933 research outputs found
Big Data and Analysis of Data Transfers for International Research Networks Using NetSage
Modern science is increasingly data-driven and collaborative in nature. Many scientific disciplines, including genomics, high-energy physics, astronomy, and atmospheric science, produce petabytes of data that must be shared with collaborators all over the world. The National Science Foundation-supported International Research Network Connection (IRNC) links have been essential to enabling this collaboration, but as data sharing has increased, so has the amount of information being collected to understand network performance. New capabilities to measure and analyze the performance of international wide-area networks are essential to ensure end-users are able to take full advantage of such infrastructure for their big data applications. NetSage is a project to develop a unified, open, privacy-aware network measurement, and visualization service to address the needs of monitoring today's high-speed international research networks. NetSage collects data on both backbone links and exchange points, which can be as much as 1Tb per month. This puts a significant strain on hardware, not only in terms storage needs to hold multi-year historical data, but also in terms of processor and memory needs to analyze the data to understand network behaviors. This paper addresses the basic NetSage architecture, its current data collection and archiving approach, and details the constraints of dealing with this big data problem of handling vast amounts of monitoring data, while providing useful, extensible visualization to end users
A sustainable method of effluent disposal: case study of Antalya sea outfall, Turkey
Antalya city, located along the Turkish Mediterranean coast, lacked a proper sanitation system till 1996. An integrated water & wastewater project has been implemented to protect groundwater resources used for drinking and seawater quality. The project involved collection, treatment and final disposal of effluents by a deep sea outfall system. A current research project has been realized to evaluate performance of Antalya Sea Outfall. Seasonal in-situ measurements and bacteriological monitoring studies have been realized. The discharged wastewater plume is observed to be submerged in summer and to reach sea surface in winter condition. The results of the monitoring program exhibit considerable spatial and temporal variations. The resultant total and fecal coliform numbers comply well with the Turkish Standards for the use of coastal and sea water for recreation
Biomimetic apatite formation on different polymeric microspheres modified with calcium silicate solutions
Proceedings of the 18th International Symposium on Ceramics in Medicine, The Annual Meeting of the International Society for Ceramics in Medicine (ISCM), Kyoto, Japan, 5-8 December 2005. Published in : Key Enggineering Materials, vol. 309 - 311Bioactive polymeric microspheres can be produced by pre-coating them with a calcium
silicate solution and the subsequent soaking in a simulated body fluid (SBF). Such combination
should allow for the development of bioactive microspheres for several applications in the medical
field including tissue engineering. In this work, three types of polymeric microspheres with different
sizes were used: (i) ethylene-vinyl alcohol co-polymer (20-30 'm), (ii) polyamide 12 (10-30 'm) and
(iii) polyamide 12 (300 'm). These microspheres were soaked in a calcium silicate solution at 36.5ºC
for different periods of time under several conditions. Afterwards, they were dried in air at 100ºC for
24 hrs. Then, the samples were soaked in SBF for 1, 3 and 7 days. Fourier transformed infrared
spectroscopy, thin-film X-ray diffraction, and scanning electron microscopy showed that after the
calcium silicate treatment and the subsequent soaking in SBF, the microspheres successfully formed a
bonelike apatite layer on their surfaces in SBF within 7 days due to the formation of silanol (Si-OH)
groups that are quite effective for apatite formation.I. B. Leonor thanks the Portuguese Foundation for Science and Technology (FCT) for providing her a PhD scholarship (SFRH/BD/9031/2002) and the European Union funded STREP Project HIPPOCRATES (NMP3-CT-2003-505758) and the European NoE EXPERTISSUES (NMP3-CT-2004-500283)
Identification of 2-Aminothiazole-4-Carboxylate Derivatives Active against Mycobacterium tuberculosis H37Rv and the β-Ketoacyl-ACP Synthase mtFabH
Background
Tuberculosis (TB) is a disease which kills two million people every year and infects approximately over one-third of the world's population. The difficulty in managing tuberculosis is the prolonged treatment duration, the emergence of drug resistance and co-infection with HIV/AIDS. Tuberculosis control requires new drugs that act at novel drug targets to help combat resistant forms of Mycobacterium tuberculosis and reduce treatment duration.
Methodology/Principal Findings
Our approach was to modify the naturally occurring and synthetically challenging antibiotic thiolactomycin (TLM) to the more tractable 2-aminothiazole-4-carboxylate scaffold to generate compounds that mimic TLM's novel mode of action. We report here the identification of a series of compounds possessing excellent activity against M. tuberculosis H37Rv and, dissociatively, against the β-ketoacyl synthase enzyme mtFabH which is targeted by TLM. Specifically, methyl 2-amino-5-benzylthiazole-4-carboxylate was found to inhibit M. tuberculosis H37Rv with an MIC of 0.06 µg/ml (240 nM), but showed no activity against mtFabH, whereas methyl 2-(2-bromoacetamido)-5-(3-chlorophenyl)thiazole-4-carboxylateinhibited mtFabH with an IC50 of 0.95±0.05 µg/ml (2.43±0.13 µM) but was not active against the whole cell organism.
Conclusions/Significance
These findings clearly identify the 2-aminothiazole-4-carboxylate scaffold as a promising new template towards the discovery of a new class of anti-tubercular agents
Surface potential change in bioactive polymer during the process of biomimetic apatite formation in a simulated body fluid
A bioactive polyethylene substrate can be produced by incorporation of sulfonic functional groups (-SO3H) on its surface and by soaking in a calcium hydroxide saturated solution. Variation of the surface potential of the polyethylene modified with -SO3H groups with soaking in a simulated body fluid (SBF) was investigated using a laser electrophoresis zeta-potential analyzer. To complement the study using laser electrophoresis, the surface was examined by X-ray photoelectron spectroscopy (XPS), thin film X-ray diffraction (TF-XRD), field-emission scanning electron microscopy (FE-SEM) and energy-dispersive electron X-ray spectroscopy (EDS). Comparing the zeta potential of sulfonated and Ca(OH)2-treated polyethylene with its surface structure at each interval of these soaking times in SBF, it is apparent that the polymer has a negative surface potential when it forms -SO3H groups on its surface. The surface potential of the polymer increases when it forms amorphous calcium sulfate. The potential decreases when it forms amorphous calcium phosphate, revealing a constant negative value after forming apatite. The XPS and zeta potential analysis demonstrated that the surface potential of the polyethylene was highly negatively charged after soaking in SBF for 0.5 h, increased for higher soaking times (up to 48 h), and then decreased. The negative charge of the polymer at a soaking time of 0.5 h is attributed to the presence of -SO3H groups on the surface. The initial increase in the surface potential was attributed to the incorporation of positively charged calcium ions to form calcium sulfate, and then the subsequent decrease was assigned to the incorporation of negatively charged phosphate ions to form amorphous calcium phosphate, which eventually transformed into apatite. These results indicate that the formation of apatite on bioactive polyethylene in SBF is due to electrostatic interaction of the polymer surface and ions in the fluid
Formation of bone-like apatite on polymeric surfaces modified with -SO3H groups
Sulfonic groups (-SO3H) were covalently attached on different polymeric surfaces
enabling them to induce apatite nucleation, for developing bioactive apatite-polymer composites with
a bonelike 3-dimensional structure. High molecular weight polyethylene (HMWPE) and
ethylene-co-vinyl alcohol co-polymer (EVOH) were used. The polymers were soaked in two types of
sulphate-containing solutions with different concentrations, sulphuric acid (H2SO4) and
chlorosulfonic acid (ClSO3H). To incorporate calcium ions into to the sulfonated polymers, the
samples were soaked in a saturated Ca(OH)2 solution for 24 hours. After soaking of the samples in a
simulated body fluid (SBF), formation of an apatite layer on both surfaces was observed. The results
obtained prove the validity of the proposed concept and show that the -SO3H groups are effective on
inducing apatite nucleation on the surface of these polymers.(undefined
Exact Solution Methods for the -item Quadratic Knapsack Problem
The purpose of this paper is to solve the 0-1 -item quadratic knapsack
problem , a problem of maximizing a quadratic function subject to two
linear constraints. We propose an exact method based on semidefinite
optimization. The semidefinite relaxation used in our approach includes simple
rank one constraints, which can be handled efficiently by interior point
methods. Furthermore, we strengthen the relaxation by polyhedral constraints
and obtain approximate solutions to this semidefinite problem by applying a
bundle method. We review other exact solution methods and compare all these
approaches by experimenting with instances of various sizes and densities.Comment: 12 page
Litters Health Status and Growth Parameters in the Sows Feeding Diets Supplemented with Probiotic Actisaf Sc 47® within Pregnancy Or Lactation
The aim of this study was to investigate the effect of supplementing standard diets for pregnant and lactating sows with live yeast culture (Saccharomyces cerevisiae) on their health status, as well as the health status and growth parameters of their litters during lactation. A total of 120 sows were divided into three groups: the first group was fed diets supplemented with probiotics during pregnancy (G+P, n=40), the second group was fed these diets during lactation (L+P, n=40), and the third group was the control group which was not fed diets supplemented with probiotics (C, n = 40). During the lactation period, a significantly (p<0.01) smaller proportion of probiotic treated sows (G+P=7.5%, L+P=12.5%) manifested clinical signs of the uterus and/or the udder disease in comparison with the control sows (22.5%). The incidence of infectious diarrhea in the nursing piglets was significantly (p<0.05) lower in the treated sows (12.5%) compared to the control sows (27.5 %). The average number of weaned piglets per litter (p/l) and average litter weight at weaning (lw) (G+P=11.6 p/l and 103.6 kg lw, L+P=11.1 p/l and 102.8 kg lw, C=10 p/l and 79 kg lw) were significantly higher (p<0.01 or p<0.05) in sows treated with probiotic compared to the control sows. These results clearly show that the use of probiotic significantly improves the health status of sows and nursing piglets, as well as the piglets growth parameters
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