5,405 research outputs found
Short-range order and precipitation in Fe-rich Fe-Cr alloys: Atomistic off-lattice Monte Carlo simulations
Short-range order (SRO) in Fe-rich Fe-Cr alloys is investigated by means of
atomistic off-lattice Monte Carlo simulations in the semi-grand canonical
ensemble using classical interatomic potentials. The SRO parameter defined by
Cowley [Phys. Rev. B 77, 669 (1950)] is used to quantify the degree of
ordering. In agreement with experiments a strong ordering tendency in the Cr
distribution at low Cr concentrations (~< 5%) is observed, as manifested in
negative values of the SRO parameters. For intermediate Cr concentrations (5%
~< c_Cr ~< 15%) the SRO parameter for the alpha-phase goes through a minimum,
but at the solubility limit the alpha-phase still displays a rather strong SRO.
In thermodynamic equilibrium for concentrations within the two-phase region the
SRO parameter measured over the entire sample therefore comprises the
contributions from both the alpha and alpha-prime phases. If both of these
contributions are taken into account, it is possible to quantitatively
reproduce the experimental results and interpret their physical implications.
It is thereby shown that the inversion of the SRO observed experimentally is
due to the formation of stable (supercritical) alpha-prime precipitates. It is
not related to the loss of SRO in the alpha-phase or to the presence of
unstable (subcritical) Cr precipitates in the alpha-phase.Comment: 9 pages, 8 figure
Rentabilidad económica de explotaciones agrarias de secano según tamaño y tipo de laboreo
RESUMEN: El objetivo de este trabajo es evaluar, desde un punto de vista económico, el efecto que supone pasar de un sistema de laboreo tradicional a uno de laboreo reducido en explotaciones cerealistas de la meseta castellana. Se utilizan datos experimentales de campo para estimar las producciones, asà como un sistema de decisión experto para seleccionar el parque de maquinaria que conlleva el menor coste de utilización. La rotación de cultivos que se ha considerado ha sido trigo/leguminosa. No se encontraron diferencias significativas entre los rendimientos obtenidos en los tres sistemas de laboreo comparados. Los resultados económicos se muestran condicionados por el sistema de laboreo empleado y el tamaño de la explotación.Economic analyses, farm size, rainfed crops, tillage systems, Agricultural and Food Policy, Q12,
Spike-based VITE control with Dynamic Vision Sensor applied to an Arm Robot.
Spike-based motor control is very important in the
field of robotics and also for the neuromorphic engineering
community to bridge the gap between sensing / processing
devices and motor control without losing the spike philosophy
that enhances speed response and reduces power consumption.
This paper shows an accurate neuro-inspired spike-based system
composed of a DVS retina, a visual processing system that detects
and tracks objects, and a SVITE motor control, where everything
follows the spike-based philosophy. The control system is a spike
version of the neuroinspired open loop VITE control algorithm
implemented in a couple of FPGA boards: the first one runs the
algorithm and the second one drives the motors with spikes. The
robotic platform is a low cost arm with four degrees of freedom.Ministerio de Ciencia e Innovación TEC2009-10639-C04-02/01Ministerio de Economía y Competitividad TEC2012-37868-C04-02/0
Fluctuating hydrodynamic modelling of fluids at the nanoscale
A good representation of mesoscopic fluids is required to combine with
molecular simulations at larger length and time scales (De Fabritiis {\it et.
al}, Phys. Rev. Lett. 97, 134501 (2006)). However, accurate computational
models of the hydrodynamics of nanoscale molecular assemblies are lacking, at
least in part because of the stochastic character of the underlying fluctuating
hydrodynamic equations. Here we derive a finite volume discretization of the
compressible isothermal fluctuating hydrodynamic equations over a regular grid
in the Eulerian reference system. We apply it to fluids such as argon at
arbitrary densities and water under ambient conditions. To that end, molecular
dynamics simulations are used to derive the required fluid properties. The
equilibrium state of the model is shown to be thermodynamically consistent and
correctly reproduces linear hydrodynamics including relaxation of sound and
shear modes. We also consider non-equilibrium states involving diffusion and
convection in cavities with no-slip boundary conditions
Hidden geometric correlations in real multiplex networks
Real networks often form interacting parts of larger and more complex
systems. Examples can be found in different domains, ranging from the Internet
to structural and functional brain networks. Here, we show that these multiplex
systems are not random combinations of single network layers. Instead, they are
organized in specific ways dictated by hidden geometric correlations between
the individual layers. We find that these correlations are strong in different
real multiplexes, and form a key framework for answering many important
questions. Specifically, we show that these geometric correlations facilitate:
(i) the definition and detection of multidimensional communities, which are
sets of nodes that are simultaneously similar in multiple layers; (ii) accurate
trans-layer link prediction, where connections in one layer can be predicted by
observing the hidden geometric space of another layer; and (iii) efficient
targeted navigation in the multilayer system using only local knowledge, which
outperforms navigation in the single layers only if the geometric correlations
are sufficiently strong. Our findings uncover fundamental organizing principles
behind real multiplexes and can have important applications in diverse domains.Comment: Supplementary Materials available at
http://www.nature.com/nphys/journal/v12/n11/extref/nphys3812-s1.pd
Épocas e intensidades de poda de frutificação na goiabeira 'Paluma', em Pinheiros-ES.
Este trabalho teve como objetivo avaliar os efeitos de diferentes intensidades de poda de frutificação realizadas em diferentes épocas do ano sobre a fenologia e a produção da goiabeira ?Paluma?, em Pinheiros-ES. As plantas foram submetidas a três intensidades de poda de frutificação (curta, média e longa), em quatro diferentes épocas (25-11-2005, 21-12-2005, 27-01-2006 e 23-02-2006). O ciclo da goiabeira ?Paluma?, entre a poda até o início da colheita dos frutos, variou de 189 dias (podas em novembro e dezembro) a 203 dias (poda em fevereiro). Independentemente da época de poda, as plantas submetidas à poda longa apresentaram maior emissão de brotos novos e maior número de ramos estabelecidos. As plantas submetidas à poda curta apresentaram menores números de brotos emitidos e de ramos estabelecidos, bem como menor índice de pegamento de frutos, menor número de frutos por planta e, conseqüentemente, menor produção; entretanto produziram frutos de maior peso médio em relação às plantas submetidas à poda longa. A maior produção e o maior número de frutos colhidos por planta ocorreram nas plantas podadas em fevereiro. A época e a intensidade da poda de frutificação afetam a brotação e a produção da goiabeira ?Paluma?. Termos para indexação: Psidium guajava L., fenologia, produção de frutos
Influence of bird faeces in the behaviour of the root rot of Quercus suber caused by Phytophthora cinnamomi at Doñana Biological Reserve (SW Spain)
2 pages, 1 reference. Presentado a The Sixth Meeting of the IUFRO Working Party 7‐02‐09, celebrado en Córdoba (España) del 9-14 de septiembre de 2012. Enlazamos con http://hdl.handle.net/10261/57038; http://hdl.handle.net/10261/57047Centennial cork oaks are considered keystone structures in the ecosystem of the stabilised sands of the
Doñana Biological Reserve. These remnant big trees are currently threatened by nesting of colonial
waterbirds, whose debris induced deep soil chemical changes.Peer reviewe
Postmortem diagnosis of acute myocardial infarction in patients with acute respiratory failure - demographics, etiologic and pulmonary histologic analysis
OBJECTIVES: Acute respiratory failure is present in 5% of patients with acute myocardial infarction and is responsible for 20% to 30% of the fatal post-acute myocardial infarction. The role of inflammation associated with pulmonary edema as a cause of acute respiratory failure post-acute myocardial infarction remains to be determined. We aimed to describe the demographics, etiologic data and histological pulmonary findings obtained through autopsies of patients who died during the period from 1990 to 2008 due to acute respiratory failure with no diagnosis of acute myocardial infarction during life. METHODS: This study considers 4,223 autopsies of patients who died of acute respiratory failure that was not preceded by any particular diagnosis while they were alive. The diagnosis of acute myocardial infarction was given in 218 (4.63%) patients. The age, sex and major associated diseases were recorded for each patient. Pulmonary histopathology was categorized as follows: diffuse alveolar damage, pulmonary edema, alveolar hemorrhage and lymphoplasmacytic interstitial pneumonia. The odds ratio of acute myocardial infarction associated with specific histopathology was determined by logistic regression. RESULTS: In total, 147 men were included in the study. The mean age at the time of death was 64 years. Pulmonary histopathology revealed pulmonary edema as well as the presence of diffuse alveolar damage in 72.9% of patients. Bacterial bronchopneumonia was present in 11.9% of patients, systemic arterial hypertension in 10.1% and dilated cardiomyopathy in 6.9%. A multivariate analysis demonstrated a significant positive association between acute myocardial infarction with diffuse alveolar damage and pulmonary edema. CONCLUSIONS: For the first time, we demonstrated that in autopsies of patients with acute respiratory failure as the cause of death, 5% were diagnosed with acute myocardial infarction. Pulmonary histology revealed a significant inflammatory response, which has not previously been reported
Fenologia da goiabeira 'Paluma' sob diferentes sistemas de cultivos, épocas e intensidades de poda de frutificação.
O trabalho teve como objetivo avaliar os efeitos de diferentes épocas e intensidades de poda de frutificação sobre a fenologia da goiabeira 'Paluma', em dois sistemas de cultivo, em Pedro Canário (ES). O delineamento experimental foi o de blocos ao acaso, em esquema de parcelas sub-subdivididas. As parcelas foram os sistemas de cultivo irrigado e sequeiro; as subparcelas foram as épocas de poda (10/11/2005, 9/12/2005, 13/1/2006 e 10/2/2006); e as sub-subparcelas foram as intensidades de poda (curta, média e longa). O ciclo da goiabeira 'Paluma', entre a poda até o início da colheita dos frutos, variou de 182 (poda em novembro e dezembro) a 203 dias (poda em fevereiro). A queda fisiológica dos frutos ocorreu até os 56 dias após o final do florescimento. A irrigação e a poda longa proporcionaram maior brotação e estabelecimento dos ramos. As plantas submetidas à poda longa em fevereiro produziram maior número de frutos por ramo. Independentemente da época de poda, as plantas submetidas à poda curta apresentaram menor número de frutos por ramo e menor índice de pegamento de frutos. A irrigação e as podas realizadas em dezembro e janeiro favoreceram a produção de frutos maiores
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