Effect of sea water interaction on strontium isotope composition of deep-sea basalts

Analyses of rim-to-interior samples of fresh tholeiitic pillow basalts, deuterically altered holocrystalline basalts, and older, weathered tholeiitic basalts from the deep sea indicate that ⁸⁷Sr/⁸⁶Sr ratios of the older basalts are raised by low temperature interaction with strontium dissolved in sea water. ⁸⁷Sr/⁸⁶Sr correlates positively with H₂O in these basalts; however, there is little detectable modification of the strontium isotope composition in rocks with H₂O contents less than 1%. The isotope changes appear to be a function of relatively long-term, low-temperature weathering, rather than high-temperature or deuteric alteration. Strontium abundance and isotopic data for these rocks suggest that strontium content is only slightly modified by interaction with sea water, and it is a relatively insensitive indicator of marine alteration. Average Rb-Sr parameters for samples of apparently unaltered basalt are: Rb= 1.11ppm; Sr= 132ppm; ⁸⁷Sr/⁸⁶Sr= 0.70247.     

Illuminating Subsurface Microbial Water Quality Patterns Using Adenosine Triphosphate and Dynamic Time Warping Approaches

Aquifer microbial water quality evaluations are often performed by collecting groundwater samples from monitoring wells. While samples collected from continuously pumped sources are seldom disputed as representative of the aquifer, natural biofilm present in the vicinity of well screens may introduce unwanted microbial artefacts in monitoring wells that are only periodically sampled. The need for well water purging to obtain samples void of these artefacts has been widely recognized. However, purging methods are not standardized; many approaches presume that physico-chemical water quality stability achieved through the removal of 3 to 5 well volumes is indicative of the stability of target analytes. Using a data set collected from a shallow unconfined aquifer in Southern Ontario, Canada, the need for using dedicated approaches that account for the time-dependent nature of microbial water quality changes was demonstrated. Specifically, the utility of adenosine triphosphate (ATP) as a rapid, field-ready biochemical indicator of microbial water quality stability was investigated. This work shows that ATP concentrations reflect time-limited (bio)colloid transport processes that are consistent with other microbial water quality parameters monitored, but different from commonly measured physical and chemical water quality indicators of well purging adequacy. ATP concentrations occasionally fluctuated even after 3 or 4 h of purging, indicating that microbial artefacts attributable to biofilms in the vicinity of the well screen can still persist. The recurrence of characteristic ATP patterns in each well was systematically examined through the novel application of dynamic time warping (DTW), a nonparametric time series analysis approach. These patterns are believed to be linked with seasonal hydrogeological conditions, which warrant consideration in the design and interpretation of subsurface microbial water quality investigations.     

Variability in the lengths of Dover sole (Solea solea) after death

This report looks at how the lengths of Dover sole can vary according to handling after death and the method of measurement. The work described is part of the UK Ministry of Agriculture, fisheries and food programme.     

Numerical experimentation with particles having non-zero terminal velocity in the atmospheric surface layer

Numerical solutions are obtained for a two-dimensional eddy diffusion equation describing aerosol particles in the atmospheric surface layer. Particles are assumed to be from either an elevated line source or a surface area source. Characteristics of the solutions are exhibited as a function of source type, lower boundary condition, and the ratio of terminal velocity () to friction velocity (u _*). This theory indicates that suspended particles tend to escape the near-surface layer, and are thus subject to long-range transport, when the ratio /u _* is less than von Karman's constant. This prediction is consistent with available data.     

Ground traces of artificial earth satellites

This paper considers the ground trace of an artificial earth satellite. It determines the effects of the trace caused by perturbations due to atmospheric drag, the oblateness of the earth, and the moon and the sun as a third body.The necessary mathematical relations giving these perturbations which are available in literature are utilized (Betz, 1967; Brouwer and Clemence, 1961; Brouwer and Hori, 1961; Danby, 1962; Escobal, 1965; Kentet al., 1963; Kozai, 1962). Those relations unavailable elsewhere are derived.The computation was done by programming in FORTRAN language and utilizing an IBM 360/65.Captain, USAF     

足尺钢框架振动台试验及动力弹塑性数值模拟

本文通过有限元分析程序OpenSees对一足尺四层钢框架结构进行静力及动力弹塑性分析,结构构件采用自由度较少的纤维模型模拟。在振动台试验之前,预测足尺钢框架结构连续在小震、中震及大震作用下的响应,将预测分析结果与振动台试验结果进行对比,结果显示该数值模拟方法能很好地反映结构的弹塑性行为及破坏机制,准确预测结构的地震响应及大震下结构倒塌时间。这进一步说明基于纤维模型的整体结构弹塑性分析方法,由于自由度数少,适用于整体结构抗震分析。