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排序方式: 共有212条查询结果,搜索用时 15 毫秒
61.
Br?uer Juliane; Kaminski Juliane; Riedel Julia; Call Josep; Tomasello Michael 《Canadian Metallurgical Quarterly》2006,120(1):38
Domestic dogs (Canis familiaris) and great apes from the genus Pan were tested on a series of object choice tasks. In each task, the location of hidden food was indicated for subjects by some kind of communicative, behavioral, or physical cue. On the basis of differences in the ecologies of these 2 genera, as well as on previous research, the authors hypothesized that dogs should be especially skillful in using human communicative cues such as the pointing gesture, whereas apes should be especially skillful in using physical, causal cues such as food in a cup making noise when it is shaken. The overall pattern of performance by the 2 genera strongly supported this social-dog, causal-ape hypothesis. This result is discussed in terms of apes' adaptations for complex, extractive foraging and dogs' adaptations, during the domestication process, for cooperative communication with humans. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
62.
63.
Food security in high mountain regions: agricultural production and the impact of food subsidies in Ladakh,Northern India 总被引:1,自引:0,他引:1
The issues of food security and its specifics in high mountain regions are often neglected in national and international science
and policy agendas. At the same time, local food systems have undergone significant transitions over the past two decades.
Whereas subsistence agriculture still forms the economic mainstay in these regions, current dynamics are generally characterized
by livelihood diversification with increased off-farm income opportunities and an expansion of external development interventions.
A case study from Ladakh (Indian Himalayas) illustrates how changes of the political and socio-economic conditions have affected
food security strategies of mountain households. In the cold, arid environment of Ladakh, where combined mountain agriculture
is the dominant land use system, reduced importance of the subsistence base for staple foods is reflected in current consumption
patterns. Seasonal shortfalls and low dietary diversity lead to micronutrient deficiencies, a phenomenon that has been described
as “hidden hunger”. This paper describes determinants of the transition of the current food system, based on land-use analyses
and quantitative and qualitative social research at the household, regional and national level. It shows how monetary income
and governmental as well as non-governmental development interventions shape food security in this peripheral region. Focusing
on the particular example of staple food subsidies through the Indian Public Distribution System, the paper illustrates and
discusses how this national-level measure addresses food security and shows the implications for household strategies. Against
the background of our findings we argue that tailor-made regional policies and programmes are needed to face the specific
challenges in high mountain regions. 相似文献
64.
Experimental investigation in the laboratory can be accelerated and supported by miniaturized automation techniques. In the design of unit operations, e.g., for crystallization and precipitation processes or for chromatographic separations where no solids should appear during the run, reliable solubility data are mandatory. The development and validation of a robotic routine for completely automated solubility measurements are introduced. The triple‐determination of automated solubility measurements of the model systems succinic acid and adipic acid/water have a relative standard deviation below 0.99 % and are comparable to literature and manual experiments. Data are generated with high precision and accuracy, and the experimental effort and the hands‐on time are reduced significantly to a few minutes necessary to prepare the platform since all subsequent pipetting and control steps are automated. 相似文献
65.
Ron Christian Antonczyk Wolfgang Breuer Astrid Juliane Salzmann 《Management International Review》2014,54(3):381-415
We examine how time preferences impact the financing decision of firms. We hypothesize that the degree of long-term orientation in a country is positively related to the use of bank relationship lending. Based on a thorough theoretical investigation and an extensive empirical analysis using a large, worldwide dataset, we find strong support for our hypothesis on the role of time preferences for financial intermediation. Our results are robust to controlling for other determinants of the choice of debt financing as well as to applying alternative variables and different estimation methods. Firms in long-term orientation countries appear to prefer relationship bank financing, since it is usually available for the long run and will not be withdrawn quickly in response to adverse developments. This allows managers to preserve a more strategic view and pursue longer planning horizons. 相似文献
66.
Wellbore failure can occur at different stages of operations. For example, wellbore collapse might happen during drilling and/or during production. The drilling process results in the removal of an already stressed rock material. If the induced stresses near the wellbore exceed the strength of rock, wellbore failure occurs. The production process also changes the effective stresses around the wellbore. Such changes in stresses can be significant for high drawdown pressures and can trigger wellbore failure. In this paper, the Mohr–Coulomb failure criterion with a hyperbolic hardening is used. The model parameters are identified from triaxial compression tests. The numerical simulations of laboratory tests showed that the model can reproduce the mechanical behaviour of sandstone. In addition, the simulations of multilateral junction stability experiments showed that the model was able to reproduce yielding and failure at the multilateral junction for different levels of applied stresses. Finally, a numerical example examining multilateral junction stability in an open borehole during drilling and production is presented. The results illustrate the development of a localized failure zone proximate to the area where two wellbore tracks join, particularly on the side with a sharp approaching angle, which would significantly increase the risk of wellbore collapse at the junction. 相似文献
67.
Despite current interest in dog (Canis familiaris) cognition, very little is known about how dogs represent objects and how they compare with other species, such as the great apes. Therefore, we investigated how dogs and great apes (chimpanzees [Pan troglodytes], bonobos [Pan paniscus], orangutans [Pongo pygmaeus], gorillas [Gorilla gorilla]) individuate objects in a classical violation of expectation paradigm. We used a container (magic cup) with a double bottom that allowed us to change the type of food that subjects had seen being placed in the container. Using a 2 × 2 design, we varied whether subjects received a generally preferred food and whether the food was substituted (surprise trials) or not (baseline trials). Apes showed increased begging and looking behaviors and dogs showed increased smelling behavior. Both species stayed near the experimenter more frequently in the surprise trials compared with baseline trials. Both species reacted to positive (i.e., good food substituted for bad food) and negative (i.e., bad food substituted for good food) surprises. These results suggest that apes and dogs were able to individuate objects according to their properties or type in comparable ways. In addition, we looked for frustration and elation effects, but subjects' behaviors were not influenced by the food they saw and which they received in previous trials. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
68.
Dirk Biermann Alexander Baschin Eugen Krebs Juliane Schlenker 《Production Engineering》2011,5(2):209-217
In this paper the results of an experimental investigation to analyze the machinability of a hardened, carbide-rich cold-work
tool steel 1.2379 (approx. 62 HRC) with coated micro end-milling cutters are discussed. Fundamental experiments were performed
to determine a cutting-parameter set, which enables an economic manufacturing of dies by 3-axis micromilling with commercially
available cemented-carbide tools. The evaluation of the applicability of different tool types is conducted by analyzing the
process forces, the tool wear, the surface quality, the material removal rate, and the entire chip volume. Design of experiments
was used to significantly reduce the number of experiments and to model the active and passive forces. Concerning the design
of tools for the micromilling of such difficult-to-machine materials, it is shown that cemented-carbide tools with robust
cutting edges are applicable for this kind of machining. Furthermore, test microstructures were manufactured with the intention
of validating the determined cutting-parameter set in combination with the selected tool types. In addition, the dimension
and shape accuracy of the microstructures are analyzed. 相似文献
69.
70.
Hoyer H Hombach J Perera G Thaurer M Bernkop-Schnürch A 《Drug development and industrial pharmacy》2011,37(3):300-309
The objective of this study was to improve the multifunctional properties of poly(acrylic acid) (PAA) by covalent attachment of 4-aminothiophenol (ATP) to its backbone. The permeation enhancing effect of PAA-ATP together with glutathione was evaluated in Ussing-type chambers using fluorescein isothiocyanate dextran as model compound. The mucoadhesive properties were evaluated in vitro on freshly excised porcine intestinal mucosa through the rotating cylinder method. The resulting conjugates PAA-ATP1 and PAA-ATP2 displayed 168 ± 35 and 426 ± 55 μmol immobilized free thiol groups per gram polymer, respectively. In addition, 279 ± 28 and 139 ± 22 μmol disulfide bonds per gram polymer, respectively, were identified on PAA-ATP1 and PAA-ATP2. Within disintegration studies in aqueous buffer solution, the modified polymers showed improved cohesive properties. Because of the immobilization of ATP, the swelling of PAA-ATP1 and PAA-ATP2 improved 12.0- and 17.8-fold, respectively. The adhesion times of the conjugates PAA-ATP1 and PAA-ATP2 were more than 20- and 30-fold increased in comparison to unmodified PAA. Furthermore, conjugates PAA-ATP1 and PAA-ATP2 exhibited a 1.86- and 2.07-fold higher permeation enhancing effect, respectively, over unmodified PAA. According to these results, PAA-ATP conjugates represent a very promising novel type of thiomer for the development of various mucoadhesive drug delivery systems. 相似文献