Relational specification as a testing oracle

Software engineering community is well aware of the usefulness of formal methods for specifying, designing and testing of the software. Despite this testing literature rarely deals with specification based testing. Testing from formal specifications offers a simple, structured and more rigorous approach to the functional tests than testing techniques. An important application of specification in testing is providing test oracles. The rise of use of computers in control safety critical systems, i.e., flight control systems, necessitates that rigorous system testing is performed before the deployment. In flight control systems, requirements are mostly concerned with the safety and maneuverability of an aircraft. In this domain, the use of formal approaches to requirements specification and system verification is strongly encouraged. In our study relational notation was used to model the requirements of generic flight control system. The advantage of relational approach is that the requirements can be partitioned into less complex components. Each component is separately specified with a set a relations. The formal aspect of the relational notation is exploited in a verification framework where the specifications are used as an oracle to test a system implementation

Sorption of lead and arsenic on soil components and effectiveness of phosphates for remediating lead and arsenic contaminated soils

High concentration of trace elements such as arsenic (As) and lead (Pb) represents one of the potentially costly threats to water and soil resources as well as serious threats to humans. Clay minerals are potential binding agents for pollutants due to their high cation exchange capacity and large surface area. Laboratory investigations were undertaken to evaluate the effect of Fe and Al hydrous oxide coatings on the sorption of Pb and As. Four clay minerals attapulgite, illite, kaolinite and montmorillonite with a range of surface characteristics were selected to investigate the Pb and As sorption. The minerals were coated with three different levels of each of Fe and Al hydrous oxides. Adsorption and desorption studies were performed for each of these heavy metals at seven different pH levels. Coating with both Fe and Al hydrous oxide increased the retention of Pb and As. Lead desorption was decreased when minerals were coated with highest levels of Fe and Al. In order to fully understand the fate and transport of metal in the environment, there is a need to accurately describe and model the complex natural system. The ability of surface complexation models (SCMs) to fit sets of titration data as a function of changes in model parameters was evaluated using FITEQL and acid base titration of clays coated with Fe and Al hydrous oxide. Three SCMs were evaluated: the constant capacitance model, the diffuse-double layer and triple layer model. For all the models evaluated, increasing the value of total number of sites resulted in a decrease in the FITEQL best fit equilibrium log K value. Generally better F value fits were obtained when the site density (Ns) value was between 1 to 10 sites/nm 2.;Sequestering heavy metals in insoluble phosphate minerals has been suggested as an in situ remediation technique for Pb contaminated soils. Lead sequestered in apatite minerals has great durability and leaching resistance, significantly exceeding other chemically stabilized forms. Sequential extractions of Pb have been used to determine the suitability of phosphates to immobilize Pb. Laboratory studies were conducted to investigate whether the lead pyromorphite formation is the artifact of the sequential extraction or it is actually formed. It was found that formation of pyromorphite might be due to the artifact of extraction process. There are concerns about the use of phosphate in soils contaminated with both Pb and As because As and phosphate compete for the same sorption sites. Greenhouse experiments were conducted on soils contaminated with both Pb and As. These soils were treated with four rates of phosphates and seeded with Japanese millet (Echinochloa crusgalli) and red clover (Trifolium pratense). Results showed that when soils were contaminated with arsenic (As) only, application of phosphates resulted in increased concentrations of As in soil solution, however when soils were contaminated with both Pb and As, application of phosphorus did not increase As concentration in soil solution. Laboratory investigations were conducted to determine the mechanism responsible for reduced As mobility in soils that are co-contaminating with Pb. The results suggested that As in Pb contaminated soils coprecipitates with lead phosphates

Catheter induced hypospadias, urethral trauma and penile abscess in completely recoverable neurological afflictions: preventable entities

Background: Catheter associated complications are very common in the emergency departments of medicine, general surgery, orthopaedics and in community. They mostly occur in patients with neurological afflictions because of inexperience of the first handlers as they lack the insight of altered physiology and anatomy in the lower urinary tract because of neurological lesions and also because of an inadequate advice at the time of discharge regarding the catheter care. Objectives of this study were to find the prevalence of per-urethral catheter associated injuries in patients with neurological lesions in a tertiary care centre of south-eastern Punjab and their prevention in completely recoverable neurological afflictions.Methods: This is a cross-sectional observational study conducted in urology department from 1st August 2017-31st August 2018. The data was taken from medicine, general surgery and orthopedic emergency departments. A total of 82 patients were taken from 19-78 years and 49 patients had per-urethral catheter placement. Analysis was done using Statistical Program of Special Sciences, version 20.Results: It was observed that overall neurological lesions are more common in males (80.48%) as compared to females (19.51%) and distributed over an age range of 19-84 years in both sexes. Out of total patients, 59.75% required per urethral catheterization. The prevalence of per-urethral catheter associated complications was 20.40%.Conclusions: Insertion of per-urethral catheter is a simple procedure but an error of omission on the part of health professionals’ results in a serious complication in a neurological patient. Proper insertion technique and catheter care are to be followed to prevent avoidable complications in this subset of patients

A phenomenological exploration of the effects of human patient simulation on undergraduate student nurses confidence to practice in the clinical environment.

There is a growing need for undergraduate students to acquire quality placements for clinical practice. However with the current state in healthcare, quality placements have been very hard to attain (Traynor, et al., 2010). Therefore HPS are become the latest trend in many nursing schools in attempt to address this issue (Traynor, et al., 2010). In this study, HPS has been seen to help with confidence levels for clinical practice. However, the benefits that students’ take away from the simulation based learning activities is very dependent on how the simulation is organized, structured and conducted. This notion is supported by the findings of this study. A qualitative phenomenological study design using two focus groups was used. A convenience sample of students from one educational institution, University of British Columbia (UBC) in the term 3, of their undergraduate nursing degree was emailed an invitation to attend a focus group session. There were six major themes and multiple sub- themes that came about during this study that impacted how students perceived their experience with HPS in relation to clinical confidence. The major themes that were evident from the participants’ experiences were classified as: Realism, building on knowledge, safe environment, critical thinking and confidence and anxiety. From this study several conclusions can be drawn about how HPS effects undergraduate student nurses confidence for clinical practice. Findings indicate it is crucial for participants to feel that the whole simulation experience depicts reality. Realism was the major theme related to clinical confidence. If the scenario was not simulating enough participants felt they did not learn much from them; however, during times when simulations were at the optimal level participants felt that they acquired many things, such as confidence, clinical techniques, linking theory to practice, identifying their own knowledge gaps, critical thinking, background knowledge to help in similar cases in the actual clinical environment. It is very important that HPS is well integrated into the nursing programs so students achieve great results from the simulations, which can be done if the simulations being conducted and organized at the right times in the programs.Applied Science, Faculty ofNursing, School ofGraduat

Algorithms for Dynamic Software Cache Coherence

In this paper, we investigate a class of cache coherence strategies in which an abstraction for shared data at the program-level, referred to as Shared Regions (SR), is used to manage caches dynamically through software. The practical value of these strategies is measured by their performance relative to existing hardware coherence protocols, and the complexity of the SR programming interface. We present detailed quantitative results highlighting the performance of a wide array of SR coherence algorithms, including some novel algorithms introduced in this paper that use direct cache-to-cache data transfers via software to improve performance. These algorithms are studied using execution-driven simulation and compared to a representative hardware strategy for a suite of parallel applications. We study the issue of programming complexity by analyzing the process of inserting Shared Regions program annotations into these applications. The experimental results show that the best SR coheren..

Shared Regions: A strategy for efficient cache management in shared-memory multiprocessors

Dealing effectively with memory access latency is one of the key challenges in the design of shared-memory multiprocessors. Processor caches offer a way to reduce this latency but also give rise to the problem of cache coherence. Existing software solutions to the cache coherence problem are usually inefficient, while hardware solutions are typically complex and expensive to implement. In this thesis, we present a new class of software cache coherence strategies based upon the integration of a program-level abstraction for shared data, called Shared Regions (SR), with run-time cache management. In this approach, user's define a set of shared regions, the unit of sharing in the application. Data is managed at the granularity of shared regions, and coherence enforcement decisions are made dynamically through software. Within the shared regions framework, we present two types of coherence solutions. In the first, called SR-Prog, program annotations mark the beginning and end of a series o..

The region trap library: Handling traps on application-defined regions of memory

User-level virtual memory (VM) primitives are used in many different application domains including distributed shared memory, persistent objects, garbage collection, and checkpointing. Unfortunately, VM primitives only allow traps to be handled at the granularity of fixedsized pages defined by the operating system and architecture. In many cases, this results in a size mismatch between pages and application-defined objects that can lead to a significant loss in performance. In this paper we describe the design and implementation of a library that provides, at the granularity of application-defined regions, the same set of services that are commonly available at a page-granularity using VM primitives. Applications that employ the interface of this library, called the Region Trap Library (RTL), can create and use multiple objects with different levels of protection (i.e., invalid, read-only, or read-write) that reside on the same virtual memory page and trap only on read/write references to objects in an invalid state or write references to objects in a read-only state. All other references to these objects proceed at hardware speeds. Benchmarks of an implementation on five different OS/architecture combinations are presented along with a case study using region trapping within a distributed shared memory (DSM) system, to implement a regionbased version of the lazy release consistency (LRC) coherence protocol. Together, the benchmark results and the DSM case study suggest that region trapping mechanisms provide a feasible region-granularity alternative for application domains that commonly rely on pagebased virtual memory primitives.

An Analytic Study of Dynamic Hardware and Software Cache Coherence Strategies

Dynamic software cache coherence strategies use information about program sharing behaviour to manage caches at run-time and at a granularity defined by the application. The program-level information is obtained through annotations placed into the application by the user or the compiler. The coherence protocols may range from simple static algorithms to dynamic algorithms that use run-time data structures similar to the directories used in hardware strategies. In this paper, we present an analytic study of five dynamic software cache coherence algorithms and compare these to a representative hardware coherence strategy. The analytic model is constructed using four input parameters -- write probability, locality, granularity, and system size -- and solved by analysis of a Markov chain. We show that the fundamental tradeoffs between the different hardware and software strategies are captured in this model. The results of the study show that hardware schemes perform better for fine-graine..

Region-Oriented Memory Management in Shared-Memory Multiprocessors

Effective caching and memory locality are essential for good performance of parallel applications on non-uniform memory access (NUMA) shared-memory multiprocessors. The need for multi-level memory coherence requires that consistency of shared data be maintained both within each level and across adjacent levels of the memory hierarchy. Existing static program analysis techniques for managing shared data at the cache level are limited because dynamic program data sharing behaviour is difficult to determine at compile time. Traditional schemes for managing shared data at the main memory level are limited because they manage shared data at page granularity and without knowledge of application behaviour. We introduce the notion of shared regions as the natural unit of data sharing in parallel applications, and show that this concept may be used in effective cache and main memory management. Algorithms for region-oriented cache and main memory management are presented. Region-oriented cache ..