Evaluación de opciones alternativas al uso de agroquímicos para el manejo de nematodos fitoparasitos en el cultivo del cafe (Coffea arabica) en fincas de Masaya, Granada y Carazo

El presente estudio se realizó de octubre 2003 a marzo 2004, en cinco fincas de pequeños productores de Masaya, Granada y Carazo, con el objetivo de evaluar el efecto de alternativas de manejo no sintéticas sobre la población de nematodos fitoparásitos asociados al cultivo de café. En cada finca, se establecieron siete parcelas en las que se evaluaron los tratamientos:Gallinaza + biofertilizante + te de papaya (1); Gallinaza + biofertilizante + caldo sulfocálcico (2); Bio green + biofertilizante + te limonaria (3); Biofertilizante + torta de nim + fertilización diluida(4); Biofertilizante + pacelyn + fertilización diluida (5); Testigo absoluto (6); Cobre + fertilización diluida + Vidate L (7). Mensualmente se tomaron muestras de suelo y de raíz, las cuales fueron procesadas en el laboratorio de Nematología Agrícola de la Universidad Nacional Agraria, mediante las técnicas de tamizado más filtro de algodón, para las muestras de suelo; y licuadora más tamices para las muestras de raíz. Las muestras fueron tomadas utilizando barreno y pala, en el área comprendida entre los 15 centímetros del tronco de la planta y a 15 centímetros de profundidad. Las variables evaluadas fueron: Número de nematodos fitoparásitos por género presentes en 100 g de suelo y Número de nematodos fitoparásitos por género presentes en 25 g de raíces.Los resultados indican que tanto en muestras de suelo como de raíces, los géneros predominantes en las cinco fincas fueron Meloidogyne spp y Helicotylenchusspp. El tratamiento que presentó las poblaciones más bajas de nematodos fue Cobre + fertilización diluida + VidateL (7), y el que presentó las poblaciones más altas fue Gallinaza + biofertilizante + te de papaya. Con relación a la fluctuación población de los géneros de nematodo en las cinco fincas fue Meloidogynespp, el género que presentó las poblaciones más altas, alcanzando poblaciones hasta de 5000 nematodos en 25g de raíces en la finca Vista Alegre.En general las poblaciones de nematodos fueron altas en los meses de Noviembre y Enero, reduciéndose en los meses de Febrero y Marzo.

浮动磁头气动力静态特性

本文给出了最新浮动磁头的气动力静态特性。文中采用了数值方法求解滑流条件下滑块轴承的修正雷诺方程,描述了运用积分离散、Newton—Raphson线性化方法的有限差分法,给出了运用Booy方法的基本思想所形成的线性化有限差分方程组的数值计算方法,计算出在压缩数很大范围内(A可达5000以上)浮动磁头的气动参数。

计算机在振动频率分析中的应用

<正> 由于现代科学技术的发展,很多科学实验往往在很短时间内得到的实验数据就多到惊人的数目。如在各种随机振动(飞机、各种车辆的运行等产生的振动都属随机振动)的测试中,每次实验就有大量的信号记录下来,要随时进行分析判断。我们在东方红——40轮式拖拉机的随机振动测试这项工作中,对不同路面、速度等各种情况下,进行了几十个工况实验,而每个工况的实验就有3000～5000个数据,这样,数据就有十几万个要进行分析。这些数据要求的二次处理部分复杂,往往牵涉到系统固有频率的计算,由此判断结构在动载荷下的安全及对其它结构的影响。例如,在车辆系统中路面对驾驶员的影响,这就是一个计算共振频率的问题,这些工作以前是用模拟仪器分析,而且依赖于使用者的技术水平,速度慢精度低。而对于

Numerical investigation of dynamic stall of an oscillating aerofoil

The flow structure around an NACA 0012 aerofoil oscillating in pitch around the quarter-chord is numerically investigated by solving the two-dimensional compressible N-S equations using a special matrix-splitting scheme. This scheme is of second-order accuracy in time and space and is computationally more efficient than the conventional flux-splitting scheme. A 'rigid' C-grid with 149 x 51 points is used for the computation of unsteady flow. The freestream Mach number varies from 0.2 to 0.6 and the Reynolds number from 5000 to 20,000. The reduced frequency equals 0.25-0.5. The basic flow structure of dynamic stall is described and the Reynolds number effect on dynamic stall is briefly discussed. The influence of the compressibility on dynamic stall is analysed in detail. Numerical results show that there is a significant influence of the compressibility on the formation and convection of the dynamic stall vortex. There is a certain influence of the Reynolds number on the flow structure. The average convection velocity of the dynamic stall vortex is approximately 0.348 times the freestream velocity.

The positive floating potential of high-temperature particles in plasma

It has been predicted that the floating potential of particles in plasma may become positive when the particle surface temperature is high enough, but, to our knowledge, no positive floating potential has been obtained yet. In the present paper the floating potential theory of high-temperature particles in plasma is developed to cover the positive potential range for the first time, and a general approximate analytical formula for the positive floating potential with a thin plasma sheath and subsonic plasma flow is derived from the new model recently proposed by the authors. The results show that when the floating potential is positive, the net flux of charge incident on the particle approaches a constant similar to the 'electron saturation' phenomena in the case of the electric probes.

Upwind compact method and direct numerical-simulation of driven flow in a square cavity

A high-order accurate finite-difference scheme, the upwind compact method, is proposed. The 2-D unsteady incompressible Navier-Stokes equations are solved in primitive variables. The nonlinear convection terms in the governing equations are approximated by using upwind biased compact difference, and other spatial derivative terms are discretized by using the fourth-order compact difference. The upwind compact method is used to solve the driven flow in a square cavity. Solutions are obtained for Reynolds numbers as high as 10000. When Re less than or equal to 5000, the results agree well with those in literature. When Re = 7500 and Re = 10000, there is no convergence to a steady laminar solution, and the flow becomes unsteady and periodic.

Localización gráfica de los expedientes patrimoniales de Vitoria en el AHPA

Direcciones de correo electrónico de las autoras: amaya999@hotmail.com ; nagores@hotmail.es

Ist das Meer so tief, wie unsere Messgeräte angeben?

Das Institut für Fischereiökologie führt regelmäßig radioökologische Untersuchungen im früheren Versenkungsgebiet für schwach radioaktive Stoffe im Nordostatlantik durch (Vobach 2002). In diesem Zusammenhang werden an bestimmten Positionen Wasserproben aus verschiedenen Tiefen, von der Oberfläche bis hinab zum Grund in knapp 5000 m Tiefe genommen. Dabei hat es sich als zweckmäßig erwiesen, mittels eines Pingersystems (kurze 12 kHz Schallsignale) Tiefen bis etwa 3000 m als Entfernung vom Schiff und darunter liegende als Entfernung vom Grund (Bethke und Kellermann 1994) zu bestimmen. Damit einheitlich für alle Ergebnisse die Probenahmetiefe angegeben werden kann, muss die Entfernung vom Schiff bis zum Grund, also die Wassertiefe, bekannt sein.

后台阶流场大涡模拟的入口边界条件研究

对不同入口边界条件下后台阶下游三维流场进行了大涡模拟。讨论了层流及湍流入口流速剖面下边界层厚度及湍流度对台阶下游平均流速剖面、再附长度的影响。模拟结果表明,对于层流入口流速剖面,边界层厚度对再附长度的影响很大,随边界层厚度的增大,再附长度将增大。对于湍流入口流速剖面,边界层厚度对再附长度的影响不大,而入口湍流度则对再附长度有较大影响。随着入口湍流度的增加,再附长度将会变短。在雷诺数为5000情况下,当采用湍流入口流速剖面并选择湍流度为0.5%时,大涡模拟能得到与直接数值模拟基本一致的结果。

Learning and using taxonomies for visual and olfactory classification

Humans are able of distinguishing more than 5000 visual categories even in complex environments using a variety of different visual systems all working in tandem. We seem to be capable of distinguishing thousands of different odors as well. In the machine learning community, many commonly used multi-class classifiers do not scale well to such large numbers of categories. This thesis demonstrates a method of automatically creating application-specific taxonomies to aid in scaling classification algorithms to more than 100 cate- gories using both visual and olfactory data. The visual data consists of images collected online and pollen slides scanned under a microscope. The olfactory data was acquired by constructing a small portable sniffing apparatus which draws air over 10 carbon black polymer composite sensors. We investigate performance when classifying 256 visual categories, 8 or more species of pollen and 130 olfactory categories sampled from common household items and a standardized scratch-and-sniff test. Taxonomies are employed in a divide-and-conquer classification framework which improves classification time while allowing the end user to trade performance for specificity as needed. Before classification can even take place, the pollen counter and electronic nose must filter out a high volume of background “clutter” to detect the categories of interest. In the case of pollen this is done with an efficient cascade of classifiers that rule out most non-pollen before invoking slower multi-class classifiers. In the case of the electronic nose, much of the extraneous noise encountered in outdoor environments can be filtered using a sniffing strategy which preferentially samples the visensor response at frequencies that are relatively immune to background contributions from ambient water vapor. This combination of efficient background rejection with scalable classification algorithms is tested in detail for three separate projects: 1) the Caltech-256 Image Dataset, 2) the Caltech Automated Pollen Identification and Counting System (CAPICS) and 3) a portable electronic nose specially constructed for outdoor use.

Role of women in fish food security and poverty alleviation

The notions about women been limited to producing children like rates alone; cooking for the family, restricted within the fenced compound without any meaningful contributions in fish food production was dispelled during the course of the study. From the data gathered, the study revealed various contributions of women as regard fish food production as about 2% of the women are involved in direct fishing as this enhance food security of the family and the society. Also women dominate the entire post harvest and marketing sector and 70% started fishing business with their personal savings.Also, some of the women own boats and other fishing inputs, which they do give to the fishermen that could catch the fish and sell it to them. This has a way of enhancing fish catch and fish food security of the people as those men that would have sit idle for lack of fishing gears are now meaningfully engaged courtesy of the women financiers. Finally, the study also revealed that 46% of the women between N2,5000 to above N4,000 from marketing of fish, and also utilizenthe income generated to enhance the welfare of the households in the area of food, clothing and paying their children school fees hence reducing the level of poverty of their households

Inter-stage line ratio of He- and Li-like Ti emissions for the electron temperature measurement

Under coronal conditions, the steady state rate-equations are used to calculate the inter-stage line ratios between Li-like Is(2)2p(P-2(3/2))-> 1s(2)2s -> ((2) S-1/2) and He-like 1s2p (P-1(1))-> 1s(2) (S-1(0)) transitions for Ti in the electronic temperature ranges from 0.1 keV to 20 keV. The results show that the. temperature sensitivities are higher at the electronic temperature less than 5000 eV and the temperature sensitivities will decrease with the increase of electronic temperature.

Phase variations and phase shift in a TE011 mode microwave cavity used for in a miniature Rb fountain frequency standard

It is the first time in China that the phase variations and phase shift of microwave cavity in a miniature Rb fountain frequency standard are studied, considering the effect of imperfect metallic walls. Wall losses in the microwave cavity lead to small traveling wave components that deliver power from the cavity feed to the walls of cavity. The small traveling wave components produce a microradian distribution of phase throughout the cavity ity, and therefore distributed cavity phase shifts need to be considered. The microwave cavity is a TE011 circular cylinder copper cavity, with round cut-hole of end plates (14mm in diameter) for access for the atomic flux and two small apertures in the center of the side wall for coupling in microwave power. After attenuation alpha is calculated, field variations in cavity are solved. The field variations of the cavity are given. At the same time, the influences of loaded quality factor QL and diameter/height (2a/d) of the microwave cavity on the phase variations and phase shift are considered. According to the phase variation and phase shift of microwave cavity we select the parameters of cavity, diameter 2a = 69.2mm, height d = 34.6mm, QL = 5000, which will result in an uncertainty delta(Delta f / f0 ) < 4.7 x 10(-17) and meets the requirement for the miniature Rb fountain frequency standard with accuracy 10(-15).

Investigations of group IVA transition metal mediated carbon-carbon bond forming reactions

Zirconocene aldehyde and ketone complexes were synthesized in high yield by treatment of zirconocene acyl complexes with trimethylaluminum or diisobutylaluminum hydride. These complexes, which are activated by dialkylaluminum chloride ligands, inserted unsaturated substrates such as alkynes, allenes, ethylene, nitriles, ketenes, aldehydes, ketones, lactones, and acid chlorides with moderate to high conversion. Insertion of aldehyde substrates yielded zirconocene diolate complexes with up to 20:1 (anti:syn) diastereoselectivity. The zirconocene diolates were hydrolyzed to afford unsymmetrical 1,2-diols in 40-80% isolated yield. Unsymmetrical ketones gave similar insertion yields with little or no diastereoselectivity. A high yielding one-pot method was developed that coupled carbonyl substrates with zirconocene aldehyde complexes that were derived from olefins by hydrozirconation and carbonylation. The zirconocene aldehyde complexes also inserted carbon monoxide and gave acyloins in 50% yield after hydrolysis.

The insertion reaction of aryl epoxides with the trimethylphoshine adduct of titanocene methylidene was examined. The resulting oxytitanacyclopentanes were carbonylated and oxidatively cleaved with dioxygen to afford y-lactones in moderate yields. Due to the instability and difficult isolation of titanocene methylidene trimethylphoshine adducts, a one-pot method involving the addition of catalytic amounts of trimethylphosphine to β,β-dimethyltitanacyclobutane was developed. A series of disubstituted aryl epoxides were examined which gave mixtures of diastereomeric insertion products. Based on these results, as well as earlier Hammett studies and labeling experiments, a biradical transition state intermediate is proposed. The method is limited to aryl substituted epoxide substrates with aliphatic examples showing no insertion reactivity.

The third study involved the use of magnesium chloride supported titanium catalysts for the Lewis acid catalyzed silyl group transfer condensation of enol silanes with aldehydes. The reaction resulted in silylated aldol products with as many as 140 catalytic turnovers before catalyst inactivation. Low diastereoselectivities favoring the anti-isomer were consistent with an open transition state involving a titanium atom bound to the catalyst surface. The catalysts were also used for the aldol group transfer polymerization of t-butyldimethylsilyloxy-1-ethene resulting in polymers with molecular weights of 5000-31,000 and molar mass dispersities of 1.5-2.8. Attempts to polymerize methylmethacrylate using GTP proved unsuccessful with these catalysts.

Influence of aniline on Daphnia magna Straus [Translation from: Trudy Saratov.Otdeleniya GosNIORKh 13 102-104, 1975]

Experiments were carried out by the method of direct effect of the tested substance on increase of biomass (1,2). Daphnia magna was cultured under laboratory conditions.The author concludes that concentrations of aniline from 5000 to 0.1 mg/1 appear acutely lethal. The disturbance of feeding, reproduction, the disorganization of the nervous system, speak of the toxicity of the substance.