Seasonal cycling of sulfur and iron in porewaters of a Delaware salt marsh

An extensive pore water data set has been gathered in the Great Marsh, Delaware over various seasons, salinities, and tides. The data all point to a complimentary redox cycle for sulfur and iron which operates seasonally and tidally. Surface oxidizing conditions prevail in summer, with more reducing conditions at depth during the winter. During the spring tides which flood the marsh, pyrite oxidation occurs releasing excess dissolved iron (II) and sulfate to the porewaters, and precipitating authigenic solid iron phases. The redox conditions in the porewaters of the upper zone during the summer is poised between mildly oxidizing and mildly reducing conditions as shown by pE calculations. This redox environment and intermediate iron-sulfur redox species may be important for the stimulation of plant growth (photosynthesis) and sustenance of a viable microbial community (heterotrophy and chemoautropy)

Relationship between Text Display Method and College Student Short Term Knowledge Retention during Self-Study.

This purpose of this study was to determine if a significant difference existed in the short-term knowledge retention of college freshmen reading informational stimulus materials presented through one of three different text display modes; 1) traditional printed text, 2) computer-displayed linear text, and 3) computer-displayed hypertext. The sample consisted of 267 college freshmen at a southern regional university. The 267 students were randomly selected from the entire population of entering freshmen during Fall 2002. These students were then randomly assigned to one of the three treatment groups. After reading the stimulus materials for a specified amount of time, students completed a multiple-choice knowledge-based test that was designed by the researcher. Analysis of variance (ANOVA) was used to compare scores on the knowledge test across the three different treatment groups. The analysis showed a significant difference in the scores of students in the computer-displayed hypertext and traditional printed text groups, with those reading traditional printed text scoring higher. There was also a main effect for gender, with females scoring higher on the knowledge test than males. There was no significant gender by text display method interaction These findings support the relative efficacy of presenting information to college students in a traditional printed text format under similar conditions

An approach for assessing software prototypes

A procedure for evaluating a software prototype is presented. The need to assess the prototype itself arises from the use of prototyping to demonstrate the feasibility of a design or development stategy. The assessment procedure can also be of use in deciding whether to evolve a prototype into a complete system. The procedure consists of identifying evaluations criteria, defining alterative design approaches, and ranking the alternatives according to the criteria

Designing with Ada for satellite simulation: A case study

A FORTRAN oriented and an Ada oriented design for the same system are compared to learn whether an essentially different design was produced using Ada. The designs were produced by an experiment that involves the parallel development of software for a spacecraft dynamics simulator. Design differences are identified in the use of abstractions, system structure, and simulator operations. Although the designs were vastly different, this result may be influenced by some special characteristics discussed

An empirical study of software design practices

Software engineers have developed a large body of software design theory and folklore, much of which was never validated. The results of an empirical study of software design practices in one specific environment are presented. The practices examined affect module size, module strength, data coupling, descendant span, unreferenced variables, and software reuse. Measures characteristic of these practices were extracted from 887 FORTRAN modules developed for five flight dynamics software projects monitored by the Software Engineering Laboratory (SEL). The relationship of these measures to cost and fault rate was analyzed using a contingency table procedure. The results show that some recommended design practices, despite their intuitive appeal, are ineffective in this environment, whereas others are very effective

Measuring software technology

Results are reported from a series of investigations into the effectiveness of various methods and tools used in a software production environment. The basis for the analysis is a project data base, built through extensive data collection and process instrumentation. The project profiles become an organizational memory, serving as a reference point for an active program of measurement and experimentation on software technology

Designing with Ada for satellite simulation: A case study

A FORTRAN-operated and an Ada-oriented design for the same system are compared to learn whether an essentially different design was produced using Ada. The designs were produced by an experiment that involves the parallel development of software for a spacecraft dynamics simulator. Design differences are identified in the use of abstractions, system structure, and simulator operations. Although the designs were significantly different, this result may be influenced by some special characteristics discussed

Managers Handbook for Software Development

Methods and aids for the management of software development projects are presented. The recommendations are based on analyses and experiences with flight dynamics software development. The management aspects of organizing the project, producing a development plan, estimation costs, scheduling, staffing, preparing deliverable documents, using management tools, monitoring the project, conducting reviews, auditing, testing, and certifying are described

Situational Position and Student Choice Criteria

The student in choosing a particular university to attend does so within a particular university-student situational context. This paper demonstrates that the situational context significantly influences the evaluative criteria used by students in deciding which university to attend. Using a Canadian university as a case study, the authors develop an analytical framework for understanding the relationship between the particular university-student situational context and the student choice of university decision criteria.Lorsqu'il(elle) choisit l'université où il(elle) va poursuivre ses études, l'étudian-te) prend en considération des facteurs relatifs à l'université et à sa situation en tant qu'étudiant(e). Cet article montre que le contexte d'une situation influence d'une façon significative les critères d'évaluation dont se servent les étudiants au cours de leur choix d'une université. Prenant une université canadienne comme exemple, les auteurs élaborent un cadre analytique qui permet de comprendre le rapport qui existe entre d'une part, le contexte de la situation particulière de V université et de l' étudiant(e) et d'autre part, les critères dont se sert l' étudiant(e) lorqu'il(elle) choisit une université