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81.
Abstract

Gertrude Käsebier made portraits of Zitkala-Sa (Red Bird)/ Gertrude Simmons (Bonnin) just four years before Zitkala-Sa's article ‘Why I Am a Pagan’ appeared in the Atlantic Monthly.1 In some pictures, she is Red Bird, with her somewhat tangled hair down, wearing a simple cloth version of a buckskin dress, an old willow basket held to her chest. In others, she is Zitkala-Sa, stage lecturer and performer, star of the ladies' reform dub lecture circuit, wearing the beaded bandolier and chokered beads of a ‘Princess’, hand to head, looking afar in the cliched Indian pose, a darker Native Drama Queen. In some, she is Gertrude Simmons, a Rossetti-esque, post-Victorian girl, just one step away from holding roses on the fainting couch. Posed in Käsebier's srudio against a flowered wallpaper background, wearing a good girl's long dress, she holds a book or her beloved violin (figure 1), the instrument she studied at the New England Conservatory of Music. Kasebier got all three personae of this complex Yankton Sioux woman in her portraits of 1898, personae we shall not recognize when we see her again, photographed in Washington, around 1930, as ‘Gertrude Simmons Bonnin’, an influential Native politico in a dark suit.  相似文献   
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83.
Central Force Optimization (CFO) is a novel and upcoming metaheuristic technique that is based upon physical kinematics. It has previously been demonstrated that CFO is effective when compared with other metaheuristic techniques when applied to multiple benchmark problems and some real world applications. This work applies the CFO algorithm to training neural networks for data classification. As a proof of concept, the CFO algorithm is first applied to train a basic neural network that represents the logical XOR function. This work is then extended to train two different neural networks in order to properly classify members of the Iris data set. These results are compared and contrasted to results gathered using Particle Swarm Optimization (PSO) in the same applications. Similarities and differences between CFO and PSO are also explored in the areas of algorithm design, computational complexity, and natural basis. The paper concludes that CFO is a novel and promising meta-heuristic that is competitive with if not superior to the PSO algorithm, and there is much room to further improve it.  相似文献   
84.
Bulk heterojunction (BHJ) solar cells are fabricated using active material blends of poly(3‐hexylthiophene) (P3HT) donor, indene‐C60 bisadduct (ICBA) acceptor, and an all‐conjugated random copolymer (RCP) additive. By optimizing RCP loading, power conversion efficiencies (PCEs) up to 20% higher than those of a binary P3HT:ICBA mixture are achieved. The improved device characteristics are rationalized in terms of the differences between the photoactive thin film morphologies. Energy‐filtered transmission electron micro­scopy reveals that incorporation of the RCP improves the degree of structural order of the BHJ fibrillar network and increases the extent of microphase separation between P3HT and ICBA. Additionally, a combination of atomic force microscopy and X‐ray photoelectron spectroscopy analysis indicates segregation of the RCP at the free interface, leading to a shift in the surface potentials measured by Kelvin probe force microscopy. These changes, both in the bulk morphology and in the interfacial composition/energetics, are correlated to improved carrier collection efficiency due to a reduction of non‐geminate recombination, which is measured by charge extraction of photo­generated carriers by linearly increasing voltage.  相似文献   
85.
Studies that estimate indoor aeroallergen exposure typically measure a pre‐selected limited range of allergens. In this study, inhalable aeroallergen particles were quantified using the halogen immunoassay (HIA) to determine the contribution of fungal and non‐fungal aeroallergens to total allergen exposure. Bioaerosols from 39 homes of fungal‐allergic subjects were sampled using inhalable fraction samplers and immunostained by HIA using resident subject's immunoglobulin E (IgE) to detect allergen‐laden particles. Fungal aerosols as well as particles carrying mite, cat, and cockroach allergens were identified and enumerated by HIA. Reservoir dust‐mite (Der p 1), cat (Fel d 1), and cockroach (Bla g 1) allergen concentrations were quantified by ELISA. Fungal particles that bound subject's IgE in the HIA were 1.7 (bedroom)‐ and 1.4 (living room)‐fold more concentrated than Der p 1, Fel d 1, and Bla g 1 allergen particles combined. Predominant fungal conidia that bound IgE were derived from common environmental genera including Cladosporium and other fungi that produce amerospores. Airborne mite, cat, and cockroach allergen particle counts were not associated with reservoir concentrations determined by ELISA. This study demonstrates that inhalable fungal aerosols are the predominant aeroallergen sources in Sydney homes and should be considered in future exposure assessments.  相似文献   
86.
Brillouin light scattering (BLS) spectroscopy is a technique that is able to detect thermally excited phonons within a material. The speed of propagation of these phonons can be determined from the magnitude of the Brillouin frequency shift between incident and scattered light, thereby providing a measure of the mechanical properties of the material in the gigahertz range. The mechanical properties of the extracellular matrices of biological tissues and their constituent biopolymers are important for normal tissue function and disturbances in these properties are widely implicated in disease. BLS offers the prospect of measuring mechanical properties on a microscopic scale in living tissues, thereby providing insights into structure–function relationships under normal and pathological conditions. In this study, we investigated BLS in collagen and elastin—the fibrous proteins of the extracellular matrix (ECM). Measurements were made on type I collagen in rat tail tendon, type II collagen in articular cartilage and nuchal ligament elastin. The dependence of the BLS spectrum on fibre orientation was investigated in a backscattering geometry using a reflective substrate. Two peaks, a bulk mode arising from phonon propagation along a quasi-radial direction to the fibre axis and a mode parallel to the surface, depending on sample orientation relative to the fibre axis, could be distinguished. The latter peak was fitted to a model of wave propagation through a hexagonally symmetric elastic solid, and the five components of the elasticity tensor were combined to give axial and transverse Young''s, shear and bulk moduli of the fibres. These were 10.2, 8.3, 3.2 and 10.9 GPa, and 6.1, 5.3, 1.9 and 8 GPa for dehydrated type I collagen and elastin, respectively. The former values are close to those previously reported. A microfocused BLS approach was also applied providing selection of single fibres. The moduli of collagen and elastin are much higher than those measured at lower frequency using macroscopic strains, and the difference between them is much less. We therefore believe, like previous investigators, that molecular-scale viscoelastic effects are responsible for the frequency dependence of the fibre biomechanics. Combining BLS with larger-scale mechanical testing methods therefore should, in the future, provide a means of following the evolution of mechanical properties in the formation of the complex structures found in the ECM.  相似文献   
87.
The nuclear debate in Australia is shaped by the nation's substantial base of energy resources, including its large reserves of uranium and recent rises in the market price of uranium. But the debate also echoes Australia's past in the development of programs for nuclear weapons. The proposals include uranium enrichment, the storage of nuclear waste in Australia, and the introduction of nuclear reactors. A national inquiry has been instituted by the government. These developments, stemming from a range of factors, have revived the opposition to uranium mining and nuclear power which has for two decades held a dominant role in Australian politics. The issue of what should be Australia's energy path in a time of climate change is beginning to be examined. The importance of the decisions, whether to be a player in the nuclear club with its attendant multiple hazards, or to play a quite different leadership role in the development and adoption of sustainable energy strategies and technologies, cannot be exaggerated.  相似文献   
88.
Innovation is invariably accepted as a central component of construction sector competitiveness. Yet, there remains a paucity of empirical research, which explores the gap between the way innovation is promoted in the policy discourse and how it is interpreted in practice. We follow the “narrative turn” in organization studies to explore the ways in which senior executives in the UK construction sector ascribe themselves with informal roles while advocating the cause of innovation. Empirical data is derived from narrative interviews with 32 senior executives who self-identify as “innovation champions”. When talking about innovation, the respondents were found to oscillate between performative narratives of innovation and more personalized stories derived from their own experience. The narratives were invariably pre-rehearsed often to the point of being monotonous. In contrast, the personalized stories tended to be engaging and emotionally laden. The tendency for senior executives to oscillate between narratives and stories is seen as an important means through which they search for meaning while at the same time legitimizing their self-identities as “innovation champions”. Of particular note is the way in which senior managers self-ascribe themselves with informal roles which are notably at odds with those described in more formalized narratives.  相似文献   
89.
90.
Although the main features of the protein folding problem are coming into clearer focus, the microscopic viewpoint of nucleic acid folding mechanisms is only just beginning to be addressed. Experiments, theory, and simulations are pointing to complex thermodynamic and kinetic mechanisms. As is the case for proteins, molecular dynamics (MD) simulations continue to be indispensable tools for providing a molecular basis for nucleic acid folding mechanisms. In this review, we provide an overview of biomolecular folding mechanisms focusing on nucleic acids. We outline the important interactions that are likely to be the main determinants of nucleic acid folding energy landscapes. We discuss recent MD simulation studies of empirical force field and Go-type MD simulations of RNA and DNA folding mechanisms to outline recent successes and the theoretical and computational challenges that lie ahead.  相似文献   
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