3,486 research outputs found
Helium mixtures in nanotube bundles
An analogue to Raoult's law is determined for the case of a 3He-4He mixture
adsorbed in the interstitial channels of a bundle of carbon nanotubes. Unlike
the case of He mixtures in other environments, the ratio of the partial
pressures of the coexisting vapor is found to be a simple function of the ratio
of concentrations within the nanotube bundle.Comment: 3 pages, no figures, submitted to Phys. Rev. Let
Local Development Applied to Energy Scheme
Manabí is a province with great potential, either in the agri-food sector or in the renewable generation of energy. However, the limitations inherited from traditional development models prevent achieving the sustainable development of this territory. This paper proposes a development model at the local level, aimed at achieving equity and, through the use of renewable energy sources and other potentials present in specific territories, to improve the quality of life and reduce the risks of societies present there. Through geographic information systems, it was possible to generate and display on maps information related to the energy demand at the provincial and cantonal levels, as well as the province's energy behavior considering the population density
A Simple Chemical Method for Rendering Wild-Type Yeast Permeable to Brefeldin A That Does Not Require the Presence of an erg6 Mutation
The present work aims to develop a growth medium to render a wild-type strain of Saccharomyces cerevisiae permeable to the antifungal drug Brefeldin A. In the current study, a synthetic medium containing 0.1% L-proline and supplemented with 3.0 × 10(-3)% SDS is employed. When Brefeldin A is added to this medium, a wild-type strain shows increased growth sensitivity and a diminished transport of the amino acid L-leucine. Since Brefeldin A exerts its effect on the endoplasmic reticulum and the Golgi apparatus, the medium permits the study of the drug effect on the intracellular traffic of L-leucine permeases
Introduced marine macroflora of Lebanon and its distribution on the Levantine coast
The marine macroflora introduced into Lebanon was studied through an analysis of historical data and field studies carried out since 1991. A total of 29 introduced species have been listed: 3 Chromobionta, 13 Rhodobionta, 12 Chlorobionta and 1 Streptobionta. Among them, Caulerpa taxifolia var. distichophylla, Spatoglossum variabile and Womersleyella setacea are recorded for the first time from Lebanon. Among them, Asparagopsis taxiformis, C. taxifolia var. distichophylla, Cladophora patentiramea, Codium arabicum, Codium parvulum, Galaxaura rugosa, Halophila stipulacea, Hypnea cornuta, Laurencia cf. chondrioides, Lophocladia lallemandii, Stypopodium schimperi, Ulva lactuca and Womersleyella setacea are potentially invasive species, and several of them already occupy extensive stretches of the Lebanese coast. The distribution of species on the Levantine coast, their dynamics and the current status of their populations are discussed.The surveys in 2012, 2013 and 2016 were conducted within the framework of the MedMPAnet Project, implemented by UNEP/MAP-RAC/SPA and funded by RAC/SPA, the European Commission (EC), the Spanish Agency for International Cooperation for Development (AECID), and the French Global Environment Facility (FFEM)
Ultrasonic tissue characterization of vulnerable carotid plaque: correlation between videodensitometric method and histological examination
BACKGROUND: To establish the correlation between quantitative analysis based on B-mode ultrasound images of vulnerable carotid plaque and histological examination of the surgically removed plaque, on the basis of a videodensitometric digital texture characterization. METHODS: Twenty-five patients (18 males, mean age 67 ± 6.9 years) admitted for carotid endarterectomy for extracranial high-grade internal carotid artery stenosis (≥ 70% luminal narrowing) underwent to quantitative ultrasonic tissue characterization of carotid plaque before surgery. A computer software (Carotid Plaque Analysis Software) was developed to perform the videodensitometric analysis. The patients were divided into 2 groups according to symptomatology (group I, 15 symptomatic patients; and group II, 10 patients asymptomatic). Tissue specimens were analysed for lipid, fibromuscular tissue and calcium. RESULTS: The first order statistic parameter mean gray level was able to distinguish the groups I and II (p = 0.04). The second order parameter energy also was able to distinguish the groups (p = 0,02). A histological correlation showed a tendency of mean gray level to have progressively greater values from specimens with < 50% to >75% of fibrosis. CONCLUSION: Videodensitometric computer analysis of scan images may be used to identify vulnerable and potentially unstable lipid-rich carotid plaques, which are less echogenic in density than stable or asymptomatic, more densely fibrotic plaques
Clustering approach applied on an artificial neural network model to predict PM10 in mega cities of México
A cluster-based artificial neural network model called CLASO (Classification-Assemblage-Association) has been proposed to predict the maximum of the 24-h moving average of PM10 concentration on the next day in the three largest metropolitan areas of Mexico. The model is a self-organised, real-time learning neural network, which builds its topology via a process of pattern classification by using an historical database. This process is based on a supervised clustering technique, assigning a class to each centroid of the hidden layer, employing the Euclidean distance as a hierarchical criterion. A set of ARIMA models was compared with CLASO model in the forecast performance of the 24-h average PM10 concentration on the next day. In general, CLASO model produced more accurate predictions of the maximum of the 24-h moving average of PM10 concentration than the ARIMA models, although the latter showed a minor tendency to underpredict the results. The CLASO model solely requires to be built a historical database of the air quality parameter, an initial radius of classification and the learning factor. CLASO has demonstrated acceptable predictions of 24-h average PM10 concentration by using exclusively regressive PM10 concentrations. The forecasting capabilities of the model were found to be satisfactory compared to the classical models, demonstrating its potential application to the other major pollutants used in the Mexican air quality index
Discovery of the first dual GSK3 beta inhibitor/Nrf2 inducer. A new multitarget therapeutic strategy for Alzheimer's disease
The formation of neurofibrillary tangles (NFTs), oxidative stress and neuroinflammation have emerged as key targets for the treatment of Alzheimer’s disease (AD), the most prevalent neurodegenerative disorder. These pathological hallmarks are closely related to the over-activity of the enzyme GSK3β and the downregulation of the defense pathway Nrf2-EpRE observed in AD patients. Herein, we report the synthesis and pharmacological evaluation of a new family of multitarget 2,4-dihydropyrano[2,3-c]pyrazoles as dual GSK3β inhibitors and Nrf2 inducers. These compounds are able to inhibit GSK3β and induce the Nrf2 phase II antioxidant and anti-inflammatory pathway at micromolar concentrations, showing interesting structure-activity relationships. The association of both activities has resulted in a remarkable anti-inflammatory ability with an interesting neuroprotective profile on in vitro models of neuronal death induced by oxidative stress and energy depletion and AD. Furthermore, none of the compounds exhibited in vitro neurotoxicity or hepatotoxicity and hence they had improved safety profiles compared to the known electrophilic Nrf2 inducers. In conclusion, the combination of both activities in this family of multitarget compounds confers them a notable interest for the development of lead compounds for the treatment of AD
Integrated polarization beam splitter with relaxed fabrication tolerances
Polarization handling is a key requirement for the next generation of photonic integrated circuits (PICs). Integrated polarization beam splitters (PBS) are central elements for polarization management, but their use in PICs is hindered by poor fabrication tolerances. In this work we present a fully passive, highly fabrication tolerant polarization beam splitter, based on an asymmetrical Mach-Zehnder interferometer (MZI) with a Si/SiO2 Periodic Layer Structure (PLS) on top of one of its arms.
By engineering the birefringence of the PLS we are able to design the MZI arms so that sensitivities to the most critical fabrication errors are greatly reduced. Our PBS design tolerates waveguide width variations of 400nm maintaining a polarization extinction ratio better than 13dB in the complete C-Band.The authors want to acknowledge the funding from the Spanish Ministry of Science (project TEC2009-10152) and the European Mirthe project (FP7-2010-257980)
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