ABSTRACT
Nonuniform heating may result from microwave (MW) irradiation of tissues and is therefore important to investigate in terms of health and safety issues. Hypothalamic (Thyp), cortical (Tctx), tympanic (Tty), and rectal (Tre) temperatures were measured in rats exposed in the far field, k-polarization (i.e., head pointed toward the transmitter horn and E-field in vertical direction) to two power densities of 2.06 GHz irradiation. The high-power density (HPM) was 1700 mW/cm2 [specific absorption rate (SAR): hypothalamus 1224 W/kg; cortex 493 W/kg]; the low-power density (LPM) was 170 mW/cm2 (SAR: hypothalamus 122.4 W/kg; cortex 49.3 W/kg). The increase (rate-of-rise, in degrees C/s) in Thyp was significantly greater than those in Tctx or Tre when rats were exposed to HPM. LPM produced more homogeneous heating. Quantitatively similar results were observed whether rats were implanted with probes in two brain sites or a single probe in one or the other of the two sites. The qualitative difference between regional brain heating was maintained during unrestrained exposure to HPM in the h-polarization (i.e., body parallel to magnetic field). To compare the temperature changes during MW irradiation with those produced by other modalities of heating, rats were immersed in warm water (44 degrees C, WWI); exposed to a warm ambient environment (50 degrees C, WSED); or exercised on a treadmill (17 m/min 8% grade) in a warm ambient environment (35 degrees C, WEX). WWI produced uniform heating in the regions measured. Similar rates-of-rise occurred among regions following WSED or WEX, thus maintaining the pre-existing gradient between Thyp and Tctx These data indicate that HPM produced a 2-2.5-fold difference in the rate-of-heating within brain regions that were separated by only a few millimeters. In contrast, more homogeneous heating was recorded during LPM or nonmicrowave modalities of heating.
Subject(s)
Body Temperature Regulation/radiation effects , Brain/physiology , Electromagnetic Fields , Hot Temperature , Microwaves , Physical Exertion/physiology , Animals , Body Temperature/physiology , Body Temperature/radiation effects , Body Temperature Regulation/physiology , Brain/radiation effects , Cerebral Cortex/physiology , Hypothalamus/physiology , Immersion , Male , Rats , Rats, Sprague-Dawley , Stereotaxic TechniquesABSTRACT
A fusiform bacterium with 3 to 14 multiple bipolar sheathed flagella and periplasmic fibers wrapped around the cell was isolated from the liver, bile, and lower intestine of aged, inbred mice. The bacteria grew at 37 and 42 degrees C under microaerophilic conditions, rapidly hydrolyzed urea, were catalase and oxidase positive, reduced nitrate to nitrite, did not hydrolyze indoxyl acetate or hippurate, and were resistant to both cephalothin and nalidixic acid but sensitive to metronidazole. On the basis of 16S rRNA gene sequence analysis, the organism was classified as a novel helicobacter, Helicobacter bilis. This new helicobacter, like Helicobacter hepaticus, colonizes the bile, liver, and intestine of mice. Although the organism is associated with multifocal chronic hepatitis, further studies are required to ascertain whether H. bilis is responsible for causing chronic hepatitis and/or hepatocellular tumors in mice.
Subject(s)
Helicobacter/isolation & purification , Mice/microbiology , Aging , Animals , Base Sequence , Bile/microbiology , DNA Primers/genetics , DNA, Bacterial/genetics , Female , Helicobacter/genetics , Helicobacter/ultrastructure , Hepatitis, Animal/microbiology , Intestines/microbiology , Liver/microbiology , Male , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Inbred CBA , Mice, Inbred DBA , Microscopy, Electron , Molecular Sequence Data , Phylogeny , Polymerase Chain Reaction , RNA, Bacterial/genetics , RNA, Ribosomal, 16S/genetics , Species SpecificityABSTRACT
Most studies of population movement have concentrated on the more developed nations and on trends that have not been influenced by man-made or natural disasters. The experience of developing countries in the Caribbean basin, as studied after the Guatemalan earthquake of 1976 and the impact of Hurricane David in the Dominican Republic of 1979, highlights the importance of socio-economic factors in the decision to make permanent migrations after a disaster, regardless of whether the migrant had personally suffered losses. In many cases the opportunities for personal betterment created by the disaster acted as a catalyst and accelerated a previously-existing trend of migration.
Subject(s)
Aged/psychology , Interpersonal Relations , Morale , Black or African American , Female , Georgia , Humans , Life Style , Longitudinal Studies , Male , Marriage , Middle Aged , Retirement , Role , Rural Population , White PeopleABSTRACT
Mortality rates have sharply decreased throughout the world in the twentieth century. While the communicable diseases that had been the principal killers of mankind have been largely brought under control, the enteric and other diseases, which are directly related to sanitation practices, have not been affected. Improvement in health status in the developing nations, especially in isolated rural areas, will hinge on changes in sanitation norms. Modification of these norms must be based on an awareness of what they are and of the values that are associated with them. Sanitation norms in rural areas of three countries--in the southeastern United States, Puerto Rico, and the Dominican Republic--are reviewed on the basis of a study in which essentially the same survey instrument was used in the three samples. Sanitation norms relating to the source of water and storage for household use are compared, as are personal hygiene practices and patterns for the disposal of liquid wastes, garbage, and other solid wastes. Selected attitudinal values are also examined.
