Oblique Flow over Dredged Channels.?I: Flow Description

A 3D investigation of flow across long, straight channels aligned obliquely to the flow direction has been conducted. The applied mathematical model solves the Reynolds-averaged Navier-Stokes equations using a k-ε model for turbulence closure in a curvilinear coordinate system. The uniformity along the channel alignment allows the three momentum equations to be solved in a 2D computational domain. With respect to a steady current entering a channel obliquely, two important flow features arise: (1) The flow will be refracted in the direction of the channel alignment, which may be described by depth-averaged models; and (2) a secondary flow will be introduced due to shear in the velocity profile. This can only be described using a 3D approach. The secondary flow will cause a horizontal deflection of streamlines over the vertical. Only by capturing the 3D flow behavior can the direction and magnitude of the bed shear stress be well modeled. When crossing a channel obliquely, the flow is gradually accelerated in the direction of the channel alignment. Results of the numerical flow model are compared with existing experimental data and good agreement is found.     

Reading strategies for children and adults: A quantitative model.

Developed an additive model to account for reading times for 2 different reading tasks (reading for retention and reading for comprehension). The reading strategies of 48 college students and 64 5th graders and individual differences between fast and slow readers were examined. Ss were assumed to have processors that handle the lexical, structural, and meaning information in sentences. The various task, age, and reading speed groups were hypothesized to use the 3 processors for differing amounts of time. The model was supported by word-by-word reading times for 80 sentences and by 9 empirical indices of lexical, structural, and meaning attributes of text. Results show that for skilled adult Ss, relatively more time was spent processing structure in the retention task, and meaning in the comprehension task. Fifth graders had not fully mastered the connection between task demands and linguistic processors shown by adults, and thus used mixtures of the adult strategies. (101 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Seasonal vitamin D intake in Quebec preschoolers.

As a number of seasonal factors affect cutaneous synthesis of vitamin D, especially in young children, our objective was to verify if winter and summer vitamin D intakes in Quebec preschoolers reach the adequate intake of 5 microg/day. A three-month retrospective food frequency questionnaire and a 24-hour food recall were used with parents of 98 children (mean age 56 months) in summer and of 72 of these children (mean age 65 months) in winter. To ensure completeness of data, vitamin D content of foods not covered in the Canadian Nutrient File was taken from other sources. According to the food frequency questionnaire, total vitamin D intakes were 9.7 +/- 4.3 microg/day in summer and 11.6 +/- 4.8 microg/day in winter. Only 10% of children in summer and 7% in winter had an intake below 5 microg/day. The 24-hour food recall vitamin D intake estimate was lower (summer 7.0 +/- 3.8 microg/day, winter 7.2 +/- 4.2 microg/day). This difference could be partly due to a discrepancy in the estimation of multivitamin supplement intake. However, according to both estimates, vitamin D intakes appeared generally adequate in this sample of Quebec preschoolers.     

Potential of cognitive plasticity as a diagnostic instrument: A cross-validation and extension.

Examination of the range and limits of cognitive developmental reserve capacity (plasticity) by means of cognitive training has been proffered as a promising diagnostic strategy for the early identification of Alzheimer's disease. Previous findings of differential gains after cognitive training for healthy older persons and older persons at risk for dementia were supported, rendering cognitive plasticity a criterion by which the overlap in performance distributions between healthy older persons and older persons at risk can be reduced. Stepwise hierarchical regression analyses demonstrated that posttraining scores, which represented developmental reserve capacity, explained significantly more variance in mental health status than pretest or baseline performance. Older persons at risk profited significantly less from training in 2 components of fluid intelligence, figural relations, and inductive reasoning. The authors discuss the possibilities of turning this testing-the-limits procedure into an instrument for screening purposes in clinical practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of dietary fatty acids on the glycerophospholipid composition in organs of cod (gadus morhua)

Cod (mean start weight of 26 g) were fed three diets for 15 months, each based on a dry pellet coated at a level of 9g/100 g with soybean oil, capelin oil or sardine oil. The fatty acid compositions of neutral lipids and four glycerophospholipids of white muscle, liver, gills and heart were determined. The fatty acid composition of dietary lipids influenced the composition of neutral lipids in all organs. Linoleic acid (18∶2n−6) from soybean oil was selectively incorporated into phosphatidylcholine of the four tissues. Similar levels of 20∶5n−3 and 22∶6n−3 in phosphatidylcholine and phosphatidylethanolamine were found in all organs from cod fed capelin oil and sardine oil in spite of highly differentiated feed fatty acid levels. The polyunsaturated fatty acid (PUFA) composition of phosphatidylinositol was least influenced by dietary lipids. The preferred monoenic fatty acid in phospholipids of cod was 18∶1n−9, independent of dietary intake, whereas the longer chain monoenoic acids seemed to be preferentially catabolized. The results suggest that 20∶4n−6 as well as 20∶5n−3 and 22∶6n−3 fatty acids are essential for cod.     

Micro–macro interactions and effect of section thickness of hpdc AZ91 Mg alloy

This work is aimed to conclude the effect of section thickness of a high pressure die cast (hpdc) Mg alloy on the tensile properties as ambiguous conclusions are presented in the literature. Tensile tests were performed on as-cast hpdc AZ91 alloy and the effect of section thickness on the tensile properties such as yield strength (YS), ultimate tensile strength (UTS), ductility and fracture strain (FS) are explained. Additionally, explanation on the microfailure mode of the material is presented to explain the influence of different microfeatures on the failure process. The average size, area fraction and clustering tendency of pores and Mg₁₇Al₁₂ (β) particles as well as average grain size are quantified and their effects on section thickness are obtained. The results confirm that the UTS, YS, ductility and FS are mainly influenced by the area fraction, size distribution and spatial arrangement of pores and phases.     

Perspectives on an internship: The passages of training directors during the internship year.

Proposes a model to explain the transitions experienced by training directors during an internship year. Six transitions are identified, including courting, bonding, rapprochement, mentoring, launching, and reunion, and the particular behaviors and events that signal each passage are described. These transitions are contrasted with those often experienced by interns. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)