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60. Air Permeability of Parachute Gloths.

Author

Goglia, M.J., LaVier, H.W.S., and Brown, C.D.

Abstract

The air permeability of 8 standard nylon parachute cloths was determined, using samples 6.05 in. in effective diameter. Fifty-nine experimental nylon cloths manu factured by the Bally Ribbon Mills were subjected to the same test procedure, as were 2 experimental fabrics of Orlon and Dacron, and 4 different samples of wire screen.Upon assuming that the pressure gradient in the flow through a parachute fabric is proportional to the arithmetic sum of an inertial (βρυ2) and the viscous contribution (αμυ), the existence of a parameter, β/α (whose measure is length), can be inferred. This length can be employed to characterize the geometry of the cloth. Experimental work to date in the case of the 8 standard nylon cloths, the Orlon and Dacron fabrics, 14 of the Bally Ribbon cloths, and the 4 wire screen samples indicates a justification of the assumption.Employing the characteristic length so determined permits writing a single relation common to all cloths between a "flow-through-drag coefficient," Cr, and a Reynolds num ber based on the characteristic length, viz., Cf = 2 + (2/NRe).A procedure is suggested for estimating the parameters α and β from physical meas urements for plain-weave cloth; thus an indication of the permeability is predicted from construction details of the fabric. [ABSTRACT FROM PUBLISHER]

Published
1955
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61. Surgical margins for excision of primary cutaneous melanoma

Author

Zitelli, J.A., Brown, C.D., and Hanusa, B.H.

Abstract

Background: A major controversy in the treatment of melanoma is the width of the surgical margin necessary for complete excision. Although surgical margins have decreased in recent years, the current recommendations are mainly based on arbitrary choices, only two of which have been tested in clinical trials. Objective: Our purpose was to use prospective data, measuring the extent of subclinical melanoma extensions, to develop guidelines for predetermined surgical margins for the excision of cutaneous melanoma. Methods: A prospectively collected series of 535 patients with 553 primary cutaneous melanomas was studied. All melanomas were excised by means of the fresh tissue technique of Mohs micrographic surgery with frozen section examination of the margin. The surgical margin needed for excision of melanoma was determined by measuring the invisible extensions of tumor around the melanoma. The minimum surgical margin was 6 mm and the total margin was calculated by adding an additional 3 mm for any melanoma requiring a subsequent stage to remove the tumor completely. Results: Eighty-three percent of melanomas were successfully excised with a 6 mm margin; 9 mm removed 95% of the melanomas; and a 1.2 cm margin was necessary to remove 97% of all melanomas. Margins to remove melanomas on the head, neck, hands, and feet were wider than those on the trunk and extremities. Margins to remove melanomas that were more than 2 to 3 cm in diameter were wider than for smaller melanomas. Conclusion: Predetermined surgical margins for excision of melanoma or melanoma in situ by standard surgical techniques should include 1 cm of normal-appearing skin for melanomas on the trunk and proximal extremities that are smaller than 2 cm in diameter, or a 1.5 cm margin for tumors larger than 2 cm in diameter. For melanomas on the head, neck, hands, and feet, a minimum surgical margin of 1.5 cm is recommended or a margin of 2.5 cm for melanomas larger than 3 cm in diameter. Mohs micrographic surgery is a useful alternative to standard surgery when more narrow margins are desired, particularly for melanomas on the head, neck, hands, and feet, or melanomas larger than 2.5 cm in diameter, or for melanomas without distinct clinical margins. (J Am Acad Dermatol 1997;37:422-9.)

Published
1997
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63. Review: Ipratropium is not more effective than β[sub2]-agonists for acute exacerbartions of chronic obstructive pulmonary disease.

Author

McCrory, D.C., Brown, C.D., and Niewoehner, Dennis E.

Subjects
*PARASYMPATHOLYTIC agents, *PLACEBOS, *OBSTRUCTIVE lung diseases, *THERAPEUTICS
Abstract

Summarizes a study that investigated whether anticholinergic agents are more effective than placebo or β[sub2]-agonists in patients with acute exacerbations of chronic obstructive pulmonary disease. Sources of the information used in the study; Main results of the study; Conclusion.

Published
2003

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