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91.
Juan A. Pajares Gonzalo Álvarez Fernando Ibeas Diego Gallego David R. Hall Dudley I. Farman 《Journal of chemical ecology》2010,36(6):570-583
The pine sawyer beetle, Monochamus galloprovincialis, is a pest of pine trees in Europe and North Africa. Previously considered a secondary pest of stressed and dying trees,
it is now receiving considerable attention as a vector of the pine wood nematode, Bursaphelenchus xylophilus, the causal agent of a lethal wilting disease in susceptible species of pines. Adult beetles are attracted to traps baited
with a kairomone blend consisting of a host volatile, α-pinene, and two bark beetle pheromone components, ipsenol and 2-methyl-3-buten-2-ol.
More recently it has been shown that mature male M. galloprovincialis produce a pheromone that attracts mature females in a laboratory bioassay. Here, volatiles were collected from mature male
and female M. galloprovincialis, and a compound produced specifically by mature males was identified as 2-undecyloxy-1-ethanol from its gas chromatographic
retention times, its mass spectrum, and by comparison with synthetic standards. The naturally-derived and synthetic compounds
elicited electroantennographic responses from both females and males. Sealed polyethylene vials and polyethylene sachets were
shown to be effective dispensers with zero-order release, the latter giving a higher release rate than the former. In two
field tests, multiple-funnel traps baited with synthetic 2-undecyloxy-1-ethanol caught both female and male M. galloprovincialis, with higher catches at the higher release rate. This compound also synergized the attractiveness of the kairomone blend,
the combined mixture catching 80–140% more beetles than the sum of the catches to each bait separately and luring up to two
beetles/trap/d in a moderate-density population. We conclude that 2-undecyloxy-1-ethanol is a male-produced aggregation pheromone
of M. galloprovincialis. This is the first example of a sex-specific compound in the cerambycid subfamily Lamiinae with significant behavioral activity
in the field at a range sufficient to make it a useful trap bait. The possible roles of this pheromone in the chemical ecology
of M. galloprovincialis and its potential use in pine wilt disease management are discussed. 相似文献
92.
Cristian I. Contescu Dipendu Saha Nidia C. Gallego Eugene Mamontov Alexander I. Kolesnikov Vinay V. Bhat 《Carbon》2012,50(3):1071-1082
Quasi-elastic neutron scattering was used for characterization of dynamics of molecular hydrogen confined in narrow nanopores of two activated carbon materials: a carbon derived from polyfurfuryl alcohol and an ultramicroporous carbon. Fast, but incomplete ortho–para conversion was observed at 10 K, suggesting that scattering originates from the fraction of unconverted ortho isomer which is rotation-hindered because of confinement in nanopores. Hydrogen molecules entrapped in narrow nanopores (<7 Å) were immobile below 22–25 K. Mobility increased rapidly with temperature above this threshold, which is higher than the melting point of bulk hydrogen (13.9 K). Diffusion obeyed fixed-jump length mechanism, indistinguishable between 2D and 3D processes. Thermal activation of diffusion was characterized between ~22 and 37 K, and structure-dependent differences were found between the two carbons. Activation energy of diffusion was higher than that of bulk solid hydrogen. Classical notions of liquid and solid do not longer apply for H2 confined in narrow nanopores. 相似文献
93.
Dovetail joints between fan blades and the disk of turbine engines are subjected to fretting. The objective of this research is to realize wear prediction by computational methods. The goal is obviously the estimation of wear kinetics, but also to obtain worn surfaces, and permit the manufacturer to realize complementary design analyses with worn surfaces. A wear law developed for titanium alloy and based on the friction dissipated energy is used. A computational method based on a three scale analysis is presented. The originality consists of coupling a semi-analytical (SA) contact solver with the FE method for the structural behavior, allowing a fine discretization of the contact zone. Contact computations are fast enough to realize cyclic wear computations. Results for the blade/disk system are exhibited. 相似文献
94.
S. Gallego M. Ortu?o C. García C. Neipp A. Beléndez I. Pascual 《Journal of Modern Optics》2013,60(11):1575-1584
In order to achieve a better understanding of the mechanisms of hologram formation and higher diffraction efficiencies in volume gratings stored in acrylamide based photopolymers, a crosslinker (N,N′methylene-bis-acrylamide) has been incorporated in the photopolymer to record holograms by pulsed laser exposure. The presence of this component increases the polymerization rate and refractive index modulation. The recording was performed using a holographic copying process. The original was a grating of 1000?lines/mm processed using silver halide sensitized gelatin. First, the effect of the pulse fluence was investigated. When the pulse fluence was optimized, the results obtained using the new composition of material were compared with those using the composition without a crosslinker. Using a pulsed laser at 532?nm the photopolymer without crosslinker presented diffraction efficiencies slightly less than 60%. On the other hand, when the crosslinker was introduced in the photopolymer composition, the diffraction efficiencies achieved were higher than 85%. The non-linearity of the material's response was also studied comparing the energetic sensitivity, diffraction efficiencies and index modulation of gratings recorded with pulsed and continuous laser exposure. This study was performed fitting the angular scan of each grating using Kogelnik's theory. 相似文献
95.
Juan José González de la Rosa Antonio Moreno-Muñoz Antolino Gallego Rosa Piotrkowski Enrique Castro 《Measurement》2010
In this paper we present the operation results of a portable computer-based measurement equipment, conceived to perform non-destructive testing of suspected termite infestations. Its signal processing nucleus is the spectral kurtosis (SK), whose pattern allows the targeting of alarms and activity signals. Data have been also de-noised using the discrete wavelet transform (DWT) in order to study its potential complementarity to SK. The DWT keeps the successive approximations of the termite emissions, supposed more non-Gaussian (less noisy) and with less entropy than the detail coefficients. For a given mother wavelet, the maximum acceptable level in the wavelet decomposition tree, which preserves the insects’ emissions features, depends on the comparative evolution of the approximations vs. details’ entropies, and the value of the global SK associated to the approximation of the separated signals. The paper explains the detection criterion by showing different types of real-life recordings (alarms, activity, and background). 相似文献
96.
Harmony Deplaine Victor A. Acosta‐Santamaría Ana Vidaurre José Luis Gómez Ribelles Manuel Doblaré Ignacio Ochoa Gloria Gallego Ferrer 《应用聚合物科学杂志》2014,131(20)
A poly(l ‐lactic acid) scaffold prepared by a combination of freeze‐extraction and porogen‐leaching methods was submitted to static degradation in a phosphate‐buffered saline solution at pH 7.4 and 37°C for up to 12 months. After 6 months of degradation, the scaffold maintained its integrity, although noticeable changes in its permeability and pore size were recorded. After 12 months, scanning electron microscopy pictures showed that most of the trabeculae were broken, and the sample disaggregated under minimum loading. Neither weight loss nor crystallinity changes in the first heating calorimetric scan were observed during the degradation experiment. However, after 12 months, a rise in the crystallinity from 13 to 38% and a drop in the glass‐transition temperature from 58 to 54°C were measured in the second heating scan. The onset of thermal degradation moved from 300 to 210°C after 12 months. Although the elastic modulus suffered only a very slight reduction with degradation time, the aggregate modulus decreased 44% after 6 months. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40956. 相似文献
97.
Vega-Carrillo HR Hernández-Dávila VM Manzanares-Acuña E Mercado GA Gallego E Lorente A Perales-Muñoz WA Robles-Rodríguez JA 《Radiation protection dosimetry》2006,118(3):251-259
An artificial neural network (ANN) has been designed to obtain neutron doses using only the count rates of a Bonner spheres spectrometer (BSS). Ambient, personal and effective neutron doses were included. One hundred and eighty-one neutron spectra were utilised to calculate the Bonner count rates and the neutron doses. The spectra were transformed from lethargy to energy distribution and were re-binned to 31 energy groups using the MCNP 4C code. Re-binned spectra, UTA4 response matrix and fluence-to-dose coefficients were used to calculate the count rates in the BSS and the doses. Count rates were used as input and the respective doses were used as output during neural network training. Training and testing were carried out in the MATLAB environment. The impact of uncertainties in BSS count rates upon the dose quantities calculated with the ANN was investigated by modifying by +/-5% the BSS count rates used in the training set. The use of ANNs in neutron dosimetry is an alternative procedure that overcomes the drawbacks associated with this ill-conditioned problem. 相似文献
98.
Gallego J.R. Hernandez-Solana A. Canales M. Lafuente J. Valdovinos A. Fernandez-Navajas J. 《IEEE transactions on information technology in biomedicine》2005,9(1):13-22
In this paper, a third-generation universal mobile telecommunications system (UMTS) solution for the delivery of biomedical information from an ambulance to a hospital is presented. The joint transmission of voice, real-time video, electrocardiogram signals, and medical scans in a realistic cellular multiuser simulation environment is considered, taking into account the advantages and particularities of UMTS technology for such transmission. The accomplishment of quality of service constraints for different services is investigated and quantitative results are provided in order to demonstrate the feasibility of using UMTS technology for emergency care services on high-speed moving ambulance vehicles. 相似文献
99.
The max–min diversity problem (MMDP) consists in selecting a subset of elements from a given set in such a way that the diversity among the selected elements is maximized. The problem is NP-hard and can be formulated as an integer linear program. Since the 1980s, several solution methods for this problem have been developed and applied to a variety of fields, particularly in the social and biological sciences. We propose a heuristic method—based on the GRASP and path relinking methodologies—for finding approximate solutions to this optimization problem. We explore different ways to hybridize GRASP and path relinking, including the recently proposed variant known as GRASP with evolutionary path relinking. Empirical results indicate that the proposed hybrid implementations compare favorably to previous metaheuristics, such as tabu search and simulated annealing. 相似文献
100.
MAC protocols designed to provide QoS in wireless ad hoc networks need to be able to reserve and control resources efficiently. To this purpose, TDMA-based networks often lie in a frame subdivision that consists of a broadcast control phase and an information phase. In the control phase, each active terminal broadcasts signalling information required to handle the access to the data resources. Analysis and modelling of the broadcast service is carried out, which allows an efficient frame dimensioning in this scenario 相似文献