Communication Network Availability Predictions Based on Measurement Data

Published data describing the probability distributions of data communication system reliability parameters such as availability are very sparse. This paper describes a set of data collected in order to model communication line availability by monitoring operational communication systems. Probability distribution functions for single line availabilities and for the durations of failures are given. A heuristic model for estimating availabilities for more complex systems is presented along with computer simulation data validating the accuracy of the model. The results presented make possible more realistic availability predictions for common types of networks than have previously been computable.     

Rewarming from immersion hypothermia: a comparison of three techniques

Analysis of measurements from the tali of 21 individual fossil primates from Africa shows that the specimens fall into five clearly defined groups. Accordingly, these specimens have been included as groups along with extant species in a subsequent canonical analysis thus allowing the fossils to play their part in the determination of the canonical separations. The results of this procedure show that the five fossil groups lie in a part of the canonical space not occupied by any extant African primate. Their positions are between the envelope of Asiatic apes (Hylobates and Pongo) and the envelope of African forms near the edge which contains Pan and Papio. One fossil group is so similar to Hylobates that its talus may have functioned in locomotion in a parallel manner. Others lie near to Pongo in directions proceeding towards Pan and Papio and it is possible that this similarity may indicate remnants of morphological adaptation for climbing in these fossils. At the same time, however, individual specimens are closer to one or another of the extant groups and this considerable spread suggests that the locomotor adaptations as evidenced by talar morphology, of the primate fauna in Africa, may have been very different from those of the present day. This would not the inconsistent with the different habitats, floras and non-primate faunas that may have characterized the East African scene at these earlier times. Particular fossils from Olduvai and Kromdraai that are supposed to be australopithecine and therefore bipeds, are confirmed (Oxnard, '72; Lisowski et al., '74) as being totally different from man in their talar morphology and essentially rather similar to the majority of the other fossil tali examined.     

Effect of normal stress on yield asymmetry in high purity tantalum crystals

Resolved yield stresses were determined in tension and compression for ultra high vacuum degassed tantalum crystals as a function of orientation at 77 K and 197 K. The yield stress at 77K was a minimum for specimens oriented to slip on the (112) [111] system, and a maxi-mum for specimens oriented to slip on the (–112) [1–11] system. The yield stress in tension was less than the yield stress in compression for all orientations. However, at 197 K, the yield stress in tension was found to be greater than in compression for specimens oriented to slip on the (121) [111] system in agreement with the results of Lachenmann and Schultz,1 who also found that, for specimens oriented to slip on the (•112) [1–11] system, the yield stress in compression was higher than the yield stress in tension, as occurs at 77 K. This behavior may be explained by the influence of a normal stress on a lattice expansion which occurs when the leading 112 stacking fault of a dissociated core dislocation as described by Dues-beryet al ² begins to move. Formerly Graduate Student in Metallurgy and Materials Science at Case Western Reserve University     

Specific changes in the in vitro production of prostanoids by the ovine cervix at parturition

A method of tissue superfusion has been used to measure in vitro prostanoid production by the ovine cervix during late pregnancy and at parturition. In late pregnancy (105-135 days of gestation) cervical tissue produced relatively large amounts of prostaglandin E (PGE); in comparison, the production rates of prostaglandin F (PGF), 13, 14-dihydro-15-oxo-prostaglandin F (PGFM) and 6-oxo-prostaglandin F1 alpha were generally low. Thromboxane B2 (TXB2) production was minimal and often unmeasurable. There were significant increases in the production rates of PGE and 6-oxo-PGF1 alpha by cervical tissue taken immediately after delivery, when compared to late pregnancy. Mean production rates of PGE increased from 19.8 +/- 4.1 to 43.8 +/- 7.4 ng/g. dry wt./min; 6-oxo-PGF1 alpha production rates increased more than three-fold from 10.0 +/- 2.7 to 34.6 +/- 9.8 ng/g. dry wt./min (means +/- S.E.M.). There were no significant differences in the rates of production of PGF, PGFM and TXB2 by the two groups.     

A regional programme to collect plasma for preparation of human immunoglobulin anti-rabies

We identified over 100 recipients of rabies vaccine (human diploid cell vaccine) and recruited them as plasma donors. Some were plasmapheresed at static centres, others by mobile teams. The operation of these teams is described in detail. No plasma was sent to the Fractionation Centre until the date of vaccination had been checked. Assay results showed that the majority of plasma collected between four and 20 weeks after the second dose of vaccine contained 6 or more IU/ml.     

A copulatory system in the hypothalamus and tegmentum of the domestic chick

A tract in the chick is described that runs from the posterior nucleus paraventricularis magnocellularis (PVM) through the lateral hypothalamus to a small area of the anterior tegmentum, which is adjacent to the ventral tegmental area. Bilateral lesions of the posterior PVM or of the PVM tract or of its tegmental destination abolish the facilitation of copulation in male chicks by testosterone. The effect is specific in that the facilitation of attack is either unaffected or only slightly depressed by such lesions, while being itself specifically depressed by other hypothalamic lesions. No other hypothalamic tracts were found that were necessary for the facilitation of copulation. An equivalent copulatory system probably exists in the mammal, with a more diffuse distribution in the preoptic area but with similar connections back to the tegmentum.     

The removal of Escherichia coli-bacteriophage T7 by magnetic filtration

Magnetic filtration effectively removed bacteriophage T₇ from water. The removal was undertaken by adsorbing the virus onto magnetite in the presence of calcium chloride and by passing the mixture through a filter placed in a magnetic field.     

Coupled-resonator acoustic-surface-wave filter

A 2-port filter using piezoelectrically coupled acoustic-surface-wave resonators is described. A lumped-element equivalent circuit is proposed, with expressions for element values. Theoretical insertion-loss/frequency characteristics of some 2-resonator filters are presented.     

A device to apply user-specified strains to biomaterials in culture

An apparatus was developed to apply user-specified displacements to biomaterial samples in culture. The device allowed cyclic waveforms of bandwidth 0 Hz to 20 Hz to be applied under physiologic thermal (37.5 degrees C) and [CO2] (5%) conditions. For a 0 Hz to 20 Hz bandwidth signal similar in shape to a ventricular pressure waveform, the mean displacement error was 0.26% of the full-scale output. The maximum overshoot was 0.700%. Environmental system evaluation tests demonstrated a specimen cartridge temperature of 37.20 +/- 0.15 degrees C during cyclic loading and 37.23 +/- 0.21 degrees C during static conditions. [CO2] was 5.29 +/- 0.54% during cyclic loading and 5.25 +/- 0.61% during static conditions. Laminar flow applied at the loading rod entrances to the specimen cartridge ensured the sample remained sterile during testing. As a preliminary evaluation, polyurethane samples were seeded with fetal foreskin fibroblasts and subject to intermittent cyclic displacements. Results demonstrated enhanced cell proliferation and increased [PGE2] for samples subjected to 10% strain compared with unstrained controls. A next step will be to evaluate cell response sensitivity to strain magnitude, duration, direction, and frequency. The long-term intent is to establish mechanical loading configurations that induce acceptable or adaptation-inducing responses for use in implant design and tissue engineering applications.     

Examining modality usage in a conversational multimodal application for mobile e-mail access

As Third Generation (3G) networks emerge they provide not only higher data transmission rates but also the ability to transmit both voice and low latency data within the same session. This paper describes the architecture and implementation of a multimodal application (voice and text) that uses natural language understanding combined with a WAP browser to access email messages on a cell phone. We present results from the use of the system by users as part of a laboratory trial that evaluated usage. The user trial also compared the multimodal system with a text-only system that is representative of current products in the market today. We discuss the observed modality issues and highlight implementation problems and usability concerns that were encountered in the trial. Findings indicate that speech was used the majority of the time by participants for both input and navigation even though most of the participants had little or no prior experience with speech systems (yet did have prior experience with text-only access to applications on their phones). To our knowledge this represents the first implementation and evaluation of its kind using this combination of technologies on an unmodified cell phone. Design implications resulting from the study findings and usability issues encountered are presented to inform the design of future conversational multimodal mobile applications.