910 research outputs found
Changes in Number and Weight of Wheat and Triticale Grains to Manipulation in Source-Sink Relationship
The source-sink ratio experimental manipulation has helped to define whether a crop is limited by source or sink or co-limited by both. There is no evidence in triticale of source-sink manipulations effects on yield and yield components. Two experiments were accomplished during 2008 and 2009 growing seasons at the Universidad Autónoma del Estado de México, México, and one in 2010 at the National Institute of Agricultural Technology in Pergamino, Argentina. Two triticale cultivars (line 4 and 7) and one wheat cultivar (Tollocan) were used. Source-sink relations were modified at anthesis by thinning, degraining, shading, and total defoliation procedures. Changes in the source-sink relation affected yields in both species differentially. The changes in yield due to cultivars and treatments were explained mainly by the number of grains rather than by their individual grain weight. The number of grains was affected by all treatments in both species, while the individual grain weight was increased by thinning and degraining mainly in triticale. A greater number of fertile florets in triticale were associated with their higher rate of abortion compared to wheat. These results could help to better understand crop management and genetic improvement.Fil: Ballesteros Rodriguez, E.. Universidad Nacional Autónoma de México; MéxicoFil: Martinez Rueda, C.G.. Universidad Nacional Autónoma de México; MéxicoFil: Morales Rosales, E.J.. Universidad Nacional Autónoma de México; MéxicoFil: Estrada Campuzano, G.. Universidad Nacional Autónoma de México; MéxicoFil: González, Fernanda Gabriela. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Modal Response of Hydraulic Turbine Runners
The mechanical design of hydraulic turbines is conditioned by the dynamic response of the runner that is usually estimated by a computational model. Nevertheless, the runner has complex boundary conditions that are difficult to include in the computational model. One of these boundary conditions is the water in which the runner is submerged. The effect of the added mass and damping of water can modify considerably the natural frequencies of the runner. In order to analyze this effect on a Francis turbine runner, an experimental and a numerical investigation in a reduced scale model was carried out. The experimental investigations was based on modal analysis. Several impact tests with the runner in air and in water were done. The response was measured with accelerometers located in different positions of the runner. Special attention was taken to determine the most suitable positions of measurements and impacts. From the modal analysis, the natural frequencies, damping ratios, and mode shapes were determined. The simulation of the same runner was also carried out using a FEM method. First, some tests including a sensitivity analysis wee done to check the accuracy of the numerical results. Second, the runner was simulated and the frequencies and mode shapes were calculated both in air and in water like in the experiment. The simulation was compared with the experimental results to determine its accuracy especially regarding the added mass effects. Similar mode shapes and frequency reduction ratios were obtained so the simulation gave rather good results. In the paper, the frequencies, damping and mode shapes obtained in air and in water both from experiment and simulation are indicated. The same mode shapes obtained in air were obtained in water bit with lower natural frequencies and higher damping ratios. The difference in the natural frequencies is shown to be dependent basically on the added mass effect of the water and not on its added damping. This difference also depends on the geometry of the mode presenting different values for different mode shapes. Using non-dimensional values, the reduction in the natural frequencies can be extrapolated to other Francis runners presenting similar geometrical characteristics
A simplified courtship conditioning protocol to test learning and memory in Drosophila
In Drosophila, a male that has previously been sexually rejected reduces its courtship behavior when confronted again with an unreceptive female. This reduced courting time reflects a memory formation process. Here, we describe a simplified protocol to perform the courtship conditioning assay for assessing the reduced courting time, using regular lab equipment and handmade tools. Every step of the procedure, from raising flies and training to testing and quantification of this memory-related behavior, can be implemented in any practice laboratory.We would like to thank Javier Gil Castillo for its invaluable help and advices in 3D printing. We also thank the flies from Bloomington Stock Center. We would like to thank BioRender (www.biorender.com) for the open-access platform used to create the graphical abstract.
This work was supported by the Spanish Research Agency (Ministerio de Innovacion y Ciencia [MICINN]) under the grant PGC2018-094630-B-100 to F.A.M., cofinanced by the European Regional Development Fund (ERDF) to F.A.M. F.A.M. is a recipient of a RyC-2014-14961 contract. B.G.-M. is a recipient of a FPI-UAM predoctoral fellowship, grant number SFPI/2020/00878. C.G.B. is a recipient of a FPU predoctoral fellowship, grant number FPU19/04449 (MEFP). S.P.-F. is a recipient of a JAE intro fellowship, grant number JAEINT_21_02520 (CSIC)
Relación entre incidencia de Fusarium verticillioides y variables de calidad de grano bajo condiciones de almacenamiento de maíz en Tucumán, Argentina
Las oportunidades de comercializar con éxito los granos de maíz dependen de factores que interfieren durante el manejo de pre y poscosecha. Es importante conocer la incidencia de patógenos con potencial toxigenico y los niveles de concentración de micotoxinas que tienen las partidas comerciales almacenadas en silo-bolsas. Por ende, se propusieron los siguientes objetivos: evaluar la incidencia de Fusarium spp. sección Liseola con potencial toxigénico en granos almacenados; establecer la relación entre niveles de incidencia y variables de calidad comercial; y cuantificar los niveles de contaminación de fumonisinas de los diferentes silos. Los resultados mostraron que la especie Fusarium verticillioides predominó en condiciones de almacenamiento. Su incidencia
promedio, entre 15 y 17 %, varió según el silo. Dos de las seis variables regresoras: grano quebrado y humedad, fueron importantes para explicar la variabilidad de la incidencia de Fusarium verticillioides en los granos almacenados. Los valores promedio de fumonisinas en los silo-bolsas variaron entre 0,01 y 7,37 ppm. Se rescató, además, que existe una relación lineal entre incidencia de F. verticillioides y los valores de fumonisinas, a pesar de un ajuste no tan alto (R2= 0,57). Este trabajo aportó información para nuestra región sobre la predominancia de una especie de Fusarium de la sección Liseola, con alto potencial en producir fumonisinas, como es Fusarium verticillioides en los granos almacenados. También se informa sobre el nivel de contaminación de los granos almacenados y sobre la importancia de la ruptura de la integridad del grano en la colonización de dicho patógeno .Successful marketing chances of corn kernels depend on interfering factors during the handle of pre and post harvesting. The knowledge of the incidence of pathogens with toxigenic potential, as well as mycotoxin levels, in the commercial consignments stored in plastic bags is important. The objectives of this research were: to evaluate the incidence of Fusarium spp. section Liseola with toxigenic potential in stored grains; to establish the relation between levels of incidence and commercial quality variables; and quantify levels of pollution of fumonisin in different silos. Results showed that Fusarium verticillioides prevailed in storage conditions. Its
average incidence was between 15 and 17 %, varying between silos. Two out of six regression variables: broken grain and humidity, were important in explaining the variability of Fusarium verticillioides incidence on the stored grains. The average values of fumonisins in plastic bags varied between 0,01 and 7,37 ppm. Also, there was a linear relation between incidence of F. verticillioides and levels of fumonisins, in spite of an adjustment not so high (R2= 0,57). This work provides information for our region on the prevailing of Fusarium spp. section Liseola in stored grains with high potential to produce fumonisins, as in the case of Fusarium verticillioides. It is also reported the level of pollution of stored grains and the importance of the breaking of grains to be colonized
by this pathogen.EEA FamailláFil: Diaz, C.G. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Rodriguez, Ricardo Antonio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Famaillá. Anexo Famaillá; ArgentinaFil: Aguaysol, Natalia Catalina. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Juárez, J. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Saleme, Pablo Manuel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Famaillá; ArgentinaFil: Ploper, L. Daniel. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; Argentin
Spin-Charge Separation in the Model: Magnetic and Transport Anomalies
A real spin-charge separation scheme is found based on a saddle-point state
of the model. In the one-dimensional (1D) case, such a saddle-point
reproduces the correct asymptotic correlations at the strong-coupling
fixed-point of the model. In the two-dimensional (2D) case, the transverse
gauge field confining spinon and holon is shown to be gapped at {\em finite
doping} so that a spin-charge deconfinement is obtained for its first time in
2D. The gap in the gauge fluctuation disappears at half-filling limit, where a
long-range antiferromagnetic order is recovered at zero temperature and spinons
become confined. The most interesting features of spin dynamics and transport
are exhibited at finite doping where exotic {\em residual} couplings between
spin and charge degrees of freedom lead to systematic anomalies with regard to
a Fermi-liquid system. In spin dynamics, a commensurate antiferromagnetic
fluctuation with a small, doping-dependent energy scale is found, which is
characterized in momentum space by a Gaussian peak at (, ) with
a doping-dependent width (, is the doping
concentration). This commensurate magnetic fluctuation contributes a
non-Korringa behavior for the NMR spin-lattice relaxation rate. There also
exits a characteristic temperature scale below which a pseudogap behavior
appears in the spin dynamics. Furthermore, an incommensurate magnetic
fluctuation is also obtained at a {\em finite} energy regime. In transport, a
strong short-range phase interference leads to an effective holon Lagrangian
which can give rise to a series of interesting phenomena including linear-
resistivity and Hall-angle. We discuss the striking similarities of these
theoretical features with those found in the high- cuprates and give aComment: 70 pages, RevTex, hard copies of 7 figures available upon request;
minor revisions in the text and references have been made; To be published in
July 1 issue of Phys. Rev. B52, (1995
Abrupt weaning type combined to stress during late pregnancy in sheep present economic losses on carcass and low testicular development in lambs
This study investigates the combined effect of the progressive or abrupt weaning after the stress during middle and late pregnancy on performance and development of lambs. Twenty-four male lambs were used, born from 18 Santa Ines ewes that were divided into three experimental groups. Pregnant ewes were submitted to the application of Lipolysaccharides E. coli (LPS) during the 70 th day of pregnancy (Ig; n=12) or at the 120 th day (Fg; n=8). Animals were kept as control (Cg; n=14). Lambs born in a 6 day interval were subjected to two types of weaning (Pw: progressive weaning; Aw: abrupt weaning at 45 days of age). Lamb data, including testicular development, yield carcass and economic cost were analyzed. Means were compared by F test and Student's t test (P0.05). The highest yields in gross margin was observed for the Cg group and the lowest for Fg (P0.05). On lambs’ testicular weight, Cg average value was higher than Fg (P0.05). The combined effect of LPS challenge as a simulated disease process during late pregnancy and abrupt weaning change the testicular weight and the yield carcass, resulting in economic losses
Effects of thermoregulation on human sleep patterns: A mathematical model of sleep-wake cycles with REM-NREM subcircuit
In this paper we construct a mathematical model of human sleep/wake regulation with thermoregulation and temperature e ects. Simulations of this model show features previously presented in experimental data such as elongation of duration and number of REM bouts across the night as well as the appearance of awakenings due to deviations in body temperature from thermoneutrality. This model helps to demonstrate the importance of temperature in the sleep cycle. Further modi cations of the model to include more temperature e ects on other aspects of sleep regulation such as sleep and REM latency are discussedPostprint (author's final draft
The Self-dual String Soliton in AdS_4\times S^7 spacetime
We construct self-dual string soliton solutions in spacetime, starting from the covariant equations of motion of M5-brane.
We study the properties of the solutions and find that their action are
linearized, indicating the BPS nature of the solutions, and they have the same
electric and magnetic charge. The straight string soliton solution represents
the configuration of the membranes ending on M5-brane with a straight string
intersection, and it behaves like the spiky solution in flat spacetime. The
spherical string soliton solution, which could be related to the straight one
by a conformal transformation, represents the membranes ending on M5-brane with
a spherical intersection.Comment: 15 pages;typos corrected, references added;published versio
Can forest management based on natural disturbances maintain ecological resilience?
Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance
Dynamical mean-field approach to materials with strong electronic correlations
We review recent results on the properties of materials with correlated
electrons obtained within the LDA+DMFT approach, a combination of a
conventional band structure approach based on the local density approximation
(LDA) and the dynamical mean-field theory (DMFT). The application to four
outstanding problems in this field is discussed: (i) we compute the full
valence band structure of the charge-transfer insulator NiO by explicitly
including the p-d hybridization, (ii) we explain the origin for the
simultaneously occuring metal-insulator transition and collapse of the magnetic
moment in MnO and Fe2O3, (iii) we describe a novel GGA+DMFT scheme in terms of
plane-wave pseudopotentials which allows us to compute the orbital order and
cooperative Jahn-Teller distortion in KCuF3 and LaMnO3, and (iv) we provide a
general explanation for the appearance of kinks in the effective dispersion of
correlated electrons in systems with a pronounced three-peak spectral function
without having to resort to the coupling of electrons to bosonic excitations.
These results provide a considerable progress in the fully microscopic
investigations of correlated electron materials.Comment: 24 pages, 14 figures, final version, submitted to Eur. Phys. J. for
publication in the Special Topics volume "Cooperative Phenomena in Solids:
Metal-Insulator Transitions and Ordering of Microscopic Degrees of Freedom
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