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排序方式: 共有509条查询结果,搜索用时 15 毫秒
71.
Due to the global increase in wood construction, it is crucial for architects to understand wood. In Finland, log building, a special subset of industrially manufactured massive timber construction materials is experiencing a renaissance. Cultural aspects combined with newer technical developments make log a complex material from the viewpoint of architectonic expression. To inform practicing architects, the aim of this study is to explore how the tectonics of logs contribute to the architectonic quality of log architecture. Semi-structured interviews among architects of twelve recently published log buildings are conducted. The results describe how architectonic quality is perceived among participants, and features of logs related to tectonics that they consider to be of importance in terms of architectonic quality. These features include the statics of log construction and log's nature as a simultaneously insulating, load-bearing and visual material. Differences between industrial and hand-hewn logs, as well as other architectural aspects of using logs in contemporary architecture are discussed. Especially the “non-settling” log was perceived to have manifold implications for the architectonic possibilities of log architecture. The results are of practical importance to designing architects and the log industry. Theoretical implications include tangible information on architectonic quality and tectonics of log building. 相似文献
72.
Role of 17 beta-hydroxysteroid dehydrogenase type 1 in endocrine and intracrine estradiol biosynthesis 总被引:1,自引:0,他引:1
Enzymes with 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity catalyse reactions between the low-active female sex steroid, estrone, and the more potent estradiol, for example. 17 beta-HSD activity is essential for glandular (endocrine) sex hormone biosynthesis, but it is also present in several extra-gonadal tissues. Hence, 17 beta-HSD enzymes also take part in local (intracrine) estradiol production in the target tissues of estrogen action. Four distinct 17 beta-HSD isozymes have been characterized so far, and the data strongly suggests that different 17 beta-HSD isozymes have distinct roles in endocrine and intracrine metabolism of sex steroids. Current data suggest that 17 beta-HSD type 1 is the principal isoenzyme involved in glandular estradiol production both in humans and rodents. During ovarian follicular development and luteinization, rat 17 beta-HSD type 1 is regulated by gonadotropins, and the effects of gonadotropins are modulated by steroid hormones and paracrine growth factors. Human 17 beta-HSD type 1 favors the reduction reaction, thereby converting estrone to estradiol both in vitro and in cultured cells. Hence, the enzymatic properties of the enzyme are also in line with its suggested role in estradiol biosynthesis. Interestingly, 17 beta-HSD type 1 is also expressed in certain target tissues of estrogen action such as normal and malignant human breast and endometrium. Hence, 17 beta-HSD type 1 could be one of the factors leading to a relatively high tissue/plasma ratio of estradiol in breast cancer tissues of postmenopausal women. We conclude that 17 beta-HSD type 1 has a central role in regulating the circulating estradiol concentration as well as its local production in estrogen target cells. 相似文献
73.
Kokkonen K Meltaus J Pensala T Kaivola M 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2012,59(3):557-559
Acoustic wave fields in a thin-film bulk acoustic wave resonator are studied using a heterodyne laser interferometer. The measurement area is extended outside the active electrode region of the resonator, so that wave fields in both the active and surrounding regions can be characterized. At frequencies at which the region surrounding the resonator does not support laterally propagating acoustic waves, the analysis of the measurement data shows exponentially decaying amplitude fields outside the active resonator area, as suggested by theory. The magnitude of the imaginary wave vectors is determined by fitting an exponential function to the measured amplitude data, and thereby the experimentally determined dispersion diagram is extended into the region of imaginary wave numbers. 相似文献
74.
The acute toxicity and the genotoxicity of four colored smokes were studied by an in vitro method based on the exposure of human bronchial epithelial cell cultures to the smokes. All smoke formulations consisted of the oxidizer fuel mixture (potassium chlorate/lactose), talcum and the following dyes: 1,4‐dihydroxy anthraquinone (orange), 1‐(p‐tolylamino)‐4‐hydroxy anthraquinone (violet), 1‐methylamino anthraquinone (red) and 4,4′‐methylidyne‐bis‐3‐methyl‐1‐phenyl‐2‐pyrazolin‐5‐one (yellow). The experiments were carried out in a laboratory scale chamber and in a large container. The toxicity was compared to that of hexachloroethane (HC)‐based reference smoke with known toxicity. All the colored smokes displayed acute toxicity. The order of toxicity in the laboratory scale tests was orange>violet≈red>HC>yellow and in the container tests orange>violet≈yellow>red. The orange smoke appeared genotoxic in all the tests. With the yellow and the violet smokes, the genotoxicity could not be totally excluded. The red smoke showed evidence of weak genotoxicity only in one test series at the highest concentration level. 相似文献
75.
The purpose of this study is to investigate the cell phone use and broad cell phone feature preferences among high school and undergraduate in Finland. Of particular interest is the issue of gender differences regarding the use of the cell phones and the broad phone feature preferences, and their conceptualization. In this research the female respondents seem to use the calendar, Internet, music, and E-mail significantly more than the male respondents. As far as the feature preferences are concerned the female respondents seem to appreciate more price, aesthetics, design, standard processes and parts used, local language capability, safety in terms of radiation, and ringing tones. Male respondents on the other hand appreciate significantly more the use of business services. Also the broad feature preferences were compared to the actual usage areas of the cell phone. With many of these (parts, process, water, solidity, safety, ease of use, and ringing tones) there were no significant relationship with the actual usage. Interestingly the game feature had a significant correlation with the usage of the games, but the correlation was quite low. Finally the conceptualization of the cell phone by different genders was analyzed, and differences in the conceptualization were discovered. 相似文献
76.
77.
Mercury (Hg) and 13 other trace elements (Al, Ti, V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb) were measured in phytoplankton, zooplankton, mysis and herring in order to examine the trophodynamics in a well-studied pelagic food chain in the Baltic Sea. The fractionation of nitrogen isotopes (δ15N) was used to evaluate food web structure and to estimate the extent of trophic biomagnification of the various trace elements. Trophic magnification factors (TMFs) for each trace element were determined from the slope of the regression between trace element concentrations and δ15N. Calculated TMFs showed fundamental differences in the trophodynamics of the trace elements in the pelagic food chain studied. Concentrations of Al, Fe, Ni, Zn, Pb and Cd showed statistically significant decreases (TMF < 1) with increasing trophic levels and thus these trace elements tropically dilute or biodilute in this Baltic food chain. Cu, As, Cr, Mn, V, Ti and Co showed no significant relationships with trophic levels. Hg was unique among the trace elements studied in demonstrating a statistically significant increase (TMF > 1) in concentration with trophic level i.e. Hg biomagnifies in this Baltic food chain. The estimated TMF for Hg in this food chain was comparable to TMFs observed elsewhere for diverse food chains and locations. 相似文献
78.
Matti Siemiatycki 《Journal of the American Planning Association. American Planning Association》2013,79(4):388-403
Problem: Information is often suppressed when public infrastructure is planned by design-build-finance-operate (DFBO) public/private partnerships, an increasingly popular strategy for procuring transportation facilities, hospitals, and schools. Purpose: I aim to identify strategies to increase transparency and accountability in large infrastructure projects delivered through public/private partnerships. Methods: I studied the case of an award winning public/private partnership to plan a rapid rail line in Vancouver by comparing confidential documents released after project approval to the information available while planning was underway. Results and conclusions: I find that although this project followed many best practices for achieving accountable and transparent public/private partnerships, in some instances it kept unfavorable study results from public view, limiting the potential for meaningful public involvement in the planning process. Takeaway for practice: I identify the following strategies to increase transparency and accountability in large infrastructure projects, including those delivered through private-public partnerships: (1) using a clear and narrow standard for what information should be kept confidential; (2) ensuring that public officials with responsibility for project decisions and their staffs have full access to all project information, including that not made public; (3) appointing a watchdog to see that these standards are upheld; and (4) implementing a decision process that allows public input and places the burden for proving that information should remain confidential on the entity making the request. 相似文献
79.
Matti Schneider Felix Ospald Matthias Kabel 《International journal for numerical methods in engineering》2016,105(9):693-720
In this article, we propose to discretize the problem of linear elastic homogenization by finite differences on a staggered grid and introduce fast and robust solvers. Our method shares some properties with the FFT‐based homogenization technique of Moulinec and Suquet, which has received widespread attention recently because of its robustness and computational speed. These similarities include the use of FFT and the resulting performing solvers. The staggered grid discretization, however, offers three crucial improvements. Firstly, solutions obtained by our method are completely devoid of the spurious oscillations characterizing solutions obtained by Moulinec–Suquet's discretization. Secondly, the iteration numbers of our solvers are bounded independently of the grid size and the contrast. In particular, our solvers converge for three‐dimensional porous structures, which cannot be handled by Moulinec–Suquet's method. Thirdly, the finite difference discretization allows for algorithmic variants with lower memory consumption. More precisely, it is possible to reduce the memory consumption of the Moulinec–Suquet algorithms by 50%. We underline the effectiveness and the applicability of our methods by several numerical experiments of industrial scale. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
80.
Kaisa Grönman Risto Soukka Terhen Järvi‐Kääriäinen Juha‐Matti Katajajuuri Mika Kuisma Heta‐Kaisa Koivupuro Margareetta Ollila Marja Pitkänen Olli Miettinen Frans Silvenius Rabbe Thun Helena Wessman Lassi Linnanen 《Packaging Technology and Science》2013,26(4):187-200
The environmental impacts of packages have been found to be relatively small compared with the food items they contain. Furthermore, from the environmental and operational point of view, the most significant task of the package is to protect the product, which is important to acknowledge in the packaging design process. This study introduces a guiding framework for designing sustainable food packaging. In this approach, the entire life cycle of the product–package combination is taken into consideration. The emphasis is on the prevention of food losses in packaging design as a major environmental criterion. Consideration of the properties of both the package and the product itself when designing the final package will lead to a better end result with smaller product losses and environmental impacts. By using different assessment methods in the different stages of the packaging design, the sustainability of the package can be enhanced. The decision making of the packaging designer is facilitated with methods that are introduced step by step and in a certain order that will also allow for corrective measures through back‐loops in the design process. The purpose is to integrate sustainability aspects at all stages firmly into the design process. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献