An Analysis of Public Clouds Elasticity in the Execution of Scientific Applications: a Survey

Elasticity can be seen as the ability of a system to increase or decrease the computing resources allocated in a dynamic and on demand way. It is an important feature provided by cloud computing, that has been widely used in web applications and is also gaining attention in the scientific community. Considering the possibilities of using elasticity in this context, a question arises: “Are the available public cloud solutions suitable to provide elasticity to scientific applications?” To answer the question, in a first moment we present a survey on the use of cloud computing in scientific scenarios, providing an overview of the subject. Next, we describe the elasticity mechanisms offered by major public cloud providers and analyzes the limitations of the solutions in providing elasticity for scientific applications. As the main contribution of the article, we also present an analysis over some initiatives that are being developed to overcome the current challenges. In our opinion, current computational clouds are developing rapidly but have not yet reached the necessary maturity level to meet all scientific applications elasticity requirements. We expect that in the coming years the efforts being taken by numerous researchers in this area identify and address these challenges and lead to better and more mature technologies that will improve cloud computing practices.     

Structure determination of phi-Bi8Pb5O17 by electron and powder X-ray diffraction

The triclinic crystal structure of phi-Bi8Pb5O17, a ionic fast conductor material, has been determined by the synergy of both electron and powder X-ray crystallography. The heavy atom positions were found by direct methods on electron diffraction data and the structure was completed by iterative use of a priori information in direct methods and difference Fourier maps on both types of data. Structure refinement was performed by the Rietveld method on powder X-ray data. The results suggest that phi-Bi8Pb5O17 is an ordered phase, with Bi and Pb atoms occupying different sites of the lattice, at variance with the other structural phases known for similar composition in the Bi-Pb-O phase diagram, which are solid solutions characterised by a wide compositional range.     

Brazilian red propolis: unreported substances, antioxidant and antimicrobial activities

BACKGROUND: Chloroform, ethyl acetate and methanol extracts of a sample of red propolis from the state of Alagoas (northeast Brazil) were analyzed by gas chromatography–mass spectrometry and high‐performance liquid chromatography–diode array detection–electrospray ionization‐mass spectrometry. Antimicrobial and antioxidant activities were also obtained. RESULTS: The propolis sample contained low content of narigenin‐8‐C‐hexoside, this being the first report of a C‐glycoside in propolis. The main constituent found was characterized as 3,4,2′,3′‐tetrahydroxychalcone. Other important constituents were the chalcone isoliquiritigenin, the isoflavans (3S)‐vestitol, (3S)‐7‐O‐methylvestitol, the pterocarpan medicarpin, the phenylpropenes trans‐anethol, methyl eugenol, elimicin, methoxyeugenol and cis‐asarone, and the triterpenic alcohols lupeol and α‐ and β‐ amyrins. The methanol extract exhibited high antioxidant activities by 2,2‐diphenyl‐1‐picrylhydrazyl and β‐carotene/linoleic acid assay methods, and antimicrobial activity toward Gram‐positive and Gram‐negative bacteria. CONCLUSION: Structures are suggested for new substances never before seen in any kind of propolis. This is the first report of 3,4,2′,3′‐tetrahydroxychalcone and a flavone C‐glycoside in a propolis sample. Copyright © 2011 Society of Chemical Industry     

Imaging features and clinical significance of perineural spread or extension of head and neck tumors

Perineural spread of head and neck tumors is a form of metastatic disease in which tumor disseminates to noncontiguous regions along the endoneurium or perineurium. Both computed tomography (CT) and magnetic resonance (MR) imaging can help detect perineural spread, although MR imaging is the modality of choice because of its multiplanar capability, its superior soft-tissue contrast, and the decreased amount of artifact from dental hardware. Perineural spread most commonly occurs in adenoid cystic carcinoma and squamous cell carcinoma. Nerve enlargement may lead to foraminal enlargement and, ultimately, to foraminal destruction, findings that are best seen at CT. Extension through the foramen ovale and involvement of the Meckel cave is best seen on coronal T1-weighted MR images, and nerve enhancement is best seen on fat-suppressed T1-weighted MR images. Other radiologic findings include obliteration of fat planes at foraminal openings, neuropathic atrophy, cavernous sinus enlargement, and replacement of the trigeminal subarachnoid cistern with soft tissue. The pathway of perineural tumor spread is predictable with knowledge of the pertinent cranial nerve anatomy; however, patients with radiologically or pathologically proved perineural spread may have normal nerve function at clinical examination. Therefore, it is imperative that the radiologist be familiar with both normal cranial nerve anatomy and the radiologic appearance and assessment of perineural tumor extension.     

Arteriovenous malformation of the base of tongue: case report and literature review

Arteriovenous malformations of the head and neck pose a challenging therapeutic and reconstructive problem. In this report we describe a rare case of an arteriovenous malformation of the base of tongue. The patient, a young adult female, was treated with embolization followed by surgical resection using a lateral pharyngotomy approach. Reconstruction of the extensive base of tongue defect was accomplished using a radial forearm free flap. Currently, the patient is decannulated, articulates clearly, tolerates a normal diet, and is without recurrence. Our treatment approach is discussed in detail and compared with alternative techniques.     

Peripheral blood lymphocyte decrease and micronucleus yields during radiotherapy

PURPOSE: To investigate the relationship between lymphocyte decrease and cytogenetic response in individual patients undergoing radiotherapy. MATERIALS AND METHODS: Peripheral blood lymphocytes obtained from 35 patients with pelvic and from 14 with head and neck tumours before and during radiotherapy were PHA-stimulated in vitro and the cultures prepared for the cytokinesis-block micronucleus test. For some patients only, the micronucleus test was carried out after 2 Gy in vitro X-irradiation, and 3-aminobenzamide (2 mM) was used to calculate the 3AB-index. RESULTS: The initially observed individual variation in the decrease of lymphocytes disappeared with increasing number of radiation exposures, reaching a stable level at about 500/microl lymphocytes in the blood. The slope of the relationship between the reciprocal of the lymphocyte decrease ratio and equivalent dose indicates the radiosensitivity of the lymphocyte pool in individual patients. The micronucleus test performed on lymphocytes obtained from patients during radiotherapy (in vivo) provided a lower cytogenetic response than the in vitro micronucleus yield for the same dose, so it was possible to calculate the cytogenetic recovery factor k. A correlation was found between the 3AB-index calculated before radiotherapy, and the recovery factor k. CONCLUSIONS: The 3AB-index, the micronucleus frequency after 2 Gy in vitro X-irradiation, and the cytogenetic recovery factor are proposed as predictive of individual response to radiotherapy.     

Deviation-Based Model Risk Measures

Computational Economics - In practice, risk forecasts are obtained by risk measures based on a given probability measure on a measurable space. In our study, we consider the probability measures as...     

Interaction and Outcomes in Collaborative Storytelling Systems: a Framework,a Field Study,and a Model

In the last decades, advances in interactive information technologies have facilitated collaborative fiction writing, which has become widespread and large-scale. This paper proposes a framework to analyze collaborative storytelling systems, made of a set of parameters divided into six conceptual areas. Four of them relate to the systems and two (process and output) to the results of the collaboration. Through this framework we can study more precisely these different factors of the systems, their interplay, and how they impact the creators’ performance. We also present a controlled extended-duration field study on collaborative storytelling, and we use this framework to comparatively analyze these observations and other relevant experiences in the field of co-creation of shared narrative spaces. As a result, we propose a human-information interaction model for collaborative narrative systems, intended to better support co-creation and address the barriers of this kind of systems turning them into new opportunities for collaboration.