Varieties and the terms of trade

This paper analyzes the dynamic adjustment of the terms of trade in an intertemporal, two country model with endogenous product variety. In the base model, all workers are identical. In an extended version, the development of new varieties requires skilled labor while manufacturing uses skilled and unskilled labor. In the model without skill, a population increase in one of the countries has no effect on its terms of trade, not even in the short run. In the model with skill, the terms of trade initially worsen, but eventually return to their original level. The terms of trade immediately and permanently worsen in response to a productivity increase in manufacturing. However, they gradually improve if the productivity in variety research rises. If productivity in both activities rises equiproportionally, the terms of trade respond in the same manner as after a population shock.

High resolution shadow mask patterning in deep holes and its application to an electrical wafer feed-through

The paper presents a technique to pattern materials in deep holes and/or on non-planar substrate surfaces. A rather old technique, namely, electron-beam evaporation of metals through a shadow mask, is used. The realization of high-resolution shadow masks using micromachining techniques is described. Further, a low ohmic electrical wafer foed-through with a small parasitic capacitance to the substrate and a high placing density is presented

Comments on "A shaped reflector antenna for 60-GHz indoor wireless LAN access points"

The author comments that the shaped reflector antenna principles and theory of Smulders, Khusial and Herben (see ibid., vol.50, p.584-91, Mar.2001) are based on the papers described by Kumar (see Proc. Montech '86 IEEE Conference on Antennas and Communication, 1986, IEEE Cat. No. TH0156-0, Inst. Elect. Eng. Proc., vol.134, p.106-108, 1987 and Technology Symposium, 1990). These papers described the X-band, circularly polarized shaped beam telemetry antenna suitable for retransmitting the radar data back to an earth terminal. Smulders et al. have used the same principle, and similar types of radiation patterns are produced. However, two points are different in their paper: (1) the design frequency (60 GHz) and (2) the application of antenna for indoor wireless LAN access points. Therefore, they authors should have referenced Kumar's papers. Smulders et al. agree with Kumar's comments that reflector shaping is nothing new. However, we took into account diffraction effects (by applying the uniform theory of diffraction) whereas the shaping in the paper of Kumar is based on geometrical optics, only. We showed that according to our approach, a more smooth illumination function can be achieved and how the smoothing effect depends on the amount of edge illumination. We also showed in which way the spatial field deviation can be minimized and that this could save a few decibels in the link budget

Cognitive function in people with and without freezing of gait in Parkinson’s disease

Freezing of gait (FOG) is common in people with Parkinson’s disease (PD) which is extremely debilitating. One hypothesis for the cause of FOG episodes is impaired cognitive control, however, this is still in debate in the literature. We aimed to assess a comprehensive range of cognitive tests in older adults and people with Parkinson’s with and without FOG and associate FOG severity with cognitive performance. A total of 227 participants took part in the study which included 80 healthy older adults, 81 people with PD who did not have FOG and 66 people with PD and FOG. A comprehensive battery of neuropsychological assessments tested cognitive domains of global cognition, executive function/attention, working memory, and visuospatial function. The severity of FOG was assessed using the new FOG questionnaire and an objective FOG severity score. Cognitive performance was compared between groups using an ANCOVA adjusting for age, gender, years of education and disease severity. Correlations between cognitive performance and FOG severity were analyzed using partial correlations. Cognitive differences were observed between older adults and PD for domains of global cognition, executive function/attention, and working memory. Between those with and without FOG, there were differences for global cognition and executive function/attention, but these differences disappeared when adjusting for covariates. There were no associations between FOG severity and cognitive performance. This study identified no significant difference in cognition between those with and without FOG when adjusting for covariates, particularly disease severity. This may demonstrate that complex rehabilitation programs may be undertaken in those with FOG

Recommendations for riparian ecosystem management based on the general frame defined in EUFORGEN and results from EUROPOP

International audienc

Lattice sites of ion-implanted Li in diamond

Published in: Appl. Phys. Lett. 66 (1995) 2733-2735 citations recorded in [Science Citation Index] Abstract: Radioactive Li ions were implanted into natural IIa diamonds at temperatures between 100 K and 900 K. Emission channelling patterns of a-particles emitted in the nuclear decay of 8Li (t1/2 = 838 ms) were measured and, from a comparison with calculated emission channelling and blocking effects from Monte Carlo simulations, the lattice sites taken up by the Li ions were quantitatively determined. A fraction of 40(5)% of the implanted Li ions were found to be located on tetrahedral interstitial lattice sites, and 17(5)% on substitutional sites. The fractions of implanted Li on the two lattice sites showed no change with temperature, indicating that Li diffusion does not take place within the time window of our measurements.

Breakdown of anomalous channeling with ion energy for accurate strain determination in gan-based heterostructures

The influence of the beam energy on the determination of strain state with ion channeling in GaN-based heterostructures (HSs) is addressed. Experimental results show that anomalous channeling may hinder an accurate analysis due to the steering effects at the HS interface, which are more intense at lower ion energies. The experimental angular scans have been well reproduced by Monte Carlo simulations, correlating the steering effects with the close encounter probability at the interface. Consequently, limitations in the determination of the strain state by ion channeling can be overcome by selecting the adequate beam energy