Effect of aluminum on cytoplasmic Ca2+ homeostasis in root hairs of Arabidopsis thaliana (L.)

Aluminum inhibition of root growth is a major world agricultural problem where the cause of toxicity has been linked to changes in cellular calcium homeostasis. Therefore, the effect of aluminum ions (Al) on changes in cytoplasmic free calcium concentration ([Ca2+]c) was followed in root hairs of wild-type, Al-sensitive and Al-resistant mutants of Arabidopsis thaliana (L.) Heynh. Generally, Al exposure resulted in prolonged elevations in tip-localized [Ca2+]c in both wild-type and Al-sensitive root hairs. However, these Al-induced increases in [Ca2+]c were not tightly correlated with growth inhibition, occurring up to 15 min after Al had induced growth to stop. Also, in 32% of root hairs examined growth stopped without a detectable change in [Ca2+]c. In contrast, Al-resistant mutants showed little growth inhibition in response to AlCl3 exposure and in no case was a change in [Ca2+]c observed. Of the other externally applied stresses tested (oxidative and mechanical stress), both were found to inhibit root hair growth, but only oxidative stress (H2O2, 10 microM) caused a prolonged rise in [Ca2+]c similar to that induced by Al. Again this increase occurred after growth had been inhibited. The lack of a tight correlation between Al exposure, growth inhibition and altered [Ca2+]c dynamics suggests that although exposure of root hairs to toxic levels of Al causes an alteration in cellular Ca2+ homeostasis, this may not be a required event for Al toxicity. The elevation in [Ca2+]c induced by Al also strongly suggests that the phytotoxic action of Al in root hairs is not through blockage of Ca2(+)-permeable channels required for Ca2+ influx into the cytoplasm.     

A fortran 77 program for automatic stratigraphic correlation

A program that performs automatic stratigraphic correlation is described. The algorithm used is a modification of the Smith and Waterman (1980) technique. It allows for gaps in the strata and the simultaneous matching of one strata to a number of others. The method obtains the best match of two sequences by the minimization of a mathematical distance or difference between them.     

Diagnostic concordance of telecytology and conventional cytology for evaluating breast aspirates

We examined the effect of a humanized anti-glycoprotein IIb/IIIa monoclonal antibody, YM337, on thrombolysis with tissue-type plasminogen activator in a copper coil-induced coronary thrombosis model in rhesus monkeys. Fifty minutes after the formation of an occlusive thrombus, a test drug was administered by either i.v. bolus injection followed by continuous infusion (YM337, 0.25 mg/kg + 1.5 microg/kg/min) or i.v. bolus injection (aspirin, 17 mg/kg). Sixty minutes after induction of the occlusive thrombus, thrombolysis was initiated with tPA at a total dose of 0.5 mg/kg intravenously administered over 60 min, with 10% given as an initial bolus. The median time to reperfusion was significantly shortened by YM337 [saline, 60 min (n = 5); aspirin, 45 min (n = 5); YM337, 30 min (n = 5)]. The incidence of reocclusion was significantly decreased by YM337 (saline, 4/4; aspirin, 5/5; YM337, 1/5), and the median time to reocclusion was significantly prolonged by YM337 [saline, 30 min (n = 4); aspirin, 30 min (n = 5); YM337, 180 min (n = 5)]. YM337 significantly reduced the thrombus protein content at the end of experiment. ADP-induced platelet aggregation was completely inhibited by YM337. These results suggest that YM337 may be of clinical value as an adjunctive agent in thrombolytic therapy for patients with acute myocardial infarction.     

Simultaneous 20 and 30 GHz attenuation measurements on a satellite-Earth path

Simultaneous 20 and 30 GHz attenuation measurements have been made along a 23° elevated slant path to the ATS-6 satellite. The ratio of 30 to 20 GHz attenuation is found to be 2.20±0.13 over the 30 GHz attenuation range of 4 to 14 dB.     

Microstrip antennas

Microstrip antennas consist of a planar resonant radiating element parallel to, but separated, from a ground plane by a thin dielectric substrate (t ll lambda). These antennas are very thin and consequently rugged and easy to mount. They may be fed from the back through the ground plane or from the edge by depositing microstrip lines on the dielectric substrate. Several varieties of microstrip antennas are discussed in this paper. Design procedures are given for both linearly and circularly polarized antennas. Measured patterns are presented for antennas from UHF throughCband.     

Semi-automatic profiling from SEM stereopairs

Modifications were made to a stereometer to permit semi-automatic profiling from SEM stereopair micrographs. The design was based upon a mirror stereoscope with a parallax measuring facility, to which was added a linear transducer to monitor the parallax readings and an X-Y digitising tablet to provide (x, y) coordinate values of specific features. Transmission to a mini computer of these digitised coordinates and parallax was triggered by a microswitch allowing the operator to maintain his attention on the measurements from the stereometer. The computer calculated the “Z” coordinates which could then be output graphically to its visual display unit or to a plotter/printer for hard copy results. This system permits the rapid accumulation of data from the stereopair micrographs while

• 1. reducing operator fatigue, due to the elimination of manual recording of data values between individual measurements, and
• 2. improving the accuracy of the results required, since errors due to misreading or misrecording data are eliminated.

     

Aerospace nomads: How professionals move

If it became necessary to locate a large, high-technology defense facility in X location, where would the technical professional work force be obtained? Attempts to answer this question, posed by the Assistant Director of Defense Research and Engineering (Engineering Management) to a Stanford Research Institute team, opened a Pandora's box. Data collected in pursuit of the answer enabled the team to develop several inferences bearing upon the movement of this technical, intellectual resource between geographical areas and between employers. After describing briefly the source and processing of the data, this article describes the team's findings concerning intergeographical and interemployer movement of technical professionals, in that order.