A Reflective Higher-order Calculus

AbstractThe π-calculus is not a closed theory, but rather a theory dependent upon some theory of names. Taking an operational view, one may think of the π-calculus as a procedure that when handed a theory of names provides a theory of processes that communicate over those names. This openness of the theory has been exploited in π-calculus implementations, where ancillary mechanisms provide a means of interpreting of names, e.g. as tcp/ip ports. But, foundationally, one might ask if there is a closed theory of processes, i.e. one in which the theory of names arises from and is wholly determined by the theory of processes.Here we present such a theory in the form of an asynchronous message-passing calculus built on a notion of quoting. Names are quoted processes, and as such represent the code of a process, a reification of the syntactic structure of the process as an object for process manipulation. Name- passing in this setting becomes a way of passing the code of a process as a message. In the presence of a dequote operation, turning the code of a process into a running instance, this machinery yields higher-order characteristics without the introduction of process variables.As is standard with higher-order calculi, replication and/or recursion is no longer required as a primitive operation. Somewhat more interestingly, the introduction of a process constructor to dynamically convert a process into its code is essential to obtain computational completeness, and simultaneously supplants the function of the ν operator. In fact, one may give a compositional encoding of the ν operator into a calculus featuring dynamic quote as well as dequote

Specifying and Analysing SOC Applications with COWS

COWS is a recently defined process calculus for specifying and combining service-oriented applications, while modelling their dynamic behaviour. Since its introduction, a number of methods and tools have been devised to analyse COWS specifications, like e.g. a type system to check confidentiality properties, a logic and a model checker to express and check functional properties of services. In this paper, by means of a case study in the area of automotive systems, we demonstrate that COWS, with some mild linguistic additions, can model all the phases of the life cycle of service-oriented applications, such as publication, discovery, negotiation, orchestration, deployment, reconfiguration and execution. We also provide a flavour of the properties that can be analysed by using the tools mentioned above

Information Needs of Hong Kong Chinese Patients Undergoing Surgery

BACKGROUND: The provision of information to patients is an important aspect of contemporary health care. Limitations in health resources necessitates that the provision of information is carefully planned and culturally specific to maximize the benefits to patients from the resources available. AIM AND OBJECTIVES: The purposes of the study were to recognize Chinese surgical patients' information needs on admission and ascertain why the information is important to assist in understanding how it is used and, therefore, its potential impact. METHODS: A descriptive study design was used. A convenience sample of 83 surgical patients took part comprising 51 men and 32 women. An eight-item questionnaire based on the right of patients to information as listed in the Patients' Charter in Hong Kong using a 5-point Likert scale and one open-ended question to comment on why the information was important to them was completed by patients on the day of admission. RESULTS: Patients rated highly the need for all types of information. They rated most highly the need for information about the signs and symptoms indicating postoperative complications and when to seek medical help. Patients did not rate as highly, information regarding why the doctor believes the surgery is important, treatment alternatives and explanation of the procedure. CONCLUSIONS: These findings indicate that Chinese patients are desirous of a range of relevant information. RELEVANCE TO PRACTICE: Nursing staff, in particular, need to consider the 'timeliness' of information and the cultural appropriateness of how information is delivered

Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020

We show the distribution of SARS-CoV-2 genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three available genomic nomenclature systems for SARS-CoV-2 to all sequence data from the WHO European Region available during the COVID-19 pandemic until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation. We provide a comparison of the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2.Peer reviewe

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

Contract-based Web Service Composition Framework with Correctness Guarantees

Abstract. We present formal and practical foundations for Web service composition framework with composition correctness guarantees. We introduce contractual composition model based on two isomorphic machines (formal notation). Composition operators (patterns) are used to perform composition which is then formally verified with respect to properties described in service contracts. We also describe Java-based implementation of the system, concentrated around Sun’s Java Web Service