Image recovery from exponential blurring

We study the following type of filtering problem: consider an image on ², that is, a nonnegative function on the vertices of a grid, which represents the brightness at each of these points. We assume that there is, however, a smudging effect. That is, what ought to be a point of light becomes the point together with a halo about it, visualized by a distribution of light which is greatest at the point itself and decreases with the distance. So what we actually see is a blurry image. In this article we investigate methods for clearing up the image, i.e. reconstructing the original function from the blurry haloed image when the halo decays exponentially, and also for some haloes with small finite support. This task is usually performed by inverting the convolution operator induced by the halo (that is, by Fourier analysis). We introduce a different recovery procedure, based upon a family of filtering operators that change from point to point. For the finitely supported haloes, this procedure compares favorably with the Fourier methods. Moreover, in principle it is more general, because it does not require assumptions of invariance under translation. In full generality, however, we are able to recover images not on grids, but only on trees.     

Behavior of the beta-splines with values of the parameters beta2 negative

In this paper we study the behavior of the beta-spline functions in the case the parameter β₂(i) is negative. We prove that a negative value exists so that if , the beta-spline functionsN_i(u) are positive. Moreover, if the control vertices are such that x₀ x_m−1, we have proved that the design curve keeps the properties already proved in the case β₂(i) 0.     

One-stage curative treatment of neoplastic colonic obstruction: long-term results, comparison with elective surgery and therapeutic implications

Over a period of ten years (1980-1989) 528 patients with colon cancer were treated at one institution. One hundred seventy nine (33.9%) were obstructed (O) and underwent emergency surgery, while 349 received elective (E) treatment; of these 363 had one-stage curative treatment. Operative mortality was 10.3% (O) and 3.5% (E) respectively (p < .0.5). Three hundred forty three patients survived surgery and entered follow-up: 96 were O (M:F, 54:42) and 247 E (M:F, 119:128, p = N.S.). Their mean age was 69.5 and 64.4 (p < .001), respectively. Dukes' stage and histological grading were evenly distributed within the two groups, but sites of the primary were not (p < .001). During the follow-up local recurrence occurred in 40 patients (13 O, 27 E, p = N.S.) and metastatic disease in 78 (28 O, 50 E, p < .05, Life Table Analysis) including liver recurrence in 17 O and 30 E (p = .063). Five year crude survival (51%) was significantly worse in obstructed patients. Multivariate analysis showed that Dukes' stage and obstruction were the only prognostic factors of recurrent disease, while survival was affected by the same variables and age over 70. When recurrent disease was introduced in the model survival depended on Dukes' stage, site of the primary and age over 70 and the variable obstruction disappeared as prognostic factor. Right sided tumours showed a better and those at the splenic flexure a worse prognosis. Despite one-stage curative treatment obstruction carries a significantly higher risk of developing metastatic disease, suggesting that obstruction enhances cancer cell dissemination. These patients might benefit from per-operative intra-portal and post-operative systemic adjuvant chemotherapy.     

Dose-effect study on the antioxidant properties of leaves and outer bracts of extracts obtained from Violetto di Toscana artichoke

Artichoke (Cynara scolymus L.) is an edible vegetable largely used in the Mediterranean diet and in folk medicine. The present paper discusses the analysis of the polyphenol content of leaves and outer bracts of Violetto di Toscana artichoke using different extraction procedures with the aim of establishing a correlation between polyphenol subclasses and antioxidant activity measured on human LDL oxidized by copper ions. HPLC/DAD and HPLC/MS analyses revealed that both the matrixes contain identical polyphenol subclasses, with mainly quantitative differences. The antioxidant effect of four artichoke extracts decreases in the following order when the sum of total phenolic compounds was considered: ethanolic extract from leaves (IC₅₀ = 2.92 ± 0.46 μM); ethanolic extract from outer bracts (IC₅₀ = 4.04 ± 0.21 μM); ethyl acetate extract from leaves (IC₅₀ = 4.91 ± 0.11 μM); ethyl acetate extract from outer bracts (IC₅₀ = 10.18 ± 1.6 μM). IC₅₀ were also calculated considering the concentrations of single polyphenol subclasses. In both cases, the potency of antioxidant properties was not related to the amount of total polyphenols or the single subclasses.     

Cooperative navigation of AUVs via acoustic communication networking: field experience with the Typhoon vehicles

A cooperative navigation procedure for a team of autonomous underwater vehicles (AUVs) is described and validated on experimental data. The procedure relies on acoustic communication networking among the AUVs and/or fixed acoustic nodes, and it is suitable as a low-cost solution for team navigation. Embedding the acoustic localization measurements in the communication scheme causes delays and sometimes loss of acoustic data, depending on acoustic propagation conditions. Despite this drawback, the results obtained show that on-board localization estimates have an error of the order of few meters, improving the overall navigation performance and leading the system towards long-term autonomy in terms of operating mission time, without the need of periodic resurfacings dedicated to reset the estimation error. The data were collected during the CommsNet ’13 experiment, led by the NATO Science and Technology Organization Center for Maritime Research and Experimentation (CMRE), and the Breaking The Surface ’14 workshop, organized by the University of Zagreb.     

Static and Dynamic Data Models for the Storage Resource Manager v2.2

We present a conceptual model for the Storage Resource Manager, the standard interface adopted for the storage systems of the Worldwide Large Hadron Collider Computing Grid. This model provides a clear and concise definition of the structural and behavioral concepts underlying the interface specification and is meant to support service and application development. Different languages (natural language, UML diagrams, and simple set-theoretic and logical notation) are used to describe different aspects of the model.     

Students’ navigation patterns in the interaction with a mechanics hypermedia program

This study investigates the interaction of a group of freshmen enrolled in a Pre Service Physics Teacher Training Course with a mechanics hypermedia program. Data were obtained to discuss hypertextual navigation guided by the following questions: (i) How can the students’ navigation in this hypermedia program be characterized? (ii) How does this relate to their prior knowledge in mechanics? The sequence analysis of the events collected from the log files was used to characterize students’ navigation and a mechanics test assessed students’ prior knowledge. The inspection of students’ navigation graphs made it possible to associate the structure of navigation to prior knowledge in mechanics. Three patterns of navigation are proposed associated to different levels of students’ prior knowledge and to different roles performed by the program. In the organized navigation, the student who best performed in the pre test seemed to be reviewing content he already knew, using the system as a database. In the conceptual navigation the students who presented difficulties in the pre test spent different times in the pages as they were addressing conceptual difficulties, using the system as a support for learning. The students who scored the lowest in the test performed a disoriented navigation, spending much less than the adequate time to interact meaningfully with the content. The role that previous knowledge in mechanics plays in these patterns of navigation was related to the function that Ausubel’s subsumers perform in learning. The results indicate that hypertextual navigation can provide information about students’ conditions to engage in meaningful learning, which could be used to help the teacher personalize instruction.     

A systematic survey of service identification methods

One of the major challenges for the adoption of the service-oriented architecture (SOA) is the service identification phase that aims to determine which services are appropriate to be implemented. In the last decade, several service identification methods (SIMs) were proposed. However, the service identification phase still remains a challenge to organizations due to the lack of systematic methods and comprehensive approaches that support the examination of the businesses from multiple perspectives and consider service quality attributes. This work aims to provide an overview of existing SIMs by detailing which service’s perspectives, stated as relevant by the industry, are addressed by the SIMs and also by synthesizing the identification techniques used by them. We have performed a systematic survey over publications about SIMs from 2002 to June 2013, and 105 studies were selected. A detailed investigation on the analyzed SIMs revealed that the identification techniques applied by them have a correlation on how they address many of the service’s perspectives. In addition, they are supporting the SOA adoption by handling many perspectives of the OASIS’ reference architecture for SOA. However, most of them do not explicitly address service quality attributes and few studies support the evaluation of both. Therefore, future research should follow the direction toward hybrid methods with mechanisms to elicit business and service’s quality attributes.