Measurement of the Energy Spectrum of the Neutrons inside the Neutron Flux Trap Assembled in the Center of the Reactor Core IPEN/MB-01

This paper presents the neutron energy spectrum in the central position of a neutron flux trap assembled in the core center of the research nuclear reactor IPEN/MB-01, obtained by an unfolding method. To this end, we have used several different types of activation foils （Au, Sc, Ti, Ni, and plates） which have been irradiated in the central position of the reactor core （setting number 203） at a reactor power level （64.57±2.91 watts）. The activation foils were counted by solid-state detector HPGe （high pure germanium detector） （gamma spectrometry）. The experimental data of nuclear reaction rates （saturated activity per target nucleus） and a neutron spectrum estimated by a reactor physics computer code are the main input data to get the most suitable neutron spectrum in the irradiation position obtained through SANDBP （spectrum analysis neutron detection code-version Budapest University） code： a neutron spectra unfolding code that uses an iterative adjustment method. the integral neutron flux, （2.41 ± 0.01） × 10^9 n·cm^-2·s^-1 for the thermal The adjustment resulted in （3.85 ± 0.14） × 10^9 n·cm^-2·s^-1 for neutron flux, （1.09 ±0.02） × 10^9n·cm^-2·s^-1 for intermediate neutron flux and （3.41 ± 0.02） × 10^8 n·cm^-2·s^-1 for the fast neutrons flux. These results can be used to verify and validate the nuclear reactor codes and its associated nuclear data libraries, besides, show how much effective it can be that the use of a neutron flux trap in the nuclear reactor core to increase the thermal neutron flux without increase the operation reactor power level. The thermal neutral flux increased 4.04 ± 0.21 times compared with the standard configuration of the reactor core.     

Mobilisation of bacteria in a fine-grained residual soil by electrophoresis

An investigation of electrokinetic bacterial mobilisation in a residual soil from gneiss is presented here. The experimental program aimed at assessing the efficacy of electrophoresis against the electro-osmotic flow to transport endospores of Bacillus subtilis LBBMA 155 and nitrogen-starved cells of Pseudomonas sp. LBBMA 81. Electrokinesis was performed on a low hydraulic reconstituted clayey soil column submitted to a 5mA electrical current for 24h. Cells were coccoid-shaped and characterised as possessing low surface hydrophobicity and less than 1microm in diameter. Distribution coefficient for B. subtilis in the soil was between 16.8 and 19.9 times higher than that for Pseudomonas sp. Distribution coefficient for B. subtilis between eluate and anionic exchange column was 11.8 times higher than that for Pseudomonas sp. After the electrokinesis, it was shown that cells and endospores were distributed hyperbolically through the soil probe and moved against the electro-osmotic flow; however, endospores were transported throughout all soil core and starved cells only till half of its length. The higher transport efficiency of B. subtilis endospores was attributed to their higher negative charge on cell surface. These results demonstrate that electrokinesis can be used for bacteria transport in soils with low hydraulic conductivity, even against the electro-osmotic flow.     

Effect of preliminary processing and method of preservation on the content of selected antioxidative compounds in kale (Brassica oleracea L. var. acephala) leaves

Vitamin C and polyphenol content as well as total antioxidative activity were investigated in fresh leaves of kale; in leaves after blanching or cooking; and in frozen and canned leaves. In 100 g fresh matter, kale leaves contained 384.9 mg polyphenols and 112.1 mg vitamin C, with a Trolox equivalent antioxidant capacity (TEAC) level of 1175 μM Trolox. Of the polyphenols identified in kale leaves, ferulic acid occurred in the highest amount (240.44 mg/100 g, constituting 62% of total polyphenols). Freezing was a better method of preserving kale leaves since the loss of nutritive constituents was lower than in the case of canning. Depending on preliminary processing and storage temperature, after one-year storage frozen leaves contained 82.9–171.3 mg polyphenols and 39.3–65.4 mg vitamin C, with TEAC at the level of 501–681 μM Trolox in 100 g. In canned leaves these values were: 91.3–94.1 mg polyphenols, 16.1–19.3 mg vitamin C and 268–293 μM Trolox.     

Ensembles of ARTMAP-based neural networks: an experimental study

ARTMAP-based models are neural networks which use a match-based learning procedure. The main advantage of ARTMAP-based models over error-based models, such as Multi-Layer Perceptron, is the learning time, which is considered as significantly fast. This feature is extremely important in complex systems that require the use of several models, such as ensembles or committees, since they produce robust and fast classifiers. Subsequently, some extensions of the ARTMAP model have been proposed, such as: ARTMAP-IC, RePART, among others. Aiming to add an extra contribution to ARTMAP context, this paper presents an analysis of ARTMAP-based models in ensemble systems. As a result of this analysis, two main goals are aimed, which are: to analyze the influence of the RePART model in ensemble systems and to detect any relation between diversity and accuracy in ensemble systems in order to use this relation in the design of these systems.     

Effect of Chenopodium ambrosioides on the healing process of the in vivo bone tissue

The focus of this double‐blind randomized study was on evaluating the effect of an aqueous extract of Mastruz (Chenopodium ambrosioides L.) on the bone repair process in vivo. In total, 36 male Wistar rats were randomly selected for this study, and divided into 3 groups (n = 12): Group HS (Hemostatic Sponge), Group SM (Hemostatic Sponge with Mastruz) and Group BC (Blood Clot). In each animal, bone defects measuring 2 mm in diameter were performed in both tibias for placement of the substances. After 3 and 10 days, the animals were sacrificed, and the tissues were analyzed under an optical microscope relative to the following events: inflammatory infiltrate; necrosis; young fibroblasts; osteoclastic and osteoblastic activity; endosteal and periosteal bone formation; and bone repair. The results were assessed by using Kruskal–Wallis and Mann–Whitney tests (p < .05). Inflammatory infiltrate demonstrated difference between Groups SM and BC in the time interval of 3 days (p = .004); an event related to the presence of the fibrin sponge and liquid of the extract, which induced a foreign body initial reaction. The presence of young fibroblasts (p = .003), osteoclastic (p = .003), and osteoblastic (p = .020) activity was statistically significant between Groups HS and BC in the time interval of 10 days; performance was related to the presence of the sponge within bone. As regards injured bone tissue repair, Group SM demonstrated a higher level of regenerative capacity (p = 0.004), due to a larger quantities of endosteal and periosteal bone formation, demonstrated in Group SM. The aqueous extract of mastruz stimulated bone neoformation, presenting wound closure with bone tissue at the end of 10 days.     

A simulation environment for performance analysis of HVAC systems

Due to the lack of a building simulation program that can simulate in details the combined heat, vapor, and liquid transfer in porous elements and the HVAC (heating, ventilation and air-conditioning) systems, a flexible computational algorithm has been elaborated in order to integrate models for both HVAC systems and multizone hygrothermal building model. In the algorithm, models for the primary system-composed of chiller, cooling tower, primary pumps, and condensation pumps—have been described. For the secondary system, models for the cooling and dehumidifying coil, humidifier, fan, and mixing box have been considered. Those mathematical models have been integrated into the whole-building PowerDomus simulation environment. The simulation environment is presented, and results show the usability aspects of the proposed computer environment by comparing air- and water-cooled equipment.     

Emergent vegetation in Netley-Libau Marsh: Temporal changes (1990–2013) in cover in relation to Lake Winnipeg level and Red River flow

A time-series (1990–2013) of classified vegetation cover maps was produced for Netley-Libau Marsh, a 26,000 ha coastal wetland on Lake Winnipeg, to assess its current status and verify earlier trends of emergent vegetation loss. Open water area in the marsh was measured from late-summer Landsat images for 20 years; three classes of vegetation types (emergents, wet meadows, upland) could also be identified for 12 images covering the same period. Temporal changes in area and distribution of marsh vegetation were related to adjoining Lake Winnipeg water-level and Red River discharge, as well as marsh connectivity and bathymetry. From 1990 to 2002, an increase in open-water areas and decrease in emergent vegetation coincided with rising levels and flows. The year 2003 marked major wetland regeneration and a decrease of open-water area under extremely low water-levels and flows. From 2005 to 2013, open-water area remained consistent, under high but variable levels and flows. A strong negative correlation was found between area of emergent vegetation and mean Red River discharge in the previous June-July. Superimposition of the limit of new emergent vegetation observed in 2003 with depth contours surveyed in 2010 revealed the dynamic nature of marsh bathymetry. Periods of extremely low water as short as one year (2003) induced a marked expansion in emergent vegetation cover that persisted over the next ten years despite higher water-levels. Rather than being gradual, changes in the spatial extent of Netley-Libau Marsh vegetation appeared to proceed by fits and starts, wherein periods of relative stasis were disrupted by major changes in abundance.     

Light-scattering studies on solutions of high and low molecular weight polystyrene mixtures used as models of microgel-containing solutions

Diluted solutions of linear polystyrene (PS) in toluene and dioxane were studied by the light-scattering method. The solutes were mixtures of high-M?_w and low M?_w PS. The dissolved PS mixtures were regarded as polymer solutions containing microgels, the high-M?_w PS being looked upon as the microgel counterpart. The calculation method as proposed by Strazielle¹ and Burchard² was used to evaluate the microgel percentage and particle size, whereby the method could be verified against mixtures with well-known weight composition and \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\left( {r_g ^2 } \right)} ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document}. The \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\left( {r_g ^2 } \right)} ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document} values evaluated for the mixtures from the experimental data were compared with those estimated from the molecular weights of the components, their weight concentrations, and their \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\left( {r_g ^2 } \right)} ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document} values. The method^1,2 was found to be useful for evaluating the microgel content in a sample, but not for \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\left( {r_g ^2 } \right)} ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document} values as calculated by Guinier's procedure nor those calculated by Zimm's procedure; the former were low and the latter were even incongruous. A comparative analysis of the theoretical function P^?1(θ)-versus-sin² (θ/2) and experimental (Kc/R(θ))_c=0-versus-sin² (θ/2) curves allowed to discuss the effect of the course of these curves at samll angles from 0° to 30° on M?_w and \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\left( {r_g ^2 } \right)} ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} $\end{document} as determined for the high and low molecular weight polystyrene mixtures in toluene as solvent.     

Low-cost clock synchronization

Summary We show how synchronized clocks can be realized in a distributed system as a byproduct of a common communication paradigm where processors periodically perform broadcasts. Our approach decouples theprecision concern of clock synchronization—limiting how much correct clocks can differ from each other—from theaccuracy concern—limiting the rate at which any correct clock may drift from real time. Given a system that guarantees only precision, we develop a protocol whereby high accuracy can be achieved on demand. In this manner, the lazy protocol we obtain incurs the cost of high accuracy only when needed while keeping the basic synchronization procedure extremely simple and cheap. Rogério Drummond is Associate Professor of Computer Science at the Universidade de Campinas (Unicamp), Brazil. He received his Ph.D. in computer science from Cornell University in 1986. He has previously worked on distributed fault-tolerant computing, such as the present paper. Currently, he heads the A_HAND project which aims to provide an object-oriented distributed programming environment for the development of very large software systems. Özalp Babaolu is Professor of Computer Science at the University of Bologna, Italy. His research interests include distributed algorithms, fault tolerance and parallel computing. He received a BS in electrical engineering from George Washington University, Washington, D.C. in 1976. From the University of California, Berkeley, he received a MS in 1977 and a Ph.D. in 1981, both in computer science. While at Berkeley, he designed and implemented the virtual memory extensions to BSD Unix. From 1981 to 1987 he was on the faculty at the Department of Computer Science, Cornell University.Partial support for this work was provided by the National Science Foundation under Grant DCR-86-01864, AT&T under a Foundation Grant, the Commission of the European Communities under the ESPRIT Programme Basic Research Action Number 3092 (Predictably Dependable Computing Systems) and the Italian Ministry of University and Research. Drummond was partially supported through a Fellowship from the CAPES Agency of the Government of Brazil