A trust-based service suggestion system using human plausible reasoning

Nowadays, there is a growing need to manage trust in open systems as they may contain untrustworthy service providers. Agent Trust Management (ATM) tries to address the problem of finding a set of the most trusted agents in multi agent systems. This paper presents ScubAA, a novel generic ATM framework based on the theory of Human Plausible Reasoning (HPR). For each user’s request, ScubAA determines a ranked list of the most trusted service agents, within the context of the request, and forwards the request to those trusted services only. ScubAA determines an agent’s degree of trust in terms of a single personalized value derived from several types of evidences such as user’s feedback, history of user’s interactions, context of the submitted request, references from third party users as well as from third party service agents, and structure of the society of agents. ScubAA is able to utilize more trust evidences towards a more accurate value of trust. We also propose a function to figure out how similar two users are in a given context. We apply the proposed HPR-based ATM framework to the domain of Web search. The resulting ATM system recommends to the user a list of the most trusted search engines ranked according to the retrieval precision of documents returned in response to the user’s query as well as the degree of trust of the search engines have gained by interacting with other related users within the context of the query. In addition, we conduct a statistical analysis of ScubAA based on ANOVA and by using a data set of forty queries in different domains. This analysis clearly reveals that ScubAA is able to successfully assess the trustworthiness of service agents.     

Influence of growth temperatures on the photoresponse of low temperature grown GaAs:As p-i-n diodes

We report a study of the sub-bandgap photoresponse of p-i-n photodetectors with 1 μm low-temperature intrinsic layers, and its dependence on the growth temperature of the intrinsic layer. Diodes with intrinsic layers grown near 250°C exhibit the highest photoresponse. The photoresponse decreases gradually as the growth temperature is raised above 250°C. For growth temperatures at or below 200°C, a drastic drop in the photoresponse is observed, along with degradation of crystal quality in the material. The extracted internal Schottky barrier heights are found to be within the range 0.7–0.8 eV.     

Identification of tyrosine phosphorylation sites in the CD28 cytoplasmic domain and their role in the costimulation of Jurkat T cells

The cytoplasmic domain of CD28 contains four tyrosine residues. Because signal transduction by CD28 appears to involve its tyrosine phosphorylation, we determined sites of CD28 tyrosine phosphorylation using mutants of mouse CD28 that retained tyrosine at one position, with the remaining three positions mutated to phenylalanine. When expressed in Jurkat cells and stimulated by mAb, only the mutants with tyrosine at position 170 or 188 were tyrosine phosphorylated. Phosphorylation of Tyr170 recruits phosphatidylinositol 3-kinase to CD28. Tyr188 has not been associated with any specific signaling event, but we found that ligation of CD28 by the natural ligand B7.2 also induced phosphorylation of Tyr188, suggesting that this event is of physiological importance. Consistent with that possibility, mutation of Tyr188 to phenylalanine severely impaired the ability of mouse CD28 to deliver a costimulus for the expression of CD69 and the production of IL-2. The functional consequences of the mutation of Tyr188 were unique; mutation of the other three tyrosines, individually or in combination, did not impair costimulation. Therefore, of the four CD28 tyrosine residues only Tyr188 is required for signaling in Jurkat cells, suggesting that its phosphorylation is a key event in the costimulation of T cells.     

Mapping oak decline through long-term analysis of time series of satellite images in the forests of Malekshahi,Iran

ABSTRACT

The Zagros Mountains forests extend across 11 provinces in Iran and constitute approximately 40.0% of the country’s woodlands. These forests have important soil conservation and water regulation functions. Over the last decade, these forests have been declining in oak populations in many places, triggered by factors such as drought, pathogens like the fungus Biscogniauxia mediterranea, and pests such as borer beetles. Mapping the regions that show such a decline is the first step to addressing and managing the risks posed by this environmental calamity. In this research, we focus on the forests surrounding Malekshahi city in the Ilam province of Iran. Using Landsat data from the years 2000 to 2016, we determined the spatial distribution of oak decline in the region. After applying a forest/non-forest classification, appropriate spectral indices including Enhanced Vegetation Index (EVI), Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) were selected. Together with ground truth data, two regression methods (linear regression and support vector regression (SVR)) were used to model the decline score of each pixel based on the slope of variation of selected spectral indices during the observed 17 years. The oak forests were then classified into four categories: healthy forests, low-severity-declined forests, mid-severity declined forests, and high-severity declined forests, based on the respective estimated decline scores. SVR mapped different severities of oak decline with an overall accuracy of 51%, which appears to be due to the dependency of the method on the time of decline during the 17-year timeframe. However, in a binary classification mode – meaning classifying decline score to be either ‘Healthy’ or ‘decline’ – both regression methods were able to detect declined pixels with a producer’s accuracy of 100%.     

Multifunctional Triboelectric Nanogenerator-Enabled Structural Elements for Next Generation Civil Infrastructure Monitoring Systems

There is a critical shortage in research needed to explore a new class of multifunctional structural components that respond to their environment, empower themselves and self-monitor their condition. Here, the novel concept of triboelectric nanogenerator-enabled structural elements (TENG-SEs) is proposed to build the foundation for the next generation civil infrastructure systems with intrinsic sensing and energy harvesting functionalities. In order to validate the proposed concept, proof-of-concept multifunctional composite rebars with built-in TENG mechanisms are developed. The developed prototypes function as structural reinforcements, nanogenerators, and distributed sensing mediums under external mechanical vibrations. Experiential and theoretical studies are performed to verify the electrical and mechanical performance of the developed self-powering and self-sensing composite structural components. The capability of the embedded structural elements to detect damage patterns in concrete beams at multiscale is demonstrated. Finally, it is discussed how this new class of TENG-SEs can revolutionize the large-scale distributed monitoring practices in civil infrastructure and construction fields.     

The Minimum Vulnerability Problem

We revisit the problem of finding \(k\) paths with a minimum number of shared edges between two vertices of a graph. An edge is called shared if it is used in more than one of the \(k\) paths. We provide a \({\lfloor {k/2}\rfloor }\) -approximation algorithm for this problem, improving the best previous approximation factor of \(k-1\) . We also provide the first approximation algorithm for the problem with a sublinear approximation factor of \(O(n^{3/4})\) , where \(n\) is the number of vertices in the input graph. For sparse graphs, such as bounded-degree and planar graphs, we show that the approximation factor of our algorithm can be improved to \(O(\sqrt{n})\) . While the problem is NP-hard, and even hard to approximate to within an \(O(\log n)\) factor, we show that the problem is polynomially solvable when \(k\) is a constant. This settles an open problem posed by Omran et al. regarding the complexity of the problem for small values of \(k\) . We present most of our results in a more general form where each edge of the graph has a sharing cost and a sharing capacity, and there is a vulnerability parameter \(r\) that determines the number of times an edge can be used among different paths before it is counted as a shared/vulnerable edge.     

Quantization effects in inversion layers of PMOSFETs on Si (100)substrates

The 2-D hole gas distributions within inversion layers of PMOSFETs have been evaluated by solving the coupled Schrodinger equation and Poisson equation self-consistently based on the effective mass approximation with the light hole and heavy hole subbands taken into account. The threshold voltage shift resulting from the carrier redistribution due to quantization effects is found to be more significant for PMOSFETs than NMOSFETs on (110) Si substrates. For a certain substrate doping concentration the threshold voltage shift from the classical value due to quantization effects is found to be a combination of substrate band bending and oxide potential differences between the classical and the quantum mechanical models     

Speed and efficiency in multiple p-i-n photodetectors

We present a theoretical evaluation of the application of multiple intrinsic layers to enhancing the quantum efficiency of high-speed p-i-n photodetectors. It is shown that the use of multiple layers may lead to substantial improvements in the efficiency of detectors operating in the 20-100-GHz range, provided that the device area is reduced to limit the intrinsic capacitance and special care is taken to avoid large parasitic effects. Potential fabrication schemes are discussed