Migration control for mobile agents based on passport and visa

Research on mobile agents has attracted much attention as this paradigm has demonstrated great potential for the next-generation e-commerce. Proper solutions to security-related problems become key factors in the successful deployment of mobile agents in e-commerce systems. We propose the use of passport and visa (P/V) for securing mobile agent migration across communities based on the SAFER e-commerce framework. P/V not only serves as up-to-date digital credentials for agent-host authentication, but also provides effective security mechanisms for online communities to control mobile agent migration. Protection for mobile agents, network hosts, and online communities is enhanced using P/V. We discuss the design issues in details and evaluate the implementation of the proposed system

Algebraic analysis of Trivium-like ciphers

Trivium is a bit-based stream cipher in the final portfolio of the eSTREAM project. In this paper, we apply the approach of Berbain et al. to Trivium-like ciphers and perform new algebraic analyses on them, namely Trivium and its reduced versions: Trivium-N, Bivium-A and Bivium-B. In doing so, we answer an open question in the literature. We demonstrate a new algebraic attack on Bivium-A. This attack requires less time and memory than previous techniques which use the F4 algorithm to recover Bivium-A's initial state. Though our attacks on Bivium-B, Trivium and Trivium-N are worse than exhaustive keysearch, the systems of equations which are constructed are smaller and less complex compared to previous algebraic analysis. Factors which can affect the complexity of our attack on Trivium-like ciphers are discussed in detail

Effect of temporal fine structure on speech intelligibility modeling

Temporal fine structure (TFS) carries important information for the speech perception of hearing-impaired listeners and for the design of novel prosthetic hearing devices. This study assessed the performance of present intelligibility indices for predicting the intelligibility of speech containing different amount of TFS information. Speech intelligibility data was collected from vocoded and wideband Mandarin sentences containing little/partial and intact TFS information, respectively, and was then subjected to the correlation analysis with existing intelligibility indices. It was found that, though performing well in predicting the intelligibility of vocoded or wideband speech separately, present intelligibility indices were not highly correlated with the intelligibility scores when a general function was used to map all intelligibility measures to intelligibility scores. Analysis further showed that the intelligibility prediction power could be significantly improved when multiple condition-dependent functions were used for mapping intelligibility measures to intelligibility scores. © 2013 IEEE.published_or_final_versio

Optimal orientations of Vertex-multiplications of Trees with Diameter 4

\noindent Koh and Tay proved a fundamental classification of $G$ vertex-multiplications into three classes $\mathscr{C}_0, \mathscr{C}_1$ and $\mathscr{C}_2$. They also showed that any vertex-multiplication of a tree with diameter at least 3 does not belong to the class $\mathscr{C}_2$. Of interest, $G$ vertex-multiplications are extensions of complete $n$-partite graphs and Gutin characterised complete bipartite graphs with orientation number 3 (or 4 resp.) via an ingenious use of Sperner\u27s theorem. In this paper, we investigate vertex-multiplications of trees with diameter $4$ in $\mathscr{C}_0$ (or $\mathscr{C}_1$) and exhibit its intricate connections with problems in Sperner Theory, thereby extending Gutin\u27s approach. Let $s$ denote the vertex-multiplication of the central vertex. We almost completely characterise the case of even $s$ and give a complete characterisation for the case of odd $s\ge 3$

A Complete Characterisation of Vertex-multiplications of Trees with Diameter 5

For a connected graph $G$, let $\mathscr{D}(G)$ be the family of strong orientations of $G$; and for any $D\in\mathscr{D}(G)$, we denote by $d(D)$ the diameter of $D$. The $\textit{orientation number}$ of $G$ is defined as $\bar{d}(G)=\min\{d(D)\mid D\in \mathscr{D}(G)\}$. In 2000, Koh and Tay introduced a new family of graphs, $G$ vertex-multiplications, and extended the results on the orientation number of complete $n$-partite graphs. Suppose $G$ has the vertex set $V(G)=\{v_1,v_2,\ldots, v_n\}$. For any sequence of $n$ positive integers $(s_i)$, a $G$ \textit{vertex-multiplication}, denoted by $G(s_1, s_2,\ldots, s_n)$, is the graph with vertex set $V^*=\bigcup_{i=1}^n{V_i}$ and edge set $E^*$, where $V_i$\u27s are pairwise disjoint sets with $|V_i|=s_i$, for $i=1,2,\ldots,n$; and for any $u,v\in V^*$, $uv\in E^*$ if and only if $u\in V_i$ and $v\in V_j$ for some $i,j\in \{1,2,\ldots, n\}$ with $i\neq j$ such that $v_i v_j\in E(G)$. They proved a fundamental classification of $G$ vertex-multiplications, with $s_i\ge 2$ for all $i=1,2,\ldots, n$, into three classes $\mathscr{C}_0, \mathscr{C}_1$ and $\mathscr{C}_2$, and any vertex-multiplication of a tree with diameter at least 3 does not belong to the class $\mathscr{C}_2$. Furthermore, some necessary and sufficient conditions for $\mathscr{C}_0$ were established for vertex-multiplications of trees with diameter $5$. In this paper, we give a complete characterisation of vertex-multiplications of trees with diameter $5$ in $\mathscr{C}_0$ and $\mathscr{C}_1$

Assessing the Impact of Retreat Mechanisms in a Simple Antarctic Ice Sheet Model Using Bayesian Calibration

The response of the Antarctic ice sheet (AIS) to changing climate forcings is an important driver of sea-level changes. Anthropogenic climate change may drive a sizeable AIS tipping point response with subsequent increases in coastal flooding risks. Many studies analyzing flood risks use simple models to project the future responses of AIS and its sea-level contributions. These analyses have provided important new insights, but they are often silent on the effects of potentially important processes such as Marine Ice Sheet Instability (MISI) or Marine Ice Cliff Instability (MICI). These approximations can be well justified and result in more parsimonious and transparent model structures. This raises the question of how this approximation impacts hindcasts and projections. Here, we calibrate a previously published and relatively simple AIS model, which neglects the effects of MICI and regional characteristics, using a combination of observational constraints and a Bayesian inversion method. Specifically, we approximate the effects of missing MICI by comparing our results to those from expert assessments with more realistic models and quantify the bias during the last interglacial when MICI may have been triggered. Our results suggest that the model can approximate the process of MISI and reproduce the projected median melt from some previous expert assessments in the year 2100. Yet, our mean hindcast is roughly 3/4 of the observed data during the last interglacial period and our mean projection is roughly 1/6 and 1/10 of the mean from a model accounting for MICI in the year 2100. These results suggest that missing MICI and/or regional characteristics can lead to a low-bias during warming period AIS melting and hence a potential low-bias in projected sea levels and flood risks.Comment: v1: 16 pages, 4 figures, 7 supplementary files; v2: 15 pages, 4 figures, 7 supplementary files, corrected typos, revised title, updated according to revisions made through publication proces

Development and application of an UHPLC-MS/MS method for the simultaneous determination of 17 steroidal hormones in equine serum

A new, fast and simple analytical method that is able to identify and quantify simultaneously 17 steroid hormones and metabolites (Pregnenolone, 17-OH-Pregnenolone, Progesterone, 17-OH Progesterone, Androsterone, Androstenedione, DHEA, DHEAS, Testosterone, Cortisol, Corticosterone, Aldosterone, 11-Deoxycortisol, 11-Deoxycorticosterone, Dihydrotestosterone, Estrone, Estradiol) has been developed in equine serum using the UHPLC-MS/MS technique. 400 μL of sample were deproteinized with 1000 µl of acetonitrile, evaporated, restored with 50 µl of a solution of 25% methanol and injected in UHPLC-MS/MS triple quadrupole. The recovery percentage obtained by spiking the matrix at two different concentrations with a standard mixture of steroid hormones was in all cases higher than 85.60 % and with the percentage of coefficient of variation (CV) lower than 8.37%. The range of the correlation coefficients of the calibration curves of the analyzed compounds was 0.9922–0.9986, and the limits of detection (LODs) and limits of quantification (LOQs) were in the range of 0.002–2 ng ml-1 and 0.0055-5.5 ng ml-1, respectively. The detected LOQ for testosterone (i.e. 50 pg ml-1) is two-fold lower with respect to its threshold admitted in geldings plasma (100 pg ml-1 free testosterone). The high sensitivity and the quantitative aspect of the method permitted to detect most of steroids in equine serum. Once validated, the method was used to quantify 17 steroid hormones in mare, stallion and gelding serum samples. The main steroids detected were corticosterone (range 37.25-51.26 ng ml-1) and cortisol (range 32.57-52.24 ng ml-1), followed by 17-OH-pregnenolone, dihydrotestosterone and pregnenolone