Elastic Resource Allocation Algorithms for Collaboration Applications

Cloud technologies can provide elasticity to real-time audio and video (A/V) collaboration applications. However, cloud-based collaboration solutions generally operate on a best-effort basis, with neither delivery nor quality guarantees, and high-quality business focused solutions rely on dedicated infrastructure and hardware-based components. This article describes our 2-year of research in the EMD project, which targets to migrate a hardware-based and business focused A/V collaboration solution to a software-based platform hosted in the cloud, providing higher levels of elasticity and reliability. Our focus during this period was an educational collaboration scenario with teachers and students (locally present in the classroom or remotely following the classes). A model of collaboration streaming (e.g. network topology, codecs, stream, streaming workflow, software components) is defined as base for software deployment and preemptive VM allocation techniques. These heuristics are evaluated using a version of the CloudSim simulator extended to generate and simulate realistic collaboration scenarios, to manage network congestion and to monitor a.o. cost and session delay metrics. Our results show that the algorithms reduce costs when compared to previously designed approaches, having an effectiveness of 99% in meeting A/V collaboration setup deadlines, which is a stringent requirement for this collaboration application.     

Taxonomy for the Network and Service Management Research Field

Network and service management has established itself as a research field in the general area of computer networks. However, up to now, no appropriate organization of the field has been carried out in terms of a comprehensive list of terms and topics. In this paper, we introduce a taxonomy for network and service management. With such a taxonomy, it is possible to better understand the landscape of research as well as to reason about possible future challenges and opportunities. As such, in addition to the taxonomy itself, we also present an initial analysis of the field’s past, present, and future, based on the records of papers submitted and accepted in major conferences in the area, as well as a site survey performed through a questionnaire answered by experts from both industry and academia.     

Eating characteristics of Chilean indigenous and non-indigenous adolescent girls

During childhood and adolescence, eating habits become established which are instrumental in determining eating behavior later in life. Various authors have described the acculturation of the Mapuche people toward Western culture. The objective of this study was to analyze the eating characteristics of indigenous and non-indigenous adolescent girls in the Araucania Region of Chile. A cross-sectional design was used with a probabilistic sample of 281 adolescents comprised of 139 indigenous and 142 non-indigenous girls attending 168 elementary schools. A modified food frequency questionnaire was applied, designed to obtain information about eating habits and consumption of Mapuche foods. The eating schedules are similar in both ethnic groups, with dinner being the meal that is least consumed. Total snack consumption per week has a mean of 7 with an interquartile range (IQR) of 5 to 10 without any differences between ethnic groups; of these snacks, only 2 were healthy (IQR = 1 to 3). The indigenous girls had a higher probability of consumption of native foods including mote (boiled wheat) (OR = 2.00; IC = 0.93-4.29), muday (fermented cereal alcohol) (OR = 3.45; IC = 1.90-6.27), and yuyo (field mustard) (OR = 4.40; IC = 2.06-9.39). The study's conclusion is that the the eating habits and behavior of indigenous adolescents are similar to those of non-indigenous girls, though the former still consume more indigenous foods.     

How far can one compress digital fault records? Analysis of a matching pursuit-based algorithm

In this paper, we verify how far electric disturbance signals can be compressed without compromising the analysis of encoded fault records. A recently proposed compression algorithm, referred to as Damped Sinusoidal Matching Pursuit (DSMP) has the remarkable feature of obtaining both compact and physically interpretable representations. However, for fault analysis applications, one is primarily interested in how accurate can be the analysis performed on compressed signals, instead of evaluating mean-squared error figures. Unlike previous works in digital fault records compression, the performance of the DSMP compression method is evaluated using a protocol based on fault analysis procedures commonly performed by expert engineers. This protocol is applied for comparing the results obtained in the analysis of both uncompressed records and their compressed versions at different compression ratios. The results show that the DSMP is a reliable compression system since it achieves high compression ratios (6.4:1) without causing fault analysis misinterpretation.     

Efficient allocation of elastic interfederation encrypted streaming sessions

Audio and video (A/V) collaboration platforms often use Internet cloud technologies to ensure elasticity. They generally operate on a best‐effort basis, without quality or delivery guarantees. However, such guarantees are a premise of business‐focused platforms, which often rely on static/dedicated infrastructure and hardware‐based components. This article presents results obtained in the final stage of the Elastic Media Distribution (EMD) project, which targets the migration of a business‐focused hardware‐based A/V collaboration tool towards a more elastic, reliable, and secure cloud‐based model. The use case under investigation is an educational scenario: teachers and students located at distributed sites collaborate under different data encryption policies. An existing model of collaboration streaming is extended to accommodate encryption‐enabled streaming components, and new resource allocation heuristics are proposed to deploy these components under stringent service level agreement (SLA) constraints. An extended version of our evaluation framework, based on the CloudSim simulator, manages encryption‐enabled components. A resource usage dataset was obtained by prototyping selected streaming components and evaluating their performance on the Virtual Wall large‐scale test bed. This dataset is fed into the extended simulation framework. Simulation results show longer than expected delays when loading streaming components, an issue that jeopardises the user experience that can be alleviated by the algorithms proposed in this article. Results show that the proposed algorithms enable policy‐based secured communications under bandwidth and virtual machine (VM) cost increases of 48% and 23%, respectively, if compared with a nonencrypted previous solution, and with set‐up times remaining under the required 2‐second deadline.     

PAH fluxes in the Laja Lake of south central Chile Andes over the last 50 years: evidence from a dated sediment core

This paper reports the occurrence of polyaromatic hydrocarbons (PAHs) deposition inferred from a sediment core of an Andean lake in south central Chile. Sediments were carefully collected from one of the deepest section of the lake and sliced every 1 cm. The samples were analyzed for PAHs, (137)Cs, (210)Pb, organic carbon and grain-size. The stratigraphic chronology and the sedimentation rates were estimated using the sedimentary signature left by the (137)Cs and (210)Pb fallout as temporal markers. PAHs were quantified by HPLC-fluorescence detection (HPLC-Fluorescence). 15 priority EPA PAHs were analyzed in this study. Based on these results, PAH deposition over the last 50 years was estimated (a period characterized by an important intervention in the area). PAH concentration ranged from 226 to 620 ng g(-1) d.w. The highest concentrations of PAHs were found in the core's bottom. The PAH profile is dominated by the presence of perylene indicating a natural source of PAH. In addition, two clear PAH deposition periods could be determined: the most recent with two-four rings PAHs, the older one with five-seven rings predomination. Determined fluxes where 71 to 972 microg m(-2) year(-1), dominated by perylene deposition. PAH levels and fluxes are lower compared to the levels found in sediments from remote lakes in Europe and North America. It is concluded that the main source of PAHs into the Laja Lake sediments are of natural origin.     

Shape changes of Pt nanoparticles induced by deposition on mesoporous silica

Polyvinylpyrollidone (PVP)-capped platinum nanoparticles (NPs) are found to change shape from spherical to flat when deposited on mesoporous silica substrates (SBA-15). Transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and extended X-ray absorption fine structure (EXAFS) analyses are used in these studies. The SAXS results indicate that, after deposition, the 2 nm NPs have an average gyration radius 22% larger than in solution, while the EXAFS measurements indicate a decrease in first neighbor co-ordination number from 9.3 to 7.4. The deformation of these small capped NPs is attributed to interactions with the surface of the SBA-15 support, as evidenced by X-ray absorption near-edge structure (XANES).     

Effect of Processing Conditions on Drying Kinetics and Particle Microstructure of Carrot

The drying of carrot particles (6 mm × 6 mm × 12 mm) was studied in a tunnel dryer; a vacuum-freeze dryer, either with or without infrared radiation; a pulsed fluidized-bed dryer assisted by microwave radiation; and combinations of these methods. The effect of two freezing rates (quick freezing in liquid nitrogen and slow freezing in a household freezer) was also studied.

The drying kinetics for these drying methods were determined and modeled, and the dried products were subjected to texture (hardness), color, and rehydration analysis, as well as 2D and 3D image analysis of pictures from scanning electron microscope.

The combination of freeze drying with other dehydration techniques reduces the drying time by 6–70%, although, in general, the structural damage increases with respect to freeze drying alone. The hybrid drying systems did not show significant differences in drying times either for quick- or slow-frozen samples. The combination of freeze drying followed by conventional drying reduces the drying time between 23 and 40% on average.

The Page empirical model represents adequately the entire drying process for combined methods, with specific parameters for each drying zone. The values of effective diffusivity calculated with the simplified constant diffusivity model agree with those reported in the literature.