The National Institute of Standards and Technology (NIST) and the Pacific Northwest National Laboratory (PNNL) are each creating quantitative databases containing the vapor-phase infrared spectra of pure chemicals. The digital databases have been created with both laboratory and remote-sensing applications in mind. A spectral resolution of approximate, equals 0.1 cm(-1) was selected to avoid degrading sharp spectral features, while also realizing that atmospheric broadening typically limits line widths to 0.1 cm(-1). Calculated positional (wave- number, cm(-1)) uncertainty is =0.005 cm(-1), while the 1sigma statistical uncertainty in absorbance values is <2% for most compounds. The latter was achieved by measuring multiple (typically >/=9) path length-concentration burdens and fitting a weighted Beer's law plot to each wavenumber channel. The two databases include different classes of compounds and were compared using 12 samples. Though these 12 samples span a range of polarities, absorption strengths, and vapor pressures, the data agree to within experimental uncertainties with only one exception.
No abstract
The brain and spinal cord of one adult sea lamprey, Petromyzon marinus, 12 cm in length, were fixed in glutaraldehyde and osmium, stained in toluidine blue, embedded in Araldite, and sectioned serially at 5 P. Over 50 large axons were traced through the spinal cord to their probable cells of origin.The axon of one giant interneuron was followed from the posterior spinal cord rostrally into the lateral medulla of the brain.A formerly unrecognized pair of Muller axons was found to originate from the reticular cells Iz.An unusual feature of some Muller axons was their migration out of the ventral columns and their subsequent branching.The central nervous system of the lamprey contains a number of large neurons which are obvious in isolated preparations and in histological sections. The midbrain and medulla contain about 50 large reticulospinal neurons, the most prominent of which are the Muller and Mauthner cells. Axons of these cells are large, unmyelinated, and usually unbranched; thus, they are well suited to the technique of tracing through serial sections. Locations of Muller and Mauthner axons in the anterior spinal cord have been determined by previous tracings (Rovainen, '67a), but they have not been followed individually to the posterior end of the cord.Giant interneurons are located in the posterior spinal cord and their axons extend towards the brain. These axons have been traced fOr a few centimeters (Rovainen, '67b), but not to their terminations. In the present study the entire brain stem and spinal cord of one animal were sectioned serially, and an attempt was made to trace axons of reticular cells and of giant interneurons over their entire lengths. 4" and was anesthetized by immersion in gm/ml Tricaine. Its brain and spinal cord were exposed by dissection under iced Ringer fluid, and then removed from the notochord and ventral skull. The central nervous system was fmed by immersion in 6% glutaraldehyde and 2% acrolein in 120 mM Tris-HC1 buffer, pH 7.2, on ice for two hours, washed in buffer, and then fixed again in buffered 1% Os04. After dehydration in ethanol it was stained with 0.5% toluidine blue in ethanol and then was embedded in Araldite. Over 20,000 serial transverse sections were cut at 5 p on a steel knife. Sections were arranged on slides in ten rows of 20 each for easy reference to their position along the animal.Large and medium-sized axons were obvious as light, oval structures in transverse sections (figs. 3-5), and they usually changed very little in position and shape in adjacent sections. Reference diagrams of labelled axons in brain and spinal cord were made at intervals of 100 p , patterns of large axons were checked at least at 50 p intervals, and smaller axons were traced through individual sections. The most difficult portion of an axon for tracing was near its cell of origin, where it narrowed to a few microns and lost contrast with the surrounding tissue. Axon
In recent sociological reconstructions of knowledge generation in science, two models of analysis have emerged. On the discourse model, reconstructions are grounded in what scientists say and write; on the praxis model, the focus is on what scientists do. The differences between these respective models are examined in this Note, particularly in the context of three studies employing elements of both models: Laboratory Life (1979), The Manufacture of Knowledge (1981), and Opening Pandora's Box (1984). The salient issues of this Note are: (a) the frequently ambiguous relation in these studies between scientists' praxis and scientists' discourse about praxis ; (b) the extent to which the discourse analysis model is successful in moving towards an understanding of scientific praxis ; (c) the problematic strategy of anthropological strangeness; and (d) the hermeneutic relation between the sociological observer's and the scientist's respective interpretive frameworks, laboratory context and situated practices.
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