Defensive alliance polynomial

We introduce a new bivariate polynomial which we call the defensive alliance polynomial and denote it by da(G; x, y). It is a generalization of the alliance polynomial [Carballosa et al., 2014] and the strong alliance polynomial [Carballosa et al., 2016]. We show the relation between da(G; x, y) and the alliance, the strong alliance and the induced connected subgraph [Tittmann et al., 2011] polynomials. Then, we investigate information encoded in da(G; x, y) about G. We discuss the defensive alliance polynomial for the path graphs, the cycle graphs, the star graphs, the double star graphs, the complete graphs, the complete bipartite graphs, the regular graphs, the wheel graphs, the open wheel graphs, the friendship graphs, the triangular book graphs and the quadrilateral book graphs. Also, we prove that the above classes of graphs are characterized by its defensive alliance polynomial. A relation between induced subgraphs with order three and both subgraphs with order three and size three and two respectively, is proved to characterize the complete bipartite graphs. Finally, we present the defensive alliance polynomial of the graph formed by attaching a vertex to a complete graph. We show two pairs of graphs which are not characterized by the alliance polynomial but characterized by the defensive alliance polynomial

Amorphous Placement and Retrieval of Sensory Data in Sparse Mobile Ad-Hoc Networks

Abstract—Personal communication devices are increasingly being equipped with sensors that are able to passively collect information from their surroundings – information that could be stored in fairly small local caches. We envision a system in which users of such devices use their collective sensing, storage, and communication resources to query the state of (possibly remote) neighborhoods. The goal of such a system is to achieve the highest query success ratio using the least communication overhead (power). We show that the use of Data Centric Storage (DCS), or directed placement, is a viable approach for achieving this goal, but only when the underlying network is well connected. Alternatively, we propose, amorphous placement, in which sensory samples are cached locally and informed exchanges of cached samples is used to diffuse the sensory data throughout the whole network. In handling queries, the local cache is searched first for potential answers. If unsuccessful, the query is forwarded to one or more direct neighbors for answers. This technique leverages node mobility and caching capabilities to avoid the multi-hop communication overhead of directed placement. Using a simplified mobility model, we provide analytical lower and upper bounds on the ability of amorphous placement to achieve uniform field coverage in one and two dimensions. We show that combining informed shuffling of cached samples upon an encounter between two nodes, with the querying of direct neighbors could lead to significant performance improvements. For instance, under realistic mobility models, our simulation experiments show that amorphous placement achieves 10% to 40% better query answering ratio at a 25% to 35% savings in consumed power over directed placement.National Science Foundation (CNS Cybertrust 0524477, CNS NeTS 0520166, CNS ITR 0205294, EIA RI 0202067

Amorphous Placement and Informed Diffusion for Timely Monitoring by Autonomous, Resource-Constrained, Mobile Sensors

Personal communication devices are increasingly equipped with sensors for passive monitoring of encounters and surroundings. We envision the emergence of services that enable a community of mobile users carrying such resource-limited devices to query such information at remote locations in the field in which they collectively roam. One approach to implement such a service is directed placement and retrieval (DPR), whereby readings/queries about a specific location are routed to a node responsible for that location. In a mobile, potentially sparse setting, where end-to-end paths are unavailable, DPR is not an attractive solution as it would require the use of delay-tolerant (flooding-based store-carry-forward) routing of both readings and queries, which is inappropriate for applications with data freshness constraints, and which is incompatible with stringent device power/memory constraints. Alternatively, we propose the use of amorphous placement and retrieval (APR), in which routing and field monitoring are integrated through the use of a cache management scheme coupled with an informed exchange of cached samples to diffuse sensory data throughout the network, in such a way that a query answer is likely to be found close to the query origin. We argue that knowledge of the distribution of query targets could be used effectively by an informed cache management policy to maximize the utility of collective storage of all devices. Using a simple analytical model, we show that the use of informed cache management is particularly important when the mobility model results in a non-uniform distribution of users over the field. We present results from extensive simulations which show that in sparsely-connected networks, APR is more cost-effective than DPR, that it provides extra resilience to node failure and packet losses, and that its use of informed cache management yields superior performance

Développement de méthodes analytiques : détermination de médicaments dans les fluides biologiques et études de stabilité de nouveaux composés antiplasmodiaux in vitro

L'analyse de composés ou de métabolites dans les fluides biologiques nécessite des méthodes sélectives et très sensibles pour leur détection et leur quantification lors des études pharmacologiques et cliniques. La première partie du travail a pour objet l'analyse d'antiinflammatoires non stéroïdiens dans des médicaments et du sérum, par HPLC et détection de fluorescence. En complément, une comparaison entre l'HPLC avec fluorescence conventionnelle et la µHPLC avec fluorescence induite par laser a été menée pour déterminer la chloroquine et la quinine dans le sérum humain en utilisant de très faibles volumes d'échantillons injectés. Ceci a conduit à la méthode la plus sensible connue à ce jour (LOD < 2 femtomoles). Dans une seconde partie, la biotransformation de nouvelles entités chimiques (NCE) à activité antiplasmodiale a été étudiée en utilisant plusieurs systèmes analytiques incluant les méthodes LC-MS. La stabilité des NCE in vitro et leurs interactions avec les globules rouges ont été recherchées afin d'approcher leurs mécanismes d'action. L'utilisation de molécules marquées a permis de confirmer l'interprétation des spectres de masse et de comprendre les premières étapes de la biotransformation.The analysis of compounds and/or metabolites in biological fluids needs very sensitive and selective methods for the detection and quantification in pharmacological and clinical studies. The first part of the work concerns the determination of NSAIDs in pharmaceuticals and human serum by dual-mode gradient HPLC and fluorescence detection. In addition a comparison between HPLC with conventional fluorescence, and µHPLC with laser induced fluorescence detection was carried out to determine chloroquine and quinine in human serum, using very small injected samples. This resulted in the most sensitive method known to date (LOD < 2 femtomoles). In the second part of the work, the biotransformation of new chemical entities (NCEs) showing promising antiplasmodial activity has been studied with several analytical systems including LC-MS methods. The stability of the NCEs in vitro and their interactions with human red blood cells have been investigated to begin to understand their mechanisms of action. Tagged molecules have been used to confirm the interpretation of the mass spectra and the first step in the biotransformation pathway

Characterizations for split graphs and unbalanced split graphs

We introduce a characterization for split graphs by using edge contraction. Then, we use it to prove that any ($2K_{2}$, claw)-free graph with $\alpha(G) \geq 3$ is a split graph. Also, we apply it to characterize any pseudo-split graph. Finally, by using edge contraction again, we characterize unbalanced split graphs which we use to characterize the Nordhaus-Gaddum graphs

Dialogic vs. Formalist Teaching in Developing Argumentative Writing Discourse and Reducing Speaking Apprehension among EFL Majors

The current study, sought to investigate the influence of both formalist and dialogic teaching on EFL majors' argumentative writing and speaking apprehension. By using a positivistic experiment research design, and on analysing students' argumentative writing essays, it has been proved that both teaching approaches developed students' argumentative writing. However, statistical analysis showed that the dialogic teaching group students surpassed those of the formalist teaching. In addition, results revealed that speaking apprehension levels of the dialogic teaching students have significantly been reduced rather than those of the formalist teaching. The study ended with some conclusion and recommendations for further research

Edge Contraction and Line Graphs

Given a family of graphs $\mathcal{H}$, a graph $G$ is $\mathcal{H}$-free if any subset of $V(G)$ does not induce a subgraph of $G$ that is isomorphic to any graph in $\mathcal{H}$. We present sufficient and necessary conditions for a graph $G$ such that $G/e$ is $\mathcal{H}$-free for any edge $e$ in $E(G)$. Thereafter, we use these conditions to characterize claw-free and line graphs.Comment: arXiv admin note: text overlap with arXiv:2203.0349

Modified Phoenix Cell for Microstrip Reflectarray Antennas

This paper presents a newly developed modification to the structure of a linearly polarized reflectarray antenna cell, called Phoenix [1]. The idea of Phoenix is based on employing multi-resonators to improve the antenna bandwidth characteristics. Another interesting feature is the phase variation cycle which is characterized by a rebirth capability that was the reason behind the Phoenix name. The new developed modifications resulted in reducing the cell size by 0:16 o. In addition to improving the linearity of the phase variation characteristics which in turn reduced the phase errors by 10o compared to Phoenix. Two reflectarray antennas (200 x 200 mm2) were designed at 9:4 GHz in order to test the new modifications applied. The simulations and measurements indicated an increased antenna directivity for the new modified phoenix reflectarray antenna. Moreover, the measured gain of Phoenix and modified Phoenix at 9:4 GHz is 17:8 dB and 20:9 dB, respectively

Assessing EFL Learners’ Consecutive Interpreting Skills

Interpreting is taught to senior EFL learners in Saudi Faculties of Arts. Since it is a branch with a vast number of skills, the present study seeks to evaluate EFL learners’ interpreting skills. Forty graduate-level majors at Uqlat Asoqour Faculty of Arts, Qassim University were chosen randomly to sit for an interpreting test. A consecutive interpreting skills rubric was used to assess twelve interpreting skills over six points scale. Results of the statistical analysis showed variances among the subjects’ interpreting skills, with a need to tackle some of interpreting skills intensively in the translation and interpreting courses presented to EFL students in Faculties of Arts