Academic literature on the topic 'Masks, Chewa'

<i>Abstract.</i>—Climatic variation is a key driver of freshwater physical processes that in turn control stream fish growth and population dynamics at fine spatial scales and species distributions across broad landscapes. A recent downturn in Chinook Salmon <i>Oncorhynchus tshawytscha </i>returns across the Yukon River basin, Alaska, USA and Yukon Territories, Canada has led to hardship among user groups and increased interest in understanding how freshwater processes affect population persistence within this important commercial, recreational, and subsistence fishery. Here, we present results for the Chena River basin, interior Alaska, where we used field observations and riverscape-scale spatially explicit models to assess the influence of stream temperature on juvenile Chinook Salmon growth potential among years (2003–2015) and across 438 stream kilometers. We ran bioenergetic simulations for warm and cool year scenarios and contrasted temperature model precision and growth among different habitat types (small and large tributaries, main stem, and side channels) based on field estimates of growth, size, diet, and measured stream temperatures. Stream temperature regimes predicted from remotely sensed land surface temperatures were precise during the open water season (<I>R</I><sup>2</sup> > 0.87; root-mean-squared error < 1.1°C), although the relationship was weakest in groundwater-mediated tributary habitats. Field observations revealed salmon were 67% larger by mass (g) in September during a warm year versus a cool year from main-stem sites. Bioenergetic simulations predicted that, on average, growth potential was 42% higher in warm years, although growth potential varied across the riverscape as much as 60% between cool upstream and warm downstream habitats. Climate variability is clearly an important driver of freshwater habitat conditions and has a large role in controlling freshwater growth of juvenile salmon. A better understanding of how climate influences growth conditions in different habitat types and across broad landscapes will be critical for conservation and management of Alaskan Chinook Salmon stocks under an expected warmer and more variable climate.

History is bunk—or so Henry Ford is reputed to have said. Folk memory, though, simplifies recorded statements. What Henry Ford actually told the Chicago Tribune was ‘History is more or less bunk. It’s tradition. We don’t want tradition. We want to live in the present, and the only tradition that is worth a tinker’s damn is the history that we make today.’ So folk memory, in this case, did pretty well reflect the kernel of his views. Henry Ford also said that ‘Exercise is bunk. If you are healthy, you don’t need it; if you are sick, you shouldn’t take it.’ Henry Ford was a very powerful, very rich man of strongly expressed views. And he was quite wrong on both counts. Not having known Henry Ford, interplanetary explorers may have their own view of history. As, perhaps, an indispensable means of understanding the present and of predicting the future. As a way of deducing how the various phenomena—physical, chemical, and biological—on any planet operate. And as a means of avoiding the kind of mistake—such as resource exhaustion or intra-species war—that could terminate the ambitions of any promising and newly emerged intelligent life-form. On Earth, and everywhere else, things are as they are because they have developed that way. The history of that development must be worked out from tangible evidence: chiefly the objects and traces of past events and processes preserved on this planet itself. The surface of the Earth is no place to preserve deep history. This is in spite of—and in large part because of—the many events that have taken place on it. The surface of the future Earth, one hundred million years from now, will not have preserved evidence of contemporary human activity. One can be quite categorical about this. Whatever arrangement of oceans and continents, or whatever state of cool or warmth will exist then, the Earth’s surface will have been wiped clean of human traces. For the Earth is active. It is not just an inert mass of rock, an enormous sphere of silicates and metals to be mined by its freight of organisms, much as caterpillars chew through leaves.

The thrust-to-weight ratio of aero-engine is increasing, the structure stiffness is reducing along with its weight, the mechanical exciting force and aerodynamic force become more and more intricate, for these reasons, dynamic interaction of different structures have to be taken into account in aero-engine vibration analysis. In traditional methods, as transfer matrix method and finite element method based on beam element, the rotor is reduced as mass point and beams, so the true dynamic interaction between the disk and shaft can’t be calculated. In this paper, MSC/NASTRAN was developed by add