The ultraviolet spectrometers that observed the atmosphere of Mars in July and August of 1969 consist of a planetary coronagraph and an Ebert-Fastie monochromator. The spectral range 1100-4300 A was measured using two photomultiplier tubes, one with a cesium iodide photocathode, the other with a bialkali photocathode. These tubes were ...

Thesis (Ph.D.)--University of Wisconsin--Madison, 2007.

The potential light shielding by intracellular gas vacuoles in Halobacterium salinarium strain 5 was examined by looking at the ultraviolet light inactivation curves of both wild-type cells and mutants which are defective in the production of gas vacuoles. Whereas strains defective in gas vacuole production were slightly more sensitive to ...

The ichthyotoxin of Prymnesium parvum is inactivated by visible (400 to 510 mμ) as well as by ultraviolet light (255 mμ). The changes in the absorption spectrum of purified (pigment-free) ichthyotoxin during this process indicate that different mechanisms may be involved in the inactivation by visible or ultraviolet light. Photoinactivation ...

1. An unidentified unit in the mechanism of the photosynthesis of Chlorella pyrenoidosa is rendered inactive by the absorption of one quantum of ultraviolet light (2537 Å wave length). 2. The same irradiation has no effect on the normal respiration of Chlorella pyrenoidosa. Experiments have not yet been made on ...

Spores and vegetative forms of a strain of B. megatherium were irradiated by ultraviolet light of the wave lengths 2536 Å, 2803 Å, and 3132 Å. The killing rate of both bacteria and spores is exponential, in agreement with irradiation results on other bacteria. Twice as much incident energy is ...

A study has been made of the effect of sudden intense flashes of ultraviolet light, acting on a wide variety of cells and tissues, with special reference to stimulation. The flashes are obtained by a high voltage condenser discharge through a quartz mercury vapor sterilamp, using the method of Rentschler. ...

Operation Bali Assist was the Australian Defence Force evacuation of injured Australians and other foreign nationals after the Bali terrorist bombing. This operation was the largest Australian aeromedical evacuation since the Vietnam War. It relied on military and civilian cooperation to move the critically injured initially from Denpasar to Darwin, ...

The age response for lethality of Chinese hamster cells to ultraviolet light shows that they are resistant in G(1), sensitive as they move into and through the S phase and resistant again in G(2) and mitosis. Survival curves determined at different times in the cycle reveal that mitotic cells are ...

Light transmission through the body wall of living, color-labile desert iguanas (Dipsosaurus dorsalis) was measured by spectrophotometry. In the dark phase, the body wall's absorption of ultraviolet light and visible light was approximately twice that of the body wall in the light phase. The shorter wavelengths of ultraviolet could penetrate ...

An attempt has been made to determine the solar ultraviolet action spectrum for dried coliphage T-1 exposed to space under various filters at sounding rocket altitudes between 80 to 150 km. The survival of these microorganisms was compared with the preliminary results of laboratory ultraviolet irradiation experiments using monochromatic light ...

Cells of Paramecium aurelia labeled with tritiated thymidine were irradiated with ultraviolet light and then were either exposed to photoreactivating light or kept in the dark as controls. In the controls, the level of thymine-containing pyrimidine dimers did not change, but in cells exposed to photoreactivating light such dimers were ...

[This corrects the article on p. 533 in vol. 15.].

Responses of the summer form of the adult female two-spotted spider mite, Tetranychus urticae Koch (Acarina: Tetranychoidea) placed in near-ultraviolet and green light are photopositive. The independent variation of these responses requires the presence of separate receptor systems.

Aligned deoxyribonucleic acid (DNA) molecules exhibit a large absorption anisotropy in the ultraviolet (UV) region of the spectrum (11). Also, the UV action spectra of most bacteria resemble the absorption spectrum of DNA (23), implying that inactivation is directly proportional to the UV absorbed by the bacterial DNA. Hence, the ...

The bacterial virus, PhiX174, which contains a single strand of DNA has been inactivated by different wave lengths of monochromatic ultraviolet light at pH 7, 2, and 12. The action spectra for inactivation at these three pH's all showed minima at 2400 A rather than at 2300 A, which is ...

Action spectra for delayed light production by several algae were determined from 250 to 750 mmicro incident light. In the visible portion of the spectrum the action spectra resemble those reported by previous workers for photosynthesis and light emission. Blue-green algae had a maximum at 620 mmicro, red algae at ...

1. Photoreversal of ultraviolet (UV) injury was studied in the ciliate protozoan Tetrahymena pyriformis (geleii) strain W, cultured in the absence of other living organisms. The division pattern of progeny of single animals was followed in hanging drop preparations. 2. A sublethal dose of 450 ergs/mm.(2) of monochromatic UV of ...

Tested by the roll-tube method, the inclusion in Dubos medium of oleic acid, Tween 80, or glucose hastens colony growth of tubercle bacilli (BCG), but the variability in counts between replicate bottles is large, and the mean count is low compared with that obtained in media free of these substances.The ...

The effect of ultraviolet light in delaying certain events in the cell division cycle has been examined. The time to fusion of the egg and sperm nucleus is not affected by doses of ultraviolet that cause considerable delay in other parts of the cycle. The principal delay occurs before anaphase. ...

The demonstration of five different effects of ultraviolet radiation on the sea urchin's egg indicates that more than one basic photochemical process goes on there. Photorecovery is observed in only one of these. The need for caution in interpreting such effects is obvious. Evidence for a different mechanism for the ...

1. Heat does not sensitize paramecia to ultraviolet light but ultraviolet light sensitizes them to heat. Paramecia of two species (Paramecium caudatum and P. multimicronucleate) are much more readily killed by heat at 42.3 degrees C. if they are first exposed to ultraviolet light. 2. From studies on paramecia irradiated ...

Results have been presented of the application of a simplified technique of ultraviolet photomicrography to a study of the specific lesions in muscle in subjects with progressive muscular dystrophy. An exact description of the histological changes occurring in this syndrome, as revealed by photomicrographs in ultraviolet light, is difficult at ...

1. An explanation has been given for the effect of subdued light on the development of anthocyanins. This effect was observed by von Sachs and by Sorby seventy years ago. Nobody has made an exhaustive study of the subject, although Askenasy, Hugo Fischer and others have done work along these ...

A study has been made of the effect of sudden intense flashes of ultraviolet light, acting on a wide variety of cells and tissues, with special reference to stimulation. The flashes are obtained by a high voltage condenser discharge through a quartz mercury vapor sterilamp, using the method of Rentschler. ...

1. Strong dosages (20,000-50,000 ergs per mm.(2)) of ultraviolet light, predominantly of the wave-length 2537 A, greatly retard and inhibit the development of rhizoids in Fucus eggs irradiated at about 8 hours after fertilization. 2. If white light shines on the eggs after the irradiation by ultraviolet is terminated, the ...

Spores and vegetative forms of a strain of B. megatherium were irradiated by ultraviolet light of the wave lengths 2536 A, 2803 A, and 3132 A. The killing rate of both bacteria and spores is exponential, in agreement with irradiation results on other bacteria. Twice as much incident energy is ...

1. Although ultraviolet irradiation of larvae did not prolong the larval stage as is the case with x-rays, the immediate effects on respiratory rates are strikingly similar. 2. Effects of irradiation at different ages were observed and also effects of successive irradiations with remarkable agreement in comparable lots.

The incident energies required to kill Staphylococcus aureus or to inactivate its homologous bacteriophage have been measured at the various wave-lengths of the quartz mercury vapor arc between 238 and 302 mmicro and found to run strictly parallel, the readings for the S. aureus phage being obtained at a uniformly ...

1. An unidentified unit in the mechanism of the photosynthesis of Chlorella pyrenoidosa is rendered inactive by the absorption of one quantum of ultraviolet light (2537 A wave length). 2. The same irradiation has no effect on the normal respiration of Chlorella pyrenoidosa. Experiments have not yet been made on ...

Typhoid bacilli are about one two-hundredth as sensitive to ultraviolet light of wave-lengths 2100 to 2800 Angström units as is the photographic plate. This sensitivity then falls off, decreasing rapidly to almost zero sensitivity at about 2970, the beginning of the sun's spectrum.