Although microbial growth on substrate mixtures is commonly encountered in bioremediation, wastewater treatment, and fermentation, mathematical modeling of mixed substrate kinetics has been limited. We report the kinetics of Pseudomonas putida F1 growing on benzene, toluene, phenol, and their mixtures, and compare mathematical models to describe these results. The three aromatics are each able to act as carbon and energy sources for this strain. Biodegradation rates were measured in batch cultivations following a protocol that eliminated mass transfer limitations for the volatile substrates and considered the culture history of the inoculum and the initial substrate to inoculum mass ratio. Toluene and benzene were better growth substrates than phenol, resulting in faster growth and higher yield coefficients. In the concentration ranges tested, toluene and benzene biodegradation kinetics were well described by the Monod model. The Monod model was also used to characterize phenol biodegradation by P. putida F1, although a small degree of substrate inhibition was noted. In mixture experiments, the rate of consumption of one substrate was found to be affected by the presence of the others, although the degree of influence varied widely. The substrates are catabolized by the same enzymatic pathway, but purely competitive enzyme kinetics did not capture the substrate interactions well. Toluene significantly inhibited the biodegradation rate of both of the other substrates, and benzene slowed the consumption of phenol (but not of toluene). Phenol had little effect on the biodegradation of either toluene or benzene. Of the models tested, a sum kinetics with interaction parameters (SKIP) model provided the best description of the paired substrate results. This model, with parameters determined from one‐ and two‐substrate experiments, provided an excellent prediction of the biodegradation kinetics for the three‐component mixture. © 2000 John Wiley & Sons, Inc. Biotechnol Bioeng 69: 385–400, 2000.

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Context: Limited ankle dorsiflexion (DF) range of motion has been correlated with decreased flexibility of the gastrocnemius/soleus complex. Decreased ankle DF range of motion can lead to an increase in lower-extremity injuries, for example, acute ankle sprains, Achilles tendinopathy. Objective: The purpose of this study was to determine whether a single application of the intervention to the gastrocnemius/soleus complex via multidirectional self-myofascial release using a foam roller, multiplanar dynamic stretch performed in downward dog, or a combination of both techniques acutely improved ankle DF. Design: Subjects were assigned to groups via random card selection. Investigators provided verbal cues as needed to yield correct performance of interventions. Both interventions were performed twice for 1 minute using a dynamic walking rest of 30.48 m at a self-selected pace between interventions. Statistical analyses were completed using a 1-way analysis of variance, at α level ≤ .05. Setting: A convenience sample study. Participants: A total of 42 asymptomatic physical therapy students (18 females and 24 males) with mean age of 26.12 (4.03) years volunteered to participate. Interventions: Multidirectional self-myofascial release using a foam roller, multiplanar dynamic stretch performed in downward dog, or a combination of both techniques. Main Outcome Measures: Weight-bearing right ankle DF measurements were recorded in centimeters using a forward lunge technique (intraclass correlation coefficient = .98, .97, and .96). Results: Data analysis revealed no significant difference between the 3 groups in all pre–post measurements (P = .82). Mean (SD) measurements from pretest to posttest for myofascial release, dynamic stretching, and combination interventions were 0.479 (0.7) cm, 0.700 (0.7) cm, and 0.907 (1.4) cm, respectively. Conclusion: Until further studies are conducted, the selection of technique to increase ankle DF range of motion should be based on each individual patient’s ability, preference, and response to treatment.

The Standard Penetration Test (SPT) and Cone Penetrometer Test (CPT) have become industry standards for subsurface geotechnical investigations using small diameter (<8-in. [20-cm]) borings and soundings. Both procedures have evolved over a period of 100 and 70 years, respectively, and have been adopted as ASTM standards. Each procedure has certain advantages over the other, but both can elicit incorrect data under particular subsurface conditions that are often overlooked, depending on the experience of field personnel operating or logging the tests. This paper seeks to explain the operative assumptions employed in both procedures, highlight the various corrections that are commonly employed, and warn the reader of common errors in interpretation. The article concludes by stating that, under most conditions, the joint employment of SPT and CPT together has the greatest potential for characterizing sites correctly.

The variable elevation of the groundwater table in the St. Louis area was estimated using multiple linear regression (MLR), ordinary kriging, and cokriging as part of a regional program seeking to assess liquefaction potential. Surface water features were used to determine the minimum water table for MLR and supplement the principal variables for ordinary kriging and cokriging. By evaluating the known depth to the water and the minimum water table elevation, the MLR analysis approximates the groundwater elevation for a contiguous hydrologic system. Ordinary kriging and cokriging estimate values in unsampled areas by calculating the spatial relationships between the unsampled and sampled locations. In this study, ordinary kriging did not incorporate topographic variations as an independent variable, while cokriging included topography as a supporting covariable. Cross validation suggests that cokriging provides a more reliable estimate at known data points with less uncertainty than the other methods. Profiles extending through the dissected uplands terrain suggest that: (1) the groundwater table generated by MLR mimics the ground surface and elicits a exaggerated interpolation of groundwater elevation; (2) the groundwater table estimated by ordinary kriging tends to ignore local topography and exhibits oversmoothing of the actual undulations in the water table; and (3) cokriging appears to give the realistic water surface, which rises and falls in proportion to the overlying topography. The authors concluded that cokriging provided the most realistic estimate of the groundwater surface, which is the key variable in assessing soil liquefaction potential in unconsolidated sediments.

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The major goal of this research was to explore low cost means by which large tracts of mountainous terrain (~75000 km 2 ) can be screened for landslide-related hazards. For upper Indus watershed study, landslide susceptibility index maps were generated by coupling two main indicators groups: 1) environmental risk factors, which mainly contain slope angle, slope aspect, elevation, lithology maps; and 2) the causative factors, which include seismicity and rainfall. GIS based expert driven weighted overlay and fuzzy logic techniques were adopted to generate susceptibility maps for this preliminary landslide hazard study. The results obtained from this study were validated with landslide inventory mapping and other landslide historic data scattered throughout the upper Indus watershed. This kind of regional level landslide susceptibility mapping can play a vital role in identifying those areas where more detailed assessments of landslide hazards should be undertaken.

Over the past [Formula: see text], the exposed stone foundations of the ancient Egyptian monuments at Luxor have deteriorated at an alarmingly accelerated rate. Accelerated deterioration is attributable to three principal factors: 1) excavation and exposure of foundation stone; 2) construction of the Aswan High Dam; and 3) changes in the regional groundwater regime. In an effort to better elucidate the hydrostratigraphy in the Luxor study area that extends from the River Nile to the boundaries of the Nile Valley and covers about [Formula: see text], a geophysical∕hydrological investigation was conducted. Forty Schlumberger vertical electrical soundings (VES), two approximately [Formula: see text] long seismic refraction profiles and a total number of 39 groundwater and surface water samples were acquired. Based on the integrated interpretation of the acquired geophysical∕hydrological data, the main contributions of this study were the geophysical definition of the hydrostratigraphy using resistivity (seven distinct geologic∕ hydrologic units were mapped), the mapping of the water table using seismic refraction and the mapping of groundwater salinity trends through geochemical sampling. The factors contributing to the rise of groundwater and its accompanying increase in salinity were identified and documented. This characterization establishes a model for evaluating various plans to lower groundwater levels and salinities in the areas of archeological monuments.