Conceptos basicos de entomologia y manejo de plagas

The natural factors affecting insect pest mortality are described as an important aspect in the regulation of populations. Through graphs of population density vs. time, the position of equilibrium of an insect population, the economic threshold, and the level of economic damage are indicated. General aspects of var. resistance are discussed, namely: antixenosis, tolerance, and antibiosis, the latter regarding Apion godmani and Empoasca kraemeri. (CIAT)Se describen los factores naturales que afectan la mortalidad de los insectos plaga como aspecto importante en la regulacion de las poblaciones. Por medio de graficas de densidad de poblacion de insectos vs. tiempo, se indican la posicion de equilibrio en una poblacion de insectos, el umbral economico y el nivel de dano economico. Se discuten aspectos generales sobre resistencia var.: antixenosis, tolerancia y antibiosis, este ultimo haciendo referencia a Apion godmani y Empoasca kraemeri. (CIAT

Metodologia de investigacion en entomologia de frijol

The general objectives of CIAT's bean entomology program are mentioned. The 1st priority has been given to var. resistance as an ideal pest control method. At CIAT's headquarters (Palmira, Colombia), studies are conducted on Empoasca kraemeri, mites, and storage insects; var. resistance to Apion godmani and Epinotia aporema is being studied at other institutions. The steps of genetic improvement of beans for resistance to E. kraemeri are described: selection of sources of resistance, hybridization of selected materials, and selection of resistant progenies. (CIAT)Se mencionan los objetivos generales del programa de entomologia de frijol del CIAT. La mayor prioridad se ha dado a la resistencia var. como metodo ideal de control de plagas. En la sede principal del CIAT (Palmira, Colombia) se adelantan estudios con Empoasca kraemeri, acaros e insectos del frijol almacenado; en otras instituciones se esta estudiando la resistencia var. a Apion godmani y a Epinotia aporema. Se describen las etapas de mejoramiento genetico del frijol por resistencia a E. kraemeri: escogencia de fuentes de resistencia, hibridacion de los materiales seleccionados y seleccion de progenies resistentes. (CIAT

Identifying the Anthropological in a Mixed- Methods Study of Transnational Students in Mexican Schools

Identifying surveying as more commonly sociological and semistructured interviewing as more commonly anthropological, which describes disciplinary histories more than any fixed formulas, we juxtapose transnational students’ survey answers collected in Mexican schools with their answers to interviewers several months later. From this, we consider what can be learned about research methodology and transnational student cosmology when different methods yield discrepant answers. Without claiming superiority for either mechanism, we find their combination illuminating, and it substantiates the claim that anthropological inquiry can add crucial value to mixed-methods, interdisciplinary inquiry

\u3ci\u3ePensando en Cynthia y su Hermana\u3c/i\u3e: Educational Implications of United States–Mexico Transnationalism for Children

We use 3 brief educational biographies of students in Mexico who have previously attended public school in the United States to introduce this literature review on United States–Mexico transnational students. This article is also the first of several planned articles stemming from a currently ongoing, Consejo Nacional de Ciencia y Tecnologia-supported research study. As such, the purpose here is to highlight some of the dynamics faced by students who need to negotiate 2 educational systems (the United States and Mexico) and who fit neither a classic United States immigrant typology nor the typical premises around which schooling in Mexico is organized

Flight test results of riblets at supersonic speeds

A flight experiment to test and evaluate the skin friction drag characteristics of a riblet surface in turbulent flow at supersonic speeds was conducted at NASA Dryden. Riblets of groove sizes 0.0030 and 0.0013 in. were mounted on the F-104G flight test fixture. The test surfaces were surveyed with boundary layer rakes and pressure orifices to examine the boundary layer profiles and pressure distributions of the flow. Skin friction reductions caused by the riblet surface were reported based on measured differences of momentum thickness between the smooth and riblet surfaces obtained from the boundary layer data. Flight test results for the 0.0030 in. riblet show skin friction reductions of 4 to 8 % for Mach numbers ranging from 1.2 to 1.6 and Reynolds numbers ranging from 2 to 3.4 million per unit foot. The results from the 0.0013 in. riblets show skin friction reductions of 4 to 15 % for Mach 1.2 to 1.4 and Reynolds numbers ranging from 3.6 to 6 million per unit foot

Nanoenabled microelectromechanical sensor for volatile organic chemical detection

A nanoenabled gravimetric chemical sensor prototype based on the large scale integration of single-stranded DNA (ss-DNA) decorated single-walled carbon nanotubes (SWNTs) as nanofunctionalization layer for aluminum nitride contour-mode resonant microelectromechanical (MEM) gravimetric sensors has been demonstrated. The capability of two distinct single strands of DNA bound to SWNTs to enhance differently the adsorption of volatile organic compounds such as dinitroluene (simulant for explosive vapor) and dymethyl-methylphosphonate (simulant for nerve agent sarin) has been verified experimentally. Different levels of sensitivity (17.3 and 28 KHz µm^2/fg) due to separate frequencies of operation (287 and 450 MHz) on the same die have also been shown to prove the large dynamic range of sensitivity attainable with the sensor. The adsorption process in the ss-DNA decorated SWNTs does not occur in the bulk of the material, but solely involves the surface, which permits to achieve 50% recovery in less than 29 s

Fuel rich ammonia-hydrogen injection for humidified gas turbines

The use of new fuels and operating strategies for gas turbine technologies plays a relevant component for carbon emissions reduction and the use of sustainable energy sources. Among non-carbon fuels, hydrogen-based fuels have been proposed as one of the main strategies for decarbonisation of the power sector. Ammonia is a good representative of these fuels as it is carbon-free and the second largest chemical commodity, having been produced worldwide for more than a century from various energy resources, i.e. fossil fuels, biomass or other renewable sources. However, the use of ammonia as a fuel in industrial gas turbines brings some practical challenges directly linked to the final efficiency of these systems, especially when the latter are compared to current Dry Low Nitrogen Oxides technologies. Thus, this work covers a series of analytical, numerical and experimental studies performed to determine the efficiency of using ammonia/hydrogen blends in combination with humidified methodologies to deliver competitive systems for the use of ammonia-hydrogen power generation. The study was conducted using CHEMKIN-PRO reaction networks employing novel reaction chemical kinetics, in combination with bespoke analytical codes to determine efficiencies of systems previously calibrated experimentally. Finally, experimental trials using steam injection were carried out to determine potential of these blends. The novel results demonstrate that the use of humidified ammonia-hydrogen injection provides similar efficiencies to both Dry Low Nitrogen Oxides and humidified methane-based technologies ∼30%, with flames that are stable and low polluting under swirling conditions, thus opening the opportunity for further progression on the topic

The Relationship between Elementary Chemical Composition and Extraction Method for Protium Strumosum Daly Species Resin

The genus Protium Burm f., the most abundant of the Burseraceae family, has its primary center of diversity in the Amazon. Its main characteristic is the exudation of “Breu”, an aromatic resin collected directly from the trunk of the trees.Stimulating pastes have been used to increase resin flow, such as 2-chloroethylphosphonic (Ethephon). It is important to evaluate variations in the composition of the resin extracted naturally and with the use of the stimulant, to guarantee the product quality. The inorganic analysis is also fundamental to verify the presence of compounds harmful to health.A quali-quantitative elemental variation of the resin between the two extraction modes was proved by WD-XRF analysis. In 15 samples, Mg and F were only observed in those using Ethephon. In samples from the same tree, the qualitative difference is 54%, proving a discrepancy in the chemical composition of Breu, which can alter its properties

LO-phonon assisted polariton lasing in a ZnO based microcavity

Polariton relaxation mechanisms are analysed experimentally and theoretically in a ZnO-based polariton laser. A minimum lasing threshold is obtained when the energy difference between the exciton reservoir and the bottom of the lower polariton branch is resonant with the LO phonon energy. Tuning off this resonance increases the threshold, and exciton-exciton scattering processes become involved in the polariton relaxation. These observations are qualitatively reproduced by simulations based on the numerical solution of the semi-classical Boltzmann equations

DNA-Decorated Carbon Nanotubes as Sensitive Layer for AlN Contour-Mode Resonant-MEMS Gravimetric Sensor

In this work a nano-enabled gravimetric chemical sensor prototype based on single-stranded DNA (ss-DNA) decorated single-walled carbon nanotubes (SWNT) as nano-functionalization layer for Aluminun Nitride (AIN) contour-mode resonant-MEMS gravimetric sensors has been demonstrated. Two resonators fabricated on the same silicon chip and operating at different resonance frequencies, 287 and 450 MHz, were functionalized with this novel bio-coating layer to experimentally prove the capability of two distinct single strands of DNA bound to SWNT to enhance differently the adsorption of volatile organic compounds such as dinitroluene (DNT, simulant for explosive vapor) and dymethyl-methylphosphonate (DMMP, a simulant for nerve agent sarin). The introduction of this bio-coating layer addresses the major drawbacks of recovery time (50% recovery in less than 29 seconds has been achieved) and lack of selectivity associated with gas sensor based on polymers and pristine carbon nanotube functionalization layers