Analysis of Secchi Depths and Light Attenuation Coefficients in the Louisiana-Texas Shelf, Northern Gulf of Mexico

We analyzed Secchi depths (Zs), scalar downwelling irradiance, and transmissometer data collected during 10 cruises that spanned two and one-half years (May 1992-Nov. 1994) over the Louisiana-Texas shelf. The Zs increases from the inner shelf (depths ≤50 m) to the outer shelf and from nonsummer (Zs =10m) to summer (Zs = 14m). These changes in Zs are induced by the shelf\u27s circulation and freshwater input, both of which vary seasonally, i.e., nonsummer to summer. Optical parameters (e.g., Zs), like the circulation, divide the shelf into an inner and outer shelf along the 50-m isobath. The inner shelf contains turbid waters with low levels of light penetration and large attenuation coefficients that decrease from nonsummer to summer. The outer shelf contains clearer water with high levels of light penetration and small attenuation coefficients year round. Linear regressions between the attenuation coefficients and Zs conform to theory and vary seasonally. The scalar downwelling attenuation coefficient and Zs are inversely related with coefficients of 1.36 in summer and 1.22 in nonsummer. The beam attenuation coefficient and Zs are also inversely related with coefficients of 6.16 in summer and 5.54 in nonsummer

A description of a knowledge broker role implemented as part of a randomized controlled trial evaluating three knowledge translation strategies

<p>Abstract</p> <p>Background</p> <p>A knowledge broker (KB) is a popular knowledge translation and exchange (KTE) strategy emerging in Canada to promote interaction between researchers and end users, as well as to develop capacity for evidence-informed decision making. A KB provides a link between research producers and end users by developing a mutual understanding of goals and cultures, collaborates with end users to identify issues and problems for which solutions are required, and facilitates the identification, access, assessment, interpretation, and translation of research evidence into local policy and practice. Knowledge-brokering can be carried out by individuals, groups and/or organizations, as well as entire countries. In each case, the KB is linked with a group of end users and focuses on promoting the integration of the best available evidence into policy and practice-related decisions.</p> <p>Methods</p> <p>A KB intervention comprised one of three KTE interventions evaluated in a randomized controlled trial.</p> <p>Results</p> <p>KB activities were classified into the following categories: initial and ongoing needs assessments; scanning the horizon; knowledge management; KTE; network development, maintenance, and facilitation; facilitation of individual capacity development in evidence informed decision making; and g) facilitation of and support for organizational change.</p> <p>Conclusion</p> <p>As the KB role developed during this study, central themes that emerged as particularly important included relationship development, ongoing support, customized approaches, and opportunities for individual and organizational capacity development. The novelty of the KB role in public health provides a unique opportunity to assess the need for and reaction to the role and its associated activities. Future research should include studies to evaluate the effectiveness of KBs in different settings and among different health care professionals, and to explore the optimal preparation and training of KBs, as well as the identification of the personality characteristics most closely associated with KB effectiveness. Studies should also seek to better understand which combination of KB activities are associated with optimal evidence-informed decision making outcomes, and whether the combination changes in different settings and among different health care decision makers.</p

Genomic Diversity and Introgression in O. sativa Reveal the Impact of Domestication and Breeding on the Rice Genome

The domestication of Asian rice (Oryza sativa) was a complex process punctuated by episodes of introgressive hybridization among and between subpopulations. Deep genetic divergence between the two main varietal groups (Indica and Japonica) suggests domestication from at least two distinct wild populations. However, genetic uniformity surrounding key domestication genes across divergent subpopulations suggests cultural exchange of genetic material among ancient farmers.In this study, we utilize a novel 1,536 SNP panel genotyped across 395 diverse accessions of O. sativa to study genome-wide patterns of polymorphism, to characterize population structure, and to infer the introgression history of domesticated Asian rice. Our population structure analyses support the existence of five major subpopulations (indica, aus, tropical japonica, temperate japonica and GroupV) consistent with previous analyses. Our introgression analysis shows that most accessions exhibit some degree of admixture, with many individuals within a population sharing the same introgressed segment due to artificial selection. Admixture mapping and association analysis of amylose content and grain length illustrate the potential for dissecting the genetic basis of complex traits in domesticated plant populations.Genes in these regions control a myriad of traits including plant stature, blast resistance, and amylose content. These analyses highlight the power of population genomics in agricultural systems to identify functionally important regions of the genome and to decipher the role of human-directed breeding in refashioning the genomes of a domesticated species

Origin of the Hurricane Ike forerunner surge

A large, unpredicted, water level increase appeared along a substantial section of the western Louisiana and northern Texas (LATEX) coasts 12-24 hrs in advance of the landfall of Hurricane Ike (2008), with water levels in some areas reaching 3 m above mean sea level. During this time the cyclonic wind field was largely shore parallel throughout the region. A similar early water level rise was reported for both the 1900 and the 1915 Galveston Hurricanes. The Ike forerunner anomaly occurred over a much larger area and prior to the primary coastal surge which was driven by onshore directed winds to the right of the storm track. We diagnose the forerunner surge as being generated by Ekman setup on the wide and shallow LATEX shelf. The longer forerunner time scale additionally served to increase water levels significantly in narrow-entranced coastal bays. The forerunner surge generated a freely propagating continental shelf wave with greater than 1.4 m peak elevation that travelled coherently along the coast to Southern Texas, and was 300 km in advance of the storm track at the time of landfall. This was, at some locations, the largest water level increase seen throughout the storm, and appears to be the largest freely-propagating shelf wave ever reported. Ekman setup-driven forerunners will be most significant on wide, shallow shelves subject to large wind fields, and need to be considered for planning and forecasting in these cases. Citation: Kennedy, A. B., U. Gravois, B. C. Zachry, J. J. Westerink, M. E. Hope, J. C. Dietrich, M. D. Powell, A. T. Cox, R. A. Luettich Jr., and R. G. Dean (2011), Origin of the Hurricane Ike forerunner surge, Geophys. Res. Lett., 38, L08608, doi: 10.1029/2011GL047090

Resposta do arroz irrigado à adubação verde e química no Estado de Tocantins Response of irrigated rice to green manure and chemical fertilization in the State of Tocantins

O arroz irrigado é uma cultura significativa para o País, do ponto de vista socioeconômico, em especial nas várzeas tropicais do Estado do Tocantins. Muitas vezes, devido ao uso de adubação inadequada, sua produtividade é limitada. Conduziram-se dois experimentos de campo, na Fazenda Xavante, município de Dueré, Estado do Tocantins, durante dois anos consecutivos, para se avaliar a resposta do arroz irrigado à adubação verde e química, cultivado em um Inceptissolo, cujos tratamentos consistiram de oito combinações de adubação: Adubo verde + N0P0K0; Adubo verde + N100P120K100; Adubo verde + N50P60K50; Adubo verde + N75P90K75; Adubo verde + N45P120K100 (aplicação de N, P e K no plantio); Adubo verde + N45P120K100 (aplicação de P e K no plantio e N em cobertura); Adubo verde + N100P120K100 + 4 Mg ha-1 calcário; e Sem adubo verde + N100P120K100. Obteve-se a produtividade máxima (kg ha-1) de grãos com o tratamento adubo verde + N45P120K100 (aplicação de P e K no plantio e N em cobertura). Entre os componentes da produtividade, o comprimento da panícula foi influenciado positiva e significativamente, pelos tratamentos de adubação. Com a prática da adubação verde, a quantidade de fertilizante nitrogenado a ser empregada pode ser reduzida e, em conseqüência, diminuir também o custo de produção do arroz irrigado.<br>Lowland rice is an important crop in Brazil due to its socio-economic value. Often due to inadequate fertilization, production is limited. Two field experiments were conducted at Xavante Farm, Municipality of Dueré, State of Tocantins, Brazil, during two consecutive years to determine the response of irrigated rice to green manure and to chemical fertilization grown in an Inceptisol. The treatments consisted of green manure + N0P0K0; green manure + N100P120K100; green manure + N50P60K50; green manure + N75P90K75; green manure + N45P120K100 (application of N, P, and K at sowing); green manure + N45P120K100 (application of P and K at sowing and N topdressing); green manure + N100P120K100 + 4 Mg lime ha-1; and without green manure + N100P120K100. Maximum grain yield was obtained with the application of green manure + N45P120K100 (application of P and K at sowing and N topdressing). Among yield components, panicle length was significantly and positively influenced by fertilization. These results show that green manure can reduce chemical fertilization, and hence cost of production