Full thermoelectric characterization of InAs nanowires using MEMS heater/sensors.

Precise measurements of a complete set of thermoelectric parameters on a single indium-arsenide nanowire (NW) have been performed using highly sensitive, micro-fabricated sensing devices based on the heater/sensor principle. The devices were fabricated as micro electro-mechanical systems consisting of silicon nitride membranes structured with resistive gold heaters/sensors. Preparation, operation and characterization of the devices are described in detail. Thermal decoupling of the heater/sensor platforms has been optimized reaching thermal conductances as low as 20 nW K(-1) with a measurements sensitivity below 20 nW K(-1). The InAs NWs were characterized in terms of thermal conductance, four-probe electrical conductance and thermopower (Seebeck coefficient), all measured on a single NW. The temperature dependence of the parameters determining the thermoelectric figure-of-merit of an InAs NW was acquired in the range 200-350 K featuring a minor decrease of the thermal conductivity from 2.7 W (m K)(-1) to 2.3 W (m K)(-1).

Morphometric analysis of renal vessels. Advantage of the multisector area approach to cross-sections.

OBJECTIVE: To determine the most accurate morphometric approach to overcoming the obstacles of limited number, angle of section and irregular contours of vascular structures in analyzing vascular sections of renal biopsies. STUDY DESIGN: The luminal area of 451 cortical arterioles in 65 Masson-trichrome-stained renal sections was assessed with a computer-assisted imaging system connected to a Leica DMR microscope (Mikroskopie und Systeme GmbH, Wetzlar, Germany). The luminal area measured by the imaging system was used as the gold standard, against which three mathematical sector approaches and one classical approach were evaluated. The accuracy of these approaches was evaluated by means of the relative deviation from the measured value and of the degree of overestimation or underestimation. Intraobserver and interobserver variability were determined for the most accurate mathematical approach. RESULTS: As compared to measured luminal area, the sector elliptical approach yielded the lowest relative deviation (13.4 +/- 12.5%), without significant overestimation or underestimation (-0.6 +/- 18.3%). The intraobserver and interobserver correlation coefficients for this method were 82.3% and 86.5%, respectively. CONCLUSION: The sector elliptical approach is the most accurate mathematical approach to vascular sections in renal biopsies.

[Between object and society: 25 years of museums of science and technology in the Netherlands]. / Tussen object en samenleving: 25 jaar musea van natuurwetenschap en techniek in Nederland.

At present 28% of the Dutch museums belongs to the group of museums of science and technology. During the second half of the twentieth century this group has developed from a small number of rather general museums into a large number of small and highly specialized museums with an emphasis on transport and crafts. Most of the new museums are collection rather than community oriented. They are about technological progress, while only a few discuss social and environmental issues. Considering the huge number of science museums it is remarkable that science centres never became popular. The two most important science centres (Evoluon at Eindhoven and newMetropolis/Nemo at Amsterdam) can hardly be described in terms of resounding success. Nevertheless, the (international) science centre movement did have its impact on the development of Dutch science museums. Whereas the young specialized museums remain quite traditional, the old general museums have eagerly adopted new methods of communication and are in the process of profiling themselves as real centres of science education.