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排序方式: 共有113条查询结果,搜索用时 31 毫秒
21.
The use of rotation‐minimizing directed frames (RMDFs) for defining smoothly varying camera orientations along given spatial paths, in real or virtual environments, is proposed. A directed frame on a space curve is a varying orthonormal basis for ℝ3 such that coincides with the unit polar vector from the origin to each curve point, and such a frame is rotation‐minimizing if its angular velocity vector maintains a vanishing component along o . To facilitate computation of rotation‐minimizing directed frames, it is shown that the basic theory is equivalent to the established theory for rotation‐minimizing adapted frames—for which one frame vector coincides with the tangent at each curve point—if one replaces the given space curve by its anti‐hodograph (i.e., indefinite integral). A family of polynomial curves on which RMDFs can be computed exactly by a rational function integration, the Pythagorean (P) curves, is also introduced, together with algorithms for their construction. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
22.
Marcos L. Dias Geraldo L. Crossetti Carlotta Bormioli Antonino Giarusso Luiz Claudio de Santa Maria Fernanda M. B. Coutinho Lido Porri 《Polymer Bulletin》1998,40(6):689-694
Summary
The polymerization of styrene with catalysts based on Ni(acac)2 supported on SiO2 and Al2O3 was investigated. Using catalysts based on MAO supported on silica, a highly isotactic polystyrene was obtained. Nevertheless,
the Al2O3-supported catalyst can promote isospecific polymerization activated by common. alkyl aluminum compounds even by any prior
support treatment with MAO.
Received: 3 March 1998/Revised version: 14 April 1998/Accepted: 14 April 1998 相似文献
23.
24.
In artificial intelligence (AI), a number of criticisms were raised against the use of probability for dealing with uncertainty.
All these criticisms, except what in this article we call the non-adequacy claim, have been eventually confuted. The non-adequacy claim is an exception because, unlike the other criticisms, it is exquisitely philosophical and, possibly for this reason, it was
not discussed in the technical literature. A lack of clarity and understanding of this claim had a major impact on AI. Indeed,
mostly leaning on this claim, some scientists developed an alternative research direction and, as a result, the AI community
split in two schools: a probabilistic and an alternative one. In this article, we argue that the non-adequacy claim has a strongly metaphysical character and, as such, should not be accepted as a conclusive argument against the adequacy
of probability.
相似文献
Mauro BirattariEmail: |
25.
Jessica Capraro Stefano De Benedetti Giuditta Carlotta Heinzl Alessio Scarafoni Chiara Magni 《International journal of molecular sciences》2021,22(7)
Food proteins and peptides are able to exert a variety of well-known bioactivities, some of which are related to well-being and disease prevention in humans and animals. Currently, an active trend in research focuses on chronic inflammation and oxidative stress, delineating their major pathogenetic role in age-related diseases and in some forms of cancer. The present study aims to investigate the potential effects of pseudocereal proteins and their derived peptides on chronic inflammation and oxidative stress. After purification and attribution to protein classes according to classic Osborne’s classification, the immune-modulating, antioxidant, and trypsin inhibitor activities of proteins from quinoa (Chenopodium quinoa Willd.), amaranth (Amaranthus retroflexus L.), and buckwheat (Fagopyrum esculentum Moench) seeds have been assessed in vitro. The peptides generated by simulated gastro-intestinal digestion of each fraction have been also investigated for the selected bioactivities. None of the proteins or peptides elicited inflammation in Caco-2 cells; furthermore, all protein fractions showed different degrees of protection of cells from IL-1β-induced inflammation. Immune-modulating and antioxidant activities were, in general, higher for the albumin fraction. Overall, seed proteins can express these bioactivities mainly after hydrolysis. On the contrary, higher trypsin inhibitor activity was expressed by globulins in their intact form. These findings lay the foundations for the exploitation of these pseudocereal seeds as source of anti-inflammatory molecules. 相似文献
26.
Kernel pooled local subspaces for classification. 总被引:1,自引:0,他引:1
Peng Zhang Jing Peng Carlotta Domeniconi 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2005,35(3):489-502
We investigate the use of subspace analysis methods for learning low-dimensional representations for classification. We propose a kernel-pooled local discriminant subspace method and compare it against competing techniques: kernel principal component analysis (KPCA) and generalized discriminant analysis (GDA) in classification problems. We evaluate the classification performance of the nearest-neighbor rule with each subspace representation. The experimental results using several data sets demonstrate the effectiveness and performance superiority of the kernel-pooled subspace method over competing methods such as KPCA and GDA in some classification problems. 相似文献
27.
Sara R. Jaeger Jayson L. Lusk Lisa O. House Carlotta Valli Melissa Moore Bert Morrow W. Bruce Traill 《Food quality and preference》2004,15(7-8):701-714
The findings from a study measuring consumer acceptance of genetically modified (GM) foods are presented. The empirical data were collected in an experimental market, an approach used extensively in experimental economics for measuring the monetary value of goods. The approach has several advantages over standard approaches used in sensory and marketing research (e.g., surveys and focus groups) because of its non-hypothetical nature and the realism introduced by using real goods, real money, and market discipline. In each of three US locations, we elicited the monetary compensation consumers required to consume a GM food. Providing positive information about the benefits of GM food production, in some cases, reduced the level of monetary compensation demanded to consume the GM food. 相似文献
28.
Stabili L Licciano M Giangrande A Longo C Mercurio M Marzano CN Corriero G 《Water research》2006,40(16):3083-3090
A study on the filtering activity has been carried out on reared specimens of the demosponge Spongia officinalis var. adriatica coming from an off-shore farm displaced off the Apulian coast (Ionian Sea). The experience was carried out under laboratory conditions, by using natural seawater collected from the sponge environment. The study demonstrates a high efficiency of the sponge in removing bacteria. Bacterial concentration significantly decreases in presence of the sponge, with a marked drop after 2 h from the start of the experience. The maximum clearance rate was 210 ml h(-1) g(-1) DW at 60 min. Retention efficiency reached the highest value of 61% at 120 min. The bacterial density removed by the S. officinalis filtering activity was 12.3 +/- 1.8 x 10(4) cells ml(-1) corresponding to a biomass of about 11.7 +/- 1.4 microg Cl(-1). The sponge fed preferentially large- and medium-size bacteria, whereas the small ones are fed after the removal of the largest size categories. The results obtained suggest that S. offcinalis is a suitable species for marine environmental bioremediation. 相似文献
29.
C Perego D Lattuada C Casnici S Gatti R Orsenigo S Panagiotis P Franco O Marelli 《Canadian Metallurgical Quarterly》1998,20(9):479-490
Somatostatin (SS) was originally described as a growth hormone release inhibiting factor synthesised in the hypothalamus. Recently, SS and its receptor (SSTR) have been demonstrated in lymphoid tissues and seem to play a regulatory, largely inhibitory, role in immune responses. The aim of the present study was to check the immunosuppressive effect of a SS derived peptide, the octreotide (SMS 201-995) and to verify whether this molecule acted synergistically with FK506. An immunosuppressive effect of SMS was observed on the proliferation of rat spleen cells induced in vitro, either by polyclonal mitogens such as PHA or by alloantigens. With PHA stimulation, 10(-14) M SMS significantly enhanced the immunosuppressive action of 0.00001 microg/ml FK506. The addition of SMS in MLR (10(-11)-10(-9)M) increased the antiproliferative effect of both 0.0001 microg/ml and 0.00001 microg/ml FK506. In consideration of the extremely low concentration of both drugs that was required to obtain a good immunosuppression in vitro, we verified the association of FK506 and SMS in vivo in an allogeneic skin graft model that used Lewis (Lew) rats as donors and Brown Norway (BN) rats as recipients. BN treated with 0.1 mg/kg FK506 and 0.5-10 microg/kg SMS showed a significant increase in mean skin allograft survival time when compared to either a monotherapy or control group. None of the animals died or showed signs of drug-related toxicity. In conclusion, a combined therapy of SMS and FK506, administered at lower dosages than those that are considered therapeutic, led to an effective immunosuppression without any undesirable side effects. 相似文献