Studying Paths of Participation in Viral Diffusion Process

Authors propose a conceptual model of participation in viral diffusion process composed of four stages: awareness, infection, engagement and action. To verify the model it has been applied and studied in the virtual social chat environment settings. The study investigates the behavioral paths of actions that reflect the stages of participation in the diffusion and presents shortcuts, that lead to the final action, i.e. the attendance in a virtual event. The results show that the participation in each stage of the process increases the probability of reaching the final action. Nevertheless, the majority of users involved in the virtual event did not go through each stage of the process but followed the shortcuts. That suggests that the viral diffusion process is not necessarily a linear sequence of human actions but rather a dynamic system.Comment: In proceedings of the 4th International Conference on Social Informatics, SocInfo 201

IMG 305 - PEMBUNGKUSAN MAKANAN NOV.05.

We discuss the use of Agent-based Modelling for the development and testing of theories about emergent social phenomena in marketing and the social sciences in general. We address both theoretical aspects about the types of phenomena that are suitably addressed with this approach and practical guidelines to help plan and structure the development of a theory about the causes of such a phenomenon in conjunction with a matching ABM. We argue that research about complex social phenomena is still largely fundamental research and therefore an iterative and cyclical development process of both theory and model is to be expected. To better anticipate and manage this process, we provide theoretical and practical guidelines. These may help to identify and structure the domain of candidate explanations for a social phenomenon, and furthermore assist the process of model implementation and subsequent development. The main goal of this paper was to make research on complex social systems more accessible and help anticipate and structure the research process

Studies On The Reproductive Biology Of Melastomataceae In 'cerrado' Vegetation

Controlled pollinations and observations of pollen tube growth, pollen fertility and cytological data were studied in 11 species of Melastomataceae growing in 'cerrado' in SE Brazil. Seven species produced apomictic fruits with viable seeds. Four species were not apomictic, with two self-incompatible (gametophytic SI) and two self-compatible, one showing spontaneous self-pollination. The apomictic species had lower pollen fertility than sexual ones - although in some cases differences were not significant - showing that low pollen fertility may be a useful indicator of apomixis if analysed using careful sampling supplemented by emasculation experiments. The apomictic species also showed meiotic irregularities, probably related to hybridization, polyploidy and the cause of low pollen fertility. Apomixis in this group probably is more associated with taxonomy and phylogeny than habitat or habit, since 85% of the apomictic species reported in the literature belong to the tribe Miconieae and occur in a wide range of vegetation types and have diverse habits. This suggests the existence of very extensive apomictic complexes comparable to those reported in mainly temperate genera of Asteraceae and Rosaceae.2111-21329Almeda, F., Systematics of the neotropical genus Centradenia (Melastomataceae) (1977) J. Arnold Arbor, 85, pp. 73-108Systematics of the genus Monochaetum (Melastomataceae) in Mexico and Central America (1978) Univ. Califonia Publ. Bot., 75, pp. 1-134Chuang, T.I., Chromosome numbers and their systematic significance in some Mexican Melastomataceae (1992) Syst. Bot., 17, pp. 583-593Baker, H.G., Bawa, K.S., Frankie, G.W., Opler, P.A., Reproductive biology of plants in tropical forests (1983) Tropical Rain Forest Ecosystems -Structure and Function, , GOLLEY, F. B., (Ed.): Amsterdam: ElsevierBaumgratz, J.F.A., Silva, N.M.F., Ecologia da polinização e biologia da reprodução de Miconia stenostachya DC. (Melastomataceae) (1988) Rodriguesia, 64-66, pp. 11-23Bayer, R.J., Patterns of clonal diversity in the Antennaria rosea (Asteraceae) polyploid agamic complex (1990) Amer. J. Bot., 77, pp. 1313-1319Berry, P.E., Tobe, H., Gomez, J.A., Agamospermy and loss of distyly in Erythroxylum undulatum from Northern Venezuela (1991) Amer. J. Bot., 78, pp. 595-600Bierzychudek, P., Patterns in plant parthenogenesis (1987) The Evolution of Sex and Its Consequences, , STEARNS, S. C., (Ed.): Basel: BirkhäuserBorges, H.B.N., (1991) Biologia Reprodutiva de Quatro Espécies de Melastomataceae, , M.Sc. Thesis, Universidade Estadual de Campinas, BrazilBurnham, C.R., (1962) Discussions in Cytogenetics, , Minneapolis: BurgessDent-Acosta, S.R., Breckon, G.J., Reproductive biology of six species of Melastomataceae in Western Porto Rico (1991) First International Melastomataceae Symposium, , Washington: Smithsonian InstitutionEthridge, A.L., Herr, J.M., The development of the ovule and megagametophyte in Rhexia mariana (1968) Canad. J. Bot., 46, pp. 133-139Gentry, A.H., Flowering phenology and diversity in tropical Bignoniaceae (1974) Biotropica, 6, pp. 64-68Giannotti, E., (1988) Composição Florística e Estrutura Fitossociológica da Vegetação de Cerrado e Mata Ciliar da Estação Experimental de Itirapina (SP), , M.Sc. Thesis, Universidade Estadual de Campinas, BrazilGibbs, P., Self-incompatibility in flowering plants: A neotropical perspective (1990) Revista Brasil. Bot., 13, pp. 125-136Gross, C.L., The breeding system and pollinators of Melastoma affine (Melastomataceae), a pioneer shrub in Tropical Australia (1993) Biotropica, 25, pp. 468-473Guimarães, P.J.F., Stranghetti, V., Ranga, N.T., Polinização e reprodução de Rhynchanthera dichotoma (LAM.) DC. (Melastomataceae) (1993) Anais do XX Colóquio de Incentivo à Pesquisa, , São José R. Preto: UNESPGustaffsson, A., Apomixis in higher plants. Part I. The mechanism of apomixis (1946) Acta Univ. Lund, 42, pp. 1-66Apomixis in higher plants. Part II. Causal aspects (1947) Acta Univ. Lund, 43, pp. 72-178Apomixis in higher plants. Part III. Biotype and species formation (1947) Acta Univ. Lund, 43, pp. 183-349Ha, C.O., Sands, V.E., Soepadmo, E., Jong, K., Reproductive patterns of selected understorey trees in the Malaysian rain forest: The apomictic species (1988) Bot. J. Linn. Soc., 97, pp. 317-331Kaur, A., Ha, C.O., Jong, K., Sands, V.E., Chan, H.T., Soepadmo, E., Ashton, P.S., Apomixis may be widespread among trees of the climax rain forest (1978) Nature, 271, pp. 404-442Magnusson, W.E., Sanaiotti, T.M., Dispersal of Miconia seeds by the rat Bolomys lasiurus (1987) J. Trop. Ecol., 3, pp. 277-278Martin, F.N., Staining and observing pollen tubes in the style by means of fluorescence (1959) Stain Technol., 34, pp. 125-128Melo, G.F.A., (1995) Biologia Floral e Sistema Reprodutivo de Cinco Espécies de Melastomataceae na Mata de Dois Irmãos, Recife, PE, , M.Sc. Thesis, Universidade Federal de Pernambuco, BrazilMogie, M., (1992) The Evolution of Asexual Reproduction in Plants, , London: Chapman & HailMori, S.A., Pipoly, J.S., Observations on the Big Bang flowering of Miconia minutiflora (1984) Brittonia, 36, pp. 337-341Nogler, G.A., Gametophytic apomixis (1984) Embryology of Angiosperms, , JOHRI, B. M., (Ed.): Berlin, Heidelberg, New York: SpringerNygren, A., Apomixis in angiosperms. Part II (1954) Bot. Rev., 20, pp. 577-649Oliveira, P.E.A.M., (1991) The Pollination and Reproductive Biology of a Cerrado Woody Community in Brazil, , Ph.D. Thesis, University of St. Andrews, UKGibbs, P.E., Barbosa, A.A., Talavera, S., Contrasting breeding systems in two Eriotheca (Bombacaceae) species of the Brazilian cerrados (1992) Pl. Syst. Evol., 179, pp. 207-219Piedade, L.H., Ranga, N.T., Ecologia da polinização de Galipea jasminiflora ENGLER (Rutaceae) (1993) Revista Brasil. Bot., 16, pp. 151-158Pinheiro, M.C.B., (1995) Biologia da Reprodução de Cinco Espécies da Melastomataceae da Restinga de Maricá - RJ, , Doctoral Thesis, Universidade Estadual de Campinas, BrazilPrance, G.T., Biogeography of neotropical plants (1987) Biogeography and Quaternary History in Tropical America, , WHITMORE, T. C., PRANCE, G. T., (Eds): Oxford: Clarendon PressRamirez, N., Brito, Y., Reproductive biology of a tropical palm swamp community in the Venezuelan llanos (1990) Amer. J. Bot., 77, pp. 1260-1271Renner, S.S., Reproductive biology of Bellucia (Melastomataceae) (1987) Acta Amazonica, 16-17, pp. 197-208Sandemania hoehnei (Melastomataceae: Tibouchineae): Taxonomy, distribution, and biology (1987) Brittonia, 39, pp. 441-446A survey of reproductive biology in neotropical Melastomataceae and Memecylaceae (1989) Ann. Missouri Bot. Gard., 76, pp. 496-518Phylogeny and classification of the Melastomataceae and Memecylaceae (1993) Nordic J. Bot., 13, pp. 519-540Richards, A.J., (1986) Plant Breeding Systems, , London: Allen & UnwinSaraiva, L.C., (1994) Biologia da Reprodução de Arbustos e Árvores do Cerrado em Corumbataí, Estado de S. Paulo, , Doctoral Thesis, Universidade Estadual Paulista, BrazilSobrevila, C., Arroyo, M.T.K., Breeding systems in a montane tropical cloud forest in Venezuela (1982) Pl. Syst. Evol., 140, pp. 19-37Sokal, R.R., Rohlf, F.J., (1981) Biometry, , New York: FreemanSolt, M.L., Wurdack, J.J., Chromosome number in Melastomataceae (1980) Phytologia, 47, pp. 199-220Stebbins, G.L., (1971) Chromosomal Evolution in Higher Plants, , London: Arnol

Optimal placement and selection of camera network nodes for target localization

Abstract. The paper studies the optimal placement of multiple cameras and the selection of the best subset of cameras for single target localization in the framework of sensor networks. The cameras are assumed to be aimed horizontally around a room. To conserve both computation and communication energy, each camera reduces its image to a binary “scan-line ” by performing simple background subtraction followed by vertical summing and thresholding, and communicates only the center of the detected foreground object. Assuming noisy camera measurements and an object prior, the minimum mean squared error of the best linear estimate of the object location in 2-D is used as a metric for placement and selection. The placement problem is shown to be equivalent to a classical inverse kinematics robotics problem, which can be solved efficiently using gradient descent techniques. The selection problem on the other hand is a combinatorial optimization problem and finding the optimal solution can be too costly to implement in an energy-constrained wireless camera network. A semi-definite programming approximation for the problem is shown to achieve close to optimal solutions with much lower computational burden. Simulation and experimental results are presented.