Nutrient concentrations and accumulations in precipitation over the north central region

The many facets of plant nutrients (e.g., N, P, and S) in the biosphere have become major environmental issues within the past decade. This concern is justified because of the increasing contamination of air and water resources by various substances on local and regional levels, especially in areas close to point sources. Little information is available, however, on variation in the amounts and concentrations of some of the substances present in air and natural water in various parts of the United States. Such information is essential for a better understanding of the transport and perhaps the fates of pollutants in the biosphere. The atmospheric component of the N and S cycles often can be a significant part of the various pools of their respective cycles (Allison, 1965; Erickson, 1963; Feth, 1966; Gambell and Fisher, 1964; Meetham, 1950; Robinson and Robbins, 1970), but the atmospheric component of the P cycle seems to be of minor significance to the cycling of this element in the environment. Among the various chemical elements present in precipitation (e.g., N, S, K, Cl, and Ca), N and S deserve special attention because N added by precipitation may contribute to nitrate pollution of surface and ground water. Sulfur and N may cause acid rain that can lead to increased leaching from soils of Ca and other nutrient elements, deterioration of aquatic ecosystems, damage to vegetation and buildings, and other agricultural and urban problems. On the other hand, the limited amounts of N and S brought down by precipitation might be useful to meet crop requirements for these elements in areas where soils have limited supplies of N and S (Allway et al., 1937; Erdman, 1923; Olson et al., 1973; Schuman and Burwell, 1974; Tabatabai and Bremner, 1972; Walker, 1969; Widdowson and Hanway, 1974)

A Simple Alkaline Hydrolysis Method for Estimating Nitrogen Mineralization Potential of Soils

A simple, precise and rapid alkaline hydrolysis method for determining nitrogen (N) availability index of soils is described. It involves direct steam distillation of 1 g field-moist soil and 1 M KOH, NaOH, LiOH or phosphate-borate buffer (pH 11.8) and the amount of NH4+-N released trapped in boric acid and its concentration determined successively every 5 min for a total of 40 min. The cumulative N hydrolyzed was fitted to a hyperbolic equation to determine the maximum hydrolyzable N (Nmax) and the time required to hydrolyze one-half of Nmax (Kt) by linear regression of the transformed data. First-order equation was also used to estimate the potentially hydrolyzable N (No), hydrolysis rate constant (k) and the time required to hydrolyze one-half of No (t1/2). Results showed that for each soil and reagent, Nmax and No values were similar, but differed significantly among soils, suggesting differences in the chemical nature or reactivity of organic N in the soils. In general, Nmax and No values ranged from 401 to 1667 mg kg-1 soil and accounted for 12-56% of total organic N in the soils. The Kt values ranged between 15 and 30 min. Among the reagents tested, KOH and NaOH showed the best promise for estimating the total hydrolyzable organic N pool in the soils. The Nmax and No values were significantly correlated with the amounts of N mineralized in two weeks under aerobic and anaerobic conditions at 30 oC, N released by 2 M KCl extraction at 80oC for 20 h, and the initial NH4+-N present in the soils. We concluded that direct steam distillation of soils with 1M KOH or NaOH offer a quick and precise mean for estimating the potentially mineralizable organic N pool and availability index in soils

Hyperbolastic modeling of tumor growth with a combined treatment of iodoacetate and dimethylsulphoxide

<p>Abstract</p> <p>Background</p> <p>An understanding of growth dynamics of tumors is important in understanding progression of cancer and designing appropriate treatment strategies. We perform a comparative study of the hyperbolastic growth models with the Weibull and Gompertz models, which are prevalently used in the field of tumor growth.</p> <p>Methods</p> <p>The hyperbolastic growth models H1, H2, and H3 are applied to growth of solid Ehrlich carcinoma under several different treatments. These are compared with results from Gompertz and Weibull models for the combined treatment.</p> <p>Results</p> <p>The growth dynamics of the solid Ehrlich carcinoma with the combined treatment are studied using models H1, H2, and H3, and the models are highly accurate in representing the growth. The growth dynamics are also compared with the untreated tumor, the tumor treated with only iodoacetate, and the tumor treated with only dimethylsulfoxide, and the combined treatment.</p> <p>Conclusions</p> <p>The hyperbolastic models prove to be effective in representing and analyzing the growth dynamics of the solid Ehrlich carcinoma. These models are more precise than Gompertz and Weibull and show less error for this data set. The precision of H3 allows for its use in a comparative analysis of tumor growth rates between the various treatments.</p

Eye of the Beholder: Investigating the Interplay between Inquiry Role Diversification and Social Perspective Taking

Students and teachers engage in specific roles in classrooms, and within inquiry classrooms, these roles tend to be more varied compared to traditional settings. Teachers may take on traditional student roles including the role of learner, and students, for example, take on the additional role of question asker, traditionally reserved for the role of a teacher. Several of these roles are specific to perspective taking, in particular, social perspective taking (SPT). SPT is critical to successful social interactions and, because group work occurs frequently within inquiry-based teaching and learning environments, a better understanding of SPT roles is required. SPT roles within two different inquiry classrooms were closely examined through audiorecorded group interactions. Additional data were collected in the form of questionnaires, interviews, student and teacher log responses, and field notes. Two teachers and eight students participated. Social perspective-taking roles were dynamic and susceptible to influences including the nature of the classroom activities and instructional choices, student personality differences, and group-work dynamics. All participants adopted SPT roles, however, students who played an active role in choosing their work partners and who were assigned a task that required a consideration of the audience’s understanding tended to adopt more Imagine Other roles as opposed to Imagine Self roles and also adopted more emotionally-based SPT roles compared to students in teacher-formed groups who were assigned more cognitively-based assignments. Implications for researchers, consultants, and students and teachers were discussed

Performance of the Alere i RSV assay for point-of-care detection of respiratory syncytial virus in children

Background: Respiratory syncytial virus (RSV) is the most important cause of severe acute respiratory tract infection in young children. Alere i RSV is a novel molecular rapid test which identifies respiratory syncytial virus in less than 13 min. Methods: We evaluated the clinical performance of the Alere i RSV assay in a pediatric point-of-care setting during winter season 2016 / 2017. Test results from 518 nasopharyngeal swab samples were compared to a real-time reverse transcription PCR reference standard. Results: The overall sensitivity and specificity of the Alere i RSV test assay was 93% (CI95 89% – 96%) and 96% (CI95 93% – 98%), respectively. Alere i RSV performed well in children of all age groups. An optimal sensitivity of 98% (CI95 94% - 100%) and specificity of 96% (CI95 90% - 99%) was obtained in children &lt; 6 months. In children ≥ 2 years, sensitivity and specificity remained at 87% (CI95 73% – 96%) and 98% (CI95 92% – 100%), respectively. False negative Alere i RSV test results mostly occurred in samples with low viral load (mean CT value 31.1; CI95 29.6 – 32.6). The Alere i RSV assay is easy to use and can be operated after minimal initial training. Test results are available within 13 min, with most RSV positive samples being identified after approximately 5 min. Conclusion: The Alere i RSV assay has the potential to facilitate the detection of RSV in pediatric point-of-care settings