1,303 research outputs found

    SMEs and internationalization: an empirical study of SMEs in Portugal

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    This paper presents the results of a survey of small and medium-sized enterprises (SMEs) in Portugal drawn from a database of 2500 SMEs supplied by COFACE – the holder of the largest company database in Portugal. It is an exploratory study presenting descriptive results on their export drive, competitiveness in external markets, analysis of the environment, and innovation concerns vis-à-vis global markets and information needs for these markets. We draw from recent literature to identify the main features global markets require of companies if they are to operate successfully and compare them with our findings. Portugal was selected as the basis of our study not only because local companies have faced great changes in the last three decades following the transition from a closed and protected economy to full membership within the European Union and the current very open economy, but also because the country and population are so small that companies face tremendous pressures to internationalize as the domestic market for many types of goods is very limited

    MAXI J1659-152: the shortest orbital period black-hole binary

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    Following the detection of a bright new X-ray source, MAXI J1659-152, a series of observations was triggered with almost all currently flying high-energy missions. We report here on XMM-Newton, INTEGRAL and RXTE observations during the early phase of the X-ray outburst of this transient black-hole candidate. We confirm the dipping nature in the X-ray light curves. We find that the dips recur on a period of 2.4139+/-0.0005 hrs, and interpret this as the orbital period of the system. It is thus the shortest period black-hole X-ray binary known to date. Using the various observables, we derive the properties of the source. The inclination of the accretion disk with respect to the line of sight is estimated to be 60-75 degrees. The companion star to the black hole is possibly a M5 dwarf star, with a mass and radius of about 0.15 M_sun and 0.23 R_sun, respectively. The system is rather compact (orbital separation is about 1.35 R_sun) and is located at a distance of roughly 7 kpc. In quiescence, MAXI J1659-152 is expected to be optically faint, about 28 mag in the V-band.Comment: 5 pages, 4 figures, to be published in the proceedings of the 4th International MAXI Workshop `The First Year of MAXI: Monitoring variable X-ray sources', 2010 Nov 30 - Dec 2, Tokyo, Japa

    Percutaneous Occlusion of Vascular Malformations in Pediatric and Adult Patients: 20-Year Experience of a Single Center

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    OBJECTIVE: A case series on different vascular malformations (VM) treated with percutaneous occlusion in children and adults is presented. BACKGROUND: Percutaneous occlusion is usually the preferred treatment method for VM. Previous series have mostly focused on single types of devices and/or VM. METHODS: Retrospective analysis of all patients who underwent percutaneous occlusion of VM in a single center, from 1995 to 2014, excluding patent ductus arteriosus. Clinical and angiographic data, procedural details, implanted devices, and complications were assessed. Procedural success was defined as effective device deployment with none or minimal residual flow. Predictors of procedural failure and complications were determined by multivariate analysis. RESULTS: A total of 123 VM were intervened in 47 patients with median age of 12 years (25 days-76 years). The VM included 55 pulmonary arteriovenous fistulae, 39 aortopulmonary collaterals, 10 systemic venovenous collaterals, 8 peripheral arteriovenous fistulae, 5 Blalock-Taussig shunts, 4 coronary fistulae, and 2 Fontan fenestrations. The 143 devices used included 80 vascular plugs, 38 coils, 22 duct occluders, and 3 foramen ovale or atrial septal defect occluders. Median vessel size was 4.5 (2.0-16.0) mm and device/vessel size ratio was 1.4 (1.1-2.0). Successful occlusion was achieved in 118 (95.9%) VM, including three reinterventions. Four (3.3%) clinically relevant complications occurred, without permanent sequelae. Lower body weight was independently associated with procedural failure and complications. CONCLUSION: To our knowledge, this is the largest series on different VM occluded percutaneously in children and adults, excluding patent ductus arteriosus. Percutaneous occlusion was effective and safe, using different devices.info:eu-repo/semantics/publishedVersio

    Photoinduced suppression of the ferroelectric instability in PbTe

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    The interactions between electrons and phonons drive a large array of technologically relevant material properties including ferroelectricity, thermoelectricity, and phase-change behaviour. In the case of many group IV-VI, V, and related materials, these interactions are strong and the materials exist near electronic and structural phase transitions. Their close proximity to phase instability produces a fragile balance among the various properties. The prototypical example is PbTe whose incipient ferroelectric behaviour has been associated with large phonon anharmonicity and thermoelectricity. Experimental measurements on PbTe reveal anomalous lattice dynamics, especially in the soft transverse optical phonon branch. This has been interpreted in terms of both giant anharmonicity and local symmetry breaking due to off-centering of the Pb ions. The observed anomalies have prompted renewed theoretical and computational interest, which has in turn revived focus on the extent that electron-phonon interactions drive lattice instabilities in PbTe and related materials. Here, we use Fourier-transform inelastic x-ray scattering (FT-IXS) to show that photo-injection of free carriers stabilizes the paraelectric state. With support from constrained density functional theory (CDFT) calculations, we find that photoexcitation weakens the long-range forces along the cubic direction tied to resonant bonding and incipient ferroelectricity. This demonstrates the importance of electronic states near the band edges in determining the equilibrium structure.Comment: 9 page, 3 figure

    Evidence for Extended Aqueous Alteration in CR Carbonaceous Chondrites

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    We are currently studying the chemical interrelationships between the main rockforming components of carbonaceous chondrites (hereafter CC), e.g. silicate chondrules, refractory inclusions and metal grains, and the surrounding meteorite matrices. It is thought that the fine-grained materials that form CC matrices are representing samples of relatively unprocessed protoplanetary disk materials [1-3]. In fact, modern non-destructive analytical techniques have shown that CC matrices host a large diversity of stellar grains from many distinguishable stellar sources [4]. Aqueous alteration has played a role in homogeneizing the isotopic content that allows the identification of presolar grains [5]. On the other hand, detailed analytical techniques have found that the aqueously-altered CR, CM and CI chondrite groups contain matrices in which the organic matter has experienced significant processing concomitant to the formation of clays and other minerals. In this sense, clays have been found to be directly associated with complex organics [6, 7]. CR chondrites are particularly relevant in this context as this chondrite group contains abundant metal grains in the interstitial matrix, and inside glassy silicate chondrules. It is important because CR are known for exhibiting a large complexity of organic compounds [8-10], and only metallic Fe is considered essential in Fischer-Tropsch catalysis of organics [11-13]. Therefore, CR chondrites can be considered primitive materials capable to provide clues on the role played by aqueous alteration in the chemical evolution of their parent asteroids

    Sustained data access and tools as key ingredients to strengthening EO capacities : examples from land application perspective + powerpoint

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    Sustainably managing agriculture and forests is key for development, in particular in Africa, and for facing global challenges such as climate change or food security, but requires reliable information. As Earth Observation (EO) satellite data can contribute to these information needs, more and more institutes integrate this technology into their daily work. Facing ever-growing and evolving EO data sources (e.g. new satellites and sensors) and access technology (both online and via EUMETCast satellite broadcast), their applications require software tools to particularly facilitate (i) the exchange of data between the analysis tools, so users can take advantage of each tool’s strengths, and (ii) the processing and analysis of time series. A first example is the Land Surface Analysis Satellite Application Facility (LSA-SAF), that entered the second part of the Continuous Development and Operations Phase (CDOP-2), under the lead of the Portuguese Institute for Sea and Atmosphere (IPMA), in 2011. VITO, joining the LSA-SAF network for the first time and building on previous experiences (e.g. http://www.metops10.vito.be), aims to contribute by producing and delivering operational, 10-daily vegetation indicators based on MetOp-AVHRR. Furthermore, a software tool is developed to aid exploitation of LSA-SAF products, provisionally called “MSG Toolbox”. A second example is the AGRICAB project, that receives funding from the European Union’s 7th Framework Programme for Research (FP7) and aims to build a comprehensive framework for strengthening capacities in the use of EO for agriculture and forestry management in Africa. This framework starts from sustained access to relevant satellite data (e.g. CBERS-3, DEIMOS) and derived products, such as those from the European Copernicus Global Land service, the 15 year time series of SPOT-VEGETATION (and its transition to PROBA-V) and Meteosat Second Generation (e.g. rainfall estimates). It combines local and EO data with tools and training into applications on crop monitoring, area statistics and yield forecasting, livestock insurance and modelling, forest and fire management, all fitted to the needs of stakeholders in the African focus countries

    The evolving jet spectrum of the neutron star X-ray binary Aql X-1 in transitional states during its 2016 outburst

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    We report on quasi-simultaneous observations from radio to X-ray frequencies of the neutron star X-ray binary Aql X-1 over accretion state transitions during its 2016 outburst. All the observations show radio to millimetre spectra consistent with emission from a jet, with a spectral break from optically thick to optically thin synchrotron emission that decreases from ~100 GHz to <5.5 GHz during the transition from a hard to a soft accretion state. The 5.5 GHz radio flux density as the source reaches the soft state, 0.82 ± 0.03 mJy, is the highest recorded to date for this source. During the decay of the outburst, the jet spectral break is detected again at a frequency of ~30-100 GHz. The flux density is 0.75 ± 0.03 mJy at 97.5 GHz at this stage. This is the first time that a change in the frequency of the jet break of a neutron star X-ray binary has been measured, indicating that the processes at play in black holes are also present in neutron stars, supporting the idea that the internal properties of the jet rely most critically on the conditions of the accretion disc and corona around the compact object, rather than the black hole mass or spin or the neutron star surface or magnetic field

    Dynamic tuning of FRET in a green fluorescent protein biosensor.

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    Forster resonance energy transfer (FRET) between mutants of green fluorescent protein is widely used to monitor protein-protein interactions and as a readout mode in fluorescent biosensors. Despite the fundamental importance of distance and molecular angles of fluorophores to each other, structural details on fluorescent protein FRET have been missing. Here, we report the high-resolution x-ray structure of the fluorescent proteins mCerulean3 and cpVenus within the biosensor Twitch-2B, as they undergo FRET and characterize the dynamics of this biosensor with B-0(2)-dependent paramagnetic nuclear magnetic resonance at 900 MHz and 1.1 GHz. These structural data provide the unprecedented opportunity to calculate FRET from the x-ray structure and to compare it to experimental data in solution. We find that interdomain dynamics limits the FRET effect and show that a rigidification of the sensor further enhances FRET

    Time- and momentum-resolved probe of heat transport in photo-excited bismuth

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    We use time- and momentum-resolved x-ray scattering to study thermalization in a photo-excited thin single crystal bismuth film on sapphire. The time-resolved changes of the diffuse scattering show primarily a quasi-thermal phonon distribution that is established in less than or similar to 100 ps and that follows the time-scale of thermal transport. Ultrafast melting measurements under high laser excitation show that epitaxial regrowth of the liquid phase occurs on the time-scale of thermal transport across the bismuth-sapphire interface. (C) 2013 AIP Publishing LLC. (DOI: 10.1063/1.4804291

    MAXI J1659-152: The shortest orbital period black-hole transient in outburst

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    MAXI J1659-152 is a bright X-ray transient black-hole candidate binary system discovered in September 2010. We report here on MAXI, RXTE, Swift, and XMM-Newton observations during its 2010/2011 outburst. We find that during the first one and a half week of the outburst the X-ray light curves display drops in intensity at regular intervals, which we interpret as absorption dips. About three weeks into the outbursts, again drops in intensity are seen. These dips have, however, a spectral behaviour opposite to that of the absorption dips, and are related to fast spectral state changes (hence referred to as transition dips). The absorption dips recur with a period of 2.414+/-0.005 hrs, which we interpret as the orbital period of the system. This implies that MAXI J1659-152 is the shortest period black-hole candidate binary known to date. The inclination of the accretion disk with respect to the line of sight is estimated to be 65-80 degrees. We propose the companion to the black-hole candidate to be close to an M5 dwarf star, with a mass and radius of about 0.15-0.25 M_sun and 0.2-0.25 R_sun, respectively. We derive that the companion had an initial mass of about 1.5 M_sun, which evolved to its current mass in about 5-6 billion years. The system is rather compact (orbital separation of larger than ~1.33 R_sun), and is located at a distance of 8.6+/-3.7 kpc, with a height above the Galactic plane of 2.4+/-1.0 kpc. The characteristics of short orbital period and high Galactic scale height are shared with two other transient black-hole candidate X-ray binaries, i.e., XTE J1118+480 and Swift J1735.5-0127. We suggest that all three are kicked out of the Galactic plane into the halo, rather than being formed in a globular cluster.Comment: 20 pages, 14 figures, accepted for publication in A&
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