Multichannel heart scanner based on high-Tc SQUIDs

A 7-channel magnetometer for magnetocardiography based on high-T c SQUIDs has been realized. This magnetometer is used for test experiments in the development of a multichannel high-Tc SQUID based heart-scanner for clinical applications. The intrinsic noise level of the channels in the 7-channel system is typically 120 fT/¿(Hz) down to 1 Hz. Magnetocardiograms were recorded inside a magnetically shielded room. Introductory experiments were performed on the suppression of noise by combining magnetometers to form planar gradiometers. The noise suppression that can be established appeared to be limited by the imbalance of the gradiometric configuration, which is roughly 2%. This relatively poor balance of the system is caused by inaccuracies in the transfer functions of the individual SQUID magnetometers, and by deviations from the planar geometr

Non-random dispersal in the butterfly Maniola jurtina: implications for metapopulation models

The dispersal patterns of animals are important in metapopulation ecology because they affect the dynamics and survival of populations. Theoretical models assume random dispersal but little is known in practice about the dispersal behaviour of individual animals or the strategy by which dispersers locate distant habitat patches. In the present study, we released individual meadow brown butterflies (Maniola jurtina) in a non-habitat and investigated their ability to return to a suitable habitat. The results provided three reasons for supposing that meadow brown butterflies do not seek habitat by means of random flight. First, when released within the range of their normal dispersal distances, the butterflies orientated towards suitable habitat at a higher rate than expected at random. Second, when released at larger distances from their habitat, they used a non-random, systematic, search strategy in which they flew in loops around the release point and returned periodically to it. Third, butterflies returned to a familiar habitat patch rather than a non-familiar one when given a choice. If dispersers actively orientate towards or search systematically for distant habitat, this may be problematic for existing metapopulation models, including models of the evolution of dispersal rates in metapopulations

Mechanics of cooling liquids by forced evaporation in bubbles

Injecting a non-dissolvable gas into a saturated liquid results in sub-cooling of the liquid due to forced evaporation into the bubble. Previous studies assumed the rate of evaporation of liquid into the bubble to be independent of the degree of sub-cooling. In our study we quantify the bubble growth by direct observation using high speed imaging and prove that this hypothesis is not true. A phenomenological model of the bubble growth as a function of the degree of sub-cooling is developed and we find excellent agreement between the measurements and theory. This bubble cooling process is employed in cooling a liquid. By identification of all heat flows, we can well describe the cool down curve using bubble cooling. Bubble cooling provides an alternative cooling method for liquids without the use of complicated cooling techniques

Effects of Feeding Brassica Mixture Cover Crops During Backgrounding on Carcass Traits and Fresh Meat Quality

Objective: Determine effects of feeding brassica-based cover crops to cattle during backgrounding on carcass characteristics and tenderness, flavor, and juiciness of longissimus dorsi steaks

Design and integration of the HARPS3 software system

We present the design of the HARPS3 software system-A distributed, event-driven control system for robotic operation of the HARPS3 spectrograph at the Isaac Newton Telescope (INT). We also describe our approach to integrating the control software components incrementally at various stages of development, using a simulation framework. HARPS3 will be a high resolution (R = 115, 000) echelle spectrograph operating at wavelengths from 380 nm to 690 nm, with a design based on the successful HARPS and HARPS-N instruments. It is being built as part of the Terra Hunting Experiment (THE)-A planned 10 year radial velocity measurement programme to discover Earth-like exoplanets around Sun-like stars

Baseline design of a sorption-based Joule-Thomson cooler chain for the METIS instrument in the E-ELT

METIS, the Mid-Infrared E-ELT Imager and Spectrograph, is one of the proposed instruments in E-ELT (European Extremely Large Telescope). Its infrared detectors require multiple operating temperatures below 77 K. Therefore, active coolers have to be deployed to provide sub-liquid-nitrogen (sub-LN2) temperature cooling. However, the sensitive imaging optical detecting system also demands very low levels of vibration. Thus, the University of Twente proposed a vibration-free cooling technique based on physical sorption. In this paper, we describe the baseline design of such a sorption-based Joule-Thomson cooler chain for the METIS instrument, that is able to deliver cooling powers of 0.4 W at 8 K, 1.1 W at 25 K and 1.4 W at 40 K from a 70-K heat sinking. This design is based on working fluid selection, cascading cooler stages and operating parameter optimization. Also, the performance of the resulting cooler design is analyzed

Multiple team membership and job performance:The role of employees' information-sharing networks

Individuals in contemporary work organizations are often involved in multiple teams at the same time. This study uses a social capital perspective to propose that employees' multiple team memberships (MTM) offer the potential for individual performance benefitsanddetriments, depending on the characteristics of an employee's information-sharing network. To test our predictions, we gathered both archival and survey data at an organization for applied research in the Netherlands. We found that individual MTM was indirectly associated with an employee's overall job performance by increasing the size of his or her information-sharing network. As expected, however, this indirect relationship was contingent on the average strength of an employee's network ties (i.e., the frequency of the respective interactions), such that MTM only improved overall performance when network ties were relatively weak. The indirect relationship between MTM and individual job performance was negative, by contrast, when an employee's network ties were relatively strong. Together, these findings advance our understanding of the mechanisms and contingency factors that shape the performance consequences associated with individuals' concurrent membership in multiple teams. Practitioner points An employee's membership in multiple teams at the same time increases the size of his or her information-sharing network within the organization. The performance consequences associated with this increased information-sharing network hinge on the characteristics of an employee's information-sharing network. If the respective information-sharing linkages are based on relatively infrequent interactions with colleagues, an employee's multiple team membership indirectly benefits his or her overall job performance. If the respective information-sharing linkages are based on relatively frequent and intense interactions with colleagues, however, an employee's multiple team membership indirectly diminishes his or her overall job performance

Further Developments on a Vibration-Free Helium-Hydrogen Sorption Cooler

In our continuous effort on the development of a passively precooled two-stage 4.5 K / 14.5 K helium-hydrogen sorption cooler, a number of important development steps were made. Firstly, an improved high-density activated carbon was used for the fabrication of four new sorption cells. Tests with these new cells showed that because of increased efficiency, the required passive radiator area for this cooler reduced by a factor of 1.3. Secondly, it was shown that this cooler architecture can easily be used to reach lower (or higher) temperatures. Without hardware changes, the cold temperature was reduced from 4.5 K to 3.1 K. Thirdly, long-term experiments were carried out on the cooler. In two separate periods of two and four months of continuous operation, no change at all was observed in the cooler performance. Fourthly, clogging effects were analyzed that occurred after a 15 months storage period of the cooler at 300 K. We concluded that hydrogen diffusion out of the stainless steel components should be prevented. Finally, a design of an integrated compact cooler chain was presented, which consists of a 50 K Stirling cooler and the helium-hydrogen sorption cooler. This package may be used in the future to test the sorption cooler technology in a zero-gravity environment