1,377 research outputs found

    Biased cosmological parameter estimation with galaxy cluster counts in the presence of primordial non-Gaussianities

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    The redshift dependence of the abundance of galaxy clusters is very sensitive to the statistical properties of primordial density perturbations. It can thus be used to probe small deviations from Gaussian initial conditions. Such deviations constitute a very important signature of many inflationary scenarios, and are thus expected to provide crucial information on physical processes which took place in the very early Universe. We have determined the biases which may be introduced in the estimation of cosmological parameters by wrongly assuming the absence of primordial non-Gaussianities. Although we find that the estimation of the present-day dark energy density using cluster counts is not very sensitive to the non-Gaussian properties of the density field, we show that the biases can be considerably larger in the estimation of the dark energy equation of state parameter ww and of the amplitude of the primordial density perturbations. Our results suggest that a significant level of non-Gaussianity at cluster scales may be able to reconcile the constraint on the amplitude of the primordial perturbations obtained using galaxy cluster number counts from the Planck Sunyaev-Zeldovich Catalog with that obtained from the primary Cosmic Microwave Background anisotropies measured by the Planck satellite.Comment: 4 pages, 1 figur

    Recovery and Purification of (Bio)Pharmaceuticals Using (Nano)Materials

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    Biopharmaceuticals main classes comprise recombinant proteins, antibodies, and nucleic-acid-derived products, while synthetic pharmaceuticals include a wide variety of organic compounds. The purification of (bio)pharmaceuticals, as part of downstream processing, is mainly carried out by chromatographic processes, which are responsible for the therapeutics high cost. Therefore, there is a crucial need on the development of novel and more efficient separation/purification processes or on the improvement of the current chromatographic-based ones, aiming at producing pharmaceuticals of high quality and at a lower cost. Amongst alternative techniques, it has been demonstrated that inorganic or organic (nano)particles, used in solid-phase extraction approaches, may be promising for the purification of (bio)pharmaceuticals. This chapter provides an overview on solid-liquid separation/purification processes used to obtain high purity and high quality pharmaceuticals. The main purification processes are described and summarized. The areas where there has been a sustainable progress, combined with improved therapeutic characteristics, are highlighted. Materials based on silica (nano)particles, carbon-based (nano)particles (carbon nanotubes, graphene and activated carbon) and magnetic (nano)particles are overviewed. Based on the reported results, nanotechnology may play a key role in future pharmaceutical developments and manufacturing, where the design of suitable functionalized (nano)particles is a crucial factor to enhance the selectivity and to obtain high purification and recovery yields of (bio)pharmaceuticals.publishe

    Exploring the spectroscopic diversity of type Ia supernovae with DRACULA: a machine learning approach

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    The existence of multiple subclasses of type Ia supernovae (SNeIa) has been the subject of great debate in the last decade. One major challenge inevitably met when trying to infer the existence of one or more subclasses is the time consuming, and subjective, process of subclass definition. In this work, we show how machine learning tools facilitate identification of subtypes of SNeIa through the establishment of a hierarchical group structure in the continuous space of spectral diversity formed by these objects. Using Deep Learning, we were capable of performing such identification in a 4 dimensional feature space (+1 for time evolution), while the standard Principal Component Analysis barely achieves similar results using 15 principal components. This is evidence that the progenitor system and the explosion mechanism can be described by a small number of initial physical parameters. As a proof of concept, we show that our results are in close agreement with a previously suggested classification scheme and that our proposed method can grasp the main spectral features behind the definition of such subtypes. This allows the confirmation of the velocity of lines as a first order effect in the determination of SNIa subtypes, followed by 91bg-like events. Given the expected data deluge in the forthcoming years, our proposed approach is essential to allow a quick and statistically coherent identification of SNeIa subtypes (and outliers). All tools used in this work were made publicly available in the Python package Dimensionality Reduction And Clustering for Unsupervised Learning in Astronomy (DRACULA) and can be found within COINtoolbox (https://github.com/COINtoolbox/DRACULA).Comment: 16 pages, 12 figures, accepted for publication in MNRA

    Synthesis of CdS and CdSe nanocrystallites using a novel single-molecule precursors approach

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    The synthesis of CdS and CdSe nanocrystallites using the thermolysis of several dithioor diselenocarbamato complexes of cadmium in trioctylphosphine oxide (TOPO) is reported. The nanodispersed materials obtained show quantum size effects in their optical spectra and exhibit near band-edge luminescence. The influence of experimental parameters on the properties of the nanocrystallites is discussed. HRTEM images of these materials show well-defined, crystalline nanosized particles. Standard size fractionation procedures can be performed in order to narrow the size dispersion of the samples. The TOPO-capped CdS and CdSe nanocrystallites and simple organic bridging ligands, such as 2,2¢-bipyrimidine, are used as the starting materials for the preparation of novel nanocomposites. The optical properties shown by these new nanocomposites are compared with those of the starting nanodispersed materials

    Men in Macau SAR have higher prevalence in metabolic syndrome and among related metabolic components: a cross-sectional Macau Health Survey

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    Background Macau has recently experienced expansive socioeconomic growth, leading to lifestyle changes that could have contributed to the development of certain diseases. Little information exists on the prevalence of metabolic syndrome (MetS) and associated risk factors. This information is important, since the management of MetS is tightly connected with prevention of cardiovascular diseases in the population. Methods This study is based on the cross-sectional Macau Health Survey 2006. Information on anthropometry, physical measurements, socio-demographics, laboratory tests and life-style habits was collected by trained health professionals from a random sub-population sample, aged 18-44 (32.6 ± 8.3). Body Mass Index (BMI) cut-offs were based on WHO criteria for Asian population. The prevalence of MetS, as defined by the International Diabetes Federation was calculated and the associated lifestyle factors were analysed. Results Among Macau’s adults (n = 1592), the age-adjusted prevalence of MetS was over two times higher in men (10.5%) than in woman (3.7%), (p <0.01). 15.8% were overweight (BMI ≥23 < 25) and 18.8% were obese (BMI ≥25). Man had significantly higher risk profile in almost all components of MetS (p <0.001), except the waist circumference and HDL. BMI, age and education were significantly related to MetS in both genders (p <0.001). Conclusions We found significant gender differences in MetS among the 18 – 44 year old population of Macau, which should be addressed separately in the gender-specific preventive strategies.published_or_final_versio

    Geochemial patterns and firing technology research on ceramic glazed tiles from the 17th-20th centuries (Lisbon region, Portugal)

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    A set of 17th – 20th century glazed tiles supplied by the Department of Cultural Heritage tile collection, Lisbon City Hall, is studied in this work. The tiles were described and classified in a chronological point of view and analytical work includes chemical and mineralogical characterization of the ceramic bodies and mortars by instrumental neutron activation analysis and X-ray diffraction. Most tile bodies consist mainly of quartz, gehlenite and calcite in variable proportions; commonly these main phases are accompanied by high temperatures phases, namely wollastonite or diopside, pointing to a Ca- or Mg-rich raw material, and mullite (in one sample) indicating the use of non-carbonated raw materials. Small amounts of K-feldspar and hematite are present in most tiles, whereas analcime, plagioclase, vaterite and cristobalite are found in just a few samples. Chemical composition points to a certain homogeneity within 18th century tile bodies; the 20th century samples analysed are heterogeneous and have a different rare earth elements (REE) pattern, two are enriched in the first transition row elements, pointing to higher amounts of ferromagnesian minerals, and the other has lower amounts of Na, Fe, Cr and Co, and higher of Cs, light rare earth elements (LREE), Th and U suggesting high aluminium silicates content. The 17th century samples have a more heterogeneous chemical composition and higher contents of As and Na, which is explained by the presence of analcime. The ancient tiles have a general depletion of chemical elements, probably due to a dilution effect of the higher calcite content. The mortars are all lime rich, but the 20th century ones have a general enrichment in all elements, and more k-feldspar and mica.info:eu-repo/semantics/publishedVersio

    Controle do míldio da videira com diferentes volumes de aplicação e degradação de fungicida em cultivo protegido por cobertura plástica.

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    Os objetivos deste trabalho foram, então, os de: a) avaliar o depósito de pulverização com diferentes volumes de aplicação e sua eficiência no controle do míldio da videira; b) comparar a degradação ou a permanência do fungicida tebuconazol em videiras cultivadas sob cobertura plástica e em videiras cultivadas sob tela.bitstream/item/81904/1/cot135.pd

    Composites of biopolymers and ZnO NPs for controlled release of zinc in agricultural soils and timed delivery for maize

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    Zinc deficiency is a widespread micronutrient deficiency problem affecting crops worldwide. Unlike conventional ionic fertilizers (Zn as salt or chelated forms), Zn-based engineered nanomaterials (ENMs) have the potential to release Zn in a controlled manner, reducing Zn losses through leaching upon application to soil. In this work, composites made of biopolymers (microcrystalline cellulose, chitosan and alginate) and ZnO nanoparticles (4-65% Zn w/w) were prepared. Their potential for Zn controlled release was tested in four agricultural soils of distinct pH and organic matter content over 30 days. While conventionally used Zn salts leached from the soil resulting in very low CaCl2-extractable Zn concentration, Zn in ZnO NPs was less labile, and ZnO-biopolymers maintained a better constant supply of CaCl2-extractable Zn than all other treatments. ZnO NPs/alginate beads prepared by crosslinking with CaCl2 presented the slowest Zn release kinetics. As assessed with maize plants grown in poor Zn acidic soil (LUFA 2.1, pH=5.2), this constant Zn release from ZnO NPs/alginate beads resulted in a steadier Zn concentration in the soil pore water over time. These results further indicate that ZnO NPs/alginate beads could meet the maize Zn needs while avoiding the early stage Zn toxicity induced by conventional Zn supplies, demonstrating that these ENMs are a sustainable way to supply Zn in a controlled manner in acidic soils. The impact of plant exudates on Zn bioavailability in the soil under maize-root influence (rhizosphere) is also discussed, underlying the need to study the fate of micronutrients in the rhizosphere to better predict its long-term bioavailability in bulk soils.publishe
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