less same pattern in cemented layer, which exhibited an enhanced stiffness
and uniformity in order to minimize the weak parts of non-uniform subgrade layer, and
provide a high rigid pavement
Interaction and observation: categorical semantics of reactive systems trough dialgebras
We use dialgebras, generalising both algebras and coalgebras, as a complement
of the standard coalgebraic framework, aimed at describing the semantics of an
interactive system by the means of reaction rules. In this model, interaction
is built-in, and semantic equivalence arises from it, instead of being
determined by a (possibly difficult) understanding of the side effects of a
component in isolation. Behavioural equivalence in dialgebras is determined by
how a given process interacts with the others, and the obtained observations.
We develop a technique to inter-define categories of dialgebras of different
functors, that in particular permits us to compare a standard coalgebraic
semantics and its dialgebraic counterpart. We exemplify the framework using the
CCS and the pi-calculus. Remarkably, the dialgebra giving semantics to the
pi-calculus does not require the use of presheaf categories
Histopatología del osteosarcoma
El diagnóstico del osteosarcoma plantea una serie de problemas específicos. De
hecho, se debe tener en cuenta la existencia de diversas variantes, con pronósticos diferentes y
que requieren enfoques terapéuticos igualmente distintos. En este mismo sentido, la introducción
de nuevos protocolos terapéuticos, incluyendo la quimioterapia preoperatoria, requiere
una evaluación histopatológica cuidadosa del especimen a fin de cuantificar la necrosis inducida
por la quimioterapia y los márgenes quirúrgicos. El presente estudio analiza las diferentes
variantes histopatológicas y los problemas que se relacionan con la evaluación de los efectos de la quimioterapia preoperatoria sobre el especimen resecado.Diagnosis of osteosarcoma presents specific problems. In fact, several and different
varieties, presenting different prognosis and requiring different treatments, have to be recognized.
Moreover, the adoption of new therapeutic protocols including preoperative chemotherapy, requires
a careful histopathological evaluation of the specimen to quantify the chemotherapy-induced necrosis
and the surgical margins. This paper analyzes the different histopathological varieties and problems
related to the evaluation of the effects on the resected specimen of preoperative chemotherapy
Asymmetric Silver to Oxide Adhesion in Multilayers Deposited on Glass by Sputtering
We have developed a wedge-loaded double-cantilever beam adhesion measurement
set-up for thin films deposited on glass by sputtering. The test is described
in details. Results on the Glass/sublayer/Ag/ZnO multilayer provide evidence
that \SnOd or \TiOd perform better than ZnO as a sublayer. Then however,
rupture within the multilayer shifts to the upper Ag/ZnO interface. The latter
is shown to be tougher than the lower ZnO/Ag interface, an asymmetry due to
non-equilibrium interfacial structures
Concurrent constraint programming with process mobility
We propose an extension of concurrent constraint programming with primitives for process migration within a hierarchical network, and we study its semantics. To this purpose, we first investigate a "pure " paradigm for process migration, namely a paradigm where the only actions are those dealing with transmissions of processes. Our goal is to give a structural definition of the semantics of migration; namely, we want to describe the behaviour of the system, during the transmission of a process, in terms of the behaviour of the components. We achieve this goal by using a labeled transition system where the effects of sending a process, and requesting a process, are modeled by symmetric rules (similar to handshaking-rules for synchronous communication) between the two partner nodes in the network. Next, we extend our paradigm with the primitives of concurrent constraint programming, and we show how to enrich the semantics to cope with the notions of environment and constraint store. Finally, we show how the operational semantics can be used to define an interpreter for the basic calculus.
The Paths to Choreography Extraction
Choreographies are global descriptions of interactions among concurrent
components, most notably used in the settings of verification (e.g., Multiparty
Session Types) and synthesis of correct-by-construction software (Choreographic
Programming). They require a top-down approach: programmers first write
choreographies, and then use them to verify or synthesize their programs.
However, most existing software does not come with choreographies yet, which
prevents their application.
To attack this problem, we propose a novel methodology (called choreography
extraction) that, given a set of programs or protocol specifications,
automatically constructs a choreography that describes their behavior. The key
to our extraction is identifying a set of paths in a graph that represents the
symbolic execution of the programs of interest. Our method improves on previous
work in several directions: we can now deal with programs that are equipped
with a state and internal computation capabilities; time complexity is
dramatically better; we capture programs that are correct but not necessarily
synchronizable, i.e., they work because they exploit asynchronous
communication
A Novel Muco-Gingival Approach for Immediate Implant Placement to Obtain Soft- and Hard-Tissue Augmentation
The aim of this article is to describe a novel approach combining muco-gingival, regenerative and prosthetics concepts for immediate implant insertion that overcomes the limits traditionally considered as contraindications for Type 1 flapless implant positioning, simultaneously obtaining soft- and hard-tissue augmentation. After pre-surgical CBCT evaluation, the surgical technique consisted in the execution of a lateral-approach coronally advanced envelope flap, with oblique submarginal interproximal incisions directed towards the flap’s center of rotation (the tooth to be extracted); after buccal-flap elevation, the atraumatic extraction of the tooth was performed. Following guided implant insertion, a mixture of biomaterial and autologous bone was placed, stabilized by a pericardium membrane and a connective-tissue graft sutured in the inner aspect of the buccal flap. The peri-implant soft tissues were conditioned with a provisional crown until the shape and position for the mucosal scallop to resemble the gingival margin of the adjacent corresponding tooth were obtained; then, the definitive screw-retained restoration was placed. Within the limitations of this case report, the proposed immediate implant placement approach combining CTG application and buccal bone regeneration showed the possibility of obtaining 1-year-follow-up implant success, stable bone level, good esthetic results and high patient satisfaction
Coinductive soundness of corecursive type class resolution
This work has been supported by the EPSRC grant “Coalgebraic Logic Programming for Type Inference” EP/K031864/1-2, EU Horizon 2020 grant “RePhrase: Refactoring Parallel Heterogeneous Resource-Aware Applications - a Software Engineering Approach” (ICT-644235), and by COST Action IC1202 (TACLe), supported by COST (European Cooperation in Science and Technology)Horn clauses and first-order resolution are commonly used to implement type classes in Haskell. Several corecursive extensions to type class resolution have recently been proposed, with the goal of allowing (co)recursive dictionary construction where resolution does not terminate. This paper shows, for the first time, that corecursive type class resolution and its extensions are coinductively sound with respect to the greatest Herbrand models of logic programs and that they are inductively unsound with respect to the least Herbrand models. We establish incompleteness results for various fragments of the proof system.Postprin
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