890 resultados para CMOS voltage reference
Resumo:
Voltage-dependent anion channels (VDAC) are pore-forming proteins found in the outer mitochondrial membrane of eukaryotes. VDACs are known to play an essential role in cellular metabolism and in early stages of apoptosis. In mammals, three VDAC isoforms have been identified. A proteomic approach was exploited to study the expression of VDAC isoforms in rat, bovine, and chicken brain mitochondria. Given the importance of mitochondrially bound hexokinase in regulation of aerobic glycolysis in brain, we studied the possibility that differences in the relative expression of VDAC isoforms may be a factor in determining the species-dependent ratio of type A/type B hexokinase binding sites on brain mitochondria. The spots were characterized, and the signal intensities among spots were compared. VDAC1 was the most abundantly expressed of the three isoforms. Moreover the expression of VDAC1 plus VDAC2 was significantly higher in bovine than in rat brain. Chicken brain mitochondria showed the highest VDAC1 expression and the lowest of VDAC2. Bovine brain mitochondria had the highest VDAC2 levels. We concluded that the nature of hexokinase binding site is not determined by the expression of a single VDAC isoform.
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New data on floral morphology, development, and vasculature in two Brazilian genera of the monocot family Velloziaceae (Pandanales) are used to explore the homologies of their unusual floral structures, especially the corona of Barbacenia and the corona-like appendages and multiple stamens of some Vellozia species. All Velloziaceae have epigynous flowers. Some species of Vellozia are polyandrous, and stamen number can be variable within species. In Vellozia jolyi, there is a single stamen opposite each sepal and a stamen fascicle (of three secondary stamens) opposite each petal. Each stamen possesses a single vascular bundle, and these are united into a single aggregate bundle in proximal regions of the fascicle. Stamens mature centripetally within each fascicle. The coronal appendages of both genera are closely associated with the stamens, but they share some vasculature with the tepals and develop late in ontogeny. The coronal organs cannot readily be homologized with any of the typical floral organs, but they show partial homology with both tepals and stamens. They are most readily interpreted as a late elaboration of the region between the petals and stamens associated with epigyny and the hypanthium.
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Broad-scale phylogenetic analyses of the angiosperms and of the Asteridae have failed to confidently resolve relationships among the major lineages of the campanulid Asteridae (i.e., the euasterid II of APG II, 2003). To address this problem we assembled presently available sequences for a core set of 50 taxa, representing the diversity of the four largest lineages (Apiales, Aquifoliales, Asterales, Dipsacales) as well as the smaller ""unplaced"" groups (e.g., Bruniaceae, Paracryphiaceae, Columelliaceae). We constructed four data matrices for phylogenetic analysis: a chloroplast coding matrix (atpB, matK, ndhF, rbcL), a chloroplast non-coding matrix (rps16 intron, trnT-F region, trnV-atpE IGS), a combined chloroplast dataset (all seven chloroplast regions), and a combined genome matrix (seven chloroplast regions plus 18S and 26S rDNA). Bayesian analyses of these datasets using mixed substitution models produced often well-resolved and supported trees. Consistent with more weakly supported results from previous studies, our analyses support the monophyly of the four major clades and the relationships among them. Most importantly, Asterales are inferred to be sister to a clade containing Apiales and Dipsacales. Paracryphiaceae is consistently placed sister to the Dipsacales. However, the exact relationships of Bruniaceae, Columelliaceae, and an Escallonia clade depended upon the dataset. Areas of poor resolution in combined analyses may be partly explained by conflict between the coding and non-coding data partitions. We discuss the implications of these results for our understanding of campanulid phylogeny and evolution, paying special attention to how our findings bear on character evolution and biogeography in Dipsacales.
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Reusable and evolvable Software Engineering Environments (SEES) are essential to software production and have increasingly become a need. In another perspective, software architectures and reference architectures have played a significant role in determining the success of software systems. In this paper we present a reference architecture for SEEs, named RefASSET, which is based on concepts coming from the aspect-oriented approach. This architecture is specialized to the software testing domain and the development of tools for that domain is discussed. This and other case studies have pointed out that the use of aspects in RefASSET provides a better Separation of Concerns, resulting in reusable and evolvable SEEs. (C) 2011 Elsevier Inc. All rights reserved.
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Objectives. A large-scale survey of doses to patients undergoing the most frequent radiological examinations was carried out in health services in Sao Paulo (347 radiological examinations per 1 000 inhabitants), the most populous Brazilian state. Methods. A postal dosimetric kit with thermoluminescence dosimeters was used to evaluate the entrance surface dose (ESD) to patients. A stratified sampling technique applied to the national health database furnished important data on the distribution of equipment and the annual number of examinations. Chest, head (skull and sinus), and spine (cervical, thoracic, and lumbar) examinations were included in the trial. A total of 83 rooms and 868 patients were included, and 1 415 values of ESD were measured. Results. The data show large coefficients of variation in tube charge, giving rise to large variations in ESD values. Also, a series of high ESD values associated with unnecessary localizing fluoroscopy were detected. Diagnostic reference levels were determined, based on the 75th percentile (third quartile) of the ESD distributions. For adult patients, the diagnostic reference levels achieved are very similar to those obtained in international surveys. However, the situation is different for pediatric patients: the ESD values found in this survey are twice as large as the international recommendations for chest radiographs of children. Conclusions. Despite the reduced number of ESD values and rooms for the pediatric patient group, it is recommended that practices in chest examinations be revised and that specific national reference doses and image quality be established after a broader survey is carried out.
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Commonly used in archaeological contexts, micromorphology did not see a parallel advance in the field of experimental archaeology. Drawing from early work conducted in the 1990`s on ethnohistoric sites in the Beagle Channel, we analyze a set of 25 thin sections taken from control features and experimental tests. The control features include animal pathways and environmental contexts (beach samples, forest litter, soils from the proximities of archaeological sites), while the experimental samples comprise anthropic structures, such as hearths, and valves of Mytilus edulis (the most important component of shell middens in the region) heated from 200 degrees C to 800 degrees C. Their micromorphological study constitutes a modern analogue to assist archaeologists studying site formation and ethnographical settings in cold climates, with particular emphasis on shell midden contexts. (c) 2010 Elsevier Ltd. All rights reserved.
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This work describes the evaluation of several parameters for the preparation of a tuna fish candidate as a reference material (RM) in order to measure the total As mass fraction by slurry sampling graphite furnace atomic absorption spectrometry (SLS-GF AAS) and slurry sampling hydride generation atomic absorption spectrometry (SLS-HG AAS). The main parameters investigated were the homogeneity, analyte segregation and composition during material production. For candidate RM preparation, tuna fish was collected at a local market, cleaned, freeze-dried and treated using different procedures as follows: (1) ground in a cutting mill and separated in different particle sizes (2) ground in cryogenic mill. The mass fraction of As in the cryogenically ground sample was (4.77 +/- A 0.19) mu g g(-1) for SLS-GF AAS and (4.61 +/- A 0.34) mu g g(-1) for SLS-HG AAS. The accuracy of the procedures was checked with tuna fish certified reference material (BCR 627) with recoveries of 102 and 94% for SLS-GF AAS and SLS-HG AAS, respectively. The homogeneity factor was calculated for different pretreatment procedures and for particle sizes in the range of 500-150 mu g, indicating good homogeneity, except for raw fish. There was no observed analyte segregation and no losses, no contamination and no changes in the microdistribution of material during preparation.
Resumo:
The capacitor test process at ABB Capacitors in Ludvika must be improved to meet future demands for high voltage products. To find a solution to how to improve the test process, an investigation was performed to establish which parts of the process are used and how they operate. Several parts which can improves the process were identified. One of them was selected to be improved in correlation with the subject, mechanical engineering. Four concepts were generated and decision matrixes were used to systematically select the best concept. By improving the process several benefits has been added to the process. More units are able to be tested and lead time is reduced. As the lead time is reduced the cost for each unit is reduced, workers will work less hours for the same amount of tested units, future work to further improve the process is also identified. The selected concept was concept 1, the sway stop concept. This concept is used to reduce the sway of the capacitors as they have entered the test facility, the box. By improving this part of the test process a time saving of 20 seconds per unit can be achieved, equivalent to 7% time reduction. This can be compared to an additional 1400 units each year.
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Background. Impaired hand function is common in patients with arthritis and it affects performance of daily activities; thus, hand exercises are recommended. There is little information on the extent to which the disease affects activation of the flexor and extensor muscles during these hand-dexterity tasks. The purpose of this study was to compare muscle activation during such tasks in subjects with arthritis and in a healthy reference group. Methods. Muscle activation was measured in m. extensor digitorium communis (EDC) and in m. flexor carpi radialis (FCR) with surface electromyography (EMG) in women with rheumatoid arthritis (RA, n = 20), hand osteoarthritis (HOA, n = 16) and in a healthy reference group (n = 20) during the performance of four daily activity tasks and four hand exercises. Maximal voluntary isometric contraction (MVIC) was measured to enable intermuscular comparisons, and muscle activation is presented as %MVIC. Results. The arthritis group used a higher %MVIC than the reference group in both FCR and EDC when cutting with a pair of scissors, pulling up a zipper and—for the EDC—also when writing with a pen and using a key (p < 0.02). The exercise “rolling dough with flat hands” required the lowest %MVIC and may be less effective in improving muscle strength. Conclusions. Women with arthritis tend to use higher levels of muscle activation in daily tasks than healthy women, and wrist extensors and flexors appear to be equally affected. It is important that hand training programs reflect real-life situations and focus also on extensor strength.
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One of a series of photographs accompanying a press release by the New York Trade School announcing the development and demonstration of a new technique in closed-circuit TV. Student Dennis Mahoney serves as one of the cameramen as William C. H. Meyers of the Automotive Department performs the demonstration. Black and white photograph.