Dancing to a somewhat different rhythm: Cell migration along the natural basement membrane

Much of our understanding of the events which underlie cell migration has been derived from studies of cells in tissue culture. One of the components that mediates this process is the dynamic actin-based microfilament system that can reorganize itself into so-called stress fibers that are considered essential components for cell motility. In contrast, relatively few studies have investigated cell movement along an extracellular matrix (ECM) which is known to influence both cellular organization and behavior. This opinion/viewpoint article briefly reviews cell migration during corneal endothelial wound repair along the tissue’s natural basement membrane, Descemet’s membrane. Because the tissue exists as a cell monolayer it affords one an opportunity to readily explore the effect of cell/matrix influences on cell motility. As such, cell movement along this substrate differs somewhat from that found in vitro and migrating endothelial cells also demonstrate an ability to move along the ECM without the benefit of having an organized actin cytoskeleton.     

Instrumentation, Control and Automation: the Grampian Way

The paper describes the experiences of Grampian Regional Council's Department of Water Services in designing, testing, and installing a regional telemetry system, together with the philosophy behind some of the decisions. The paper also describes the hardware involved and some of its capabilities.     

PUBLIC OPINION,TRADITION, AND INFORMATION HALF-LIFE†

The information needs of a complex society are not met by an information-flow technology invented and developed in traditional societies. This article provides a theoretical framework derived from modern systems theory by which to understand the technology of public opinion policy formation in guidance operations of a complex society. Qualitative models of information flow systems are presented together with a discussion of the kind of society each information flow technology produces. Three are considered: tradition-based information-flow societies, managed information-flow societies (Utopian and elitist), and cybernetic issue-based information-flow societies.     

A Review of “ Microwave Remote Sensing of the Atmosphere”. Edited by A. JANSSEN, (Chichester: Wiley, 1993.) [Pp. 572.] Price £79.

This Letter presents an adapiive contexiual filler, developed by Ihe addition of a heterogeneity rule and a confidence rule to The conventional majority filter. Experiments have been carried out using a Landsat Thematic Mapper (TM) image. Results show that the adaptive majority filter has a capability of reducing the classification errors due to spectrally mixed pixels and preserves The connection of thin features. The proposed filler needs only a moderate increase in processing time compared with the conventional majority filter.     

Effect of EHL Contact Conditions on the Behavior of Traction Fluids

New infinitely variable transmission (IVT) systems are under development for the automotive industry as a means to achieving significant fuel economy benefits. These systems rely on the lubricating fluid to transmit the drive train loads across the interface of the transmission components. This requires the development of new fluids that exhibit high traction properties under elastohydrodynamic lubrication (EHL) conditions. However, it has been reported recently that the traction performance of some fluids can reduce dramatically as temperature is reduced. This may place severe operational limits on IVT systems and suggests that the low-temperature traction properties of fluids for these systems should be studied in order to understand the mechanism for the observed reduction in traction.

The work reported here is an experimental study aimed at identifying whether low temperature traction reduction is related to a fundamental change in rheological behavior specific to the fluids tested or to more generic changes in the EHL contact conditions. A series of model experiments were performed using a mini traction machine (MTM) on three high-viscosity polybutene samples. The results have been mapped against previously reported non-dimensional parameters used to identify different EHL regimes. The results show that dramatic reductions in traction occur when the contact transitions from the rigid piezo-viscous (RP) toward the rigid iso-viscous (RI) region. Similar results were also found for two other high-viscosity fluids of different molecular structure and lower traction properties. The results support the hypothesis that the reduction in traction observed at low temperature is due to a change in EHL contact conditions rather than being solely due to a change in the rheological performance of the test fluids.     

Preparation and Magnetic Properties of Some Hexagonal Magnetic Oxides

The preparation of nonoriented as well as magnetically oriented specimens of 2MeO · 2BaO·-6Fe₂O₃ and 2MeO·3BaO·12Fe₂O₃ is described. The MeO component is limited to NiO, ZnO, CoO, and CuO and mixtures of these in this discussion. The orienting apparatus and technique employed are briefly described. The magnetic permeability and loss as measured at 250 Mc is shown for many of these prepared compositions. The effect of the orienting magnetic field strength as well as firing temperature on the observed magnetic properties is discussed.     

Creep of Polycrystalline MgO and MgO-Fe2O3 Solid Solutions at High Temperatures

Polycrystalline MgO and MgO-Fe₂O₃ solid solutions (0.10 to 8.08 wt% Fe₂O₃) were fabricated to almost theoretical density by vacuum hot-pressing. Specimens were creep-tested in air under four-point dead-load conditions between 1000° and 1400°C at stresses between 50 and 550 kg/cm². Steady-state creep was never achieved in the experiments, which sometimes lasted more than 50 h. The strain rate vs time ( t ) data were described by an equation of the form = c₁/(t+C₂)^p , which is consistent with the assumptions that creep occurs at least in part by a "viscous" mechanism and that grain growth occurs simultaneously. Doping MgO with Fe₂O₃ enhanced the viscous contributions to creep and inhibited the nonviscous ones. Creep rates in these specimens increased with increasing Fe₂O₃ additions. The occurrence of simultaneous grain growth during the high-temperature creep of magnesiowustite (i.e. MgO-Fe₂O₃ solid solutions) was used in establishing the strain rate vs grain size dependence. The results of this study are consistent with a transition between grain boundary and lattice diffusion mechanisms as the grain size increases (4 to 44 μan). The creep of polycrystalline MgO is a mixed process in that viscous and nonviscous (dislocation) contributions are present.     

Reproducibility of Microbiological Counts on Frozen Cod: A Collaborative Study

Reproducibility of aerobic plate count (APC), coliform and fecal coliform counts in frozen cod was examined by 14 laboratories (3 government, 4 university and 7 industry) using primarily FDA recommended procedures. In order to assure homogeneity of samples, the fish was comminuted and thoroughly mixed. The 35°C and the “room temperature” (26°C) APC on Sample A (a good quality product) were 1.3 × 10⁵/g and 2.6 × 10⁵/g, respectively, and for Sample B (a questionable quality product) the counts were 2.9 × 10⁵/g and 6.4 × 10⁵/g, respectively. Standard deviations among counts (log₁₀ values) were 0.26 and 0.32 for the 35°C counts and 0.24 and 0.40 for the 26°C counts of Sample A and B, respectively. The std. dev. were reduced to 0.19, 0.22, 0.17 and 0.25, respectively, when counts that did not show significant overlap (based on Dur can's New Multiple Range Test) were excluded from the calculations. Coliform counts on Sample A (not inoculated) ranged from <30 to 4.6 × 10⁵/100g. Coliform and fecal coliform counts for Sample B (inoculated at estimated level of 1 × 10⁴/100g) were 5.8 × 10³/100g and 5.5 × 10³/100g, with a std. dev. of 0.43 and (.37, respectively. The std. dev. for the coliform counts was reduced to 0.30 when counts from one laboratory were excluded, based on Duncan's New Multiple Range Test.