Preventing Atomicity Violations with Contracts

Software developers are expected to protect concurrent accesses to shared regions of memory with some mutual exclusion primitive that ensures atomicity properties to a sequence of program statements. This approach prevents data races but may fail to provide all necessary correctness properties.The composition of correlated atomic operations without further synchronization may cause atomicity violations. Atomic violations may be avoided by grouping the correlated atomic regions in a single larger atomic scope. Concurrent programs are particularly prone to atomicity violations when they use services provided by third party packages or modules, since the programmer may fail to identify which services are correlated. In this paper we propose to use contracts for concurrency, where the developer of a module writes a set of contract terms that specify which methods are correlated and must be executed in the same atomic scope. These contracts are then used to verify the correctness of the main program with respect to the usage of the module(s). If a contract is well defined and complete, and the main program respects it, then the program is safe from atomicity violations with respect to that module. We also propose a static analysis based methodology to verify contracts for concurrency that we applied to some real-world software packages. The bug we found in Tomcat 6.0 was immediately acknowledged and corrected by its development team

Determinants of continuance intention to use mobile self-scanning applications in retail

Retailers are increasingly using self-service technologies to improve customer experience and reduce costs. The purpose of this study is to identify factors that could explain the level of continuance intention of mobile self-scanning applications in retail. Based on previous theoretical streams, the present study integrates technology readiness (TR) and service quality into the technology acceptance model (TAM). Using data collected through an online survey of 217 users of a mobile self-scanning application of a large supermarket chain operating in Portugal, the study uses partial least squares structural equation modeling to test the proposed hypotheses. The results indicate that the continuance usage of the self-scanning Apps is directly driven by users’ satisfaction, and perceived usefulness. Findings also show that technology readiness has a positive and significant impact on ease of use and perceived usefulness. Ease of use has a positive impact on users’ satisfaction and perceived usefulness but has no direct effect on the continuance intention to use the application. Perceived quality has a positive direct effect on satisfaction, and a positive indirect effect on continuance intention. Finally, need for interaction has a negative effect on technological readiness. This work contributes to a better understanding of the emerging market for mobile self-scanning applications in retail applications, particularly relevant in a digital transition context.info:eu-repo/semantics/acceptedVersio

Patrón de reconocimiento de bellotas procedentes de diferentes especies Quercus basado en el contenido de aceite y en el perfil de ácidos grasos

The aim of this study was (i) to characterize different species of Quercus genus and (ii) to discriminate among them on the basis of the content and fatty acid composition of the oil in their fruits and/or their morphological aspects via pattern recognition techniques (Principal Component Analysis, PCA, Cluster Analysis, CA, and Discriminant Analysis, DA). Quercus rotundifolia Lam., Quercus suber L. and Quercus pyrenaica Willd., grown in the same stand in the centre of Portugal, were investigated. When oil content and respective fatty acid composition were used to characterize samples, well-separated groups corresponding to each of the species were observed by PCA and confirmed by CA and DA. The ‘‘width’’ and ‘‘length’’ of acorns exhibited a low discriminant power. Acorns from Q. rotundifolia showed the highest average oil content followed by Q. suber and Q. pyrenaica acorns (9.1, 5.2 and 3.8%, respectively). Fatty acid profiles of Q. rotundifolia and Q. suber oils are similar to olive oil while the oil from Q. pyrenaica acorns is more unsaturated.El objetivo de este estudio fué (i) la caracterización de diferentes especies del género Quercus y (ii) la clasificación de las mismas en base al contenido y composición de ácidos grasos del aceite de sus frutos y/o en sus caracteres morfológicos, via técnicas de patrón de reconocimiento (Análisis de Componentes Principales, ACP, Análisis de Cluster, AC, y Análisis Discriminante, AD). Se han estudiado Quercus rotundifolia Lam., Quercus suber L. y Quercus pyrenaica Willd., pertenecientes a la misma zona del centro de Portugal. Al emplear el contenido de aceite y sus respectivas composiciones de ácidos grasos para caracterizar a las muestras, el ACP reveló grupos bien separados correspondientes a cada especie, los cuales, a su vez, se confirmarón con el AC y el AD. El ‘‘ancho’’ y ‘‘longitud’’ de las bellotas exhibieron un poder discriminante bajo. Las bellotas de Q. rotundifolia mostraron el contenido más elevado de aceite, seguidas de las de Q. suber y Q. pyrenaica (9.1, 5.2 y 3.8%, respectivamente). Los perfiles de ácidos grasos de los aceites de Q. rotundifolia y Q. suber son similares al del aceite de oliva, mientras que el aceite de las bellotas de Q.pyrenaica es más insaturado

Severe Megaloblastic Anaemia in an Infant

Vitamin B 12 or cobalamin deficiency, a rare clinical entity in pediatric age, is found most exclusively in breastfed infants, whose mothers are strictly vegetarian non-supplemented or with pernicious anaemia. In this article, the authors describe a 10-month-old infant admitted for vomiting, refusal to eat and prostration. The infant was exclusively breastfed and diffi culties in introduction of new foods were reported. Failure to thrive since 5 months of age was also noticed. Laboratory evaluation revealed severe normocytic normochromic anaemia and cobalamin defi cit. A diagnosis of α-thalassemia trait was also made. Maternal investigation showed autoimmune pernicious anaemia. This case shows the severity of vitamin B 12 deficiency and the importance of adopting adequate and precocious measures in order to prevent potentially irreversible neurologic damage

Evaluation of the rheological behaviour of Warm Mix Asphalt (WMA) modified binders

Several processes and products are available to produce warm mix asphalt (WMA). The use of those may reduce the mixing and compaction temperatures in relation to hot mix asphalt (HMA), ensuring a good performance of the pavement. Lower plant mixing temperatures mean reduction in fuel consumption and lower emissions, what may contribute to diminish odours and health problems. A laboratory study on the properties of the modified binders (using two commercial WMA additives—Sasobit® and Cecabase®) was carried out through conventional (penetration, softening point), dynamic viscosity and rheology (DSR) tests, in order to establish the optimum additive content. Stripping of binder from the aggregates is a reported problem in WMA. Thus, the affinity of the modified binders was assessed without encountering significant problems. It was also observed that only Sasobit® alters the viscosity of the binder. A maximum temperature reduction of 15°C was achieved using 4% of Sasobit® with a softer binder

Uma introdução à técnica SVET

Este artigo apresenta uma introdução à Técnica do Eléctrodo Vibrante de Varrimento (SVET). Começa por uma breve resenha histórica, seguida da descrição do princípio de funcionamento, exemplos da aplicação a casos de corrosão, alguns cálculos possíveis, limitações, instrumentação, detalhes experimentais e exemplos da sua associação a outras técnicas electroquímicas

Avaliação do desempenho de misturas betuminosas temperadas

A diminuição do consumo de combustíveis e das emissões de gases com efeitos de estufa são um grande desafio da sociedade actual. No fabrico de misturas betuminosas desenvolveram-se recentemente diversas tecnologias para redução da temperatura de produção e aplicação em obra que promoveram a produção de misturas betuminosas temperadas (MBT). Inúmeros benefícios no uso das MBT têm potenciado o seu crescente desenvolvimento, destacando-se a redução das emissões no fabrico e a diminuição do combustível gasto nos queimadores. Na colocação em obra, as MBT garantem uma trabalhabilidade adequada à sua aplicação e compactação a menores temperaturas, reduzindo a produção de fumos, possibilitando o transporte a longas distâncias, alargando a época de pavimentação, e permitindo a sua aplicação a temperaturas atmosféricas inferiores. Neste trabalho compara-se o desempenho mecânico de uma mistura betuminosa (AC 14 Surf 50/70) produzida a temperaturas convencionais e a menores temperaturas (125 a 135 ºC), através da introdução de dois aditivos (Sasobit® e Cecabase®). Foram determinadas as propriedades dos ligantes base e modificados (penetração, anel e bola, viscosidade e reologia) para observação do comportamento, determinação das temperaturas de fabrico e aferição da percentagem de aditivo. A caracterização das misturas foi realizada inicialmente em laboratório (propriedades volumétricas, sensibilidade à água e resistência à deformação permanente), realizando-se em seguida um trecho experimental onde foram extraídos provetes para determinação das características anteriormente referidas, além do módulo de rigidez. Em comparação com a mistura convencional, conseguiu-se reduzir a temperatura das MBT cerca de 15 a 25 ºC mantendo idênticas propriedades volumétricas e mecânicas em laboratório, o que não se conseguiu no trecho devido a um problema de contaminação com o combustível usado no queimador

A probabilistic fusion framework for 3-D reconstruction using heterogeneous sensors

This letter proposes a framework to perform 3-D reconstruction using a heterogeneous sensor network, with potential use in augmented reality, human behavior understanding, smart-room implementations, robotics, and many other applications. We fuse orientation measurements from inertial sensors, images from cameras and depth data from Time of Flight sensors within a probabilistic framework in a synergistic manner to obtain robust reconstructions. A fully probabilistic method is proposed to efficiently fuse the multi-modal data of the system

Calcium identification and scoring based on echocardiography. An exploratory study on aortic valve stenosis

Currently, an echocardiography expert is needed to identify calcium in the aortic valve, and a cardiac CT-Scan image is needed for calcium quantification. When performing a CT-scan, the patient is subject to radiation, and therefore the number of CT-scans that can be performed should be limited, restricting the patient’s monitoring. Computer Vision (CV) has opened new opportunities for improved efficiency when extracting knowledge from an image. Applying CV techniques on echocardiography imaging may reduce the medical workload for identifying the calcium and quantifying it, helping doctors to maintain a better tracking of their patients. In our approach, a simple technique to identify and extract the calcium pixel count from echocardiography imaging, was developed by using CV. Based on anonymized real patient echocardiographic images, this approach enables semi-automatic calcium identification. As the brightness of echocardiography images (with the highest intensity corresponding to calcium) vary depending on the acquisition settings, echocardiographic adaptive image binarization has been performed. Given that blood maintains the same intensity on echocardiographic images—being always the darker region—blood areas in the image were used to create an adaptive threshold for binarization. After binarization, the region of interest (ROI) with calcium, was interactively selected by an echocardiography expert and extracted, allowing us to compute a calcium pixel count, corresponding to the spatial amount of calcium. The results obtained from these experiments are encouraging. With this technique, from echocardiographic images collected for the same patient with different acquisition settings and different brightness, obtaining a calcium pixel count, where pixel values show an absolute pixel value margin of error of 3 (on a scale from 0 to 255), achieving a Pearson Correlation of 0.92 indicating a strong correlation with the human expert assessment of calcium area for the same images.info:eu-repo/semantics/publishedVersio