The effect of hyperosmotic treatment on the functioning of ampullary electroreceptor organs

The condition of the microvilli of the apical membrane in ampullary electroreceptor organs of the freshwater catfish, Ictalurus nebulosus, was manipulated by administration of hyperosmotic solutions (500 mM) in order to investigate to what extent the apical surface area determines the sensitivity and the shape of the frequency curves. Electrophysiological recordings demonstrated that hyperosmotic sucrose and glucose solutions reduce the sensitivity by 80%, and alter the shape of the frequency curves. The synaptic delay and the average spontaneous activity remained almost unchanged. Calculations with an equivalent electric circuit of an electroreceptor cell indicate that a reduction in apical surface area can account for these effects. Apparently, the sensitivity and the frequency curves in ampullary organs in freshwater catfish depend on the apical surface area. A hyperosmotic urea solution proved to be less suitable to investigate the effect of manipulations of the apical surface area. The almost total loss in sensitivity caused by administration of urea is caused by both shunting of the stimulus by leaky tight junctions and a reduced synaptic efficacy. The repetitive activity observed after exposure to glucose or sucrose must be attributed to malfunctioning of postsynaptic parts of the receptor organ.     

Self-assembly route for photonic crystals with a bandgap in the visible region

Three-dimensional photonic crystals, or periodic materials, that do not allow the propagation of photons in all directions with a wavelength in the visible region have not been experimentally fabricated, despite there being several potential structures and the interesting applications and physics that this would lead to. We show using computer simulations that two structures that would enable a bandgap in the visible region, diamond and pyrochlore, can be self-assembled in one crystal structure from a binary colloidal dispersion. In our approach, these two structures are obtained as the large (Mg) and small (Cu) sphere components of the colloidal analogue of the MgCu(2) Laves phase, whose growth can be selected and directed using appropriate wall patterning. The method requires that the particles consist of different materials, so that one of them can be removed selectively after drying (for example, by burning or dissolution). Photonic calculations show that gaps appear at relatively low frequencies indicating that they are robust and open for modest contrast, enabling fabrication from more materials.     

Relative validation of a food frequency questionnaire for national health and nutrition monitoring

Background  

Validation of a food frequency questionnaire (FFQ) is important as incorrect information may lead to biased associations. Therefore the relative validity of an FFQ developed for use in the German Health Examination Survey for Adults 2008-2011 (DEGS) was examined.     

The effects of Project Management Information Systems on decision making in a multi project environment

Project Management Information Systems (PMIS) should provide project managers with decision making support for planning, organizing and controlling projects. Most project managers are dissatisfied with the information produced by PMIS. Based on a survey among 101 project managers the interactions between six factors related to PMIS information quality and usage and their effect on decision making are examined in a multi project environment. Using structural equation modeling, new insights were gained in these complex relationships. Results indicate that the use of a project management information system is advantageous to project managers, while no adverse effects were observed due to project and information overload. PMIS information quality is positively related to quality of the decisions, satisfaction of project managers with PMIS and use of PMIS information. Simultaneous handling of multiple projects causes project managers to extend conclusions about the information quality for one project to all projects at hand.     

Speed choice and mental workload of elderly cyclists on e-bikes in simple and complex traffic situations: A field experiment

To study the speed choice and mental workload of elderly cyclists on electrical assisted bicycles (e-bikes) in simple and complex traffic situations compared to these on conventional bicycles, a field experiment was conducted using two instrumented bicycles. These bicycles were identical except for the electric pedal support system. Two groups were compared: elderly cyclists (65 years of age and older) and a reference group of cyclists in middle adulthood (between 30 and 45 years of age). Participants rode a fixed route with a length of approximately 3.5 km on both bicycles in counterbalanced order. The route consisted of secluded bicycle paths and roads in a residential area where cyclist have to share the road with motorized traffic. The straight sections on secluded bicycle paths were classified as simple traffic situations and the intersections in the residential area where participants had to turn left, as complex traffic situations. Speed and mental workload were measured. For the assessment of mental workload the peripheral detection task (PDT) was applied. In simple traffic situations the elderly cyclists rode an average 3.6 km/h faster on the e-bike than on the conventional bicycle. However, in complex traffic situations they rode an average only 1.7 km/h faster on the e-bike than on the conventional bicycle. Except for the fact that the cyclists in middle adulthood rode an average approximately 2.6 km/h faster on both bicycle types and in both traffic conditions, their speed patterns were very similar. The speed of the elderly cyclists on an e-bike was approximately the speed of the cyclists in middle adulthood on a conventional bicycle. For the elderly cyclist and the cyclists in middle adulthood, mental workload did not differ between bicycle type. For both groups, the mental workload was higher in complex traffic situations than in simple traffic situations. Mental workload of the elderly cyclists was somewhat higher than the mental workload of the cyclists in middle adulthood. The relatively high speed of the elderly cyclists on e-bikes in complex traffic situations and their relatively high mental workload in these situations may increase the accident risk of elderly cyclist when they ride on an e-bike.     

Integration of the Big Five and circumplex approaches to trait structure.

To integrate the 5-dimensional simple-structure and circumplex models of personality, the Abridged Big Five Dimensional Circumplex (AB5C) taxonomy of personality traits was developed, consisting of the 10 circumplexes that can be formed by pitting each of the Big Five factors against one another. The model maps facets of the Big Five dimensions as blends of 2 factors. An application to data consisting of 636 self-ratings and peer ratings on 540 personality trait adjectives yielded 34 well-defined facets out of a possible 45. The AB5C solution is compared with simple-structure and lower dimensional circumplex solutions, and its integrative and corrective potential are discussed, as well as its limitations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hierarchical self-assembly of suspended branched colloidal nanocrystals into superlattice structures

Self-assembly of molecular units into complex and functional superstructures is ubiquitous in biology. The number of superstructures realized by self-assembly of man-made nanoscale units is also growing. However, assemblies of colloidal inorganic nanocrystals are still at an elementary level, not only because of the simplicity of the shape of the nanocrystal building blocks and their interactions, but also because of the poor control over these parameters in the fabrication of more elaborate nanocrystals. Here, we show how monodisperse colloidal octapod-shaped nanocrystals self-assemble, in a suitable solution environment, on two sequential levels. First, linear chains of interlocked octapods are formed, and subsequently the chains spontaneously self-assemble into three-dimensional superstructures. Remarkably, all the instructions for the hierarchical self-assembly are encoded in the octapod shape. The mechanical strength of these superstructures is improved by welding the constituent nanocrystals together.     

The impact of childhood experiences and family members outside the household on residential environment choices

Choices of urban, suburban or rural residential environments have often been studied from a life-course perspective. In this paper, an examination is made of the influence of childhood experiences and of residential environment choices of family members outside the household. It is argued that socialisation, location-specific capital and the wish to maintain close family ties may result in living in a similar residential environment later in life and in similar environments to siblings and parents. Results of multinomial logistic regression analyses of data from the Netherlands Kinship Panel Study show that the residential environment during childhood is indeed strongly associated with the current residential environment. Moreover, individuals show a strong similarity to their parents and siblings in their residential environment, even after accounting for residential inertia and return migration.     

The substantive nature of psycholexical personality factors: A comparison across languages.

The psycholexical approach to personality structure in American English has led to the Big Five factors. The present study considers whether this result is similar or different in other languages. Instead of placing the usual emphasis on quantitative indices, this study examines the substantive nature of the factors. Six studies in European languages were used to develop a taxonomy of content categories. The English translations of the relevant terms were then classified under this taxonomy. The results support the generality of Big Five Factor III (Conscientiousness). Factors IV (Emotional Stability) and V (Intellect) generally did not cohere. Factors I (Extraversion) and II (Agreeableness) tended to split when this was necessary to produce 5 factors. The analysis was extended to several additional studies. (PsycINFO Database Record (c) 2011 APA, all rights reserved)