Trade in services : IT and task content

In this paper we investigate the determinants of the dramatic increase in services tradability focusing on the extensive margin of the phenomenon. We use balance sheet and firm-level service trade information over the period 1995-2005 provided by the National Bank of Belgium and we merge it with information on the evolution of information technology use and tasks performed by workers from the qualification and career survey provided by the BIBB-IAB. We show that technological change, measured either by the more intensive use of information technologies or by changes in the task content of jobs, has substantially contributed to the increase in the number of service-trading firms. Interestingly, we find evidence of a churning effect. While technological change has induced net entry into service trading, it has also increased the likelihood of both gross entry and exit of firms. Furthermore, our evidence suggests that due to the peculiar nature of services provision, the change in the tasks content of jobs is a better measure of technological change than the use of information technologies. Our results are robust to controlling for service trade liberalization and offshoring.trade in services; extensive margin; technological change; task content

Service Trade and Occupational Tasks: An Empirical Investigation

Using micro data for Belgium we investigate the relationship between occupational tasks changes and the rise of service trade. We focus the analysis on the extensive margin and look at the heterogeneous proliferation of firms involved in exports and imports of services across sectors characterized by different tasks changes patterns. Occupational tasks changes display an extremely consistent relationship with participation to service trade across firm groups pointing to strong churning effects. The change in analytical (interactive and routine cognitive) tasks intensity has a positive (negative) impact across the board meaning that, in industries characterized by larger changes, firms have experienced both higher (lower) likelihood of entry and exit. The negative relationship between the change in interactive tasks and service exports participation underlines the special role that proximity between demand and supply plays for services. Interestingly, we find exactly the opposite result (a positive relationship) between the extensive margin of goods exports and interactive tasks. Moreover, our analysis suggests that the change in IT use per se does not strike as being a key underlying force behind the increase in the extensive margin of service exports.Trade in services, extensive margin, occupational tasks, technological change

Charge doping and large lattice expansion in oxygen-deficient heteroepitaxial WO3

Tungsten trioxide is a versatile material with widespread applications ranging from electrochromic and optoelectronic devices to water splitting and catalysis of chemical reactions. For technological applications, thin films of WO3 are particularly appealing, taking advantage from high surface-to-volume ratio and tunable physical properties. However, the growth of stoichiometric, crystalline thin films is challenging because the deposition conditions are very sensitive to the formation of oxygen vacancies. In this work, we show how background oxygen pressure during pulsed laser deposition can be used to tune the structural and electronic properties of WO3 thin films. By performing X-ray diffraction and low-temperature transport measurements, we find changes in WO3 lattice volume up to 10%, concomitantly with an insulator-to-metal transition as a function of increased level of electron doping. We use advanced ab initio calculations to describe in detail the properties of the oxygen vacancy defect states, and their evolution in terms of excess charge concentration. Our results depict an intriguing scenario where structural, electronic, optical, and transport properties of WO3 single-crystal thin films can all be purposely tuned by a suited control of oxygen vacancies formation during growth

ON THE STRUCTURAL VALIDITY OF BESTEST, MINI-BESTEST AND BRIEF-BESTEST.

Missing (Letter

Electrical Characteristics of Pantograph Arcs in DC Railways: Infrastructure Influence

Electric arcs are an unavoidable by-product of current collection by sliding contact in electrified transportation systems. Electric arcs are transient phenomena with implications for PQ measurements and wearing estimation and prevention of the sliding contact and catenary. Besides being heavily influenced by mechanical characteristics and material properties, their electrical characterization encompasses spectral properties and the influence of train and traction line circuits and relative position of infrastructure elements. This paper identifies the influence of such electrical and system characteristics onto the spectral signature of electric arcs for DC railways

Thermal effects on fracture and brittle-to-ductile transition

The fracture behavior of brittle and ductile materials can be strongly influenced by thermal fluctuations, especially in micro- and nano-devices as well as in rubberlike and biological materials. However, temperature effects, in particular on the brittle-to-ductile transition, still require a deeper theoretical investigation. As a step in this direction we propose a theory, based on equilibrium statistical mechanics, able to describe the temperature dependent brittle fracture and brittle-to-ductile transition in prototypical discrete systems consisting in a lattice with breakable elements. Concerning the brittle behavior, we obtain closed form expressions for the temperature-dependent fracture stress and strain, representing a generalized Griffith criterion, ultimately describing the fracture as a genuine phase transition. With regard to the brittle-to-ductile transition, we obtain a complex critical scenario characterized by a threshold temperature between the two fracture regimes (brittle and ductile), an upper and a lower yield strength, and a critical temperature corresponding to the complete breakdown. To show the effectiveness of the proposed models in describing thermal fracture behaviors at small scales, we successfully compare our theoretical results with molecular dynamics simulations of Si and GaN nanowires.Comment: 27 pages, 20 figure