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排序方式: 共有108条查询结果,搜索用时 234 毫秒
91.
Studying the evolution of nesting behavior within the human-chimpanzee clade is problematic because evidence is sparse and difficult to interpret. Lacking a fossil or archaeological record for proto-chimpanzees, reconstructions of the antecedents of modern chimp nesting patterns can be reconstructed only from careful studies of variation in current chimpanzee and bonobo nesting patterns within the context of spatial and temporal landscape parameters. The ethology of nesting also provides an important frame of reference for reconstructions of early hominid nesting behavior. If the contemporary contrast between human and chimpanzee nesting patterns is seen as an evolutionary dichotomy, then African prehistoric landmarks that mark the origin of this split might include bipedalism and the origins of the hominidae, the first stone tools and the origins of Homo, the developmental and behavioral adaptations of Homo ergaster, shifts in Late Acheulian settlement patterns, and the origins of anatomically modern humans and the Middle Stone Age. The issue of whether Early Stone Age archaeological sites were used for nesting is unresolved because potential markers of such behavior, such as hearths, structures, or bedding, are not unambiguously recognizable in the archaeological record until the Middle Stone Age. 相似文献
92.
Zack Kelly Funsho Ojebuoboh 《JOM Journal of the Minerals, Metals and Materials Society》2002,54(4):42-45
Bismuth trioxide (Bi2O3) is the prevalent commercial oxide of bismuth. A precursor to the preparation of other compounds of bismuth, including the
chemical reagents, bismuth trioxide has specialized uses in optical glass, flame-retardant paper, and, increasingly, in glaze
formulations where it substitutes for lead oxides. In the last decade, bismuth trioxide has also become a key ingredient in
flux formulations used by mineral analysts in fire assaying. The production of bismuth trioxide generally begins with the
minor metal bismuth. This paper describes bismuth trioxide production and the properties and basis for its use in environmentally
sound fire assaying. 相似文献
93.
A macro model of the 6.2-V 1N5920B Zener diode which very accurately represents the measured characteristics both in the DC and AC domain is presented. For users who do not have access to optimization software, the model can still be easily customised for other Zener diodes by replacing the emission coefficients (N), saturation currents (Is) and series resistance (Rs) under forward and reverse bias. One would also need to modify the temperature coefficient and measure the capacitance (CIO) at Vd=0 V bias, to have a functional model of the Zener diode. However, there is no easy technique to extract the TT parameter without going through an extraction process. Therefore, without modification to the T1 parameter, one has to be careful when using the customized model for switching applications 相似文献
94.
Hong Ouyang Jeffrey L. Goldberg Shuyi Chen Wei Li Guo-Tong Xu Wei Li Kang Zhang Robert B. Nussenblatt Yizhi Liu Ting Xie Chi-Chao Chan Donald J. Zack 《International journal of molecular sciences》2016,17(3)
Stem cells hold promise for treating a wide variety of diseases, including degenerative disorders of the eye. The eye is an ideal organ for stem cell therapy because of its relative immunological privilege, surgical accessibility, and its being a self-contained system. The eye also has many potential target diseases amenable to stem cell-based treatment, such as corneal limbal stem cell deficiency, glaucoma, age-related macular degeneration (AMD), and retinitis pigmentosa (RP). Among them, AMD and glaucoma are the two most common diseases, affecting over 200 million people worldwide. Recent results on the clinical trial of retinal pigment epithelial (RPE) cells from human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) in treating dry AMD and Stargardt’s disease in the US, Japan, England, and China have generated great excitement and hope. This marks the beginning of the ocular stem cell therapy era. The recent Zhongshan Ophthalmic Center Ocular Stem Cell Symposium discussed the potential applications of various stem cell types in stem cell-based therapies, drug discoveries and tissue engineering for treating ocular diseases. 相似文献
95.
This paper describes ThermalOpt—a methodology for automated BIM-based multidisciplinary thermal simulation intended for use
in multidisciplinary design optimization (MDO) environments. ThermalOpt mitigates several technical barriers to BIM-based
multidisciplinary thermal simulation found in practice today while integrating and automating commercially available technologies
into a workflow from a parametric BIM model (Digital Project) to an energy simulation engine (EnergyPlus) and a daylighting
simulation engine (Radiance) using a middleware based on the open data model Industry Foundation Classes (IFC). Details are
discussed including methods for: automatically converting architectural models into multiple consistent thermal analytical
models; integration/coordination of analysis inputs and outputs between multiple thermal analyses; reducing simulation times;
and generating consistent annual metrics for energy and daylighting performance. We explain how ThermalOpt can improve design
process speed, accuracy, and consistency, and can enable designers to explore orders of magnitude larger design spaces using
MDO environments to better understand the complex tradeoffs required to achieve zero energy buildings. 相似文献
96.
Zack Sullivan 《Computer Physics Communications》2005,168(1):25-31
A few changes to the routines that calculate CTEQ parton distribution functions allow modern compilers to optimize the evaluations, while having no quantitative effect on the results. Overall computation time is reduced by a factor of 4-5 in matrix-element calculations, and by 1.3-2.5 in showering Monte Carlo event generators. Similar improvements in performance may be expected in any calculations relying heavily on interpolation or multiple calls to functions. 相似文献
97.
Barry J. Darien A. Dawkins B. Freedman P. Heitman J. Kennedy C. Lyon J. Mattassov G. Matulka D. Whited C. Zack D. 《Communications, IEEE Transactions on》1976,24(4):470-478
The technology advances made in the development of an engineering feasibility model of a Nd:YAG laser communication system for space test are discussed and details of evaulations presented. The model includes the baseplate, optomechanical structure, 19-cm (7.5-in) diameter telescope and prototype space qualifiable components. The main technological achievements are in the areas of laser and its operation, the modulator and the digital format, and the integration of the various optical components into one optomechanical structure. These as well as other technology advances will be discussed and the system performance capabilities indicated. 相似文献
98.
L Gu A Weinreb XP Wang DJ Zack JH Qiao R Weisbart AJ Lusis 《Canadian Metallurgical Quarterly》1998,161(12):6999-7006
MRL-lpr/lpr (MRL/lpr) mice are a model of human autoimmune disease. They exhibit a number of characteristics of systemic lupus erythematosus, including anti-DNA Abs, anti-cardiolipin Abs, immune complex-mediated vasculitis, lymphadenopathy, and severe glomerulonephritis. Although the autoimmune disorder is mediated primarily by mutation of the Fas gene (lpr), which interferes with lymphocyte apoptosis, MRL/lpr mice also have other predisposing genetic factors. In an effort to identify these additional factors, we have applied quantitative trait locus (QTL) mapping using an intercross between MRL/lpr mice and the nonautoimmune inbred strain BALB/cJ. A complete linkage map spanning the entire genome was constructed for 189 intercross progeny, and genetic loci contributing to features of the autoimmunity were identified using statistical analytic procedures. As expected, the primary genetic determinant of autoimmune disease in this cross was the Fas gene on mouse chromosome 19, exhibiting a lod score of 60. In addition, two novel loci, one on chromosome 2 (lod score, 4.3) and one on chromosome 11 (lod score, 3.1), were found to contribute to levels of anti-DNA Abs. Interestingly, the chromosome 19 and chromosome 11 QTLs, but not the chromosome 2 QTL, also exhibited associations with anti-cardiolipin Abs (lod scores, 38.4 and 2.6). We further examined the effects of these QTLs on the development of coronary vasculitis in the F2 mice. Our results indicate that the QTLs on chromosomes 11 and 19 also control the development of vasculitis, demonstrating common genetic determinants of autoantibody levels and vasculitis. 相似文献
99.
The amount of research related to Internet marketing has grown rapidly since the dawn of the Internet Age. A review of the literature base will help identify the topics that have been explored as well as identify topics for further research. This research project collects, synthesizes, and analyses both the research strategies (i.e., methodologies) and content (e.g., topics, focus, categories) of the current literature, and then discusses an agenda for future research efforts. We analyzed 411 articles published over the past eighteen years (1994-present) in thirty top Information Systems (IS) journals and 22 articles in the top 5 Marketing journals. The results indicate an increasing level of activity during the 18-year period, a biased distribution of Internet marketing articles focused on exploratory methodologies, and several research strategies that were either underrepresented or absent from the pool of Internet marketing research. We also identified several subject areas that need further exploration. The compilation of the methodologies used and Internet marketing topics being studied can serve to motivate researchers to strengthen current research and explore new areas of this research. 相似文献
100.
Cantilevers are useful as sensor devices with high sensitivity and have shown great promise for dense, multianalyte arrays. One of the difficulties has been the fabrication of multianalyte arrays that are capable of the simultaneous detection of a wide range of chemical and biological species. Functionalization procedures for one class of analytes are often incompatible with other classes and cross contamination is a significant concern when ink-jet deposition processes are used. In this study, we used surface micromachined cantilevers designed and fabricated using Sandia National Laboratories SUMMiT V MEMS process. The cantilevers are fabricated with a base that can be detached from the parent substrate after functionalization and mounted into a daughter array. We have utilized an IBM-fabricated 8-cantilever array chip as our daughter substrate due to its compatibility with a Scentris 8-cantilever readout system. Our initial work demonstrates that this is a feasible procedure for decoupling functionalization from array assembly. 相似文献