Astronomical Limitations on Detecting Habitable Planets Beyond the Solar System

As a possible method of detecting an extrasolar planet, astrometric spectroscopic, and photometric methods are considered. Interest has been focused on the search for a planet whose physical conditions appear to favor biological evolution that could lead to the development of life as advanced as that on the Earth. In order to avoid speculative arguments, the set of assumptions introduced consists of only those that are acceptable at the present stage of our scientific knowledge. These basic assumptions are: (1) The speed of biological evolution is about the same as on the Earth; (2) a planet of our interest has to be within a certain distance from the parent star, so that the planetary temperature can be kept on a range where life can exist; and (3) atmospheric conditions, and the chemical composition of the air, are similar to those on the Earth and such conditions depend only on the ratio of mean thermal to escape velocities. Theoretically computed planetary models are used in determining mass-radius relations. It has been found that the photometric method is far superior to the other two. In fact, it is the only means of detecting a planet of the proposed kind, and as a consequence, the conclusions do not strongly depend on the basic assumptions. Since the probability of success in the search appears to be quite high and various by-products are anticipated, the author proposes that an extensive photometric survey of late type stars be planned before much effort is expended on any radio astronomical search

Metabolism of fatty acids and lipid hydroperoxides in human body monitoring with Fourier transform Infrared Spectroscopy

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Photoelectro-Photometric Survey of Night Sky Conditions in the Vicinity of Iowa City

During the summer 1962, a systematic survey of night sky conditions in the vicinity of Iowa City was carried out for the purpose of selecting the best site for the proposed research observatory of the State University of Iowa. A photoelectric photometer was attached to the Newtonian focus of an 11-inch reflector whose equatorial mounting was modified to a horizontal system. The equipment was carried by a truck and observations were made at six different sites, ranging in distance from eight to twenty-three miles in all directions from the city. In order to eliminate random errors due to variations in sky conditions from night to night, measurements of scattered city lights and the atmospheric extinctions were taken on at least two different sites during the same night and were repeated for six or seven different moonless nights at each site. As a result, it was concluded that the region about twelve miles south-southwest of the city is least affected by the artificial city light

Three Color Photometry of the Total Eclipse of the Moon, December 29, 1963

A three-color photometry of the eclipsed moon was carried out with a 12-inch reflector during the total eclipse on December 30. 1963. In order to examine the intensity and color distribution of refracted light in the umbral region, the observation was centered at Mare Crisium during the course of the eclipse. The decrease in brightness was found to be about 16 magnitudes for each of the three colors, and no significant reddening effect was observed during the totality. The magnitude differences between different colors appear to be nearly the same on the uneclipsed and the totally eclipsed moon

Optimization of salt concentration in PEG-based crystallization solutions

Optimal salt concentration in a PEG-based crystallization solution is important for successful crystal growth and can be predicted prior to performing crystallization experiments

Stimulatory Effects of CO2 Laser, Er:YAG Laser and Ga-Al-As Laser on Exposed Dentinal Tubule Orifices

We investigated the effects of lasers irradiation on the exposed dentinal tubule. Human tooth specimens with exposed dentinal tubule orifices were used. Three types of lasers (CO2 laser, Er:YAG laser and Ga-Al-As laser) were employed. The parameters were 1.0 W in continuous-wave mode with an irradiation time of 30 s for the CO2 laser, 30 mJ in continuous-wave mode with an irradiation time of 60 s for the Er:YAG laser, and 1.0 W in continuous-wave mode with an irradiation time of 60 s for the Ga-Al-As laser. A non-irradiated group was used as a control. After laser irradiation, the dentinal surface of each sample was observed using SEM. Afterwards, all samples were immersed in methylene blue dye solution in order to evaluate the penetration of the dye solution and observe the change in dentinal permeability after laser irradiation. SEM observation showed that the control group had numerous exposed dentinal tubule orifices, whereas these orifices were closed in the laser-irradiated groups. There was consistent dye penetration into the pulp chamber in the control group, whereas no dye penetration was evident in the laser-irradiated groups. Therefore, laser appears to be a promising treatment for reducing permeation through exposed dentinal tubules