The development of a glove-box/Vitrobot combination: air-water interface events visualized by cryo-TEM

Aqueous interfaces are of paramount importance in the study of biological systems as well as in the biomedical sciences. To study these interfaces at the nanometer level it is of interest to develop methods that allow their observation with cryogenic transmission electron microscopy (cryo-TEM). Prevention of dehydration to preserve the "native" state during sample preparation prior to vitrification is often one of the most important parameters to control in cryo-TEM experiments. For the preparation of these types of samples, we felt the need for an extended workspace with temperature and humidity control; a 'glove-box' that seamlessly connects to the vitrification instrument, the Vitrobot. In this paper we describe the use of the glove-box in the 2D and 3D cryo-TEM study of DNA adsorption and calcium carbonate mineralization to Langmuir films. The data presented illustrates the necessity of a humidity-controlled environment to preserve the original "native" state of the monolayer system.     

Calculation of the effective index for nonguiding regions: reply to comment

Here we point out that in their comment Bastiaansen et al. Appl. Opt. 33, this issue (1994)] overlooked both the context of and the assumptions in Jaeger and Lai's paper [Appl. Opt. 31, 7183-7190 (1992)]. This omission appears to have resulted in their applying the Jaeger and Lai method inappropriately to a particular rib waveguide structure, yielding strange results. Therefore we present the underlying theory and ad hoc a simple and theoretically consistent method for applying it to rib waveguides. We demonstrate that good results may be obtained for a weakly guiding rib waveguide structure when field separability may be assumed, i.e., one that better meets the assumptions; this structure was chosen because numerical results were available for comparison.     

Rater reliability and concurrent validity of the Keyboard Personal Computer Style instrument (K-PeCS)

This paper describes the inter-rater and intra-rater reliability, and the concurrent validity of an observational instrument, the Keyboard Personal Computer Style instrument (K-PeCS), which assesses stereotypical postures and movements associated with computer keyboard use. Three trained raters independently rated the video clips of 45 computer keyboard users to ascertain inter-rater reliability, and then re-rated a sub-sample of 15 video clips to ascertain intra-rater reliability. Concurrent validity was assessed by comparing the ratings obtained using the K-PeCS to scores developed from a 3D motion analysis system. The overall K-PeCS had excellent reliability [inter-rater: intra-class correlation coefficients (ICC)=.90; intra-rater: ICC=.92]. Most individual items on the K-PeCS had from good to excellent reliability, although six items fell below ICC=.75. Those K-PeCS items that were assessed for concurrent validity compared favorably to the motion analysis data for all but two items. These results suggest that most items on the K-PeCS can be used to reliably document computer keyboarding style.