Collaborative Semantic Authoring

In the context of the semantic Web, notions of collaboration, interoperability, and reuse are intrinsically interrelated: interoperability implies reuse, which in turn is a form of collaboration. If we adopt this viewpoint, the semantic Web becomes essentially a medium for knowledge exchange, in which the knowledge produced by one agent is consumed by another agent, possibly to create new knowledge. A collaboration-centric perspective on the semantic Web introduces both challenges and interesting research directions. Clearly, it's no longer desirable that the process of authoring semantic content necessarily take place in a room full of experts and ontologists. Indeed, as we move from classic Web 2.0 technologies to scenarios in which semantic content is created, our technologies need to change so that it becomes possible to create and exchange knowledge transparently, in accordance with the medium's openness and the knowledge producers' various goals and skill levels. In this article, we examine three modalities for collaborative semantic authoring based on selecting and reusing external, open semantic resources. These three ways of creating semantic content correspond to three levels of interaction between the user and the created resources. We illustrate each level by describing a tool we designed in the context of our research on semantic Web applications at the Knowledge Media Institute.     

Factorization of multipliers in passivity and IQC analysis

Multipliers are often used to find conditions for the absolute stability of Lur’e systems. They can be used either in conjunction with passivity theory or within the more recent framework of integral quadratic constraints (IQCs). We compare the use of multipliers in both approaches. Passivity theory requires that the multipliers have a canonical factorization and it has been suggested in the literature that this represents an advantage of the IQC theory. We consider sufficient conditions on the nonlinearity class for the associated multipliers to have a canonical factorization.     

Recognition of depressed affect in hospitalized psychiatric patients: staff and patient perceptions

A comparison of self-report vs. observer rating of depressed mood in a heterogenous inpatient population revealed wide variations in concordance among diagnostic groups. Patients diagnosed as having Affective Psychosis and "Other' illnesses showed the highest correlation between four self-report scales and an observer rating scale. Patients with a diagnosis of depressive Neurosis showed only modest correlation, while Schizophrenics revealed no significant correlation, on these instruments, suggesting inconsistent communication of affect from Schizophrenic patients to observers. In contrast, when self-report scales were intercorrelated, patients in all four diagnostic categories showed highly significant correlations, indicating that they were consistently reporting their affective state on these instruments. The implications of these findings for future research as well as for practical clinical management are discussed.     

Channel Adaptive Quantization for Limited Feedback MIMO Beamforming Systems

Multiple-input multiple-output (MIMO) wireless systems can achieve significant diversity and array gain by using transmit beamforming and receive combining techniques. In the absence of full channel knowledge at the transmitter, the transmit beamforming vector can be quantized at the receiver and sent to the transmitter using a low-rate feedback channel. In the literature, quantization algorithms for the beamforming vector are designed and optimized for a particular channel distribution, commonly the uncorrelated Rayleigh distribution. When the channel is not uncorrelated Rayleigh, however, these quantization strategies result in a degradation of the receive signal-to-noise ratio (SNR). In this paper, switched codebook quantization is proposed where the codebook is dynamically chosen based on the channel distribution. The codebook adaptation enables the quantization to exploit the spatial and temporal correlation inherent in the channel. The convergence properties of the codebook selection algorithm are studied assuming a block-stationary model for the channel. In the case of a nonstationary channel, it is shown using simulations that the selected codebook tracks the distribution of the channel resulting in improvements in SNR. Simulation results show that in the case of correlated channels, the SNR performance of the link can be significantly improved by adaptation, compared with nonadaptive quantization strategies designed for uncorrelated Rayleigh-fading channels     

Edge-Packing in Planar Graphs

Maximum G Edge-Packing (EPack _G ) is the problem of finding the maximum number of edge-disjoint isomorphic copies of a fixed guest graph G in a host graph H . This paper investigates the computational complexity of edge-packing for planar guests and planar hosts. Edge-packing is solvable in polynomial time when both G and H are trees. Edge-packing is solvable in linear time when H is outerplanar and G is either a 3-cycle or a k -star (a graph isomorphic to K _1,k ). Edge-packing is NP-complete when H is planar and G is either a cycle or a tree with edges. A strategy for developing polynomial-time approximation algorithms for planar hosts is exemplified by a linear-time approximation algorithm that finds a k -star edge-packing of size at least half the optimal. Received May 1995, and in revised form November 1995, and in final form December 1997.     

Normalizing Behavior of Unsaturated Granular Pavement Materials

One of the important components of a flexible pavement structure is granular material layers. Unsaturated granular pavement materials (UGPMs) in these layers influence stresses and strains throughout the pavement structure, and have a large effect on asphalt concrete fatigue and pavement rutting (two of the primary failure mechanisms for flexible pavements). The behavior of UGPMs is dependent on water content, but this effect has been traditionally difficult to quantify using either empirical or mechanistic methods. This paper presents a practical mechanistic framework for determining the behavior of UGPMs within the range of water contents, densities, and stress states likely to be encountered under field conditions. Both soil suction and generated pore pressures are determined and compared to confinement under typical field loading conditions. The framework utilizes a simple soil suction model that has three density-independent parameters, and can be determined using conventional triaxial equipment that is available in many pavement engineering laboratories.     

Assessing the impact of palmitic,myristic and lauric acids on hydrogen production from glucose fermentation by mixed anaerobic granular cultures

The effects of lauric (LUA), myristic (MA), palmitic (PA), and a mixture of myristic:palmitic (MA:PA) acids on hydrogen (H₂) production from glucose degradation using anaerobic mixed cultures were assessed at 37 °C with an initial pH set at 5.0 and 7.131 mM of each acid. The maximum H₂ yield (2.53 ± 0.18 mol mol⁻¹ glucose) was observed in cultures treated with PA. A principal component analysis (PCA) of the by-products and the microbial population data sets detected similarities between the controls and PA treated cultures; however, differences were observed between the controls and PA treated cultures in comparison to the MA and LUA treated cultures. The flux balance analysis (FBA) showed that PA decreased the quantity of H₂ consumed via homoacetogenesis compared to the other LCFAs. The control culture was dominated by Thermoanaerovibrio acidaminovorans (60%), Geobacillus sp. and Eubacterium sp. (28%), while Clostridium sp. was less than 1%. Treatment with PA, MA, MA:PA, or LUA increased the H₂ producers (Clostridium sp. and Bacillus sp.) population by approximately 48, 67, 86, and 86%, respectively.     

Impact of culture source and linoleic acid (C18:2) on biohydrogen production from glucose under mesophilic conditions

Genomic and statistical methods were used to demonstrate the effects of linoleic acid (LA) on hydrogen (H₂) production in mixed anaerobic cultures from two sources (designated as A and B). The microbial composition of the control cultures CA and CB were statistically different. Bacteroidaceae (26%) and Clostridiaceae (10%) dominated CA whereas Clostridiaceae (33%) and Bacteroidaceae (10%) dominated CB. Homoacetogens directed 42% of the electron equivalents to acetate production and decreased the H₂ yield by 50% in CA compared to CB. The maximum H₂ yields (3.11 ± 0.02 and 3.11 ± 0.07 mol H₂ mol⁻¹ glucose in LA-treated cultures ALA and BLA, respectively) were statistically the same. Cultures ALA and BLA followed the acetate-butyrate pathway while CA and CB followed propionate and homoacetogenic pathways. LA-treated and control cultures were statistically different based on the type and quantity of metabolites; the differences were also confirmed by principal component analysis (PCA).