397 research outputs found

    Experiencia, conocimiento histórico e idealismo en Michael Oakeshott

    Get PDF
    The study of Michael Oakeshott’s concept of history as a form sub specie praeteritorum of human understanding constitutes not only an important explication of this subject but also serves as the cornerstone of his treatment of other philosophical topics. Thus the purpose of this article is to present his idealistic defense of history in relation with his more general theory of human knowledge.El estudio sobre la historia en Michael Oakeshott como forma peculiar del conocimiento humano sub specie praeteritorum constituye no sólo una relevante explicación de la naturaleza de esta materia sino que, además, se erige en la piedra angular de otros temas filosóficos abordados por este pensador. El presente artículo pretende exponer la defensa que Oakeshott hizo de la historia en un sentido idealista poniéndola en relación con su teoría general sobre el conocimiento humano

    The SIMPLE Phase II Dark Matter Search

    Full text link
    Phase II of SIMPLE (Superheated Instrument for Massive ParticLe Experiments) searched for astroparticle dark matter using superheated liquid C2_{2}ClF5_{5} droplet detectors. Each droplet generally requires an energy deposition with linear energy transfer (LET) \gtrsim 150 keV/μ\mum for a liquid-to-gas phase transition, providing an intrinsic rejection against minimum ionizing particles of order 1010^{-10}, and reducing the backgrounds to primarily α\alpha and neutron-induced recoil events. The droplet phase transition generates a millimetric-sized gas bubble which is recorded by acoustic means. We describe the SIMPLE detectors, their acoustic instrumentation, and the characterizations, signal analysis and data selection which yield a particle-induced, "true nucleation" event detection efficiency of better than 97% at a 95% C.L. The recoil-α\alpha event discrimination, determined using detectors first irradiated with neutrons and then doped with alpha emitters, provides a recoil identification of better than 99%; it differs from those of COUPP and PICASSO primarily as a result of their different liquids with lower critical LETs. The science measurements, comprising two shielded arrays of fifteen detectors each and a total exposure of 27.77 kgd, are detailed. Removal of the 1.94 kgd Stage 1 installation period data, which had previously been mistakenly included in the data, reduces the science exposure from 20.18 to 18.24 kgd and provides new contour minima of σp\sigma_{p} = 4.3 ×\times 103^{-3} pb at 35 GeV/c2^{2} in the spin-dependent sector of WIMP-proton interactions and σN\sigma_{N} = 3.6 ×\times 106^{-6} pb at 35 GeV/c2^{2} in the spin-independent sector. These results are examined with respect to the fluorine spin and halo parameters used in the previous data analysis.Comment: 20 pages, 19 figures; accepted Physical Review

    Scattering images from autocorrelation functions of P-wave seismic velocity images : the case of Tenerife Island (Canary Islands, Spain)

    Get PDF
    We thank Edoardo Del Pezzo for the valuable idea of this paper and suggestions regarding the methodology. J. Prudencio is partially supported by NSF1521855 Hazard SEES project. This paper has been partially supported by the Spanish project KNOWAVES (TEC2015-68752-R (MINECO/FEDER)), the European project MED-SUV funded by the European Union’s Seventh Framework Program for research, technological development and demonstration under Grant Agreement No 308665, and by the Regional project ‘Grupo de Investigación en Geofísica y Sismología de la Junta de Andalucía, RNM104’.Peer reviewedPostprin

    Long-Term Soil Fertility Trials in Niger, West Africa

    Get PDF
    Soils of tropical Africa have been formed mainly from Pre-Cambrian materials and others from erosion process. Because of the type of parent material, the soils are characterized by poor native fertility surface crusting and low water holding capacity. In Africa 65% of the agricultural land, 31% of the permanent pasture land, and 19% of the forest and woodland is affected by human-induced soil degradation. Nutrient depletion is the most important element in the land degradation equation. With increasing population pressure on the land, the traditional farming system (natural fallow) to restore soil fertility is no longer possible. The present farming systems are unsustainable and destructive to the environment with negative plant nutrient balances resulting to mining of nutrients. Many long term trials show that although application of mineral fertilizers is an effective mean of increasing yields in arable farming systems, mineral fertilizers alone cannot sustain yields in the long run. When mineral fertilizers are combined with crop residue or manure, added to cereal-legume intercrops or rotated, sustainable production can be obtained. Any future interventions redressing distorted nutrient budgets, to be sustainable have to develop an integrated nutrient management, conceptualized as the judicious manipulation of the nutrient inputs and outputs processes

    TRIO gene segregation in a family with cerebellar ataxia

    Get PDF
    Aim of the study: To report a family with a novel TRIO gene mutation associated withphenotype of cerebellar ataxia. Materials and methods: Seven family members of Caribbean descent were recruited through our ataxia research protocol; of the family members, the mother and all 3 children were found to be affected with severe young-onset and rapidly progressive truncal and appendicular ataxia leading to early disability. Array comparative genomic hybridization, mitochondrial DNA analysis, and whole-exome sequencing were performed on 3 of the family members (mother and 2 daughters). Results: While the maternal grandmother, great uncle and great aunt were unaffected, the mother and 3 children displayed cognitive dysfunction, severe ataxia, spasticity, and speech disturbances. Age of onset ranged between 3 and 17 years, with average current disease duration of 21 years. Whole-exome sequencing showed a variant p.A1214V in exon 22 of the TRIO gene in 3 of the family members. Array comparative genomic hybridization and mitochondrial DNA analysis were normal. The same variant was later discovered in all but one family member. Conclusions and clinical implications: The TRIO p.A1214V variant is associated with cerebellar ataxia in the studied family; it was present in all affected and unaffected family members. Phenotype is severe and broad. Anticipation seems to be present (based on 2 affected generations). It is warranted to screen additional familial early-onset and rapidly progressive ataxia cases for this genotype. TRIO gene mutations may well represent a novel spinocerebellar ataxia subtype

    Geochemistry and Fe speciation in active volcanic environments – the case of Fogo Island, Cape Verde

    Get PDF
    Topsoils developed in different geological formations/ages, and the top layer of the lava flow from the most recent eruption (2014/2015) of Fogo Island (Cape Verde archipelago), were studied. The specific objectives of this work are: i) to estimate the REE contents and patterns in the whole sample of topsoils developed on different geological formations/ages and their correlation with the iron speciation; and ii) to study the top layer of a lava flow from the most recent eruption after two years of exposure. REE contents are in general higher in the topsoils of the pre-caldera than in those developed on the post-caldera formation, particularly the light REE probably due to their incorporation into hematite. Positive Eu anomalies found in recent topsoils suggest the existence of hydrothermal processes with intrusion of hot fluids with higher concentration of Eu2+. In the top layer of the lava flow of the most recent eruption, Fe is incorporated in pyroxenes and iron oxides (magnetite and/or maghemite). This study can be a benchmark for further knowledge of the chemical evolution and weathering rate in semi-arid climate of Fogo Island.The authors would like to thank the financial support by Fundação para a Ciência e a Tecnologia (FCT, Portugal) through the projects UID/GEO/04035/2013 and UID/Multi/04349/2013

    Experimental study and calculation of the electron transfer coefficients on the dissolution behavior of chitosan in organic acids

    Full text link
    Chitosan (CH) consists of water-insoluble N-acetylglucosamine and D-glucosamine molecules and has a higher solubility at a pH below six. This studyevaluated the solubility of chitosan in solutions of organic acids for the formation of films. HyperChemTMsoftware was used to perform the quantum analysis. In the experimental trials, the total soluble mass (TSM) and the viscosity of the solutions were measured by capillary viscometer. The chitosan filmswere made by the plate melting method, and the filmcharacteristics were evaluated. A quantum simulation suggested that lactic acid (LA) has a greater stability to react with chitosan. It was then verified experimentally that LA is a better solvent for chitosan due to the increase in its viscosity. The chemical interaction between CH and LA in solution favors the polymerization of films with better physical properties. We thereforeconclude that the uniformity in the formation of films of this polymer depends on the chemical interaction between the CH and the acid and not on the degree of solubility of the polymer

    PARTOS - Passive and Active Ray TOmography Software: description and preliminary analysis using TOMO-ETNA experiment’s dataset.

    Get PDF
    In this manuscript we present the new friendly seismic tomography software based on joint inversion of active and passive seismic sources called PARTOS (Passive Active Ray TOmography Software). This code has been developed on the base of two well-known widely used tomographic algorithms (LOTOS and ATOM-3D), providing a robust set of algorithms. The dataset used to set and test the program has been provided by TOMO-ETNA experiment. TOMO-ETNA database is a large, highquality dataset that includes active and passive seismic sources recorded during a period of 4 months in 2014. We performed a series of synthetic tests in order to estimate the resolution and robustness of the solutions. Real data inversion has been carried out using 3 different subsets: (i) active data; (ii) passive data; and (iii) joint dataset. Active database is composed by a total of 16,950 air-gun shots during 1 month and passive database includes 452 local and regional earthquakes recorded during 4 months. This large dataset provides a high ray density within the study region. The combination of active and passive seismic data, together with the high quality of the database, permits to obtain a new tomographic approach of the region under study never done before. An additional user-guide of PARTOS software is provided in order to facilitate the implementation for new users.PublishedS04351V. Storia e struttura dei sistemi vulcaniciJCR Journalope

    First Attempt to Implement Ophthalmia Neonatorum Prophylaxis in Angola: Microorganisms, Efficacy, and Obstacles

    Get PDF
    Purpose. To determine the efficacy of povidone-iodine (P-I) prophylaxis for ophthalmia neonatorum (ON) in Angola and to document maternal prevalence and mother-to-child transmission rates. Methods. Endocervical samples from mothers n=317 and newborn conjunctival smears n=245 were analysed by multiplex polymerase chain reaction (PCR) for Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Mycoplasma genitalium (MG). Newborns were randomized into a noninterventional group and an interventional group that received a drop of P-I 2.5% bilaterally after conjunctival smear collection. Mothers were trained to identify signs of ON and attend a follow-up visit. Results. Forty-two newborns had ocular pathology, and 11 (4.4%) had clinical signs of ON at the time of delivery. Maternal PCR was positive for MG n=19, CT n=8, and NG n=2. Six newborns were positive for CT n=4, MG n=2, and NG n=1. Mother-to-child transmission rates were 50% for CT and NG and 10.5% for MG. Only 16 newborns returned for follow-up. Conclusions. Lack of maternal compliance prevented successful testing of prophylactic P-I efficacy in ON prevention. Nevertheless, we documented the prevalence and mother-to-child transmission rates for CT, NG, and MG. These results emphasize the need to develop an effective Angolan educational and prophylactic ON program
    corecore