During the last six years several incidents have occurred with dioxins in feed, stressing the need for rapid screening methods for these compounds. The most recent incident was the contamination of bakery waste used for animal feed due to the use of waste wood for drying of the material. In addition to Germany, the material was also shipped to the Netherlands. Levels up to 12 ng TEQ/kg have been detected, being about 15 times over the current limit of 0.75 ng TEQ/kg. In the Netherlands a combined strategy of screening with the CALUX-bioassay and the HRGC/HRMS confirmatory method was used to rapidly control the incident. Pigs were contaminated by the incident but only to a very limited extent. Despite the rather low limits for pig meat, the CALUX bioassay showed excellent performance, once again confirming the value of this assay. 相似文献
Recently, unusual giant magnetic properties were found experimentally in some organized organic monolayers adsorbed on solid substrates. A model is presented which explains the observed phenomenon. The model is based on the special properties of electrons transferred from the substrate to the layer as a result of the adsorption process. Triplet pairing of those electrons is forced by the special 2D properties of the organic layer. Such pairs are confined within domains in the organic layer and their quantum statistics provide a model that explains the unique magnetization as well as all other features of the experimental observations. The model suggests the possible existence of Bose-Einstein condensation at room temperature on the scale of the domains. 相似文献
The goal of this paper is to study some Poincaré series associated to the invariants of the symplectic and odd orthogonal
groups. These series turn out to be rational functions and our main results will describe the denominators. This work will
generalize some known results on the invariants of the general linear groups. In addition to whatever intrinsic interest we
hope our results may have, the subject involves an interesting interplay of invariant theory and complex variables.
The first author gratefully acknowledges Support from DePaul University Research Council.
The second author was supported in part by the Israel Science Foundation, founded by the Israel Academy of Sciences and Humanities,
and by an Internal Research Grant from Bar-Ilan University. 相似文献
Combining the strengths of both proximity communication and optical communication, a new hybrid input-output (I/O) platform delivers on-chip bandwidth off-chip and over distance. We demonstrate, for the first time, a four-channel hybrid I/O interface by integrating proximity communication and vertical-cavity surface-emitting-laser-based parallel optical interconnects on the same commercial 90-nm complementary metal-oxide-semiconductor platform. The optical I/O can operate at 5 Gb/s per channel, and the complete hybrid I/O interface achieved 2.5 Gb/s per channel. We characterize the I/O link performance for various data rates and chip separations, and show 10-mum chip separation tolerance for proximity communication 相似文献
Fully functional HIV-1-specific CD8 and CD4 effector T-cell responses are vital to the containment of viral activity and disease
progression. These responses are lacking in HIV-1-infected patients with progressive disease. We attempted to augment fully
functional HIV-1-specific CD8 and CD4 effector T-cell responses in patients with advanced chronic HIV-1 infection. 相似文献
Multimedia content currently accounts for over three quarters of all Internet traffic. This increase in traffic volume and content availability derives from a paradigm shift from the traditional text and picture based Web, to more resource demanding audio and video content. A controversial driver for this development is content distribution systems based on peer-to-peer overlay networks. Flooding the Internet with often illegal content, these networks now pose challenges to all actors in the value chain. However, if viewed as surmountable challenges in an evolutionary path, peer-to-peer technology has the potential of increasing efficiency in content distribution and unleashing resources to form scalable and resilient overlay networks of unprecedented dimensions.
In this paper we examine the potentials and challenges of peer-to-peer technology in content distribution, and analyse how, and under which circumstances, peer-to-peer technology can be used to increase the efficiency of multimedia services. The paper provides an up-to-date overview of the development of peer-to-peer networks as well as describing the economics laws governing their use. To conclude the study, the paper analyses Skype, a well known telecommunications service utilising the peer-to-peer technology, as well as demonstrating the benefits of peer-to-peer based content distribution using empirical data from the Danish Broadcasting Corporation. 相似文献
This article presents a model of enjoyment rooted in self‐determination theory (Deci & Ryan, 1985) that includes the satisfaction of three needs related to psychological well‐being: autonomy, competence, and relatedness. In an experiment designed to validate this conceptualization of enjoyment, we manipulate video game characteristics related to the satisfaction of these needs and examine their relative effects on enjoyment. The validated model explains 51% of the variance in enjoyment, even without including needs usually studied in relation to enjoyment such as pleasure seeking. Results indicate the utility of defining enjoyment as need satisfaction. These results are discussed in terms of a broader conceptualization of enjoyment represented as the satisfaction of a comprehensive set of functional needs.相似文献
at arguments of its choice, the test always accepts a monotone f, and rejects f with high probability if it is ε-far from being monotone (i.e., every monotone function differs from f on more than an ε fraction of the domain). The complexity of the test is O(n/ε).
The analysis of our algorithm relates two natural combinatorial quantities that can be measured with respect to a Boolean
function; one being global to the function and the other being local to it. A key ingredient is the use of a switching (or sorting) operator on functions.
Received March 29, 1999 相似文献