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Stellar Archeology: What White Dwarf Stars Tell Us About the History of the Galaxy
Terry D. Oswalt 한국우주과학회 2012 Journal of Astronomy and Space Sciences Vol.29 No.2
White dwarf stars have played important roles in rather diverse areas of astrophysics. This paper outlines how these stellar remnants, especially those in widely separated “fragile” binaries, have provided unique leverage on difficult astrophysical problems such as the ages of stars, the structure and evolution of the Galaxy, the nature of dark matter and even the discovery of dark energy.
Ecological changes affecting vector-borne diseases in Korea
Terry A. Klein,Heung Chul Kim 한국응용곤충학회 2009 한국응용곤충학회 학술대회논문집 Vol.2009 No.10
Ecological changes, both man-made and natural, have changed the landscape of the Republic of Korea following the end of Japanese occupation at the end of World War II (1939-1945). During the Japanese occupation, forested hillsides were cleared and wood products shipped to Japan, leaving the hills and mountains largely covered by grasses and other shrub vegetation. Following WWII, the country of Korea was divided into North and South Koreas, with North Korea under communist powers, while South Korea was established as a democratic government. In South Korea poverty was rampant and local populations scavenged for wood for cooking and heating during the cold winters. Just as economic conditions were increasing, South Korea was attached by North Korea, beginning a long drawn-out conflict from 1950 to the summer of 1953, whereby an armistice was signed and an often uneasy peace between the two countries continues today. Again, the Republic of Korea emerged from a War as an impoverished country with treeless country sides, hills, and mountains. In the 1960’s, president Chung-Hee Park established a tree planting policy to reestablish long-ago lavish forested mountains and hillsides that make up more than 70% of the South Korean landscape. Today, mountains and hillsides are generally not used for agriculture and are completely forested, with planted groves and volunteer trees ranging in age from 10-50 years. These forested areas have led to increased protection for large and small mammals and birds, increasing the potential for zoonotic pathogens that there ectoparasites harbor to be transmitted to man during work and leisure activities. While forested areas provided an expanded habitat for some animals, agriculture expanded and modernized, resulting in short-cut grasses on banks separating much of the rice paddies, orchards, ditches, and dry-land farming that increased competition for small mammal habitat. As a result of increased surveillance of small and large animals and their ectoparasites, the increased prevalence of known pathogens and identification of new pathogens, especially those harbored by ticks, has demonstrated the presence of tick-borne encephalitis, several species of spotted fever group Rickettsia, and a host of other zoonotic diseases in wild animals, their ectoparasites, and man. As tick-borne diseases are not reportable diseases in Korea, the extent and impact on civilian and military populations is unknown as diagnoses are often likely sought for the wrong pathogen. While agriculture modernized, military training sites largely consist of unmanaged lands with tall grasses that are conducive to large and small mammal populations, which are host to a number of zoonotic diseases, e.g., hantaviruses, scrub typhus, murine typhus, leptospirosis, tick-borne encephalitis, spotted fever group rickettsial pathogens, Lyme disease, bartonellosis, etc. that impact on military populations training in those areas. The impact of training sites habitat modification has not been assessed, but for many sites is impractical. To reduce health risks of vectorborne diseases, the US Army has established better housing (tents to barracks with screened windows and air conditioning) at some field training sites, reducing the potential for the transmission of mosquito-borne pathogens (malaria and Japanese encephalitis virus). The increased use of permethrin-treated all climate uniforms (ACUs) and repellents, also reduce the potential for transmission of mosquito-, tick-, mite-, and flea-borne pathogens. However, training conditions at some field training sites remain largely unchanged, with personnel working and sleeping in tents that abut to forested areas where animals and their ectoparasites are present. While some training and maneuver sites are well planned for weapons qualifications of wheeled and tracked vehicles, others sites are in areas of unmanaged lands which are rodent infested. Increased surveillance by the 65th Medical Brigade not only provides a baseline and relative distribution for vector-borne diseases in Korea, but also provides disease trends and risk assessments that are necessary for protecting US military personnel training in Korea.
Terry Lopez,Samuel E. Schriner,Michael Okoro,David Lu,Beatrice T. Chiang,Jocelyn Huey,Mahtab Jafari 한국식품영양과학회 2014 Journal of medicinal food Vol.17 No.12
Green tea is a popular beverage believed to have many health benefits, including a reduction in the risks of heart disease and cancer. Rich in polyphenolic compounds known as catechins, green tea and its components have been shown to increase the lifespan of various animal models, including Drosophila melanogaster. Here, we investigated the genderspecific effects of green tea on the lifespan of fruit flies and observed that green tea extended the lifespan of male flies only. This effect was found to be independent of typical aging interventions, such as dietary restriction, modulation of oxidative energy metabolism, and improved tolerance to environmental stresses. The one exception was that green tea did protect male flies against iron toxicity. Since there is an inverse correlation between lifespan and reproduction, the impact of green tea on male reproductive fitness was also investigated. We found that green tea negatively impacted male fertility as shown by a reduced number of offspring produced and increased mating latency. We further identified that the lifespan extension properties of green tea was only observed in the presence of females which alludes to a reproductive (or mating) dependent mechanism. Our findings suggest that green tea extends the lifespan of male flies by inhibiting reproductive potential, possibly by limiting iron uptake. To our knowledge, our study is the first to report the negative impact of green tea on Drosophila male reproduction. Our results also support previous studies that suggest that green tea might have a negative effect on reproductive fitness in humans.