This study investigates how European journalists evaluate the changes that have occurred in their profession since the Internet has been integrated in newsrooms. How do journalists perceive the features and innovations associated with the Internet? What are the principal changes in the profession? Do practitioners believe that the quality of journalism has been raised or lowered? To answer to these research questions, we carried out a survey across 11 European countries–Cyprus, Estonia, Finland, Greece, Ireland, Italy, Lithuania, United Kingdom, Slovenia, Spain, Sweden–of 239 journalists, working for 40 of the most‐read print/online news outlets in these countries. The survey shows that the opportunity to use the Internet to reinforce the social functions of journalism has not been fully recognised.相似文献
The joint estimation of the location vector and the shape matrix of a set of independent and identically Complex Elliptically Symmetric (CES) distributed observations is investigated from both the theoretical and computational viewpoints. This joint estimation problem is framed in the original context of semiparametric models allowing us to handle the (generally unknown) density generator as an infinite-dimensional nuisance parameter. In the first part of the paper, a computationally efficient and memory saving implementation of the robust and semiparmaetric efficient R-estimator for shape matrices is derived. Building upon this result, in the second part, a joint estimator, relying on the Tyler’s M-estimator of location and on the R-estimator of shape matrix, is proposed and its Mean Squared Error (MSE) performance compared with the Semiparametric Cramér-Rao Bound (SCRB).
Despite a long history of continuously improved magnetic properties, the further development of grain‐oriented electrical steel is still an exciting field for industrial and joint fundamental research. Today, the driving forces for research and development (R&D) are on one hand increasing quality demands, i.e. still lower losses for more energy‐efficient transformers and less transformer noise, and on the other hand the pressure to reduce manufacturing costs in order to stay competitive on the market. Evidently in the last years, the latter aspect has become the mainspring for most of the industrial R&D activities. Now nearly all producers are aiming at more compact and less expensive production routes. From the new techniques under development, most advanced in commercial realization is the application of low slab reheating temperatures in the range 1150… 1300°C instead of up to 1400°C in the classical processes. A radical new method is thin slab casting and direct hot rolling used for steels with a system of inherent plus acquired inhibitors, the latter formed by nitriding the cold rolled strip. This method is very promising and far advanced in industrial tests. Another way for process shortening is to cast directly the hot strip from the steel melt by a twin‐roll method. In pilot line tests, good cold workability and good magnetic properties have been achieved by optimising chemical composition, casting conditions, and subsequent thermo‐mechanical treatments and by working with inherent plus acquired inhibitors. Another theoretical potential for cost and time saving is to replace box annealing for secondary recrystallization by short‐time continuous annealing. Such processes are under development, partly using special in‐line procedures to realize fast inhibitor creation after primary recrystallization, but are today still far away from commercial realization. 相似文献
Fully bio-based and biodegradable active films based on poly(lactic acid) (PLA) blended with poly(3-hydroxybutyrate) (PHB) and incorporating lactic acid oligomers (OLA) as plasticizers and carvacrol as active agent were extruded and fully characterized in their functional properties for antimicrobial active packaging. PLA_PHB films showed good barrier to water vapor, while the resistance to oxygen diffusion decreased with the addition of OLA and carvacrol. Their overall migration in aqueous food simulant was determined and no significant changes were observed by the addition of carvacrol and OLA to the PLA_PHB formulations. However, the effect of both additives in fatty food simulant can be considered a positive feature for the potential protection of foodstuff with high fat content. Moreover, the antioxidant and antimicrobial activities of the proposed formulations increased by the presence of carvacrol, with enhanced activity against Staphylococcus aureus if compared to Escherichia coli at short and long incubation times. These results underlined the specific antimicrobial properties of these bio-films suggesting their applicability in active food packaging. 相似文献
New nanocomposite films based on a biodegradable poly (DL-Lactide-co-Glycolide) copolymer (PLGA) and different concentration
of silver nanoparticles (Ag) were developed by solvent casting. In vitro degradation studies of PLGA/Ag nanocomposites were
conducted under physiological conditions, over a 5 week period, and compared to the behaviour of the neat polymer. Furthermore
the silver ions (Ag+) release upon degradation was monitored to obtain information on the properties of the nanocomposites during the incubation.
The obtained results suggest that the PLGA film morphology can be modified introducing a small percentage of silver nanoparticles
that do not affect the degradation mechanism of PLGA polymer in the nanocomposite. However results clearly evinced the stabilizing
effect of the Ag nanoparticles in the PLGA polymer and the mineralization process induced by the combined effect of silver
and nanocomposite surface topography. The Ag+ release can be controlled by the polymer degradation processes, evidencing a prolonged antibacterial effect. 相似文献
Effect of Ti, Nb, Ti+Nb and of cold rolling shedule on formability of stabilized ELI 18 Cr 2 Mo and 21 Cr 3 Mo steels. Single step reduction of around 80 % followed by continuous annealing: 3 min at 900 °C confer exceptional deep drawing properties. Ti strongly favours textures, Nb slackens them, Ti+Nb is a satisfactory balance of very high deep drawing properties and low planar anisotropy. 相似文献
The development of a solution‐deposited up‐converted distributed feedback laser prototype is presented. It employs a sol–gel silica/germania soft‐lithographed microcavity and CdSe–CdZnS–ZnS quantum dot/sol–gel zirconia composites as optical gain material. Characterization of the linear and nonlinear optical properties of quantum dots establishes their high absorption cross‐sections in the one‐ and two‐ photon absorption regimes to be 1 × 10?14 cm2 and 5 × 104 GM, respectively. In addition, ultrafast transient absorption dynamics measurements of the graded seal quantum dots reveal that the Auger recombination lifetime is 220 ps, a value two times higher than that of the corresponding CdSe core. These factors enable the use of such quantum dots as optically pumped gain media, operating in the one‐ and two‐photon absorption regime. The incorporation of CdSe–CdZnS–ZnS quantum dots within a zirconia host matrix affords a quantum‐dot ink that can be directly deposited on our soft‐lithographed distributed feedback grating to form an all‐solution‐processed microcavity laser. 相似文献