Exploring the structure of a neuropsychological battery across healthy elders and those with questionable dementia and Alzheimer's disease.

An exploratory factor analysis (EFA) and a series of confirmatory factor analyses were conducted on 17 variables designed to assess different cognitive abilities in a sample of healthy older adults. In the EFA, 4 factors emerged corresponding to language, memory, processing speed, and fluid ability constructs. The results of the confirmatory factor analyses suggested that a 5-factor model with an additional Attention factor improved the fit. The invariance of the 5-factor model was examined across 3 groups: a group of cognitively healthy older adults, a group of patients diagnosed with questionable dementia (QD), and a group of patients diagnosed with probable Alzheimer's disease (AD). Results of the invariance analysis suggest that the model may have configural invariance across the 3 groups but not metric invariance. Specifically, preliminary analyses suggest that the memory construct may represent something different in the QD and AD groups as compared to the healthy older adult group, consistent with the underlying pathology in early AD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do neuropsychological tests have the same meaning in Spanish speakers as they do in English speakers?

Objective: The purpose of this study was to examine whether neuropsychological tests translated into Spanish measure the same cognitive constructs as the original English versions. Method: Older adult participants (N = 2,664), who did not exhibit dementia from the Washington Heights Inwood Columbia Aging Project (WHICAP), a community-based cohort from northern Manhattan, were evaluated with a comprehensive neuropsychological battery. The study cohort includes both English (n = 1,800) and Spanish speakers (n = 864) evaluated in their language of preference. Invariance analyses were conducted across language groups on a structural equation model comprising four neuropsychological factors (memory, language, visual-spatial ability, and processing speed). Results: The results of the analyses indicated that the four-factor model exhibited partial measurement invariance, demonstrated by invariant factor structure and factor loadings but nonequivalent observed score intercepts. Conclusion: The finding of invariant factor structure and factor loadings provides empirical evidence to support the implicit assumption that scores on neuropsychological tests are measuring equivalent psychological traits across these two language groups. At the structural level, the model exhibited invariant factor variances and covariances. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is There Anything Special About the Aging of Source Memory?

A battery of cognitive tests designed to measure the constructs of episodic memory, perceptual speed, fluid ability, executive functioning, and vocabulary was administered to 330 adults between the ages of 18 and 89. Each participant also performed 4 different tasks designed to assess source memory. Structural equation modeling was used to evaluate the validity of a source-memory construct and to explore the relation of the source-memory construct to age and to the other cognitive variables. The variance common to the source-memory variables was strongly related to other cognitive abilities, suggesting that source memory may not have discriminant validity, and there were only small unique age-related effects on the source-memory construct after the influence of other abilities was considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A mixed method approach to examining Facebook use and its relationship to self-esteem

The current study examined the relationship between self-esteem and Facebook use in sample of college-age participants (N = 201). Online methods were used to collect data. Consistent with the social compensation hypothesis, results indicate that self-esteem level was related to engaging in different on-line behaviors. For example, lower self-esteem was associated with feelings of connectedness to Facebook, more frequently untagging oneself in photos, and accepting friend requests from individuals that one does not know well. Qualitative analyses indicated that individuals with higher self-esteem were more likely to report that a positive aspect of Facebook was the ability to share pictures, thoughts, and ideas, and to report that other posts could become annoying or bothersome.     

Investigating the structure and age invariance of episodic memory across the adult lifespan.

The structure of episodic memory was investigated by assessing different modalities of material (verbal, figural, and spatial) and different types of tests (recall, cued recall, and recognition). A 3-factor model that distinguished among modalities of material was found to be the best representation of memory and the verbal, figural, and spatial memory factors exhibiting construct validity. This 3-factor modality of material model also demonstrated configural, metric, and structural age invariance across a sample of adults (N = 327) between the ages of 18 and 94. There was evidence that latent constructs corresponding to recall, cued recall, and recognition could be distinguished from one another within the verbal domain but not within the figural and spatial domains. A mediation model examining the retrieval constructs was examined within the verbal domain, and there were unique age-related influences on cued recall and recall performance. This result is consistent with findings that increased age is associated with increased difficulty in retrieving information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Young children's acquisition of the movement aspect in American Sign Language: parental report findings

The acquisition of the movement aspect of American Sign Language signs was examined longitudinally in 9 young children of deaf parents. During monthly home visits, the parents demonstrated on videotape how their children formed the different signs in their lexicons. The parents also demonstrated how they formed or modeled these same signs. Overall, the children correctly produced 61.4% of the movements that were present in the adult sign models. Although the production accuracy of the movement aspect of signs did not improve over the course of the study, the number and complexity of movements produced by the children did increase as they got older and their vocabularies grew in size. Of the different sign movements, contacting action was by far the most frequently produced. The children were also relatively successful in their production of closing action and downward movement. The order of acquisition for the remaining ASL movements, however, was quite variable, with the exception that bidirectional movements tended to be produced more accurately than unidirectional movements. The relationship between children's early rhythmical motor behaviors and the development of sign movements is discussed.     

Short communication: Antimicrobial susceptibility profiling and genotyping of Staphylococcus aureus isolates from bovine mastitis in Poland

Staphylococcus aureus is the predominant causative agent of bovine mastitis, a disease that remains a major economic burden for the dairy industry worldwide. In this study, the antimicrobial resistance patterns and the genetic composition of 80 S. aureus mastitis isolates collected from 14 dairy farms in Eastern Poland were determined. Of the 10 antimicrobial agents evaluated, only testing for penicillin G produced drug resistance. As 41% of the S. aureus isolates were penicillin resistant, this drug along with other β-lactamase-sensitive β-lactams, should rather not be considered for the treatment of bovine mastitis caused by S. aureus. Upon genotyping, with a triplex PCR method, a total of 11 distinct PCR types were produced. The population structure of S. aureus isolates was highly clonal, with 1 predominant genotype circulating on each farm. The observed similarities in the genotype composition of S. aureus populations from geographically distant farms underscore the significance of interfarm transmission of S. aureus in Poland. This, in turn, argues for the establishment of a nationwide surveillance program for bovine mastitis due to this pathogen.     

Biomass gasification as the first hot step in clean syngas production process – gas quality optimization and primary tar reduction measures in a 100 kW thermal input steam–oxygen blown CFB gasifier

Syngas production based on biomass gasification is an attractive, feasible alternative to fossil fuel feedstock for the production of transportation fuels. However, the product gas from biomass gasification must be cleaned and tailored to comply with strict syngas quality requirements, as it consists of a wide variety of major and minor components and impurities. The characterization of such species is important to determine downstream gas treatment steps, and to assess the efficiency of the gasification process.This paper gives an overview of the results obtained during experiments on steam–oxygen gasification of biomass using 100 kW maximal thermal input circulating fluidized bed gasifier (CFBG) that have been performed at Delft University of Technology during the CHRISGAS project. The unit is also equipped with a high-temperature ceramic gas filter and downstream reactors for upgrading of the gas.In the experiments biomass types of both woody and agricultural origin have been used. They were represented by clean wood, demolition wood, an energy crop species (miscanthus) and a true residue (Dutch straw), respectively. Moreover, different bed materials have been applied, namely quartz sand, treated and untreated olivine and magnesite. During the experiments extensive measurements of gas composition have been carried out throughout the integrated test rig. The gas characterization included major gas components as well as certain minor species and tar.The results show that with the use of magnesite as bed material, remarkable increases of hydrogen yield were attained, as compared to sand or olivine; up to a volume fraction of almost 40% (dry, nitrogen-free basis). Also the H₂:CO ratio increased from values near or lower than 1 to 2.3–2.6. This is near the values needed, for e.g., Fischer–Tropsch diesel production, indicating a potential for simplification of the gas upgrading. Furthermore, by using magnesite tar content of the raw gas was reduced to values near 2 g m^?3 (STP). Moreover, magnesite complied with the expectation to have a positive impact on agglomeration prevention for the agricultural fuels containing alkali and chlorine in the ash. The kind of olivine applied during the experiments did not yield the expected tar reduction; the measured tar concentration was even higher than when quartz sand was used as bed material. Finally kaolin proved to be an effective additive to counteract the agglomeration when fuels with high alkali content in the ash are gasified using bed material that is rich in silica, as it is the case with quartz sand and olivine.     

Dynamic changes in corneal topography and its influence on the point-spread function of the eye

The dynamic changes of the anterior surface of the eye are investigated. A Twyman-Green interferometer is used to record topographic images at 40 ms intervals. A method of analysis of the dynamic changes in topography by use of Zernike polynomials enables a general distinction to be made between dynamic alterations in the shape of the cornea itself and the changes in the layer of the tears. The influence of deviations in the shape of the anterior surface of the eye on the retinal image is estimated.