Manejo antecipado do nitrogênio nas principais culturas anuais.

Introdução; Balanço do nitrogênio com ênfase em suas perdas; Manejo do nitrogênio; Antecipação da adubação nitrogenada; Efeito salino dos adubos nitrogenados; Resultados práticos obtidos com o manejo antecipado do nitrogênio; Considerações importantes; Perguntas, na visão da Fitotecnia, sobre a prática da adubação nitrogenada em cobertura, para as quais, possivelmente, ainda não se tem resposta; Conclusões.bitstream/CNPAF/25056/1/doc_188.pd

Onset of virus systemic infection in plants is determined by speed of cell-to-cell movement and number of primary infection foci

The cornerstone of today's plant virology consists of deciphering the molecular and mechanistic basis of host-pathogen interactions. Among these interactions, the onset of systemic infection is a fundamental variable in studying both within-and between-host infection dynamics, with implications in epidemiology. Here, we developed a mechanistic model using probabilistic and spatio-temporal concepts to explain dynamic signatures of virus systemic infection. The model dealt with the inherent characteristic of plant viruses to use two different and sequential stages for their within-host propagation: cell-to-cell movement from the initial infected cell and systemic spread by reaching the vascular system. We identified the speed of cell-to-cell movement and the number of primary infection foci in the inoculated leaf as the key factors governing this dynamic process. Our results allowed us to quantitatively understand the timing of the onset of systemic infection, describing this global process as a consequence of local spread of viral populations. Finally, we considered the significance of our predictions for the evolution of plant RNA viruses.This work was supported by the grant no. BFU2012-30805 from Spain Ministerio de Economia y Competitividad (MINECO) to S. F. E. G. R. was supported by an EMBO long-term fellowship co-funded by Marie Curie actions (ALTF-1177-2011) and an AXA post-doctoral fellowship, and M.P.Z. by a Juan de la Cierva post-doctoral contract (JCI-2011-10379) from MINECO.Rodrigo Tarrega, G.; Zwart, MP.; Elena Fito, SF. (2014). Onset of virus systemic infection in plants is determined by speed of cell-to-cell movement and number of primary infection foci. Interface. 11(98):1-8. https://doi.org/10.1098/rsif.2014.0555S181198Waigmann, E., Ueki, S., Trutnyeva, K., & Citovsky, V. (2004). The Ins and Outs of Nondestructive Cell-to-Cell and Systemic Movement of Plant Viruses. Critical Reviews in Plant Sciences, 23(3), 195-250. doi:10.1080/07352680490452807Waterhouse, P. M., Wang, M.-B., & Lough, T. (2001). Gene silencing as an adaptive defence against viruses. Nature, 411(6839), 834-842. doi:10.1038/35081168Dunoyer, P., Lecellier, C.-H., Parizotto, E. A., Himber, C., & Voinnet, O. (2004). RETRACTED: Probing the MicroRNA and Small Interfering RNA Pathways with Virus-Encoded Suppressors of RNA Silencing. The Plant Cell, 16(5), 1235-1250. doi:10.1105/tpc.020719Kermack, W. O., & McKendrick, A. G. (1927). A Contribution to the Mathematical Theory of Epidemics. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 115(772), 700-721. doi:10.1098/rspa.1927.0118Segarra, J., Jeger, M. J., & van den Bosch, F. (2001). Epidemic Dynamics and Patterns of Plant Diseases. Phytopathology, 91(10), 1001-1010. doi:10.1094/phyto.2001.91.10.1001Keeling, M. (2005). The implications of network structure for epidemic dynamics. Theoretical Population Biology, 67(1), 1-8. doi:10.1016/j.tpb.2004.08.002Dolja, V. V., McBride, H. J., & Carrington, J. C. (1992). Tagging of plant potyvirus replication and movement by insertion of beta-glucuronidase into the viral polyprotein. Proceedings of the National Academy of Sciences, 89(21), 10208-10212. doi:10.1073/pnas.89.21.10208Zwart, M. P., Daròs, J.-A., & Elena, S. F. (2011). One Is Enough: In Vivo Effective Population Size Is Dose-Dependent for a Plant RNA Virus. PLoS Pathogens, 7(7), e1002122. doi:10.1371/journal.ppat.1002122Bedoya, L. C., Martínez, F., Orzáez, D., & Daròs, J.-A. (2012). Visual Tracking of Plant Virus Infection and Movement Using a Reporter MYB Transcription Factor That Activates Anthocyanin Biosynthesis. Plant Physiology, 158(3), 1130-1138. doi:10.1104/pp.111.192922Lafforgue, G., Tromas, N., Elena, S. F., & Zwart, M. P. (2012). Dynamics of the Establishment of Systemic Potyvirus Infection: Independent yet Cumulative Action of Primary Infection Sites. Journal of Virology, 86(23), 12912-12922. doi:10.1128/jvi.02207-12Holmes, F. O. (1929). Local Lesions in Tobacco Mosaic. Botanical Gazette, 87(1), 39-55. doi:10.1086/333923BALD, J. G. (1937). THE USE OF NUMBERS OF INFECTIONS FOR COMPARING THE CONCENTRATION OF PLANT VIRUS SUSPENSIONS: DILUTION EXPERIMENTS WITH PURIFIED SUSPENSIONS. Annals of Applied Biology, 24(1), 33-55. doi:10.1111/j.1744-7348.1937.tb05019.xBaulcombe, D. (2004). RNA silencing in plants. Nature, 431(7006), 356-363. doi:10.1038/nature02874Kunkel, B. N., & Brooks, D. M. (2002). Cross talk between signaling pathways in pathogen defense. Current Opinion in Plant Biology, 5(4), 325-331. doi:10.1016/s1369-5266(02)00275-3Kørner, C. J., Klauser, D., Niehl, A., Domínguez-Ferreras, A., Chinchilla, D., Boller, T., … Hann, D. R. (2013). The Immunity Regulator BAK1 Contributes to Resistance Against Diverse RNA Viruses. Molecular Plant-Microbe Interactions, 26(11), 1271-1280. doi:10.1094/mpmi-06-13-0179-rRodrigo, G., Carrera, J., Jaramillo, A., & Elena, S. F. (2010). Optimal viral strategies for bypassing RNA silencing. Journal of The Royal Society Interface, 8(55), 257-268. doi:10.1098/rsif.2010.0264Kleczkowski, A. (1950). Interpreting Relationships between the Concentrations of Plant Viruses and Numbers of Local Lesions. Journal of General Microbiology, 4(1), 53-69. doi:10.1099/00221287-4-1-53Van der Plank, J. E. (1965). Dynamics of Epidemics of Plant Disease: Population bursts of fungi, bacteria, or viruses in field and forest make an interesting dynamical study. Science, 147(3654), 120-124. doi:10.1126/science.147.3654.120Zwart, M. P., Daròs, J.-A., & Elena, S. F. (2012). Effects of Potyvirus Effective Population Size in Inoculated Leaves on Viral Accumulation and the Onset of Symptoms. Journal of Virology, 86(18), 9737-9747. doi:10.1128/jvi.00909-12Carrington, J. C., Kasschau, K. D., Mahajan, S. K., & Schaad, M. C. (1996). Cell-to-Cell and Long-Distance Transport of Viruses in Plants. The Plant Cell, 1669-1681. doi:10.1105/tpc.8.10.1669Gibbs, A. (1976). Viruses and Plasmodesmata. Intercellular Communication in Plants: Studies on Plasmodesmata, 149-164. doi:10.1007/978-3-642-66294-2_8Hillung, J., Elena, S. F., & Cuevas, J. M. (2013). Intra-specific variability and biological relevance of P3N-PIPO protein length in potyviruses. BMC Evolutionary Biology, 13(1), 249. doi:10.1186/1471-2148-13-249Dengler, N., & Kang, J. (2001). Vascular patterning and leaf shape. Current Opinion in Plant Biology, 4(1), 50-56. doi:10.1016/s1369-5266(00)00135-7SAMUEL, G. (1934). The Movement of Tobacco Mosaic Virus Within the Plant. Annals of Applied Biology, 21(1), 90-111. doi:10.1111/j.1744-7348.1934.tb06891.xKawakami, S., Watanabe, Y., & Beachy, R. N. (2004). Tobacco mosaic virus infection spreads cell to cell as intact replication complexes. Proceedings of the National Academy of Sciences, 101(16), 6291-6296. doi:10.1073/pnas.0401221101Bedoya, L., Martínez, F., Rubio, L., & Daròs, J.-A. (2010). Simultaneous equimolar expression of multiple proteins in plants from a disarmed potyvirus vector. Journal of Biotechnology, 150(2), 268-275. doi:10.1016/j.jbiotec.2010.08.006Wei, T., Zhang, C., Hong, J., Xiong, R., Kasschau, K. D., Zhou, X., … Wang, A. (2010). Formation of Complexes at Plasmodesmata for Potyvirus Intercellular Movement Is Mediated by the Viral Protein P3N-PIPO. PLoS Pathogens, 6(6), e1000962. doi:10.1371/journal.ppat.1000962Bragard, C., Caciagli, P., Lemaire, O., Lopez-Moya, J. J., MacFarlane, S., Peters, D., … Torrance, L. (2013). Status and Prospects of Plant Virus Control Through Interference with Vector Transmission. Annual Review of Phytopathology, 51(1), 177-201. doi:10.1146/annurev-phyto-082712-102346Sacristan, S., Diaz, M., Fraile, A., & Garcia-Arenal, F. (2011). Contact Transmission of Tobacco Mosaic Virus: a Quantitative Analysis of Parameters Relevant for Virus Evolution. Journal of Virology, 85(10), 4974-4981. doi:10.1128/jvi.00057-11Sanchez-Navarro, J. A., Zwart, M. P., & Elena, S. F. (2013). Effects of the Number of Genome Segments on Primary and Systemic Infections with a Multipartite Plant RNA Virus. Journal of Virology, 87(19), 10805-10815. doi:10.1128/jvi.01402-1

Network structure of social coding in GitHub

Abstract—Social coding enables a different experience of software development as the activities and interests of one developer are easily advertized to other developers. Developers can thus track the activities relevant to various projects in one umbrella site. Such a major change in collaborative software development makes an investigation of networkings on social coding sites valuable. Furthermore, project hosting platforms promoting this development paradigm have been thriving, among which GitHub has arguably gained the most momentum. In this paper, we contribute to the body of knowledge on social coding by investigating the network structure of social coding in GitHub. We collect 100,000 projects and 30,000 developers from GitHub, construct developer-developer and project-project relationship graphs, and compute various characteristics of the graphs. We then identify influential developers and projects on this subnetwork of GitHub by using PageRank. Understanding how developers and projects are actually related to each other on a social coding site is the first step towards building tool supports to aid social programmers in performing their tasks more efficiently. I

Popularity, interoperability, and impact of programming languages in 100,000 open source projects

Abstract—Programming languages have been proposed even before the era of the modern computer. As years have gone, computer resources have increased and application domains have expanded, leading to the proliferation of hundreds of programming languages, each attempting to improve over others or to address new programming paradigms. These languages range from procedural languages like C, objectoriented languages like Java, and functional languages such as ML and Haskell. Unfortunately, there is a lack of large scale and comprehensive studies that examine the “popularity”, “interoperability”, and “impact ” of various programming languages. To fill this gap, this study investigates a hundred thousands of open source software projects from GitHub to answer various research questions on the “popularity”, “interoperability ” and “impact ” of various languages measured in different ways (e.g., in terms of lines of code, development teams, issues, etc.). Keywords-Programming languages; Popularity; Interoperability; Open source; Software projects; GitHu

Orion: A software project search engine with integrated diverse software artifacts

Abstract—Software projects produce a wealth of data that is leveraged in different tasks and for different purposes: researchers collect project data for building experimental datasets; software programmers reuse code from projects; developers often explore the opportunities for getting involved in the development of a project to gain or offer expertise. Finding relevant projects that suit one needs is however currently challenging with the capabilities of existing search systems. We propose Orion, an integrated search engine architecture that combines information from different types of software repositories from multiple sources to facilitate the construction and execution of advanced search queries. Orion provides a declarative query language that gives to users access to a uniform interface where it transparently integrates different artifacts of project development and maintenance, such as source code information, version control systems metadata, bug tracking systems elements, and metadata on developer activities and interactions extracted from hosting platforms. We have built an extensible system with an initial capability of over 100,000 projects collected from the web, featuring several types of software repositories and software development artifacts. We conducted an experiment with 10 search scenarios to compare Orion with traditional search engines, and explore the need for our approach as well as the productivity of the proposed infrastructure. The results show with strong statistical significance that users find relevant projects faster and more accurately with Orion. I

Empirical evaluation of bug linking

International audienceTo collect software bugs found by users, development teams often setup bug trackers using systems such as Bugzilla. Developers would then fix some of the bugs and commit corresponding code changes into version control systems such as svn or git. Unfortunately, the links between bug reports and code changes are missing for many software projects as the bug tracking and version control systems are often maintained separately. Yet, linking bug reports to fix commits is important as it could shed light into the nature of bug fixing processes and expose patterns in software management. Bug linking solutions, such as ReLink, have been proposed. The demonstration of their effectiveness however faces a number of issues, including a reliability issue with their ground truth datasets as well as the extent of their measurements. We propose in this study a benchmark for evaluating bug linking solutions. This benchmark includes a dataset of about 12,000 bug links from 10 programs. These true links between bug reports and their fixes have been provided during bug fixing processes. We designed a number of research questions, to assess both quantitatively and qualitatively the effectiveness of a bug linking tool. Finally, we apply this benchmark on ReLink to report the strengths and limitations of this bug linking tool

Diagnóstico das pragas do arroz em assentamentos do Incra em Formoso do Araguaia, TO.

Com o objetivo de diagnosticar a situação atual de controle de pragas no ambiente dos assentamentos, foram aplicados questionários dirigidos aos produtores