Ecological interface design for Pasteurizer II: a process description of semantic mapping

Ecological interface design (EID) is proving to be a promising approach to the design of interfaces for complex dynamic systems. Although the principles of EID and examples of its effective use are widely available, few readily available examples exist of how the individual displays that constitute an ecological interface are developed. This paper presents the semantic mapping process within EID in the context of prior theoretical work in this area. The semantic mapping process that was used in developing an ecological interface for the Pasteurizer II microworld is outlined, and the results of an evaluation of the ecological interface against a more conventional interface are briefly presented. Subjective reports indicate features of the ecological interface that made it particularly valuable for participants. Finally, we outline the steps of an analytic process for using EID. The findings presented here can be applied in the design of ecological interfaces or of configural displays for dynamic processes.     

Whither Compatibility Testing?

Excipient compatibility studies are of limited value in the selection of ingredients which will provide a stable dosage form. These empirical tests are often substituted for estimates of potential instability based on known chemical interactions. They are inefficient, and their predictive value has not been rigorously established. It is more meaningful and economical to prepare initial formulations for stability screening than to test for excipient compatibilities in powder mixtures     

Oligonucleotide-functionalized gold nanoparticles as probes in a dry-reagent strip biosensor for DNA analysis by hybridization

The highly specific molecular recognition properties of oligonucleotides are combined with the unique optical properties of gold nanoparticles for the development of a dry-reagent strip-type biosensor that enables visual detection of double stranded DNA within minutes. The assay does not require instrumentation and avoids the multiple incubation and washing steps performed in most current assays. Gold nanoparticle reporters with oligo(dT) attached to their surface form an integral part of the strip. Biotinylated PCR products (233 bp or 495 bp) are hybridized (5 min) with a poly(dA)-tailed oligo and applied on the strip, which is then immersed in the appropriate buffer. As the buffer migrates upward, it rehydrates the nanoparticles that are linked to the target DNA through poly(dA)/(dT) hybridization. Capture of the hybrids by immobilized streptavidin in the test zone of the strip generates a characteristic red band. A second red band is formed, by hybridization, in the control zone of the strip to indicate proper test performance. The sensor offers at least 8 times higher detectability than ethidium bromide staining of agarose gels and provides confirmation of the amplified fragments. Quantitative data are obtained by densitometric analysis of the bands. As low as 2 fmol of amplified DNA were detectable by the strip sensor. Also, 500 copies of prostate-specific antigen cDNA were detected by combining PCR and the strip sensor. The sensor was used successfully for detection of hepatitis C virus in plasma samples from 20 patients. The strip detected 16 out of 16 positive samples and gave no signal for 4 samples that were negative for the virus. To our knowledge, this is the first dry-reagent system that makes use of oligonucleotide-conjugated gold nanoparticles as probes.     

Evaluation of critical formulation factors in the development of a rapidly dispersing captopril oral dosage form

New methods of manufacture have enabled the creation of novel dosage forms with unique rapid-dispersion properties. This study combines one such technique with a statistical experimental design to develop dosage forms from captopril, an angiotensin-converting enzyme inhibitor used to treat cases of hypertensive emergency. The TheriForm™ process, a novel microfabrication technique, was used to build the dosage forms in a layer-by-layer fashion. Three key formulation factors were chosen for the design of experiments. A modified central composite design (Box-Behnken design) was used to maximize the efficiency of the experiments. A total of 13 distinct formulations were fabricated and tested, using mannitol as the bulk excipient. In addition, three replicates of the center point were tested to assess variability and experimental error. These formulations were tested for speed of dispersion (flash time), active content, hardness, friability, and moisture absorption. Regression analysis was performed to fit data responses to quadratic equations. Excellent dose accuracy (95% to 102% of target) and content uniformity (between 1.03% to 2.84%) were observed from all experimental formulation batches. As expected, the choice of powder additive (maltitol, maltodextrin, polyvinyl pyrrolidone), level of additive (2.5% to 7.5%), and saturation level of the binder liquid (45% to 65%) were all found to be significant factors for the TheriForm process. The regression analysis suggested that a rapidly dispersing dosage form of optimal physical properties would be obtained when a powder mixture of mannitol (97.5%) and maltitol (2.5%) is used at a saturation level of 45%. In conclusion, rapidly dispersing captopril oral dosage forms were successfully fabricated and tested. A wide range of physical properties, flash time, and hardness, were determined experimentally, and the effects of key formulation factors were identified.     

Antecedents and consequences of verbal disagreements during small-group learning.

Investigated controversy in 40 2nd- and 3rd-grade mathematics students in 2 mixed-grade mathematics classes through analysis of dissension episodes. A dissension episode was defined as the interaction that followed a verbal assertion of disagreement about a mathematics answer. Episodes were identified from 32 videotapes of small-group seatwork during a 2-wk unit on time and money. Preserving the group as the unit of analysis, the relation of ability and sex with 4 dissension variables (initiation, participation, demonstrations, and prevailing answers) was examined. The 4 process variables were then related to 2 outcome measures: adjusted achievement and peer nominations of competence. Results show that boys and higher ability students had significantly more prevailing answers and demonstrations. Participation, demonstration, and prevailing answers were positively related to peer competence nominations. Prevailing answer was also positively related to adjusted achievement. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuropsychological sequelae of central nervous system prophylaxis in survivors of childhood acute lymphoblastic leukemia.

We assessed neuropsychologically 106 children with acute lymphoblastic leukemia (ALL) who had all received cranial irradiation for the prevention of central nervous system (CNS) leukemia 1–23 years previously. Children were assessed for adverse late effects of their therapy, using age-appropriate Wechsler measures of overall intellectual ability and supplementary tests. Forty-five siblings near in age to the patients were tested as controls. The patient who had had the most intensive CNS prophylaxis were found to have a WISC-R Full Scale IQ 17 points lower than the sibling control group. Performance IQ was more affected than verbal IQ. The patients were more easily distracted and less able to concentrate. The severity of the aftereffects was related to younger age at the time of CNS prophylaxis and to a higher dose of cranial irradiation but not to time since CNS prophylaxis. CNS prophylaxis using a combination of cranial irradiation and intrathecal methotrexate has lowered the incidence of CNS relapse in childhood ALL but is associated with considerable long-term morbidity in survivors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characteristics of hiding places and the transition to Stage IV performance in object permanence tasks.

Three studies with 53 6–10 mo old infants tested T. G. Bower's (1974, 1975) conjecture that infants' Stage IV object permanence difficulties can be attributed to their interpretation of occlusion as replacement. In Study 1, several types of barriers (upright screen, inverted cup, upright box, cloth) were used in a standard object permanence procedure. Results partially support an order of difficulty predicted by Bower's explanation. Ss were consistently delayed, however, in retrieving objects from inside the upright box. Study 2 investigated the role of previous training and found no effect. When barrier size was varied in Study 3, only the smaller box had the lower successful retrieval rate. Measures of looking and mode of manual search indicated that Ss looked appropriately but did not know how to search inside the small box. An argument is made for standardizing barriers and for measuring looking and searching patterns as well as successful retrieval in object permanence studies. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive task analysis of a complex work domain: a case study

Conducting an analysis of a work domain is a necessary prerequisite for making sound and effective human factors design recommendations. There are several properties of complex work domains which put very strong requirements on the type of analysis methods which can be meaningfully used. Traditional task analysis methods based on observable actions are no longer appropriate. In this paper, we describe a set of methods that we have adopted and have found to be useful in conducting a cognitive task analysis of a complex work domain. From our experience with this particular case study, we have found that it is necessary to adopt a variety of different methods to examine a particular work domain, and use the converging evidence from these several methods to attain a final, comprehensive understanding of that domain.     

Modeling and predicting mental workload in en route air traffic control: critical review and broader implications

OBJECTIVE: We perform a critical review of research on mental workload in en route air traffic control (ATC). We present a model of operator strategic behavior and workload management through which workload can be predicted within ATC and other complex work systems. BACKGROUND: Air traffic volume is increasing worldwide. If air traffic management organizations are to meet future demand safely, better models of controller workload are needed. METHOD: We present the theoretical model and then review investigations of how effectively traffic factors, airspace factors, and operational constraints predict controller workload. RESULTS: Although task demand has a strong relationship with workload, evidence suggests that the relationship depends on the capacity of the controllers to select priorities, manage their cognitive resources, and regulate their own performance. We review research on strategies employed by controllers to minimize the control activity and information-processing requirements of control tasks. CONCLUSION: Controller workload will not be effectively modeled until controllers' strategies for regulating the cognitive impact of task demand have been modeled. APPLICATION: Actual and potential applications of our conclusions include a reorientation of workload modeling in complex work systems to capture the dynamic and adaptive nature of the operator's work. Models based around workload regulation may be more useful in helping management organizations adapt to future control regimens in complex work systems.