Geoelectric potential changes: possible precursors to earthquakes in Japan.
(25/1260)
Whether electromagnetic precursors to earthquakes (EQs) exist is an important question not only for EQ prediction but also for understanding the physical processes of EQ generation. Slow transient geoelectric potential changes have been observed before several recent EQs in Japan. In most cases, they appeared 1-19 days before the EQs, and their duration and intensity were several minutes to 1 h and 1-2 mV/100 m. The changes appeared before five of all six EQs with magnitude >/= 5 that occurred within 20 km of our stations during the observation period. Changes were also detected at greater epicentral distances (up to 75 km) before two other EQs, including one EQ of magnitude 4.7, which was preceded by a signal simultaneously recorded at three widely separated stations. These geoelectric potential changes have been distinguished through the following criteria from a multitude of other changes, which were noise of various origins. (i) The selected changes were proportional in amplitude to the length of the recording station's short ( approximately 100 m) dipoles and were simultaneously detected also on long (1-10 km) dipoles when the latter were in operation. (ii) No such changes occurred during the observation period that were not followed by EQs. Although the EQ precursory nature of these geoelectric potential changes is admittedly unproven, it seems that the present results warrant continued serious research into the occurrence, generation, and transmission of these signals and their possible causal relationship to EQs. (+info)
Propagation of seismic ground motion in the Kanto Basin, Japan.
(26/1260)
The pattern of ground motion for a magnitude 5.7 earthquake near Tokyo was captured by 384 strong ground motion instruments across the Kanto sedimentary basin and its surroundings. The records allow the visualization of the propagation of long-period ground motion in the basin and show the refraction of surface waves at the basin edge. The refracted wave does not travel directly from the earthquake epicenter, but traverses the basin obliquely to the edge. The surface wave inside the basin propagates more slowly than that outside such that the wavefronts separate from each other, and the refracted wave heals the discrepancy in the speed of advance of the wavefronts inside and outside the basin. The refracted arrival is dominant near the edge of the Kanto basin. (+info)
Morbidity and mortality associated with Hurricane Floyd--North Carolina, September-October 1999.
(27/1260)
On September 16, 1999, Hurricane Floyd, a storm extending 300 miles with sustained winds of 96-110 miles per hour, made landfall in North Carolina, dropping up to 20 inches of rain in eastern regions of the state. Rain from Hurricane Floyd, combined with rains from Hurricane Dennis beginning on August 30 and Hurricane Irene on October 17, caused extensive flooding along the Neuse, Tar, Roanoke, Lumbar, and Cape Fear rivers, affecting an estimated 2.1 million persons. This report presents data about injuries, illnesses, and deaths during and following Hurricane Floyd in North Carolina and identifies the leading cause of death as drowning involving occupants of motor vehicles trapped in flood waters. (+info)
Simulation of disaster recovery of a picture archiving and communications system using off-site hierarchal storage management.
(28/1260)
The purpose of this communication is to report on the testing of the disaster recovery capability of our hierarchical storage management (HSM) system. Disaster recovery implementation is a requirement of every mission-critical information technology project. Picture archiving and communications systems (PACS) certainly falls into this category, even though the counterpart, conventional film archive, has no protection against fire, for example. We have implemented a method for hierarchical storage with wavelet technology that maximizes on-site case storage (using lossy compression), retains bit-preserved image data for legal purposes, provides an off-site backup (lossless bit-preserving wavelet transform), and provides for disaster recovery. Recovery from a natural (earthquake and subsequent fire) or technical (system crash and data loss) disaster was simulated by attempting to restore from the off-site image and database backup to clean core PACS components. The only existing loaded software was the operating system. The database application was reloaded locally, and then the database contents and image store were loaded from the off-site component of the HSM system. The following measurements were analyzed: (1) the ability to recover all data; (2) the integrity of the recovered database and image data; (3) the time to recover the database relative to the number of studies and age of the archive, as well as bandwidth between the local and remote site; and (4) the time to recover image data relative to compression ratio, number of studies, number of images, and time depth of the archive. This HSM system, which maximizes on-site storage, maintains a legal record, and provides off-site backup, also facilitates disaster recovery for a PACS. (+info)
Increased acute myocardial infarction mortality following the 1995 Great Hanshin-Awaji earthquake in Japan.
(29/1260)
BACKGROUND: This study examined the factors affecting mortality from acute myocardial infarction (AMI) following the 1995 Great Hanshin-Awaji earthquake. METHODS: We examined the death certificates of all decedents between January 1994 and December 1996 in 16 municipalities, which covered most of the area affected by the 1995 Great Hanshin-Awaji earthquake. We analysed the extent and duration of the increased mortality from AMI. The standardized mortality ratio (SMR) of AMI was calculated weekly after the earthquake, taking the number of AMI deaths during the same period in 1994 as a reference. The main outcome measures were the number of deaths from AMI (ICD-9 410; ICD-10 I21, I22) in the study area before and after the earthquake, and the weekly SMR after the earthquake. RESULTS: A significant increase in mortality from AMI in the study area as a whole continued for about 8 weeks after the earthquake. There was wide variation amongst the regions with respect to the extent and duration of the increased mortality from AMI. The SMR of AMI showed a positive relationship with the percentage of houses which were completely destroyed, and was almost significant (r = 0.530, P = 0.062). CONCLUSIONS: The duration of increased cardiac mortality after the 1995 Great Hanshin-Awaji earthquake was longer than seen with previous earthquakes. Further analysis to identify the factors affecting cardiac mortality is needed so that we may reduce adverse health effects during the recovery stage following natural disaster. (+info)
Long term relations between earthquake experiences and coronary heart disease risk factors.
(30/1260)
The authors analyzed the relations between a variety of earthquake-related experiences incurred in 1983-1984 (financial loss, evacuation, indices of disruption of social networks) and coronary heart disease risk factors (heart rate, blood pressure, total serum cholesterol) assessed in 1987 among 693 Italian male factory workers. Multivariate analyses (adjusting for age, body mass index, smoking, and educational level) revealed no long term relations between the quake-related experiences and blood pressure or cholesterol level. However, higher resting heart rates were observed for individuals who reported financial loss, increased distance from family/friends, or decreased visiting as a result of relocation after the quakes. Findings were unchanged after further adjustment for self-reported psychological distress (assessed using the global symptom index of the Symptom Checklist). These findings, while limited by the cross-sectional nature of the data, suggest that a number of psychosocial consequences of relocation due to a natural disaster are unrelated in the long term to coronary heart disease risk factors, except for small but significant differences in heart rate among individuals who have experienced financial loss and/or social network disruptions. (+info)
Genetic engineering of drought resistant potato plants by introduction of the trehalose-6-phosphate synthase (TPS1) gene from Saccharomyces cerevisiae.
(31/1260)
In yeast, trehalose-6-phosphate synthase is a key enzyme for trehalose biosynthesis, encoded by the structural gene TPS1. Trehalose affects sugar metabolism as well as osmoprotection against several environmental stresses, such as heat and desiccation. The TPS1 gene of Saccharomyces cerevisiae was engineered under the control of the CaMV 35S promoter for constitutive expression in transgenic potato plants by Ti-plasmid of Agrobacterium-mediated transformation. The resulting TPS1 transgenic potato plants exhibited various morphological phenotypes in culture tubes, ranging from normal to severely retarded growth, including dwarfish growth, yellowish lancet-shaped leaves, and aberrant root development. However, the plants recovered from these negative growth effects when grown in a soil mixture. The TPS1 transgenic potato plants showed significantly increased drought resistance. These results suggest that the production of trehalose not only affects plant development but also improves drought tolerance. (+info)
Effects of drought on photosynthesis in Mediterranean plants grown under enhanced UV-B radiation.
(32/1260)
The effects of drought on the photosynthetic characteristics of three Mediterranean plants (olive, Olea europea L.; rosemary, Rosmarinus officinalis L.; lavender, Lavandula stoechas L.) exposed to elevated UV-B irradiation in a glasshouse were investigated over a period of weeks. Drought conditions were imposed on 2-year-old plants by withholding water. During the onset of water stress, analyses of the response of net carbon assimilation of leaves to their intercellular CO2 concentration were used to examine the potential limitations imposed by stomata, carboxylation velocity and capacity for regeneration of ribulose 1,5-bisphosphate on photosynthesis. Measurements of chlorophyll fluorescence were used to determine changes in the efficiency of light utilization for electron transport, the occurrence of photoinhibition of photosystem II photochemistry and the possibility of stomatal patchiness across leaves. The first stages of water stress produced decreases in the light-saturated rate of CO2 assimilation which were accompanied by decreases in the maximum carboxylation velocity and the capacity for regeneration of ribulose 1,5-bisphosphate in the absence of any significant photodamage to photosystem II. Leaves of rosemary and lavender were more sensitive than those of olive during the first stages of the drought treatment and also exhibited increases in stomatal limitation. With increasing water stress, significant decreases in the maximum quantum efficiency of photosystem II photochemistry occurred in lavender and rosemary, and stomatal limitation was increased in olive. No indication of any heterogeneity of photosynthesis was found in any leaves. Drought treatment significantly decreased leaf area in all species, an important factor in drought-induced decreases in photosynthetic productivity. Exposure of plants to elevated UV-B radiation (0.47 W m(-2)) prior to and during the drought treatment had no significant effects on the growth or photosynthetic activities of the plants. Consequently, it is predicted that increasing UV-B due to future stratospheric ozone depletion is unlikely to have any significant impact on the photosynthetic productivity of olive, lavender and rosemary in the field. (+info)