共查询到20条相似文献,搜索用时 15 毫秒
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《Journal of Manufacturing Processes》2003,5(1):24-32
This paper presents the model-based tampering (MBT) methodology to address performance degradation in complex nonlinear processes. MBT involves characterizing the dynamics of a process through experiments to derive nonlinear stochastic differential equation (n-SDE) models that can accurately and compactly represent a process, and using these models to dynamically compensate for the effects of process degradation on the performance. This research has yielded a new method to derive n-SDE models of complex processes through a signal-based reconstruction of Fokker-Planck equations.MBT was applied to control surface finish during cylindrical grinding of shafts of air bearings used in aircraft environmental control systems (ECS)—a core competency of Honeywell. It has been shown that n-SDE models help capture patterns in process outputs that cannot be captured using any simpler models, and that MBT reduces the surface finish variation by 62% over the current industry practice. 相似文献
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《Journal of Cleaner Production》2003,11(5):499-509
Plant materials which are available from farming regions in the moderate Austrian climate were investigated to serve as sources for natural dyes in textile dyeing operations. The extraction of the dye components from the plant materials was performed with boiling water without addition of chemicals or solvents. Based upon a rigorous selection of possible plant sources, a selection of natural dyestuffs applicable in a one-bath dyeing step was established. A broad variation in shade and color depth can be achieved by applying mixtures of natural dyestuffs in various combinations of iron- and alum-mordants. More than 60% of tested dyeings achieved acceptable fastness properties.On the basis of the developed natural dyestuff-based dyeing procedures, a comparison was made between the effluents from processes based upon them and those based upon the current ‘state-of-the-art’ techniques utilizing synthetic dyes. The comparison revealed that a lowering of the chemical load released with waste water can be expected by shifting to the plant-based dyes. 相似文献
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Pigeons released away from their loft usually fly around at the release site for a while before they finally leave. Visual
observations had suggested that the moment when the birds decide to head home is associated with a certain change in flying
style. To see whether this change is also reflected by GPS-recorded tracks, a group of pigeons equipped with flight recorders
was released at two sites about 10 km from their home loft. The initial part of their flight paths was analyzed in order to
find objective criteria indicating the point of decision. We selected the highest increase in steadiness as the best estimate
for the moment of decision. This criterion allows us to divide the pigeons’ paths in two distinct phases, an initial phase
and the homing phase, with the moment of decision, on an average, 2 min after release. The moment of decision marks a change
in behavior, with a significant increase in steadiness and flying speed and headings significantly closer to the home direction.
The behavior of the individual birds at the two sites was not correlated, suggesting no pronounced individual traits for the
length of the initial phase. The behavior during this phase seems to be controlled by flight preparation, exploration, and
non-navigational motivations rather than by navigational necessities alone.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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Agenesis of the corpus callosum (ACC) is one of the most common brain malformations, with an incidence estimated to range from 0.5 to 70 in 10,000 among the general population. Prenatal diagnosis is made via ultrasound; however, fetal MRI is useful to confirm or exclude the presence of associated cerebral abnormalities–mostly cortical malformations–that may affect postnatal prognosis. When no additional central nervous system (CNS) or extra CNS anomalies are identified and no genetic cause is found, an isolated ACC is diagnosed. Overall, in cases of ACC, an underlying genetic cause can be identified in up to 12.5% with chromosomal microarray (CMA) and up to 47% with whole exome sequencing (WES). In cases where ACC is the only anomaly detected, the yield of WES is 30%. Postnatal outcomes are variable and depend on whether the condition is isolated or not. In truly isolated ACC, outcomes range from normal in 65% of cases through mild to severe neurodevelopmental impairments in 35% of cases. An interdisciplinary team of medical experts is key in guiding parents toward informed decision-making in pregnancies complicated by ACC. Considering current and expected advancements in genetic testing and imaging technologies in upcoming years, we herein summarize current recommendations for the management and prenatal counseling of expecting parents of fetuses with ACC. Our review pertains primarily to expecting parents of fetuses with complete ACC. 相似文献
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Tianjiao Wang Paul Scuffham Joshua Byrnes Martin B. Delatycki Martin Downes 《黑龙江环境通报》2023,43(11):1416-1424
Background & Aim
Reproductive carrier screening seeks to identify couples at a high risk of having offspring affected by autosomal recessive and X-linked (XL) conditions. The aim of this paper is to provide a comprehensive overview of existing carrier screening panels by examining their gene content and characteristics, identifying the most common genes/conditions included in these panels, and analyzing their listed prices.Methods
A comprehensive evaluation of existing carrier screening panels was conducted by searching for web-based content, reviewing information brochures, and establishing direct contact with the providers via email or phone.Results
Twenty-two panels and their providers were identified with a cumulative total of 2205 unique genes. The number of genes included in these panels varied from 44 to 2054. Only 15 genes (0.7%) were included in all the panels. The carrier frequency of these 15 common genes and their associated conditions varied greatly, but the conditions associated with the genes are “severe”. The price of these 22 panels ranged from $349 to $4320 per couple (USD in 2023). The correlation between the listed price and the number of selected genes among these panels was small and not statistically significant (r = 0.1023, p = 0.6959).Conclusion
Considerable discrepancies exist among carrier screening panels. Ongoing research and monitoring are necessary to capture the dynamic nature of the carrier screening landscape, providing up-to-date information for clinical practice and informed decision-making. 相似文献11.
Feeding the growing population of the world poses significant policy challenges for the sustainability of global ecosystems. A prime example is the degradation of water quality due to the growing imbalance in the terrestrial nitrogen (N) cycle linked to increasing production of reactive N (Nr). Environmental impacts such as groundwater quality degradation and eutrophication of coastal estuaries tend to be local in nature but may be closely connected to global economic factors. Environmental accounting of the N fluxes entering, leaving or remaining in Prince Edward Island (PEI), a small agricultural region, demonstrate the importance of a single industry (potato production) in controlling the local N cycle. The resulting burden of Nr has its most profound effect on groundwater, the sole source of drinking water and the primary pathway of N to the Province's economically and ecologically important estuaries. At the same time, agriculture is a vital part of the local economy, and regulators are faced with the challenge of meeting environmental goals and still maintaining an industry that is competitive and responsive to global market trends. New, innovative policy alternatives are needed to foster more effective implementation of sustainable agricultural practices. An approach that focuses on influencing consumer choices toward more environmentally responsible production practices at the point of origin may help remove some of the important, non-technical barriers to sustainable food production practices. In practice, a system that documents the environmental performance throughout the full supply chain from producer to retailer would have to be implemented. 相似文献
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Felix G. Marx Mónica R. Buono R. Ewan Fordyce R. W. Boessenecker 《Die Naturwissenschaften》2013,100(3):257-261
The origin of the pygmy right whale (Caperea marginata) has long been one of the most vexing conundrums of marine mammal evolution. The extremely disparate skeletal structure of Caperea and a patchy fossil record have left morphology and molecules at odds: whereas most morphological analyses ally Caperea with right whales (Balaenidae), most molecular studies instead suggest a close relationship with rorquals (Balaenopteridae) and grey whales (Eschrichtiidae). The morphological evidence supporting a Caperea-balaenid clade consists of several shared features of the skull and mandible, as traditionally observed in adult individuals. Here, we show that at least two of these features, the ascending process of the maxilla and the coronoid process, arise from substantially different precursors early during ontogeny and therefore likely do not represent genuine synapomorphies. Both of these juvenile morphologies have adult counterparts in the fossil record, thus indicating that the ontogenetic variation in the living species may be a genuine reflection of differing ancestral states. This new evidence contradicts previous morphological hypotheses on the origins of Caperea and may help to reconcile morphological and molecular evidence. 相似文献
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Coming out of the woods: do termites need a specialized worker caste to search for new food sources? 总被引:1,自引:0,他引:1
Most small-colony termites live confined within a single piece of wood on which they feed and do not possess permanent workers: Tasks are done by developmentally flexible immatures (pseudergates). By contrast, large-colony termites possess a specialized (true) worker caste and forage outside their nest for food. To shed light on possible transitional steps between these contrasting patterns of social organization, we studied an atypical Rhinotermitidae, Prorhinotermes inopinatus. In this species, despite the absence of a true worker caste, soldiers, pseudergates, and neotenic reproductives may leave the nest and explore their surroundings. Although evidence presented in this study indicates that termites recognize unknown areas, there is no directional recruitment toward them. The discovery of a food source, i.e., a piece of wood, is followed by the establishment of a long-lasting trail between the nest and the food source. A large fraction of the colony, including neotenic reproductives, ultimately migrates into the piece of wood. Our results thus demonstrate that multiple features of external foraging behavior can evolve independently of the existence of a true worker caste in termites. We suggest that large colonies with true workers, like those of most Rhinotermitidae, may easily have evolved from a Prorhinotermes-like pattern if submitted to increasing selective pressures for worker efficiency in a stable environment. 相似文献
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Esther García-de Blas Rafael Mateo Francisco Javier Guzmán Bernardo Rosa Carmen Rodríguez Martín-Doimeadios Carlos Alonso-Alvarez 《Die Naturwissenschaften》2014,101(5):407-416
Carotenoids are organic pigments involved in several important physiological functions and may serve as indicators of individual quality in animals. These pigments are only obtained by animals from the diet, but they can be later transformed into other carotenoids by specific enzymatic reactions. The diet of farm-reared and probably wild red-legged partridges (Alectoris rufa) is mainly based on cereals that contain high levels of lutein and zeaxanthin. These two carotenoids are also predominant in internal tissues and blood of red-legged partridges. However, in their integuments, astaxanthin and papilioerythrinone (the last one identified in this work) are mainly present in their free form and esterified with fatty acids. According to available literature about carotenoid metabolism in animals, we propose that astaxanthin (λ max?=?478 nm) and papilioerythrinone (λ max?=?452–478 nm) are the result of a chromatic convergence of the transformation of dietary zeaxanthin and lutein, respectively. Moreover, the results obtained in this work provide the first identification by liquid chromatography coupled to accurate mass quadrupole time-of-flight mass spectrometer system of papilioerythrinone (m/z 581.3989 [M?+?H]+) in the skin (i.e., not feathers) of a vertebrate. Astaxanthin and papilioerythrinone are very close in terms of chemical structure and coloration, and the combination of these two keto-carotenoids is responsible for the red color of the ornaments in red-legged partridges. 相似文献
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This paper describes experiments on the locomotor activity rhythm of queens of the ant species Camponotus compressus, which were performed to investigate the consequences of mating on circadian clocks. Locomotor activity rhythm of virgin and mated queens was monitored individually under constant conditions of the laboratory. The locomotor activity rhythm of virgin queens entrained to a 24 h (12:12 h) laboratory light/dark (LD) cycle and free-ran under constant dim red light (RR) with a free-running period () of approximately 24 h. The locomotor activity of the mated queens on the other hand was arrhythmic during the period when they were laying eggs, and robust rhythmicity appeared soon after the egg-laying phase was over. The of the locomotor activity rhythm of mated queens was significantly greater than that of virgin queens. These results are contrary to the commonly held belief that the role of circadian clocks in ant queens ceases after mating flights, thus suggesting that circadian clocks of ant queens are adaptively plastic and display activity patterns, perhaps depending on their physiological state and tasks in the colony. 相似文献
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Anders Malmendal Jesper Givskov Sørensen Johannes Overgaard Martin Holmstrup Niels Chr. Nielsen Volker Loeschcke 《Die Naturwissenschaften》2013,100(5):417-427
We investigated the global metabolite response to artificial selection for tolerance to stressful conditions such as cold, heat, starvation, and desiccation, and for longevity in Drosophila melanogaster. Our findings were compared to data from other levels of biological organization, including gene expression, physiological traits, and organismal stress tolerance phenotype. Overall, we found that selection for environmental stress tolerance changes the metabolomic 1H NMR fingerprint largely in a similar manner independent of the trait selected for, indicating that experimental evolution led to a general stress selection response at the metabolomic level. Integrative analyses across data sets showed little similarity when general correlations between selection effects at the level of the metabolome and gene expression were compared. This is likely due to the fact that the changes caused by these selection regimes were rather mild and/or that the dominating determinants for gene expression and metabolite levels were different. However, expression of a number of genes was correlated with the metabolite data. Many of the identified genes were general stress response genes that are down-regulated in response to selection for some of the stresses in this study. Overall, the results illustrate that selection markedly alters the metabolite profile and that the coupling between different levels of biological organization indeed is present though not very strong for stress selection at this level. The results highlight the extreme complexity of environmental stress adaptation and the difficulty of extrapolating and interpreting responses across levels of biological organization. 相似文献