3,454 research outputs found

    Drivers of and barriers to the SME internationalisation process in a small open economy

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    Small and medium-sized enterprises (SMEs) have actively increased their participation in international markets. This research's primary objective was to identify, based on 11 case studies, the main barriers to and drivers of the SME internationalisation process in a small open economy. Content analysis of in-depth interviews used Leximancer software to identify 7 themes that describe both internal and external barriers and 12 themes that characterise drivers, which were classified into five groups: SME human capital, technology, institutional support, networks and other drivers.info:eu-repo/semantics/publishedVersio

    Geopolymers based on the valorization of Municipal Solid Waste Incineration residues

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    he proper management of Municipal Solid Waste (MSW) has become one of the main environmental commitments for developed countries due to the uncontrolled growth of waste caused by the consumption patterns of modern societies. Nowadays, municipal solid waste incineration (MSWI) is one of the most feasible solutions and it is estimated to increase in Europe where the accessibility of landfill is restricted. Bottom ash (BA) is the most significant by-product from MSWI as it accounts for 85-95 % of the solid product resulting from combustion, which is classified as a non-hazardous residue that can be revalorized as a secondary aggregate in road sub-base, bulk lightweight filler in construction. In this way, revalorization of weathered BA (WBA) for the production of geopolymers may be a good alternative to common reuse as secondary aggregate material; however, the chemical process to obtain these materials involves several challenges that could disturb the stability of the material, mainly from the environmental point of view. Accordingly, it is necessary that geopolymers are able to stabilize heavy metals contained in the WBA in order to be classified as non-hazardous materials. In this regard, the SiO2/Al2O3 ratio plays an important role for the encapsulation of heavy metals and other toxic elements. The aim of this research is to formulate geopolymers starting from the 0-2 mm particle size fraction of WBA, as a unique raw material used as aluminumsilicate precursor. Likewise, leaching tests of the geopolymers formulated were performed to assess their environmental impact. The findings show that it is possible to formulate geopolymers using 100 % WBA as precursor, although more investigations are needed to sustain that geopolymer obtained can be considered as non-hazardous materials

    Pharmacological Primary Cardiovascular Prevention and Subclinical Atherosclerosis in Men: Evidence from the Aragon Workers' Health Study.

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    The objective of this study is to describe the profile of primary preventive treatment for cardiovascular disease in adult males and to analyze the association between treatment profile and subclinical atherosclerosis. We selected male workers who had undergone ultrasound imaging and had no previous history of cardiovascular disease (n = 2138). Data on the consumption of primary cardiovascular drugs from the previous year were obtained. We performed bivariate analyses to compare patient characteristics according to cardiovascular treatment and the presence of subclinical atherosclerosis, and logistic regression models to explore the association between these two variables. Among participants with no personal history of cardiovascular disease, subclinical atherosclerosis was present in 77.7% and 31.2% had received some form of preventive treatment. Of those who received no preventive treatment, 73.6% had subclinical atherosclerosis. Cardiovascular preventive treatment was associated only with CACS > 0 (odds ratio (OR), 1.37; 95% confidence interval (95% CI), 1.06-1.78). Statin treatment was associated with a greater risk of any type of subclinical atherosclerosis (OR, 1.73) and with CACS > 0 (OR, 1.72). Subclinical atherosclerosis existed in almost 75% of men who had no personal history of cardiovascular disease and had not received preventive treatment for cardiovascular disease

    Influencia de la ceniza de bagazo de caña sin tratamiento en la microestructura y propiedades mecánicas de morteros

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    This study investigated the effects of the addition of untreated sugarcane bagasse ash (UtSCBA) on the microstructural and mechanical properties of mortars. The SCBA was sieved for only five minutes through a No. 200 ASTM mesh, and fully characterized by chemical composition analysis, laser ray diffraction, the physical absorption of gas, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Mortar mixtures with 0, 10 and 20% UtSCBA as cement replacement and a constant 0.63 water/cementitious material ratio were prepared. Fresh properties of the mortars were obtained. The microstructural characteristics of the mortars at 1, 7, 28, 90 and 600 days were evaluated by SEM and XRD. The compressive strengths of the mortars at the same ages were then obtained. The results show that the addition of 10 and 20% UtSCBA caused a slight decrease in workability of the mortars but improved their microstructure, increasing the long-term compressive strength.En esta investigación se evaluó el efecto de la adición de ceniza de bagazo de caña (CBC) en la microestructura de morteros. La CBC fue tamizada durante 5 minutos a través de la malla No. 200 ASTM y evaluada mediante pruebas de análisis químico, difracción láser, absorción física de gases, Microscopia Electrónica de Barrido (MEB) y Difracción de Rayos X (DRX). Se elaboraron mezclas de mortero con 0, 10 y 20% de CBC como sustituto parcial del cemento manteniendo una relación agua/materiales-cementantes de 0.63. Se realizaron pruebas en estado fresco y pruebas de caracterización microestructural a través de MEB y DRX y de resistencia a la compresión a edades de 1, 7, 28, 90 y 600 días. Los resultados muestran que la adición de 10 y 20% de CBC decrementa la trabajabilidad de los morteros, sin embargo, mejora su microestructura e incrementa su resistencia a la compresión a edades tardías

    Efficient metallic spintronic emitters of ultrabroadband terahertz radiation

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    Terahertz electromagnetic radiation is extremely useful for numerous applications such as imaging and spectroscopy. Therefore, it is highly desirable to have an efficient table-top emitter covering the 1-to-30-THz window whilst being driven by a low-cost, low-power femtosecond laser oscillator. So far, all solid-state emitters solely exploit physics related to the electron charge and deliver emission spectra with substantial gaps. Here, we take advantage of the electron spin to realize a conceptually new terahertz source which relies on tailored fundamental spintronic and photonic phenomena in magnetic metal multilayers: ultrafast photo-induced spin currents, the inverse spin-Hall effect and a broadband Fabry-P\'erot resonance. Guided by an analytical model, such spintronic route offers unique possibilities for systematic optimization. We find that a 5.8-nm-thick W/CoFeB/Pt trilayer generates ultrashort pulses fully covering the 1-to-30-THz range. Our novel source outperforms laser-oscillator-driven emitters such as ZnTe(110) crystals in terms of bandwidth, terahertz-field amplitude, flexibility, scalability and cost.Comment: 18 pages, 10 figure

    The HADES RV Programme with HARPS-N at TNG XI. GJ 685 b: a warm super-Earth around an active M dwarf

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    Small rocky planets seem to be very abundant around low-mass M-type stars. Their actual planetary population is however not yet precisely understood. Currently several surveys aim to expand the statistics with intensive detection campaigns, both photometric and spectroscopic. We analyse 106 spectroscopic HARPS-N observations of the active M0-type star GJ 685 taken over the past five years. We combine these data with photometric measurements from different observatories to accurately model the stellar rotation and disentangle its signals from genuine Doppler planetary signals in the RV data. We run an MCMC analysis on the RV and activity indexes time series to model the planetary and stellar signals present in the data, applying Gaussian Process regression technique to deal with the stellar activity signals. We identify three periodic signals in the RV time series, with periods of 9, 24, and 18 d. Combining the analyses of the photometry of the star with the activity indexes derived from the HARPS-N spectra, we identify the 18 d and 9 d signals as activity-related, corresponding to the stellar rotation period and its first harmonic respectively. The 24 d signals shows no relations with any activity proxy, so we identify it as a genuine planetary signal. We find the best-fit model describing the Doppler signal of the newly-found planet, GJ 685\,b, corresponding to an orbital period Pb=24.1600.047+0.061P_b = 24.160^{+0.061}_{-0.047} d and a minimum mass MPsini=9.01.8+1.7M_P \sin i = 9.0^{+1.7}_{-1.8} M_\oplus. We also study a sample of 70 RV-detected M-dwarf planets, and present new statistical evidence of a difference in mass distribution between the populations of single- and multi-planet systems, which can shed new light on the formation mechanisms of low-mass planets around late-type stars.Comment: 18 pages, 13 figures, accepted for publication in A&

    The HADES RV Programme with HARPS-N@TNG IV. Time resolved analysis of the Ca ii H&K and H{\alpha} chromospheric emission of low-activity early-type M dwarfs

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    M dwarfs are prime targets for planet search programs, particularly of those focused on the detection and characterization of rocky planets in the habitable zone. Understanding their magnetic activity is important because it affects our ability to detect small planets, and it plays a key role in the characterization of the stellar environment. We analyze observations of the Ca II H&K and H{\alpha} lines as diagnostics of chromospheric activity for low-activity early-type M dwarfs. We analyze the time series of spectra of 71 early-type M dwarfs collected for the HADES project for planet search purposes. The HARPS-N spectra provide simultaneously the H&K doublet and the H{\alpha} line. We develop a reduction scheme able to correct the HARPS-N spectra for instrumental and atmospheric effects, and to provide flux-calibrated spectra in units of flux at the stellar surface. The H&K and H{\alpha} fluxes are compared with each other, and their variability is analyzed. We find that the H and K flux excesses are strongly correlated with each other, while the H{\alpha} flux excess is generally less correlated with the H&K doublet. We also find that H{\alpha} emission does not increase monotonically with the H&K line flux, showing some absorption before being filled in by chromospheric emission when H&K activity increases. Analyzing the time variability of the emission fluxes, we derive a tentative estimate of the rotation period (of the order of a few tens of days) for some of the program stars, and the typical lifetime of chromospheric active regions (a few stellar rotations). Our results are in good agreement with previous studies. In particular, we find evidence that the chromospheres of early-type M dwarfs could be characterized by different filaments coverage, affecting the formation mechanism of the H{\alpha} line. We also show that chromospheric structure is likely related to spectral type

    Advances in the phylogenetic study of the tribe Cinchoneae (Rubiaceae) with emphasis on the genus Cinchona and Ladenbergia

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    In its current circumscription, the Cinchoneae tribe includes 9 genera of neotropical distribution. Its species occur mostly in the Andes in South America, with few reaching Central America. Preliminary phylogenetic studies have suggested the monophyly of Cinchoneae but intrageneric relationships are still debatable. In this study, we sampled 8 genera of Cinchoneae (with ca 50% of species for Cinchona and Ladenbergia) and obtained multiple single-copy nuclear loci (ca 207 genes) by using the “Angiosperm353 universal probe set”, which was complemented with a taxonomic review of Cinchoneae. Phylogenetic inferences were realized with multispecies pseudo-coalescent (ASTRAL III) and gene concatenation analysis (ML). Our results strongly support the monophyly of the tribe and most of the genera, except for Ladenbergia. Furthermore, Ciliosemina, Ladenbergia, and Remijia formed a clade, although the position of Ciliosemina (= Remijia pedunculata) and Ladenbergia muzonensis is still elusive. The position of Ladenbergia muzonensis is intriguing due to its intermedíate floral morphology, which resembles both Remijia and Ladenbergia species. Additionally, our phylogeny also supports the recognition of a new species in Cinchona. Finally, our results show that sequencing data using the probe set designed for multiple gene capture is a useful tool for phylogenetic reconstructions in taxonomically complex groups

    HADES RV Programme with HARPS-N at TNG. VII. Rotation and activity of M-Dwarfs from time-series high-resolution spectroscopy of chromospheric indicators

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    We aim to investigate the presence of signatures of magnetic cycles and rotation on a sample of 71 early M-dwarfs from the HADES RV programme using high-resolution time-series spectroscopy of the Ca II H & K and Halpha chromospheric activity indicators, the radial velocity series, the parameters of the cross correlation function and the V-band photometry. We used mainly HARPS-N spectra, acquired over four years, and add HARPS spectra from the public ESO database and ASAS photometry light-curves as support data, extending the baseline of the observations of some stars up to 12 years. We provide log(R'hk) measurements for all the stars in the sample, cycle length measurements for 13 stars, rotation periods for 33 stars and we are able to measure the semi-amplitude of the radial velocity signal induced by rotation in 16 stars. We complement our work with previous results and confirm and refine the previously reported relationships between the mean level of chromospheric emission, measured by the log(R'hk), with the rotation period, and with the measured semi-amplitude of the activity induced radial velocity signal for early M-dwarfs. We searched for a possible relation between the measured rotation periods and the lengths of the magnetic cycle, finding a weak correlation between both quantities. Using previous v sin i measurements we estimated the inclinations of the star's poles to the line of sight for all the stars in the sample, and estimate the range of masses of the planets GJ 3998 b and c (2.5 - 4.9 Mearth and 6.3 - 12.5 Mearth), GJ 625 b (2.82 Mearth), GJ 3942 b (7.1 - 10.0 Mearth) and GJ 15A b (3.1 - 3.3 Mearth), assuming their orbits are coplanar with the stellar rotation.Comment: 19 pages, 16 figures, 10 table
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