Small domains of cobalt on silica (CoSBA) were prepared by the reaction of Co[N(SiMe3)2]2 and SBA-15, resulting in a range of surface structures as the cobalt loading varied from 0.27 to 5.11 wt%. X-ray absorption spectroscopy (XAS) was employed to characterize these surface structures, which range from single-site cobalt atoms to small clusters of Co3O4. The CoSBA materials exhibit photochemical water oxidation catalysis, revealing distinct catalytic activities associated with characteristic types of surface structures that are dominant in particular concentration regimes. The catalytic turnover frequency for water oxidation of an isolated single-site cobalt atom (0.0143 s−1) is much greater than that observed for a surface atom of a small cluster Co3O4 on silica (0.0006 s−1). The CoSBA catalysts were recyclable for more than seven catalytic cycles (>200 turnovers) with additional sacrificial oxidant, and no leaching of cobalt was observed. Post-catalytic analysis of CoSBA by XAS revealed that the cobalt atoms were partially oxidized to Co3+, without exhibiting significant surface migration and aggregation of cobalt atoms.
Prestar atenção aos primeiros estudos de campo de Pierre Bourdieu, conduzidos concomitantemente na Argélia colonial e na sua aldeia natal no Béarn, no sudoeste francês, permite avaliar sua abordagem sociológica e seus resultados científicos numa nova chave interpretativa. Eles revelam as raízes etnográficas gêmeas da sua empresa teórica, dissolvem a figura caricatural do "teórico da reprodução", indiferente à mudança histórica, e afastam a ficção acadêmica do "teórico da prática". Mostram como as inovações conceituais de Bourdieu (como o conceito de habitus) eram guiadas por questões de pesquisa de campo centradas na transformação social, na disjunção cultural e na divisão da consciência. A utilização de cada local como um laboratório vivo para analisar de modo cruzado o outro local, permitiu a Bourdieu descobrir a especificidade da "universalmente pré-lógica lógica da prática" e levou-o a romper com o paradigma estruturalista. Ligar seus estudos de juventude na Cabília e no Béarn revela ainda que pressagiando o "repatriamento" da Antropologia depois do encerramento da era imperial, Bourdieu revogou a concepção dominante da Etnografia como uma exploração heróica da alteridade, sendo o pioneiro no desenvolvimento da Etnografia multissituada como um meio de controle da construção do objeto de pesquisa. Os estudos de campo sobre a estrutura social e sobre o sentimento na colônia longínqua e na terra natal, não só apagam na prática a divisão disciplinar entre Sociologia e Antropologia, como também demonstram que se pode conduzir Etnografia "insider" e reconhecer a inserção social e a subjetividade dividida do pesquisador sem, para tal, reduzir a Etnografia ao ato de contar histórias e sem abandonar a teoria à poesia.
Collaborative filtering (CF) is valuable in e-commerce, and for direct recommendations for music, movies, news etc. But today's systems have several disadvantages, including privacy risks. As we move toward ubiquitous computing, there is a great potential for individuals to share all kinds of information about places and things to do, see and buy, but the privacy risks are severe. In this paper we describe a new method for collaborative filtering which protects the privacy of individual data. The method is based on a probabilistic factor analysis model. Privacy protection is provided by a peer-to-peer protocol which is described elsewhere, but outlined in this paper. The factor analysis approach handles missing data without requiring default values for them. We give several experiments that suggest that this is most accurate method for CF to date. The new algorithm has other advantages in speed and storage over previous algorithms. Finally, we suggest applications of the approach to other kinds of statistical analyses of survey or questionaire data.
We present a framework for learning single-view shape and pose prediction\nwithout using direct supervision for either. Our approach allows leveraging\nmulti-view observations from unknown poses as supervisory signal during\ntraining. Our proposed training setup enforces geometric consistency between\nthe independently predicted shape and pose from two views of the same instance.\nWe consequently learn to predict shape in an emergent canonical (view-agnostic)\nframe along with a corresponding pose predictor. We show empirical and\nqualitative results using the ShapeNet dataset and observe encouragingly\ncompetitive performance to previous techniques which rely on stronger forms of\nsupervision. We also demonstrate the applicability of our framework in a\nrealistic setting which is beyond the scope of existing techniques: using a\ntraining dataset comprised of online product images where the underlying shape\nand pose are unknown.\n
Abstract As a result of their unique architecture and structural as well as functional versatility, dendrimers have generated considerable interest in numerous areas of the physical sciences, engineering, as well as the biological sciences. Both their size ‐ in the 1‐10 nm range ‐ and their globular shape resemble those of many proteins suggesting a host of biomimetic and nanotechnological applications. This brief highlight describes some of our recent work with nascent applications of dendrimers as unimolecular nanoreactors, as nanoscale antennae for energy harvesting and transduction, and as nanosized carriers for diagnostic or therapeutic applications. While implementation of some of these applications may still be distant, the impatient critic might remember that new markets are not created overnight as demonstrated by the slow commercial acceptance of many promising molecules and technologies with development frequently extending decades after their initial discovery.
