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Predicting New Hampshire indoor radon concentrations from geologic information and other covariates 总被引：2，自引：2，他引：0
Generalized geologic province information and data on house construction were used to predict indoor radon concentrations
in New Hampshire (NH). A mixed-effects regression model was used to predict the geometric mean (GM) short-term radon concentrations
in 259 NH towns. Bayesian methods were used to avoid over-fitting and to minimize the effects of small sample variation within
towns. Data from a random survey of short-term radon measurements, individual residence building characteristics, along with
geologic unit information, and average surface radium concentration by town, were variables used in the model. Predicted town
GM short-term indoor radon concentrations for detached houses with usable basements range from 34 Bq/m3 (1 pCi/l) to 558 Bq/m3 (15 pCi/l), with uncertainties of about 30%. A geologic province consisting of glacial deposits and marine sediments was
associated with significantly elevated radon levels, after adjustment for radium concentration and building type. Validation
and interpretation of results are discussed.
Received: 20 October 1997 · Accepted: 18 May 1998 相似文献
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A new information criterion, the extended information criterion (EIC) was applied in order to determine an optimum solution in simultaneous iterative reconstruction technique (SIRT) P-wave velocity tomography. The EIC is derived from information theory and statistics, and it measures the goodness-of-fit between the true (unknown) data distribution and the observed data distribution: the former gives the probability of data realization from the true (unknown) model, whereas the latter gives a probability of data realization calculated from a particular model of which parameters are estimated. The EIC is calculated using bootstrap statistics, a numerical technique for calculating statistical estimators. Bootstrap statistics enables us to obtain the bias between the log likelihood and the expected log likelihood, and then to obtain the expected log likelihood from the log likelihood. Since the EIC is obtained numerically, we can use it for most problems of model parameter estimation without employing the maximum likelihood method. Taking weak anisotropy into account, we reconstructed the P-wave velocity structure of a rock sample during water infiltration under differential stress loading conditions. The results indicate that we can remove unrealistic solutions sometimes encountered when too many iterations are made. In spite of much computation time, the EIC is a promising technique for the near future, prompted by the rapid progress in current computer technology. 相似文献
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Halloysite A, which is a weathering product of feldspar in granitic rocks and of matrix clay minerals in sand, takes the shape of long tubes. Halloysite B which is a weathering product of pyroclastic materials takes the shape of balls, nodules, scrolls or short tubes. Stability of the interlayer water of halloysite varies from sample to sample, but does not show a simple relation to these genetical types. Chemical analysis and ESR show that halloysite B contains more structural Fe than halloysite A. 相似文献
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Urban soils, although crucial to defining urban vegetation types and strengthening the resilience of urban ecosystems, can be severely modified by human activities. Yet understanding of these modifications and their implications for soil properties is limited. This study examined the vertical and spatial variability of selected soil physicochemical properties (pH, SOM, OC, TN, and bulk density) in Kumasi, Ghana, using a stratified random sampling technique. Soil samples were collected at three depths (0–15, 15–30, and 30–60 cm) from 161 plots in eight green space types within two urban zones. Mean topsoil pH ranged between 5.0 in the natural forest and 6.5 in home gardens. Mean bulk density, nitrogen, and carbon concentrations differed among green space types and depths (p?<?0.0001). Soil nitrogen and carbon concentrations in the 0–15 cm depth were two times greater than those of the 30–60 cm depth. Soil pH and organic matter concentrations were higher in the core urban soils than in the peri-urban while the reverse was true for total soil N and bulk density. Canonical discriminant analysis showed considerable separation of green space types based on the soil physicochemical properties. Higher total nitrogen and C:N ratios separated natural forest and cemetery from the other UGS types, whereas higher pH and bulk densities separated plantations and home gardens from the rest of the UGS types. Furthermore, the subsoil layers were laden with undecomposed cloths, plastics, concrete, and metal parts which can obstruct root growth and water movement. Results generally demonstrate considerable variability in soil properties among urban green spaces and highlight the need for a better understanding of these patterns to ensure continued support for plant growth, green space sustenance and maintenance, and the ecosystem services derived from them. 相似文献
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Nero R.W. Thompson C.H. Feuillade C. Love R.H. 《Oceanic Engineering, IEEE Journal of》2001,26(2):259-265
A low cost biplanar reflector target has been developed and used in a system performance test of a near surface omnidirectional source and receiver. The target was constructed from sheets of closed cell plastic bubble sheeting. Theoretically, this material should have very high reflectance characteristics, and this was demonstrated by the experiment. The strongly reflecting target was located at the sea surface, and allowed the interpretation of data as the ship passed through a range of azimuthal angles. The higher than expected backscatter from the target was presumed to be due to the bubble sheeting behaving as a coherent reflector, like a thin layer of air, rather than an ensemble of individually resonating bubbles. This was verified by the data analysis. Lloyd's mirror effects were strong, because practically all of the return signals from the 10-ms continuous wave pulses were overlapping. The target strength (TS) of the reflector was strongly reduced at ranges over 100 m. The experiment shows that studies of the statistical distribution of fish school TS must consider the effects of Lloyd's mirror 相似文献
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Hisashi Hayakawa Harufumi Tamazawa Yurina Uchiyama Yusuke Ebihara Hiroko Miyahara Shunsuke Kosaka Kiyomi Iwahashi Hiroaki Isobe 《Solar physics》2017,292(1):12
A significant carbon-14 enhancement has recently been found in tree rings for the year 994, suggesting an extremely strong and brief cosmic ray flux event. The origin of this particular cosmic ray event has not been confirmed, but one possibility is that it might be of solar origin. Contemporary historical records of low-latitude auroras can be used as supporting evidence of intense solar activity around that time. We investigate previously reported as well as new records that have been found in contemporary observations from the 990s to determine potential auroras. Records of potential red auroras in late 992 and early 993 were found around the world, i.e. in the Korean Peninsula, Saxonian cities in modern Germany, and the Island of Ireland, suggesting the occurrence of an intense geomagnetic storm driven by solar activity. 相似文献
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