Language Constructs for Distributed Real-Time Programming

For many distributed applications, it is not sufficient for programs to be logically correct. In addition, they must satisfy various timing constraints. This paper discusses primitives that support the construction of distributed real-time programs. Our discussion is focused in two areas: timing specification and communication. To allow the specifications of timing constraints, we introduce the language constructs for defining temporal scope and specifying message deadline. We also identify communication primitives needed for real-time programming. The issues underlying the selection of the primitives are explained, including handling of timing exceptions. The primitives will eventually be provided as part of a distributed programming system that will be used to construct distributed multi-sensory systems

Nets as Tensor Theories

This report is intended to describe and motivate a relationship between a class of nets and the fragment of linear logic built from the tensor connective. In this fragment of linear logic a net may be represented as a theory and a computation on a net as a proof. A rigorous translation is described and a soundness and completeness theorem is stated. The translation suggests connecticns between concepts from concurrency such as causal dependency and concepts from proof theory such as cut elimination. The main result of this report is a cut reduction theorem which establishes that any proof of a sequent can be transformed into another proof of the same sequent with the property that all cuts are essential . A net-theoretic reading of this result tells that unnecessary dependencies from a computation can be eliminated resulting in a maximally concurrent computation. We note that it is possible to interpret proofs as arrows in the strictly symmetric strict monoidal category freely generated by a net and establish soundness of our proof reduction rules under this interpretation. Finally, we discuss how other linear connectives may be related to the concepts of internal and external choice

Quality of Service (QoS) in Healthcare Applications: Colored Petri Net Simulation for Design of Heterogeneous, Multi-Vendor, Integrated, Life-Critical Wireless (802.x) Patient Care Device Networks

The ability to deploy wireless patient monitors using industry-standard IEEE 802.x technologies allows patient mobility and clinical flexibly. However, interconnecting multiple life-critical medical devices from multiple vendors can introduce unintended life-threatening risks unless delivery of critical patient alarms to central monitoring systems and/or clinical personnel is assured. Petri net tools allow automated testing of all possible states and transitions between devices and/or systems to detect potential failure modes in advance. Colored Petri Net (CPN) tools allow tracking and controlling each message in a network based on pre-selected criteria. This paper describes a research project using CPN to simulate and validate alarm integrity in a small multi-modality wireless patient monitoring system. Free research CPN software, CPNTool, is used to simulate two, 20-monitor wireless patient monitoring networks. One network simulated standard nonprioritized 802.x IP protocols and simulated Quality of Service (QoS) capabilities similar to 802.11e, allowing message priority management. In the standard 802.x network, dangerous heart arrhythmia and pulse oximetry alarms were missed, but QoS priority management reduced that risk significantly

Personal Health Technology: CPN based Modeling of Coordinated Neighborhood Care Environments (Hubs) and Personal Care Device Ecosystems

Healthcare supported by mobile devices, or “mHealth,” has rapidly emerged as a very broad ecosystem that can empower safer, more affordable, and more comfortable independent living environments and assist residents to age in place with a variety of well-understood chronic diseases. mHealth ecosystems leverage every available type of regulated medical and consumer-grade Patient Care Devices (or PCDs). mHealth technologies can also support innovative care and reimbursement models like the Patient-Centered Medical Home (PCMH) and Accountable Care Organizations (ACOs). Although consumer-grade PCDs are becoming ubiquitous, they typically do not provide a large variety of integrated system options for care coordination beyond single individuals. Understanding how to safely implement and use those devices to support heterogeneous mixes of patients, illnesses, devices, medications, and situations in neighborhood contexts is still a case-by-case challenge. By utilizing a well-formalized Colored Petri Nets (CPNs) based approach, this paper provides a proof-of-concept simulation framework for modeling and designing coordinated community care hubs

Quality of Service (QoS) in Healthcare Applications: Colored Petri Net Simulation for Design of Heterogeneous, Multi-Vendor, Integrated, Life-Critical Wireless (802.x) Patient Care Device Networks

ABSTRACT The ability to deploy wireless patient monitors using industry-standard IEEE 802.x technologies allows patient mobility and clinical flexibly. However, interconnecting multiple life-critical medical devices from multiple vendors can introduce unintended life-threatening risks unless delivery of critical patient alarms to central monitoring systems and/or clinical personnel is assured. Petri net tools allow automated testing of all possible states and transitions between devices and/or systems to detect potential failure modes in advance. Colored Petri Net (CPN) tools allow tracking and controlling each message in a network based on pre-selected criteria. This paper describes a research project using CPN to simulate and validate alarm integrity in a small multi-modality wireless patient monitoring system. Free research CPN software, CPNTool, is used to simulate two, 20-monitor wireless patient monitoring networks. One network simulated standard nonprioritized 802.x IP protocols and simulated Quality of Service (QoS) capabilities similar to 802.11e, allowing message priority management. In the standard 802.x network, dangerous heart arrhythmia and pulse oximetry alarms were missed, but QoS priority management reduced that risk significantly

A Precision Post-Operative Wellness Monitoring Solution

Multiple orthogonal challenges around escalating costs and providing quality care plague healthcare delivery, especially in OECD countries. This research in progress paper addresses the post-operative discharge phase of the patient journey and proffers a technology enabled model that both supports a quality care experience post discharge but also prudent management to minimize costly unplanned readmissions and thereby subscribe to a value-based care paradigm. The chosen context is stoma patients but the solution can be easily generalized to other contexts. Next steps include the conducting of clinical trials to establish proof of concept, validity and usability

COVID-19 and Beyond: Taming the Virtual Healthcare Tiger with Colored Petri Nets based Modeling and Simulation

The Coronavirus crisis has forced hospitals globally to develop new virtual service portals and systems to: 1) triage, diagnose, and manage new patients virtually for every clinical specialty at home as their symptoms emerge, avoiding COVID-19 exposure to patient or physicians, and hospitalization, as much as possible, and 2) discharge, track, and support recovered patients via homecare and virtual visits to free as many critical care beds as possible. This paper focuses on simulating and modeling an episode of care with innovative initial patient contact and triage processes using the Colored Petri Net (CPN) formalism to help optimize workflow, patient throughput, and overall system efficacy. The two patient triage programs under consideration are a health system in Australia and an orthopedic surgical program in the US. We describe our model for the US program. Our presented results establish a desired stratification of patients through a virtual musculoskeletal triage

A proof-theoretic approach to semantics of concurrency

A central problem in the area of concurrency is the very definition of concurrency. Despite several years of research, there is no general agreement whether one should take the interleaving approach, or the partial order approach is better. In this thesis we establish a precise relationship between different views of concurrency. This is done in the setting of Petri nets. In particular, we establish in a precise technical sense that a truly concurrent computation indeed represents a canonical object in an abstract class of all computations of the appropriate type on a net. To achieve this, we show that there is a tight correspondence between reachability in nets and provability in the associated tensor theory. Thus nets become theories and computations on a net become proofs. This also allows us to import decidability results from net theory to a fragment of linear logic. To relate various computations, we interpret cut as describing causal dependency and analyze the relevance of cut elimination in the context of a net. We give a normalizing system of rewrites which gives us a notion of canonicity. To understand the relevance of cut reduction to concurrency, we assign a suitable semantics to proofs. The semantics we assign is dynamic in the sense that it gives meaning to the very phenomena of cut reduction--the meaning being removal of spurious causal dependencies. Thus, we establish that a cut reduced proof is indeed a maximally concurrent computation on a net. The semantics we propose also gives us a notion of equivalence of proofs (or computations). We then analyze the dynamics of an induced notion of rewrite. We establish the Church-Rosser property for such rewrites which also gives another notion of equivalence. We then show that this equivalence coincides with another equivalence that has been proposed in the literature for which the motivations were entirely category theoretic. Using these rewrites, we induce a natural order on proofs to characterize transition sequences. We also give implementations of a theorem prover for a fragment of linear logic and of our cut reduction algorithm