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The study develops the Blinder-Oaxaca decomposition technique for the independent double hurdle model. The proposed decomposition is done at the aggregate level. Using the Second Malawi Integrated Household Survey (IHS2), the paper applies the proposed decomposition to explain the rural-urban difference in parental spending on own primary school children. The results show that at least 66% of the expenditure differential is explained by differences in characteristics between rural and urban households.

This article reports on the development and testing of a continuous passive motion device suitable for experimental animals and on the effect of 1 week of continuous passive motion on the thickness of the condylar cartilage in adult guinea pigs. Continuous passive motion is currently used for postsurgical joint therapy and consists of moving a synovial joint passively and constantly through its normal range of motion. In this study continuous passive motion was applied to the temporomandibular joints of two experimental animals for 7 hours per day for 5 days. Two animals were restrained for the same amount of time that the experimental animals were on the continuous passive motion machines (control group 1), and two animals were allowed normal cage activity (control group 2). Six weeks later all animals were sacrificed. Each mandibular condyle was sectioned sagitally, and routine histologic sections were prepared with hematoxylin-eosin stain. Microscopic examination of the mandibular condylar cartilage of the animals placed on continuous passive motion showed a marked increase in thickness compared with the condylar cartilage found on the control animals. The condylar cartilage of the animals placed on continuous passive motion averaged 345 @mm, and the controls averaged 232 @mm. These findings demonstrate the application of continuous passive motion in an experimental model and provide interesting information regarding the response of the mandibular condyle to increased motion. More studies are necessary to further investigate the effect of continuous passive motion on the condylar cartilage. (Am J Orthod Dentofacial Orthop 1999;115:360-7)

A cylindrical scintillating-fiber tracker for the measurement of the polar coordinate θhas been built for experiment E835 at Fermilab. This detector combines the high granularity, flexibility and fast response of the scintillating fibers with the high quantum efficiency of the Visible-Light Photon Counters (VLPC). Complete results about the tracker performance are given: tracking and timing resolution, photoelectron yield per mip, detection efficiency, single–double-track discrimination.

A tracking detector made of scintillating fibers wound on a cylinder is being developed at FNAL, for the experiment E835 (study of the spectroscopy of charmonium formed in ppannihilations, at the Fermilab Antiproton Accumulator). The tracker will be used for the measurement of the polar angle, i.e. of the longitudinal coordinate. The small amount of light from the fibers will be detected by solid state devices (Visible Light Photon Counters) with very high QE, currently being developed and tested by the D0 Fiber Tracking Group at FNAL. This paper reports the performance of a prototype fiber tracker, as measured at FNAL. We present results on light yield/mip, attenuation, efficiency, homogeneity of response and cross-talk. The data are then compared with Monte Carlo predictions. We measured an average number of 14 photoelectrons per mip and a very low noise level. An efficiency greater than 99% is foreseen for the future double layered tracker.

The design of a hardware pipelined system to collect, monitor and broadcast the trigger information in the CERN NA48 high-rate experiment is presented. Implementation details for a VME-based prototype are also presented. The solutions adopted to cope with a synchronous-asynchronous pipelined trigger system are discussed.<>

A proportional chamber made with aluminized mylar drift tubes is described. The design is optimized for lightness and good performance in drift time and charge division on resistive sense wires. The design makes it possible to minimize the effect of failures, since a broken wire does not prevent the rest of the chamber from operation, and allows a very low weight. The use of resistive wire, not common to other detectors of this kind, makes it possible to measure the longitudinal coordinate by comparing the charges collected at the two anode ends. The design of the chamber is described, its readout characteristics are examined, and preliminary results are reported.<>