Three-Dimensional Ultrasonic Crack Detection in Anisotropic Materials

The scattering of probe-generated ultrasonic fields incident upon a strip-like crack in an anisotropic half-space is discussed. In the situation considered, two possibly coinciding probes are attached to the surface of the half-space. One is transmitting waves incident upon the crack and the other one is receiving the scattered waves. An electric signal response is calculated via an electromechanical reciprocity relation. For a crack far away from the probes and the surface, an approximate expression is calculated. Several numerical examples are presented for an isotropic and a transversely isotropic solid. The results are presented as A-, B-, and C-scans.     

Enhanced incorporation of n−3 fatty acids from fish compared with fish oils

This work was undertaken to study the impact of the source of n−3 FA on their incorporation in serum, on blood lipid composition, and on cellular activation. A clinical trial comprising 71 volunteers, divided into five groups, was performed. Three groups were given 400 g smoked salmon (n=14), cooked salmon (n=15), or cooked cod (n=13) per week for 8 wk. A fourth group was given 15 mL/d of cod liver oil (CLO) (n=15), and a fifth group served as control (n=14) without supplementation. The serum content of EPA and DHA before and after intervention revealed a higher rise in EPA and DHA in the cooked salmon group (129% rise in EPA and 45% rise in DHA) as compared with CLO (106 and 25%, respectively) despite an intake of EPA and DHA in the CLO group of 3.0 g/d compared with 1.2 g/d in the cooked salmon group. No significant changes were observed in blood lipids, fibrinogen, fibrinolysis, or lipopolysaccharide (LPS)-induced tissue factor (TF) activity, tumor necrosis factor-α (TNFα), interleukin-8 (IL-8), leukotriene B₄ (LTB₄), and thromboxane B₂ (TxB₂) in whole blood. EPA and DHA were negatively correlated with LPS-induced TNFα, IL-8, LTB₄, TxB₂, and TF in whole blood. In conclusion, fish consumption is more effective in increasing serum EPA and DHA than supplementing the diet with fish oil. Since the n−3 FA are predominantly in TAG in fish as well as CLO, it is suggested that the larger uptake from fish than CLO is due to differences in physiochemical structure of the lipids.     

Is it time to use activity-based urban transport models? A discussion of planning needs and modelling possibilities

For some decades now, transport researchers have put considerable efforts into developing what is called activity-based approaches for modelling urban travel demand. The basic idea is that travel demand is derived from people’s desires to take part in different activities. In particular, the interrelationships among different activities with respect to temporal and spatial constraints are in focus. It means that such models treat the activities and the travelling of the households with respect to where and when the activities can be carried out and how they may be scheduled, given characteristics of the households and potential opportunities, the transport networks and various institutional constraints. We discuss what demands we see on future travel demand models, with a focus on urban analysis. This discussion is somewhat biased towards what role activity-based models could play in meeting these demands. We then review in some detail three prominent and distinctly different representatives of operational activity-based models to give an indication of what new modelling possibilities they offer. Theoretical appeal, empirical validity, usefulness for planning, need for data and easiness of implementation are discussed. In the final section we draw some conclusions about the prospects of these models and of their descendants.     

Organic and minerogenic acidity in Finnish rivers in relation to land use and deposition

The role of organic and minerogenic acidity in controlling pH levels in Finnish rivers was studied by measuring total organic carbon (TOC) and non-marine sulphate (*SO(4)) concentrations in river water of the main river basins and their sub-basins. The basins are located along a latitudinal gradient (60 degrees N to 69 degrees N) and cover 297,322 km(2), 88% of the total area of Finland. The basins are predominately covered by coniferous forests and peatlands, and are located in areas with low sulphate deposition (80-430 mg S m(-2) a(-1)). The proportion of the basin covered by forests on mineral soils ranges from 29 to 64% and the proportion of peatlands from 3 to 60%. The percentage of peatland is highest in northern Finland (28-60%), whereas the proportion of forests on mineral soils increases towards the south. The majority of the agricultural land is located in southern and western Finland. *SO(4) concentrations were positively correlated with the proportion of agricultural land in the basin. Moreover, the percentage of peatlands had a positive correlation with the concentrations of TOC and organic anion. High peatland proportion and high TOC and organic anion concentrations decreased pH values in the river water, whereas no correlation between *SO(4) concentrations and pH was observed. The average organic anion concentration exceeded the average *SO(4) concentration in river water in 17 basins out of the 86 studied basins. The organic anion-dominated areas were situated in northern basins, reflecting the high extent of peatlands in these areas. *SO(4) dominated in southern Finland and in western coastal areas, where the extent of agricultural land, acid sulphate soils and the deposition of sulphate is highest.     

Proximity,accessibility and choice: A matter of taste or condition?*

Drawing on a combination of register data and travel survey data, this research explores changes in the accessibility to different amenities for the Swedish population between 1995 and 2005, as well as the reasons behind the changes: redistribution of either amenities or the population. Overall, proximity has increased concerning most of the amenities during the period. However, despite decreasing ‘potential’ distances, actual travel distances are growing longer due to, for example, an increasing selectivity in preferences. An analysis of the accessibility development for service amenities shows that restructuring within the service sector is the main cause of the changes, and to a lesser extent population redistribution. Resumen. Haciendo uso de una combinación de datos de registros y encuestas de viajes, este estudio explora cambios en la accesibilidad de diferentes servicios y lugares de recreo para la población sueca entre 1995 y 2005, así como las razones detrás de dichos cambios: una redistribución de los servicios o de la población. En conjunto, la proximidad ha aumentado con respecto a la mayoría de los servicios durante el periodo estudiado. Sin embargo, a pesar de las reducciones en distancias “potenciales”, las distancias de viaje están aumentando debido a por ejemplo una mayor selectividad en las preferencias. Un análisis del desarrollo de la accesibilidad de servicios y ocio muestra que la reestructuración dentro del sector servicios es la causa principal de los cambios y, en menor medida, la redistribución de la población.      

Alkyl polyglucosides as hydrotropes

The hydrotropic effect of different alkyl polyglucosides (APG) has been studied and compared with a model hydrotrope, toluol-4-sulfonic acid. The effect has been assessed by two different methods: (i) as the cloud point elevation of a solution containing different nonionic surfactants upon addition of the hydrotrope and (ii) the destabilization of liquid crystaline phases in a ternary system. The effect of the hydrophobic alkyl group length was found to be opposite in the two methods. APG with intermediate alkyl chain lengths (octyl and decyl) was shown to be very effective in elevating the cloud point, while APG with a short (butyl) group was the most efficient in destabilizing liquid crystalline phases in the system of water, sodium dodecyl sulfate and pentanol. Effects on phase behavior and cloud point elevation with addition of an APG are highly dependent on its structure. However, the correlation between structural effects, as observed in the two methods requires further study.     

Dielectrophoresis-induced separation of metallic and semiconducting single-wall carbon nanotubes in a continuous flow microfluidic system

The AC dielectrophoresis-induced separation of metallic and semiconducting single-wall carbon nanotubes has been carried out in a continuous flow microfluidic system with isolated electrodes. The separation has been studied for single-wall carbon nanotube aqueous suspensions with ionic (sodium dodecylsulphate) and non-ionic (TritonX-100) surfactants. The efficiency of separation has been determined with the help of resonant Raman spectroscopy using various excitation energies. The prototype microfluidic cell presently shows somewhat inferior separation efficiency with respect to static dielectrophoretic filtering on arrays of microelectrodes but has potential for improvements. Factors influencing the separation efficiency and scaling up of the process are discussed.     

Dimensions of teacher self-efficacy and relations with strain factors, perceived collective teacher efficacy, and teacher burnout.

In this study, the authors developed and factor analyzed the Norwegian Teacher Self-Efficacy Scale. They also examined relations among teacher self-efficacy, perceived collective teacher efficacy, external control (teachers' general beliefs about limitations to what can be achieved through education), strain factors, and teacher burnout. Participants were 244 elementary and middle school teachers. The analysis supported the conceptualization of teacher self-efficacy as a multidimensional construct. They found strong support for 6 separate but correlated dimensions of teacher self-efficacy, which were included in the following subscales: Instruction, Adapting Education to Individual Students' Needs, Motivating Students, Keeping Discipline, Cooperating With Colleagues and Parents, and Coping With Changes and Challenges. They also found support for a strong 2nd-order self-efficacy factor underlying the 6 dimensions. Teacher self-efficacy was conceptually distinguished from perceived collective teacher efficacy and external control. Teacher self-efficacy was strongly related to collective teacher efficacy and teacher burnout. (PsycINFO Database Record (c) 2010 APA, all rights reserved)