Northern Taiwan Area Research Articles

Prediction of Ka-Band Terrestrial Rain Attenuation using 2-year Rain Drop Size Distribution Measurements in Northern Taiwan

In this paper, we study rain attenuation at Ka-band in northern Taiwan from long-term experimental measurements using a Ka-band (28.35 GHz) CW system at vertical polarization, optical rain gauge, and 2D optical distrometer that measures the rain drop size distribution (DSD). The DSD were measured and analyzed for different seasons under various rain rates. The variability of DSD in both space and time was clearly shown even in the not so large area of Northern Taiwan. It follows that a relationship between rain rate and DSD was established. From statistical regress, it was also found that the DSD follows the Gamma distribution best in most cases. Making use of the Gamma-distribution for DSD along with a two-year set of continuously measured data (2002–2003), a semi-empirical rain attenuation model was then developed. To validate the model, we compared it with the measured data. The results show that the proposed model matched very well with in-situ measurement from a two-year data set.

Married women's satisfaction with their choice of contraception.

Fertility reduction has been promoted in Taiwan for almost 40 years. However, little research has been done into women's satisfaction with the methods of contraception they use. The purpose of this study is to explore their level of satisfaction, along with the related factors of demographic data, giving birth and types of contraceptives used. Employing a cross-sectional design, self-administered questionnaires were distributed to women in the northern area of Taiwan. Purposive sampling was used to collect data from 97 women. The results reveal a mean age of 37.21 years. The mean length of marriage was 13.53 years. The majority (43.29 %) of the subjects were graduates of high school or vocational school. Of the subjects, 92.78 % had given birth, while 35.05 % had experienced abortion. IUDs (Intrauterine Devices) were the most commonly used form of contraceptive, while 63.92 % used other types. Satisfaction was divided into four categories: satisfaction with contraceptive services, satisfaction with contraceptive knowledge source, satisfaction with contraceptive experience and satisfaction with spousal support. Overall, subjects were happy with the contraceptive methods they used. There was no statistical difference in satisfaction between demographic variances, fertility or contraceptive methods applied. Though subjects showed satisfaction with contraception, we feel women's subjective experiences should be investigated in order to promote even better satisfaction. Possible future studies could include random sampling and an examination of the related factors of contraceptive satisfaction.

Variations of U/Th-series nuclides with associated chemical factors in the hot spring area of northern Taiwan

The relationship of the activity ratios (ARs) of U/Th-series nuclides and associated factors (pH, Eh, and the concentrations of Cl- and SO42-) in the hot spring area of Taipei were determined. The contents of U and Th in water decreased with increasing pH. The 234U/238U ARs have been ascribed to alpha recoil and selective leaching of 234U, while the 234U/238U disequilibrium was not significant with regard to the statistical error. Variations of 230Th/234U ARs can be attributed to the different chemical properties of 230Th and 234U. The disequilibrium of 226Ra/230Th can be ascribed to the complexation of thorium with Cl- and SO42-, and to the co-precipitation of radium with sulfates. The disequilibrium of228Th/232Th can be due to the co-precipitation of 228Ra with (Ba,Pb)SO4 and to the migration of 228Th from the sediment into the water.

Applying SPOT data to estimate the aerosol optical depth and air quality

The improvement in the structure function method for retrieving aerosol optical depth (AOD) with SPOT HRV data and its application in air quality monitoring are highlighted in this paper. Generally speaking, estimation of the aerosol optical depth will be affected by the temporal change of surface canopy, observation geometry and terrain effect when applying the contrast reduction method to the multi-temporal satellite image set. In order to reduce the errors induced by such effects, the single-directional structure function is replaced by the multi-directional mode, which can describe the real characteristics of the surface structure more completely. Comparison of the results with in-site observations show a significant improvement in the accuracy of the retrieved AOD. Furthermore, due to the linear relationship between aerosol optical depth and turbidity coefficient, satellite images can be employed for monitoring air quality. Application of the method is demonstrated with a case study situated around the northern Taiwan area.

Geomagnetic Basement Relief of the Northern Taiwan Area

A detailed magnetic survey has been carried out in the northern Taiwan area in order to determine the topographic surface of the magnetic basement. This survey covers an area of about 900 km2, and totally the observation point is 269. After geomagnetic corrections of the observed data, the magnetic anomaly map was obtained. For the purpose of resolving the deeper (relative to the shallow effects) magnetic basement, a low-pass filter was applied to the magnetic anomaly to obtain a smoothed magnetic anomaly. Thirteen profiles were designed to cross and cover evenly the smoothed geomagnetic anomaly in the study area. These geomagnetic anomaly profiles were inverted to obtain the magnetic basement profiles by trial and error method. Compiling these 1-D magnetic basement profiles, we outlined the 2-D magnetic basement relief. The pattern of the relief of the geomagnetic basement shows that the depth is ranged from 2.6 to 6 km. There exists a basement high under the Tatun volcano area. Compiling with the topographic relief, we can find that they correlate to each other well, except for a contravention in the mountainous area surrounding the Taipei basin. This converse can be explained by supposing that tectonic forces lifted the mountainous area after the basement was formed. In order to verify the “truth” of the solution, we calculated the theoretical geomagnetic anomaly using the model we have inverted. Comparing the result with the observed geomagnetic anomaly map, we can find that they are quite similar to each other, with only a small variance.

Westward Extension of the Okinawa Trough at its Western End in the Northern Taiwan Area: Bathymetric and Seismological Evidence

In this paper, we used detailed bathymetry, earthquake distribution and focal mechanisms to study the phenomenon of active westward extension of the Okinawa trough in the northern Taiwan area. We found a distinguishable subsiding and collapsing area on the continental shelf edge and the continental slope on the northern side of the Okinawa trough. This area extends westwards to at least 121.5?E and includes several morphological units related to the existence and formation of three major canyons. The canyons and the morphological units are still evolving through the sediment transport and through the subsidence and collapse of material due to the formation of the Okinawa trough. According to the degree of development, we found that these morphological units have developed from the asst to the west. There are two parallel E-W trending central graben at the westernmost part of the Okinawa trough, with each corresponding to a narrow shallow seismic belt. The widths of the central graben are 10-15 km. There is geophysical and geological evidence that the formation of these central graben has been extended westwards to the onland area of Taiwan. Focal mechanisms of earthquakes and the topographic features show that the formation of the Okinawa trough is associated with the down-dip extensional stress along the subducting slab of the Philippine Sea plate, and most of northern Taiwan and all the northeastern offshore area of Taiwan are under tensional stress. New portions of the Okinawa trough have been forming across the whole width at its western end through subsidence in the continental shelf, the continental slope and the traditionally recognized area of the Okinawa trough in the northeastern Taiwan area, to make the Okinawa trough develop gradually and extend westwards.

Fault Detection by 2D Resistivity Inversion on a Topographic Area

Direct current (DC) resistivity data acquired on rough terrain can be interpreted by using an appropriate two-dimensional (2-D) finite element inversion with the topography-incorporated technique developed by Tong and Yang (1990). This technique is computation ally efficient and provides a geological interpretation that is an improvement on the standard 2-D inversion. The main feature of this scheme is that sounding data incorporated the topography into the inversion without any previous topographic correction of field data. Thus errors inherited by the inversion data from an imperfect topographic correction can be avoided, especially in an area that has complex subsurface structures. In addition, the penetration depth of a Schlumberger four symmetric collinear electrode (4-electrode survey) array is often limited by obstacles at ground-level; especially in mountainous areas. This drawback may be overcome by using a Schlumberger three asymmetric collinear electrode (3-electrode survey) array. In order to demonstrate the advantage of using the 3-electrode survey, model studies were performed, and the results show that the DC resistivity responses obtained from the 4-electrode and 3-electrode surveys have similar features for a given spread length. However, under the same topographic constraints, the 3-electrode configuration has a more extension of a spread length, and therefore, a greater penetration depth. To seek verification of our strategy, DC resistivity sounding was applied to the Kanchiao fault area of northern Taiwan. The results stressed fault detection in this area. A Schlumberger 3-electrode survey was carried out in the field, and the data collected were inverted to the geoelectric models by using Tong and Yang's scheme (1990). In addition, synthetic apparent resistivity pseudosections were also computed from the final inversion models. Comparison of the synthetic with the observed apparent resistivity profiles is sufficient to reveal the Kanchiao fault position. The implications of the results obtained by combining the special electrode layout of the DC resistivity soundings with the previously mentioned finite element inversion technique are highlighted. The techniques used here does provide users with a guide of what to do in a topographic area. The techniques are superior to conventional techniques as applied to a complex subsurface structure.

Transfer of radionuclides from soil to grass in Northern Taiwan

The transfer factors of radionuclides, such as 40K, 137Cs, 60Co and 54Mn, from soil to grass in northern Taiwan area were studied. The results showed that the transfer factors were much influenced by the contents of potassium and the pH values of the soils. The transfer factors of 40K, 137Cs, 60Co and 54Mn from soil to grass were estimate to be about 0.67–2.84, 0.06–0.63, 0.04–0.92 and 0.40–3.30, respectively.

Characteristics of Submarine Topography off Northern Taiwan

Based on bathymetric data collected in recent years, the topographic features and their structural implications on the northern offshore area of Taiwan are described. The Chilung Shelf is representative of the submarine physiographic units in this region. It occupies the shallow water area eastward to the City of Chilung between the Chilung Valley and the Mien-Hua Canyon. To its north and west, the East China Sea Shelf reveals a gentle ocean bottom such that water depths on its edge (the shelf break) are found to be at least 150 meters shallower than those on the Chilung Shelf. Taiwan is a product of orogeny which resulted in compressive imprints throughout the island. On the Chilung Shelf, a series of topographical lineaments extending from onland Taiwan and oriented in the SW-NE direction are present; however, seismic profiles indicate that these lineaments are a factor of normal faulting mechanics. It is suggested that the offshore area of northern Taiwan has been under a different tectonic stress from that represented on the island. (

Diabetes mellitus and hypertension based on the family history and 2-h postprandial blood sugar in the Ann-Lo district (Northern Taiwan)

From July 1988 to June 1990, we performed an epidemiological study on the prevalence of hypertension and diabetes mellitus (DM) in the Ann-Lo district, a suburban area of Northern Taiwan. One third of the population in the district was randomly sampled. A total of 9087 persons were screened with 67.4% participating. Following completion of the questionnaire blood pressure, 2 h postprandial blood sugar were determined. DM was defined when the blood sugar was over 200 mg/dl or the subject had a diabetic history. Hypertension was defined if the systolic blood pressure was over 160 mmHg or the diastolic blood pressure over 95 mmHg. Statistical comparisons were performed with a chi-square test, analysis of covariance, stepwise multiple regression and Pearson correlation matrix. In this study, the prevalence rate of DM was 2.6% and of hypertension was 6.4%. For those patients 40 years or older, the prevalence rate for DM was 8.0% and for hypertension was 19.7%. The prevalence of hypertension was 24.8% in overt diabetes and 5.2% in the normal subjects. Analysis of the data between risk factors of DM revealed that DM correlated with age, body mass index, hypertension, smoking, family history of DM and correlated negatively with education. Hypertension correlated with gender, alcohol intake and smoking, sugar level, age and body mass index. The prevalence rate of diabetes and hypertension were quite high in the district and this study pointed out the important risk factors for hypertension and DM in Taiwan.

The Winter Diurnal Circulation and Its Influence on Precipitation over the Coastal Area of Northern Taiwan

Wind and rainfall data for December, January and February, 1976–80, over the northern coastal area of Taiwan were analyzed to examine the diurnal patterns of these parameters. Results show that the diurnal variation of rainfall was strongly modulated by the diurnal cycle of local circulation. Local circulations exhibit maximum onshore flow and divergence at 1400 LST and maximum offshore flow and convergence in 0200–0500 UT. Convective heavy rainfall appears to be triggered by the diurnal divergence pattern. Finally, the diurnal rainfall was primarily controlled by the dynamical processes within the planetary boundary layer and the thermodynamic process only plays a minor role in modifying the temporal rainfall pattern.

Japanese Encephalitis Virus in Northern Taiwan, 1969–1973 *

Sentinel pigs were bled and mosiquitoes were collected for isolation of Japanese encephalitis virus (JEV) between 1969 and 1973 in a rural area of northern Taiwan which reported a high annual incidence of human cases. The study site included a farmyard, schools, a bat cave, rice paddies and a heronry. Although Culex annulus was collected in every month of the year, isolations were made only in midsummer and only from Culex annulus and (once) from Culex tritaeniorhynchus. These isolates were usually collected from pig-related sources. Human cases in the vicinity of the study site were reported 3 to 6 weeks following the initial isolations from sentinel pigs. Isolations were made only for 4 to 8 weeks each summer. The isolation of JEV was not related to the availability of susceptible pigs or the spring or summer peaks in prevalence of Culex annulus. Despite periodic draining of rice paddies and the application of insecticides, sufficient numbers of Culex annulus were available to support transmission of JEV in each year of the study.

Epidemiologic characteristics of cancer of the breast in Taiwan.

An attempt was made to identify and interview all cases of breast cancer diagnosed during a 3-year period in the population of a defined area of Northern Taiwan; 232 cases were identified, and 213 were interviewed. For comparison, similar interviews were conducted with 648 patients with diseases other than breast cancer. Mortality data for Taiwan as a whole have also been used in certain analyses. The average annual incidence rate in the study area was 6.11 per 100,000 female population. Age-specific incidence rates show a pattern similar to that noted in Japan and in the Chinese population of Singapore, rates plateauing in middle-age and then declining in the older age groups. However, mortality rates show a consistent increase with age throughout the life span. There was no evidence of an increase or decrease in mortality rates over the decade 1954-1963. Mortality and incidence rates were both substantially higher among persons born in mainland China than among nativeborn Taiwanese. Risk of breast cancer was sharply lower in women of parity 1 than in nulliparous women, and in women of parity 2 than in those of parity 1. There was no further appreciable decline with increase in parity higher than parity 2. Association with parity was particularly marked for women whose breast cancer was diagnosed after 50 years of age. There was no significant or consistent difference between cases and controls with respect to any of several measures of lactation experience. There was a tendency towards earlier menarche and later menopause in the cases than in the controls, but the differences were not significant. A strong and significant association with weight was found, women weighing more than 55 kg having more than twice the breast cancer risk of those weighing less than 45 kg. There was no consistent or significant association with height. In general, these findings are similar to observations made both in Japan and in high risk areas, but the data from Taiwan are unusual in showing a strong relationship to parity and only a weak association with age at first pregnancy.