Corrugated stainless steel tubing (CSST) has been used for more than 20 years as a replacement for conventional black iron gas piping. CSST has a thinner tubing wall and is susceptible to damage from lightning activity when discharges enter a structure, potentially resulting in perforation of the CSST wall and fire ignition. Grounding has been promoted by CSST manufacturers as a solution to this problem. We use modeling and simulation of voltage potentials and arc currents to evaluate the effects of grounding on the voltage potential across CSST, which can result in arc initiation, and charge through the arc, which can result in melting and perforation of the CSST wall. Our results show multiple scenarios where a 10 kA 10 9 350 s current waveform with 1 X grounding of the CSST still results in voltages greater than the arc initiation threshold of 25 kV and charge through the arc greater than 1.2 C, the perforation threshold we measured. For the case where lightning enters the structure through an outdoor light fixture or chimney, the presence of a grounding wire increases the charge through the arc from 0.13 C to 2.22 C. These results indicate that good grounding of CSST will not necessarily prevent arc initiation nor perforation of the CSST wall by lightning. Good grounding may in fact exacerbate the problem of lightning damage to CSST depending on where lightning enters the building and the electrical parameters of the path to ground.
The agreement of our results with other sources indicates that our premise regarding latent expert knowledge holds. The disease relationships unique to our network may be used to generate hypotheses for future biological and clinical research as well as drug repurposing and design. Our results provide an example of using experimental data on humans to generate biologically useful information and point to a set of new and promising strategies to link clinical outcomes data back to biological research.
Quantitative phase imaging has many applications for label-free studies of the nanoscale structure and dynamics of cells and tissues. It has been demonstrated that optical coherence phase microscopy (OCPM) can provide quantitative phase information with very high sensitivity. The excellent phase stability of OCPM is obtained by use of a reflection from the microscope cover glass as a local reference field. For detailed intracellular studies a large numerical aperture (N.A.) objective is needed in order to obtain the required resolution. Unfortunately, this also means that the depth of field becomes too small to obtain sufficient power from the cover glass when the beam is focused into the sample. To address this issue, we designed a setup with a dual-beam sample arm. One beam with a large diameter (filling the 1.2 N.A. water immersion objective) enabled high-resolution imaging. A second beam with a small diameter (underfilling the same objective) had a larger depth of field and could detect the cover glass used as a local phase reference. The phase stability of the setup was quantified by monitoring the front and back of a cover glass. The standard deviation of the phase difference was 0.021 rad, corresponding to an optical path displacement of 0.9 nm. The lateral and axial dimensions of the confocal point spread function were 0.42 and 0.84 μm, respectively. This makes our dual-beam setup ideal for three-dimensional intracellular phase imaging.
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