Exact solutions for the interaction between two concentric cylindrical waves and between two concentric spherical waves are presented. The scattered-pressure amplitude in the far field is shown to be constant in the cylindrical case and to be proportional to r−1 lnr in the spherical case, where r is the distance to the source of primary waves. A near-field solution is derived for the scattered waves generated when two sharply defined, plane-wave beams of square cross section intersect at right angles. A comparison is made of the theory with recent experiments in which beams of circular cross section were used. It is concluded that if the scattered waves do exist, their amplitudes are at least 40 dB below those that are predicted by this theory. When a hard object is placed in the region of intersection, scattered waves are observed. This effect can be explained by the fact that with the addition of the hard object (a cylinder) the primary waves have components of the same symmetry. These components are the waves scattered from the primary beams by the object. Evidence is presented to show that these components, having the same symmetry, interact strongly in the volume surrounding the object.
SUMMARY Eighty-four children with at least 2 lines of amblyopia were treated with the CAM vision stimulator. 91 % of the children who had received no previous amblyopia therapy showed improvement, 73 % achieving 6/12 vision or better. Of children in whom previous occlusion therapy had failed 73 8 % improved. The treatment appears to be effective, rapid, and well tolerated. Our initial impressions have been sufficiently favourable to stimulate further clinical evaluation.Amblyopia probably affects between 4%1 and 7%2 of children in this country. Our understanding of the pathophysiology of amblyopia has blossomed over the last 20 years,3-5 yet the treatment has remained essentially unchanged since 1746..6 Occlusion continues to be the mainstay of treatment, and though it is recognised to be both psychologically and educationally disruptive, alternative methods have not as yet proved sufficiently effective to supplant it.' Recent reports of experience with a new, physiologically based, form of treatment have been encouraging.89 We report an independent, preliminary assessment of this treatment. Materials and methodsChildren attending the Orthoptic Departments of the Birmingham and Midland Eye Hospital and the Birmingham Childrens' Hospital were included in the study if they had 2 or more lines of amblyopiaas measured by linear optotypes-and were able to co-operate with treatment. All children had a full ophthalmological examination, and no child with anterior segment or fundus pathology commensurate with the visual acuity was included.All the children were refracted under cyclopentolate cycloplegia, and full optical correction was prescribed. When the spectacles had been worn for at least 1 week, treatment was started. Each child was shown a series of high-contrast square-wave gratings of different spatial frequencies, and treat- The children had a full orthoptic examination at the beginning and end of treatment, and the visual acuity was measured before and after each session. Four weeks after treatment had been discontinued the children had a further orthoptic examination.Between sessions the children received no additional treatment.
A teamster, aged 41, became hoarse in May 1941. The hoarseness increased and at the end of four months severe cough, stridor and dyspnea were present on exertion, followed later by dysphagia, pain deep in the ears and generalized weakness. There was a loss in weight of 20 pounds (9.1 Kg.) during this period.When first seen at Barnes Hospital in January 1942 (seven and a half months after the onset of the illness), the patient appeared poorly nourished; he was unable to speak above a whisper and was in mild distress, due to inspiratory stridor.The epiglottis was thick, nodular and pale. It was tilted in a position preventing indirect examination of the larynx and encroached on the airway. Direct examination showed the whole interior of the larynx to be white and nodular. The false and true cords were involved to such an extent as to be entirely obliterated. The glottic chink was converted into an irregularly rounded tube.There was a daily rise in temperature of about 1 degree (F.). A presumptive diagnosis of keratosis of the larynx with carcinomatous change was made.With use of the Lynch suspension, most of the epiglottis was amputated and tracheotomy performed.Microscopic sections showed generalized keratosis with a greatly thickened tunica propria, infiltrated with plasma cells, lymphocytes and numerous multinucleated giant cells ( fig. 1). Within the giant cells were oval bodies, about 3 microns in diameter and possessing a central nuclear body ( fig. 2) and an outer thick retractile membrane. Dr. Morris Moore identified the organism as Histoplasma capsulatum.Treatment consisted of daily intravenous injections of 5 cc. of fuadin (an antimony preparation) for one week, followed by two weeks of rest and then another week of fuadin injections. No effect on the larynx was noted.Fractional irradiation of the larynx was given, but this therapy was stopped after twelve days because of uncontrollable pain in the ears and throat.At the time this report is made there are a proliferative lesion of the skin about the tracheotomy wound, an ulcération on the knee and a large amount of granulomatous tissue in the trachea and the main bronchi, which on one occasion neces¬ sitated bronchoscopy to prevent suffocation. Microscopic sections of tissue from these sites showed histoplasmosis.
Marked differences in the structure and physiology of the mucous membranes as compared with the skin would lead one to expect differences in their reaction to irritants. This is borne out by the observations of Duncan' and of Cooper,2 who showed that poison ivy leaf (Rhus toxicodendron) may be chewed with impunity by susceptible persons, but contact of the leaf or saliva with the skin about the month results in a severe reaction. The nasal mucosa is the primary shock tissue in cases of allergic rhinitis. Nasal tests, therefore, should be more specific and give more reliable information than skin tests in such cases.The advantages of the skin tests are principally the relative ease of application, the large number of tests that can be run at one time, and the relative freedom from severe reactions. The failure of the skin to react in many cases of allergic rhinitis, and its tendency to react to great numbers of allergens that the nasal mucosa is not sensitive to, reduces the value of the test as a diagnostic procedure in this condition. Rackemann and Simon 3 found 8 per cent of positive skin reactions in persons showing no symptoms of hypersensitiveness. It is obvious that any of the various methods of parenteral administration of antigenic substance, which results in absorption into the blood stream, may cause sensitization of the skin.The limited number of tests that can be performed, and the severe symptoms often resulting from the methods of testing m vogue, has prevented general use of mucosal tests in the nose.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.