Stereological analysis of spherical particles: Experimental assessment and comparison to laser diffraction

Spherical polymer particles in five different size ranges from ∼2 to 200 μm were measured by optical microscopy/image analysis of polished cross sections. From the two-dimensional (2-D) section-size distributions, two stereological techniques were employed to determine the three-dimensional (3-D) particle-size distributions: the classical Schwartz-Saltykov (SS) method, further developed by Takahashi and Suito, and the technique of Harayama, which was applied by Basak and Sengupta (HBS). The objectives of this study were to assess the viability of image analysis and the SS or HBS techniques as quantitative particle analysis methods and to compare them to laser diffraction (LD) of loose powders. It was found that the image analysis/stereology (IA/S) and LD results agreed within about 15 pct over most of the size range studied. Moreover, the IA/S technique accurately estimates experimental particle-size distributions with nonsymmetric or multimodal characteristics. Stereological parameters were studied, such as the number of size classes (histogram step intervals), and methods of displaying the size distributions were compared to develop best practices. The effect of oversight of small particles, which is an area of concern with stereological techniques, was also investigated in terms of changes to the mean and standard deviations of the 3-D particle-size distributions.     

Digital library information-technology infrastructures

This paper charts a research agenda on systems-oriented issues in digital libraries. It focuses on the most central and generic system issues, including system architecture, user-level functionality, and the overall operational environment. With respect to user-level functionality, in particular, it abstracts the overall information lifecycle in digital libraries to five major stages and identifies key research problems that require solution in each stage. Finally, it recommends an explicit set of activities that would help achieve the research goals outlined and identifies several dimensions along which progress of the digital library field can be evaluated.     

A responsive parenting intervention: The optimal timing across early childhood for impacting maternal behaviors and child outcomes.

This study examined the optimal timing (infancy, toddler-preschool, or both) for facilitating responsive parenting and the intervention effects on maternal behaviors and child social and communication skills for children who vary in biological risk. The intervention during infancy, Playing and Learning Strategies (PALS I), showed strong changes in maternal affective-emotional and cognitively responsive behaviors and infants' development. However, it was hypothesized that a 2nd intervention dose in the toddler-preschool period was needed for optimal results. Families from the PALS I phase were rerandomized into either the PALS II, the toddler-preschool phase, or a Developmental Assessment Sessions condition, resulting in 4 groups. Facilitation of maternal warmth occurred best with the PALS I intervention, while cognitive responsive behaviors were best supported with the PALS II intervention. Behaviors that required responsiveness to the child's changing signals (contingent responsiveness, redirecting) required the intervention across both the early and later periods. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Weight-of-evidence evaluation in environmental assessment: Review of qualitative and quantitative approaches

Assessments of human health and ecological risk draw upon multiple types and sources of information, requiring the integration of multiple lines of evidence before conclusions may be reached. Risk assessors often make use of weight-of-evidence (WOE) approaches to perform the integration, whether integrating evidence concerning potential carcinogenicity, toxicity, and exposure from chemicals at a contaminated site, or evaluating processes concerned with habitat loss or modification when managing a natural resource. Historically, assessors have relied upon qualitative WOE approaches, such as professional judgment, or limited quantitative methods, such as direct scoring, to develop conclusions from multiple lines of evidence. Current practice often lacks transparency resulting in risk estimates lacking quantified uncertainty. This paper reviews recent applications of weight of evidence used in human health and ecological risk assessment. Applications are sorted based on whether the approach relies on qualitative and quantitative methods in order to reveal trends in the use of the term weight of evidence, especially as a means to facilitate structured and transparent development of risk conclusions from multiple lines of evidence.     

The effect of limited proteolysis on canola protein gelation

The objective of this study was to improve canola protein gelation properties through limited enzymatic hydrolysis with trypsin, ficin and bromelin either alone or in combination with the cross-linking enzyme transglutaminase (TG). Proteolysis alone was found to reduce gel strength to below that of the control. This was accompanied by a decrease in molecular weight, observable through SDS-PAGE analysis. Micrographs corroborated the rheological data and showed that protease application brought about a loss of structure. In contrast, limited proteolysis was shown to be a suitable pretreatment to cross-linking with TG, a frequently used cross-linking enzyme. Previous research suggests and this study corroborates that opening the protein structure prior to TG treatment, can enhance its effectiveness. Gels, treated with both a protease and TG, were significantly stronger than those treated with TG alone. It was concluded that while limited proteolysis does not improve canola protein gelation on its own, it can significantly improve gelation properties when combined with TG.     

Postnatal Protein Intake as a Determinant of Skeletal Muscle Structure and Function in Mice—A Pilot Study

Sarcopenia is characterised by an age-related decrease in the number of muscle fibres and additional weakening of the remaining fibres, resulting in a reduction in muscle mass and function. Many studies associate poor maternal nutrition during gestation and/or lactation with altered skeletal muscle homeostasis in the offspring and the development of sarcopenia. The aim of this study was to determine whether the musculoskeletal physiology in offspring born to mouse dams fed a low-protein diet during pregnancy was altered and whether any physiological changes could be modulated by the nutritional protein content in early postnatal stages. Thy1-YFP female mice were fed ad libitum on either a normal (20%) or a low-protein (5%) diet. Newborn pups were cross-fostered to different lactating dams (maintained on a 20% or 5% diet) to generate three groups analysed at weaning (21 days): Normal-to-Normal (NN), Normal-to-Low (NL) and Low-to-Normal (LN). Further offspring were maintained ad libitum on the same diet as during lactation until 12 weeks of age, creating another three groups (NNN, NLL, LNN). Mice on a low protein diet postnatally (NL, NLL) exhibited a significant reduction in body and muscle weight persisting up to 12 weeks, unlike mice on a low protein diet only prenatally (LN, LNN). Muscle fibre size was reduced in mice from the NL but not LN group, showing recovery at 12 weeks of age. Muscle force was reduced in NLL mice, concomitant with changes in the NMJ site and changes in atrophy-related and myosin genes. In addition, μCT scans of mouse tibiae at 12 weeks of age revealed changes in bone mass and morphology, resulting in a higher bone mass in the NLL group than the control NNN group. Finally, changes in the expression of miR-133 in the muscle of NLL mice suggest a regulatory role for this microRNA in muscle development in response to postnatal diet changes. Overall, this data shows that a low maternal protein diet and early postnatal life low-protein intake in mice can impact skeletal muscle physiology and function in early life while postnatal low protein diet favours bone integrity in adulthood.     

Deletion of Neuronal CuZnSOD Accelerates Age-Associated Muscle Mitochondria and Calcium Handling Dysfunction That Is Independent of Denervation and Precedes Sarcopenia

Skeletal muscle suffers atrophy and weakness with aging. Denervation, oxidative stress, and mitochondrial dysfunction are all proposed as contributors to age-associated muscle loss, but connections between these factors have not been established. We examined contractility, mitochondrial function, and intracellular calcium transients (ICTs) in muscles of mice throughout the life span to define their sequential relationships. We performed these same measures and analyzed neuromuscular junction (NMJ) morphology in mice with postnatal deletion of neuronal Sod1 (i-mn-Sod1^-/- mice), previously shown to display accelerated age-associated muscle loss and exacerbation of denervation in old age, to test relationships between neuronal redox homeostasis, NMJ degeneration and mitochondrial function. In control mice, the amount and rate of the decrease in mitochondrial NADH during contraction was greater in middle than young age although force was not reduced, suggesting decreased efficiency of NADH utilization prior to the onset of weakness. Declines in both the peak of the ICT and force were observed in old age. Muscles of i-mn-Sod1^-/- mice showed degeneration of mitochondrial and calcium handling functions in middle-age and a decline in force generation to a level not different from the old control mice, with maintenance of NMJ morphology. Together, the findings support the conclusion that muscle mitochondrial function decreases during aging and in response to altered neuronal redox status prior to NMJ deterioration or loss of mass and force suggesting mitochondrial defects contribute to sarcopenia independent of denervation.     

Tuning Compiler Optimizations for Simultaneous Multithreading

Simultaneous Multithreading (SMT) is a processor architectural technique that promises to significantly improve the utilization and performance of modern wide-issue superscalar processors. An SM T processor is capable of issuing multiple instructions from multiple threads to a processor's functional units each cycle. Unlike shared-memory multiprocessors, SMT provides and benefits from fine-grained sharing of processor and memory system resources; unlike current uniprocessors, SMT exposes and benefits from inter-thread instruction-level parallelism when hiding long-latency operations. Compiler optimizations are often driven by specific assumptions about the underlying architecture and implementation of the target machine, particularly for parallel processors. For example, when targeting shared-memory multiprocessors, parallel programs are compiled to minimize sharing, in order to decrease high-cost inter-processor communication. Therefore, optimizations that are appropriate for these conventional machines may be inappropriate for SMT, which can benefit from finegrained resource sharing within the processor. This paper reexamines several compiler optimizations in the context of simultaneous multithreading. We revisit three optimizations in this light: loop-iteration scheduling, software speculative execution, and loop tiling. Our results show that all three optimizations should be applied differently in the context of SMT architectures: threads should be parallelized with a cyclic, rather than a blocked algorithm; non-loop programs should not be software speculated, and compilers no longer need to be concerned about precisely sizing tiles to match cache sizes. By following these new guidelines, compilers can generate code that improves the performance of programs executing on SMT machines.     

Knowledge Discovery in an Oceanographic Database

Knowledge discovery from image data is a multi-step iterative process. This paper describes the procedure we have used to develop a knowledge discovery system that classifies regions of the ocean floor based on textural features extracted from acoustic imagery. The image is subdivided into rectangular cells called texture elements (texels); a gray-level co-occurence matrix (GLCM) is computed for each texel in four directions. Secondary texture features are then computed from the GLCM resulting in a feature vector representation of each texel instance. Alternatively, a region-growing approach is used to identify irregularly shaped regions of varying size which have a homogenous texture and for which the texture features are computed. The Bayesian classifier Autoclass is used to cluster the instances. Feature extraction is one of the major tasks in knowledge discovery from images. The initial goal of this research was to identify regions of the image characterized by sand waves. Experiments were designed to use expert judgements to select the most effective set of features, to identify the best texel size, and to determine the number of meaningful classes in the data. The region-growing approach has proven to be more successful than the texel-based approach. This method provides a fast and accurate method for identifying provinces in the ocean floor of interest to geologists.