Minimum Eccentricity Multicast Trees

We consider the problem of constructing a multicast tree that connects a group of source nodes to a group of sink nodes (receivers) and minimizes the maximum end-to-end delay between any pair of source/sink nodes. This is known as the \emphminimum eccentricity multicast tree problem, and is directly related to the quality of service requirements of real multipoint applications. We deal directly with the problem in its general form, meaning that the sets of source and sink nodes need not be overlapping nor disjoint. The main contribution of this work is a polynomial algorithm for this problem on general networks which is inspired by an innovative method that uses geometric relationships on the xy-plane

Associations of phase angle with platelet-activating factor metabolism and related dietary factors in healthy volunteers

IntroductionPhase angle (PA) is derived from bioelectrical impedance analysis (BIA). It reflects cell membrane function and decreases in disease. It is affected by inflammation, oxidative stress, and diet. Platelet-activating factor (PAF) is a potent inflammatory lipid mediator. Its levels, along with the activity of its metabolic enzymes, including CDP-choline:1-alkyl-2-acetyl-sn-glycerol-cholinephosphotransferase, acetyl-CoA:lyso-PAF-acetyltransferases, and PAF-AH/Lp-PLA2 are also related to dietary factors, such as the dietary antioxidant capacity (DAC). The aim of the study was to estimate whether the PAF metabolic circuit and related dietary factors are associated with PA in healthy volunteers.MethodsIn healthy subjects, PAF, its metabolic enzyme activity, and erythrocyte fatty acids were measured, while desaturases were estimated. Food-frequency questionnaires and recalls were used, and food groups, macronutrient intake, MedDietScore, and DAC were assessed. Lifestyle and biochemical variables were collected. DXA and BIA measurements were performed.ResultsLp-PLA2 activity was positively associated with PA (rho = 0.651, p < 0.001, total population; rho = 0.780, p < 0.001, women), while PAF levels were negatively associated with PA only in men (partial rho = −0.627, p = 0.012) and inversely related to DAC. Estimated desaturase 6 was inversely associated with PA (rho = −0.404, p = 0.01, total sample). Moreover, the DAC correlated positively with PA (rho = 0.513, p = 0.03, women). All correlations were adjusted for age, body mass index, and sex (if applicable).ConclusionPA is associated with PAF levels and Lp-PLA2 activity in a gender-dependent fashion, indicating the involvement of PAF in cell membrane impairment. The relationship of PA with DAC suggests a protective effect of antioxidants on cellular health, considering that antioxidants may inhibit PAF generation

Context-Driven Tour Planning Service: An Approach Based on Synthetic Coordinates Recommendation

The paper presents a hybrid context/model-based tour planning service aimed at recommendation generation by providing the tourists the sequence of attractions that are more interesting for him/her based on previous activity with the service. The service is developed based on SCoR recommender system that is aimed at recommendation generation based on calculating the synthetic coordinate between tourists of the service in according with their ratings. SCoR is a model-based collaborative filtering algorithm, constructing a model based on the user's personal ratings as well as exploiting collaborative information from the ratings of the rest of the users. One of the main advantages of SCoR's model is its ability to incorporate additional training information (new ratings) without having to perform the training process from the beginning. The prototype has been implemented for Android-based smartphone and has been evaluated for St. Petersburg city. For the evaluation the attraction database has been formed that includes attraction location information from OpenStreeMaps platform, location description and media from Wikipedia, and ratings from Google Place

Lipoprotein-associated phospholipase A2 (Lp-PLA2) activity, platelet-activating factor acetylhydrolase (PAF-AH) in leukocytes and body composition in healthy adults

<p>Abstract</p> <p>Background</p> <p>Lipoprotein-associated phospholipase A₂(Lp-PLA₂) also known as serum platelet activating factor acetylhydrolase (PAF-AH) activity constitutes a novel risk marker for cardiovascular disease. Leukocytes constitute one main cellular source of circulating Lp-PLA₂. The aim of the present study was to evaluate the association of both serum and leukocyte PAF-AH activities with fat distribution and lean tissue. One hundred healthy volunteers without cardiovascular disease history participated in this study (n = 52 men, 44 ± 13 years and n = 48 women, 43 ± 13 years). Body composition was assessed with dual-energy X-ray absorptiometry, while anthropometrical indices were also measured. The activity of Lp-PLA₂and levels of lipid and glycemic parameters were determined in fasting samples.</p> <p>Results</p> <p>Mean Lp-PLA₂activity was 24.8 ± 4.5 and 19.6 ± 5.0 nmol/min/mL in men and women, respectively (P < 0.001). Mean activity of PAF-AH in leukocyte homogenates was 386 ± 127 pmol/min/mg and 292 ± 92 pmol/min/mg in men and women, correspondingly (P < 0.001). In multiple regression models upper and total adiposity measures were positively associated with Lp-PLA₂activity in men after adjusting for LDL-cholesterol, age, smoking, hs-CRP and physical activity, whereas no associations were found with PAF-AH leukocyte homogenates activity. Hierarchical analysis revealed that the variables with the highest explanatory ability of Lp-PLA₂activity in men, were DXA deriving L1–L4 region of interest and arms fat (increase in R²= 0.136, P = 0.005 and increase in R²= 0.118, P = 0.009, respectively), followed by trunk fat and total fat. In women, no association of body composition variables with Lp-PLA₂nor PAF-AH leukocyte homogenates activity was found.</p> <p>Conclusion</p> <p>Lp-PLA₂activity is differentiated across levels of adiposity and topology of adipose tissue, whereas no association was found regarding PAF-AH leukocyte homogenates activity. Our findings suggest that Lp-PLA₂may compensate for the adiposity-associated increases in inflammatory and oxidative burden, in men.</p

Discovery and classification of Twitter bots

A very large number of people use Online Social Networks daily. Such platforms thus become attractive targets for agents that seek to gain access to the attention of large audiences, and influence perceptions or opinions. Botnets, collections of automated accounts controlled by a single agent, are a common mechanism for exerting maximum influence. Botnets may be used to better infiltrate the social graph over time and to create an illusion of community behavior, amplifying their message and increasing persuasion. This paper investigates Twitter botnets, their behavior, their interaction with user communities and their evolution over time. We analyzed a dense crawl of a subset of Twitter traffic, amounting to nearly all interactions by Greek-speaking Twitter users for a period of 36 months. We detected over a million events where seemingly unrelated accounts tweeted nearly identical content at nearly the same time. We filtered these concurrent content injection events and detected a set of 1,850 accounts that repeatedly exhibit this pattern of behavior, suggesting that they are fully or in part controlled and orchestrated by the same software. We found botnets that appear for brief intervals and disappear, as well as botnets that evolve and grow, spanning the duration of our dataset. We analyze statistical differences between bot accounts and human users, as well as botnet interaction with user communities and Twitter trending topics

Minimum Eccentricity Multicast Trees

We consider the problem of constructing a multicast tree that connects a group of source nodes to a group of sink nodes (receivers) and minimizes the maximum end-to-end delay between any pair of source/sink nodes. This is known as the \emphminimum eccentricity multicast tree problem, and is directly related to the quality of service requirements of real multipoint applications. We deal directly with the problem in its general form, meaning that the sets of source and sink nodes need not be overlapping nor disjoint. The main contribution of this work is a polynomial algorithm for this problem on general networks which is inspired by an innovative method that uses geometric relationships on the xy-plane

Minimum Eccentricity Multicast Trees

International audienceWe consider the problem of constructing a multicast tree that connects a group of source nodes to a group of sink nodes (receivers) and minimizes the maximum end-to-end delay between any pair of source/sink nodes. This is known as the \emphminimum eccentricity multicast tree problem, and is directly related to the quality of service requirements of real multipoint applications. We deal directly with the problem in its general form, meaning that the sets of source and sink nodes need not be overlapping nor disjoint. The main contribution of this work is a polynomial algorithm for this problem on general networks which is inspired by an innovative method that uses geometric relationships on the xy-plane

A Framework For Optimal Communication On The Multidimensional Torus Network

Efficient interprocessor communication is crucial to increasing the performance of parallel computers. In this paper, a special framework is developed on the multidimensional torus, a network that is currently receiving considerable attention. Using this framework as the basic tool, a number of spanning graphs with special properties, to fit various communication needs, are constructed on the network. The importance of these spanning graphs is demonstrated with the development of optimal algorithms for four fundamental communication problems, namely the single node and multinode broadcasting and the single node and multinode scattering, on the multidimensional torus network. Broadcasting is the distribution of the same group of messages from a source processor to all other processors, and scattering is the distribution of distinct groups of messages from a source processor to all other processors. We consider broadcasting and scattering from a single processor of the network (single n..

Optimal communication algorithms on star graphs using spanning tree constructions

In this paper we consider three fundamental communication problems on the star interconnection network: the problem of simultaneous broadcasting of the same message from every node to all other nodes, or multinode broadcasting, the problem of a single node sending distinct messages to each one of the other nodes, or single node scattering, and nally the problem of each node sending distinct messages to every other node, or total exchange. All of these problems are studied under two di erent assumptions: the assumption that each node can transmit a message of xed length to one of its neighbors and simultaneously it can receive a message of xed length from one of its neighbors (not necessarily the same one) at each time step, or single link availability (SLA), and the assumption that each node can exchange messages of xed length with all of its neighbors at each time step, or multiple link availability (MLA). In both cases communication is assumed to be bidirectional. The cases where the originating processor wishes to send only one or more than one message to each one of the other processors are distinguished when necessary. Lower bounds are derived for these problems under the stated assumptions, and optimal algorithms are designed in terms both of time and number of message transmissions. Although the algorithms derived for the rst two problems require the minimum amount of the above resources, the algorithm designed for the total exchang