Phosphorus removal in the activated sludge process

The results from this research suggest that both calcium phosphate precipitation and enhanced biological uptake play a role in phosphorus removal in the activated sludge process when a non-nitrifying, anaerobic-aerobic system is used to treat a low calcium wastewater. The primary removal mechanism was found to be biological uptake, as calcium phosphate precipitation accounted for only 15–27% of the total phosphorus removed. Calcium phosphate precipitation in the aerobic unit was enhanced because of the pH increase in that reactor. This was the result of low CO₂ production (indicated by low specific oxygen uptake values) and intense aeration which caused excessive CO₂ stripping in the aerobic unit     

Nonaqueous potentiometry of coal-derived asphaltenes and model nitrogen-containing compounds in acetophenone and nitrobenzene

A series of 34 nitrogen-containing compounds with a wide range of basicities was examined under differential nonaqueous potentiometric conditions in acetophenone and nitrobenzene. These compounds could be resolved into five classes based on pK_aand half-neutralization-potential (HNP) values. Asphaltenes isolated from the vacuum still overhead (VSO) and vacuum still bottoms (VSB) fractions of the H-coal process were titrated under similar conditions. The titration results of both asphaltenes indicated the presence of two classes of nitrogen-containing compounds, a titratable class of the pyridine-ring or aniline type and a nontitratable class.     

Measuring computer software reliability

Under certain conditions, traditional hypothesis-testing techniques may be used as a management tool by software developers or software purchasers who wish to insure that their packages have some specified reliability level. These conditions are: (1) the existence of independent collections of test data, (2) a way of determining the correctness of processing of these collections, and (3) a way of randomly selecting test data.Two basic approaches have been described. In a fixed sample size test, the user decides on the reliability desired. He can then determine the number of test cases which must be examined and the acceptance/rejection criteria. In a sequential test, the desired reliability level is again pre-determined, but samples are tested one at a time until an accept/reject decision can be made.Experiments with a large amount of error data derived from six separate systems indicate that reliability results derived from these models are consistent with actual reliability figures.Most current acceptance procedures are based on a naive assumption that a large program can be exhaustively tested and delivered in an error-free condition. Because these expectations cannot be fulfilled, the manager of a software development project or the purchaser of a software product is provided with no quantitative information on which to base an acceptance decision and is thus forced to make these decisions based mostly on intuition and his own experience in similar situations. These models allow one to replace these intuition-based decisions with quantitatively-based decisions and thus constitute an important contribution to the science of management of software development efforts.     

Analysis of Buffering Techniques in MRP Systems with a Matrix Loading Model

This paper addresses the development of a matrix model for the initial loading procedure in material requirement planning systems with variable lead time. This model expresses the relationship between the planned production quantity in the Master Production Schedule and the production lead time required. Using this model, an analysis of the functions of buffering techniques before loading are discussed. Methods for allocating safety stock and safety lead time using the service level approach are presented to accommodate quantity or lead-time uncertainties. The matrix model is used to study fixed-lead-time loading. The relationships between fixed-lead-time loading and variable-lead-time loading are examined. Methods for allocating buffering quantities for fixed-lead-time loading are developed.     

Effects of the reader's schema at different points in time.

In 2 experiments, 215 high school sophomores and juniors and 71 undergraduates were instructed to take a distinctive point of view while reading and recalling a story. Perspectives assigned before reading, shortly after reading, and long after reading all had substantial effects on recall. Results are interpreted to mean that the schema brought into play by the perspective instructions selectively enhanced encoding when operative during reading and selectively enhanced retrieval when operative during attempts at recall. The schema operative during reading appeared to influence not only the likelihood that certain text elements would be learned but also their longevity in memory. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit versus explicit importance of career values in making a career decision.

353 high school seniors rated 10 individually selected occupational alternatives on 10 individually selected career values. Values were ranked according to explicit importance in making a decision and according to agreement with overall preference ordering of occupations. It was found that explicit importance agreed weakly with implicit importance in ranking occupations. Results agree with those of P. Slovic (1969) and Slovic et al (1972) who used different methods, content (stocks), and sample (stockbrokers). Results contribute to a growing literature on humans' limited capacity to process information, and consequently, limitations in using rational decision models without assistance. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reliability of the Beck Depression Inventory with older adults.

Examined the test–retest, split-half, and coefficient alpha reliability of the Beck Depression Inventory with a sample of 82 elderly community volunteers (mean age 69.9 yrs) and 77 depressed outpatients (mean age 67.8 yrs). All 3 indexes were reasonably high in the total sample and fell within the accepted range of reliability for a clinical screening instrument. As expected, internal consistency was lower when determined for the 2 separate samples. (6 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Beck Depression Inventory and Research Diagnostic Criteria: Congruence in an Older Population.

This study examined the congruence between conventional cutoff scores on the Beck Depression Inventory (BDI) and selected diagnostic classifications of the Research Diagnostic Criteria in a sample of 102 elders seeking psychological treatment. Only 16.67% were misclassified by customary BDI cutoff scores. Minor Depressive Disorders were less clearly identified than Major Depressive Disorders or nondepressed status. Similar results were obtained in a second sample of elders not seeking treatment. Findings support the utility of the BDI as a screening instrument for identification of clinically depressed elders. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attraction of a free-living nematode, Caenorhabditis elegans, to foodborne pathogenic bacteria and its potential as a vector of Salmonella poona for preharvest contamination of cantaloupe

Caenorhabditis elegans was studied to determine the potential role of free-living microbivorous nematodes as vectors for preharvest contamination of fruits and vegetables with foodborne pathogens. The propensity of C. elegans to be attracted to seven strains of Escherichia coli O157:H7, eight serotypes of Salmonella, six strains of Listeria monocytogenes, and cantaloupe juice was investigated. Twenty to 30 adult worms were placed on the surface of K agar midway between a 24-h bacterial colony and 10 microl of uninoculated tryptic soy broth (TSB) or cantaloupe juice positioned 1.5 cm apart. The numbers of nematodes that migrated to the colony, to the TSB, and to the cantaloupe juice within 5, 10, 15, and 20 min at 21 degrees C were determined, and then the plates were incubated at 37 degrees C for up to 7 days to determine the ability of C. elegans to survive and reproduce in bacterial colonies. The nematode was attracted to colonies of all test pathogens and survived and reproduced within colonies for up to 7 days. C. elegans was not attracted to cantaloupe juice. The potential of C. elegans to serve as a vector for the transport of Salmonella Poona to cantaloupe rinds was investigated. Adult worms that had been immersed in a suspension of Salmonella Poona were deposited 1 or 3 cm below the surface of soil on which a piece of cantaloupe rind was placed. The rind was analyzed for the presence of Salmonella Poona after 1, 3, 7, and 10 days at 21 degrees C. The presence of Salmonella Poona was evident more quickly on rinds positioned on soil beneath which C. elegans inoculated with Salmonella Poona was initially deposited than on rinds positioned on soil beneath which Salmonella Poona alone was deposited. The time required to detect Salmonella Poona on rinds was longer when the rind was placed 3 cm above the inoculum than when the rind was placed 1 cm above the inoculum. Free-living nematodes may play a role in the preharvest dispersal of incidental human pathogens in soil to the surfaces of raw fruits and vegetables in contact with soil during development and maturation, as evidenced by the behavior of C. elegans as a test model.