Perturbative evolution of far off-resonance driven two-level systems: Coherent population trapping, localization, and harmonic generation

The time evolution of driven two-level systems in the far off-resonance regime is studied analytically. We obtain a general first-order perturbative expression for the time-dependent density operator which is applicable regardless of the coupling strength value. In the strong field regime, our perturbative expansion remains valid even when the far off-resonance condition is not fulfilled. We find that, in the absence of dissipation, driven two-level systems exhibit coherent population trapping in a certain region of parameter space, a property which, in the particular case of a symmetric double-well potential, implies the well-known localization of the system in one of the two wells. Finally, we show how the high-order harmonic generation that this kind of systems display can be obtained as a straightforward application of our formulation.Comment: 14 pages, LaTeX, 2 figures, acknowledgments adde

Sampling bias in systems with structural heterogeneity and limited internal diffusion

Complex systems research is becomingly increasingly data-driven, particularly in the social and biological domains. Many of the systems from which sample data are collected feature structural heterogeneity at the mesoscopic scale (i.e. communities) and limited inter-community diffusion. Here we show that the interplay between these two features can yield a significant bias in the global characteristics inferred from the data. We present a general framework to quantify this bias, and derive an explicit corrective factor for a wide class of systems. Applying our analysis to a recent high-profile survey of conflict mortality in Iraq suggests a significant overestimate of deaths

Nuevo grillo (Orthoptera, Gryllidae) para Castilla-La Mancha y la península Ibérica

We report Tartarogryllus tartarus (Saussure, 1874), a species with disjunct distribution in the Mediterranean-Turanean area, for the first time in the Iberian Peninsula. We summarize morphological charateristics for the species identification adding some new relevant traits to distinguish it from Acheta domesticus and Eumodicogryllus bordigalensis, particularly the interior tympanic opening that is shaped like a narrow slot whereas it is almost rounded in Acheta and Eumodicogryllus. We have found the species in cereal crops and vegetation around hiper-saline lagoons of arid lands (Castilla-La Mancha, Spain). Adult emergence occurs in May with maximum sexual activity at the end of this month and in June. We suspect that this species may be more widely distributed in other regions of the Iberian Peninsula with appropriate habitat.Encontramos por primera vez en la península Ibérica Tartarogryllus tartarus (Saussure, 1874), especie de distribución disjunta en el área Turano-Mediterránea. Resumimos los distintos caracteres morfológicos utilizados para identificar esta especie y añadimos algunos nuevos para distinguirla de especies similares como Acheta domesticus y Eumodicogryllus bordigalensis. Destacamos la apertura timpánica interior en forma de ranura estrecha y poco perceptible en esta especie mientras que es redondeada en Acheta y en Eumodicogryllus. Habita cultivos de cereal y vegetación en zonas áridas alrededor de lagunas hipersalinas (Castilla-La Mancha, España). Los adultos emergen a partir de mediados de mayo con máxima actividad reproductiva a finales de este mes y en junio. Sugerimos que la especie puede tener una distribución más amplia en la península Ibérica en aquellas regiones que presentan el hábitat adecuado

Comparison of the ENATE approach and discontinuous Galerkin spectral element method in 1D nonlinear transport equations

In this paper a comparison of the performance of two ways of discretizing the nonlinear convection-diffusion equation in a one-dimensional (1D) domain is performed. The two approaches can be considered within the class of high-order methods. The first one is the discontinuous Galerkin method, which has been profusely used to solve general transport equations, either coupled as the Navier-Stokes equations, or on their own. On the other hand, the ENATE procedure (Enhanced Numerical Approximation of a Transport Equation), uses the exact solution to obtain an exact algebraic equation with integral coefficients that link nodal values with a three-point stencil. This paper is the first of thorough assessments of ENATE by comparing it with well-established high-order methods. Several test cases of the steady Burgers' equation with and without source have been chosen for comparison

Adaptation of Proximal Femur to Mechanical Loading in Young Adults: Standard Vs Localized Regions Evaluated by DXA

Regions of the proximal femur with less adaptive protection by mechanical loading may be at increased risk of structural failure. Since the size and location of these regions diverge from those defined by the dual-energy X-ray absorptiometry manufacturers the purpose of this study was to compare areal bone mineral density (aBMD) of different regions of the proximal femur considering impact loads from physical activity (PA). The participants were 134 young adults divided into 2 groups according to the impact of PA performed in the last 12 mo: high-impact PA and low-impact PA. The aBMD of the proximal femur was assessed by dual-energy X-ray absorptiometry at the standard femoral neck, intertrochanter, and trochanter, and at specific locations of the superolateral femoral neck and intertrochanteric region. The bone-specific physical activity questionnaire was used to estimate the impact load of PA. Comparisons between groups were adjusted for body height and body lean mass. Interaction analysis between sex and PA groups were conducted with analysis of variance. Comparisons of aBMD between bone regions were analyzed separately for men and women with repeated measures analysis of variance. In the high-impact PA group, men benefit more than women at all bone regions, except the aBMD at intertrochanteric region. Analyses of repeated measures did not reveal any significant interaction effect between bone regions (standard vs specific) and PA groups (low vs high-impact). In conclusion, aBMD differences due to mechanical loading were more pronounced in men than in women; the magnitude of the aBMD differences as a result of different levels of PA was similar between standard and localized regions

Transmission of OFDM wired-wireless quintuple-play services along WDM LR-PONs using centralized broadband impairment compensation

This paper was published in OPTICS EXPRESS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OE.20.013748 . Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] The simultaneous transmission of four orthogonal frequencydivision multiplexing (OFDM)-based signals used to provide quintuple-play services along wavelength division multiplexing (WDM) long-reach passive optical networks (LR-PONs) is demonstrated experimentally. Particularly, the transmission performance of custom signal bearing Gigabit Ethernet data, Worldwide Interoperability for Microwave Access, Long Term Evolution and Ultra Wideband (sub-bands 2 and 3) signals is evaluated for different LR-PONs reaches, considering single-wavelength andWDMtransmission, and using a centralized impairment compensation technique at the central office that is transparent to the services provided. It is shown that error vector magnitude-compliant levels are obtained for all the OFDM-based signals in WDM LR-PONs reaching 100 km and that negligible inter-channel crosstalk is obtained for a channel spacing of 100 GHz regardless the OFDM-based signal considered. The successful multi-format OFDM transmission along the 100 km-long WDM LR-PON is achieved in the absence of optical dispersion compensation or single sideband modulation, and it is enabled by the performance improvement provided by the centralized impairment compensation realized. © 2012 Optical Society of America.M. Morant's work was supported by FPU-MEC grant AP2007-01413. This work was also supported in part by the European FIVER-FP7-ICT-2009-4-249142 project and by Fundacao para a Ciencia e a Tecnologia from Portugal under the TURBO-PTDC/EEA-TEL/104358/2008 project.Alves, T.; Morant Pérez, M.; Cartaxo, A.; Llorente Sáez, R. (2012). Transmission of OFDM wired-wireless quintuple-play services along WDM LR-PONs using centralized broadband impairment compensation. Optics Express. 20(13):13748-13761. https://doi.org/10.1364/OE.20.013748S13748137612013Jia, Z., Yu, J., Ellinas, G., & Chang, G.-K. (2007). Key Enabling Technologies for Optical–Wireless Networks: Optical Millimeter-Wave Generation, Wavelength Reuse, and Architecture. Journal of Lightwave Technology, 25(11), 3452-3471. doi:10.1109/jlt.2007.909201Armstrong, J. (2009). OFDM for Optical Communications. Journal of Lightwave Technology, 27(3), 189-204. doi:10.1109/jlt.2008.2010061Cvijetic, N. (2012). OFDM for Next-Generation Optical Access Networks. Journal of Lightwave Technology, 30(4), 384-398. doi:10.1109/jlt.2011.2166375Shieh, W., & Athaudage, C. (2006). Coherent optical orthogonal frequency division multiplexing. Electronics Letters, 42(10), 587. doi:10.1049/el:20060561Alves, T., Morant, M., Cartaxo, A., & Llorente, R. (2011). Performance Comparison of OFDM-UWB Radio Signals Distribution in Long-Reach PONs Using Mach-Zehnder and Linearized Modulators. IEEE Journal on Selected Areas in Communications, 29(6), 1311-1320. doi:10.1109/jsac.2011.110618Llorente, R., Alves, T., Morant, M., Beltran, M., Perez, J., Cartaxo, A., & Marti, J. (2008). Ultra-Wideband Radio Signals Distribution in FTTH Networks. IEEE Photonics Technology Letters, 20(11), 945-947. doi:10.1109/lpt.2008.922329Alves, T., & Cartaxo, A. (2011). Distribution of Double-Sideband OFDM-UWB Radio Signals in Dispersion Compensated Long-Reach PONs. Journal of Lightwave Technology, 29(16), 2467-2474. doi:10.1109/jlt.2011.2160616Chow, C.-W., Yeh, C.-H., Wang, C.-H., Shih, F.-Y., Pan, C.-L., & Chi, S. (2008). WDM extended reach passive optical networks using OFDM-QAM. Optics Express, 16(16), 12096. doi:10.1364/oe.16.012096Tang, J. M., Lane, P. M., & Shore, K. A. (2006). Transmission performance of adaptively modulated optical OFDM signals in multimode fiber links. IEEE Photonics Technology Letters, 18(1), 205-207. doi:10.1109/lpt.2005.861631Duong, T.-N., Genay, N., Ouzzif, M., Le Masson, J., Charbonnier, B., Chanclou, P., & Simon, J. C. (2009). Adaptive Loading Algorithm Implemented in AMOOFDM for NG-PON System Integrating Cost-Effective and Low-Bandwidth Optical Devices. IEEE Photonics Technology Letters, 21(12), 790-792. doi:10.1109/lpt.2009.2016978Alves, T., & Cartaxo, A. (2009). Performance Degradation Due to OFDM-UWB Radio Signal Transmission Along Dispersive Single-Mode Fiber. IEEE Photonics Technology Letters, 21(3), 158-160. doi:10.1109/lpt.2008.200923

Estudio taxonómico preliminar de los Grylloidea de España (Insecta, Orthoptera)

In the present paper a taxonomic and faunistic study of the superfamily of Grylloidea of Spain including the Balearic and Canary Islands is carried on. Sixty species and subspecies are reported for the study area, six of them new to science: Petaloptila (P.) fermini, P. (P.) isabelae, P. (Zapetaloptila) venosa, P. (Z.) barrancoi, Paramogoplistes dentatus sp. n. and Grylloderes orlovskajae adventicius subsp. n.; likewise are erected two new subgenera Italoptila and Zapetaloptila. One correct synonymy of the genus Grylloderes Bolívar, 1894 (=Platygryllus Chopard, 1961, syn. dist.), seven specific synonymies are established: Gryllomorpha (G.) dalmatina (Ocskay, 1832) (=Gryllomorpha dalmatina strumae Andreeva, 1982, syn. n.), Petaloptila (P.) aliena (Brunner-Wattenwyl, 1882) (=Discoptila eitschbergeri Harz, 1976, syn. n.), Acheta hispanicus Rambur, 1839 (=Gryllus erythrospilus Walker, 1869, syn. n., Gryllus hispanicus var. fusculus Bolívar, 1927, syn. n.), Eumodicogryllus bordigalensis (Latreille, 1802) (=Gryllodes ferdinandi Bolívar, 1899, syn. n., Gryllus chinensis var. intermedia Bolívar, 1927, syn. n.), Eugryllodes pipiens (Dufour, 1820) (=Gryllodes pipiens var. provincialis Azam, 1901, syn. n.) and besides five new status and one new combination. Three species [Eumodicogryllus theryi (Chopard, 1943), Sciobia natalia Gorochov, 1985 and Oecanthus dulcisonans Gorochov, 1993] are recorded for the first time for the Iberian Peninsula, being the former two also new for Europe, one (Svercus p. palmetorum Krauss, 1902) for Peninsular Spain, three [Natula averni (Costa, 1855), comb. n., Acanthogryllus acus Gorochov, 1988, under this name, and Pseudomogoplistes vicentae Gorochov, 1996], for the Canary Islands, being latter recorded also for the first time for Algeria and Modicogryllus (M.) algirius (Saussure, 1877) is also recorded for the first time for France. On the other hand, we recognise Eugryllodes panteli (Cazurro, 1888) as a good species. An identification key with figures for the species of the genus Petaloptila is presented. The male genitalia of several species is also studied for the first time. The type series of Gryllodes macropterus Fuente, 1894 and Gryllotalpa septemdecimchromosomica Ortiz, 1958 and two paratypes of Gryllomorpha adspersa merobricensis Fernandes, 1959, stat. n. are localized. Lectotypes and paralectotypes of 17 taxons are designated. The distribution of all species is revised.En el presente trabajo se realiza un estudio taxonómico y faunístico de la superfamilia Grylloidea de España, incluyendo las islas Baleares y Canarias. Se examinan las 60 especies y subespecies que se han encontrado hasta ahora en este país, siendo seis de ellas nuevas para la ciencia: Petaloptila (P.) fermini, P. (P.) isabelae, P. (Zapetaloptila) venosa, P. (Z.) barrancoi, Paramogoplistes dentatus sp. n. y Grylloderes orlovskajae adventicius subsp. n.; asimismo se crean dos nuevos subgéneros Italoptila y Zapetaloptila. Se establece una sinonimia correcta del género Grylloderes Bolívar, 1894 (=Platygryllus Chopard, 1961, syn. dist.), así como siete sinonimias específicas: Gryllomorpha (G.) dalmatina (Ocskay, 1832) (=Gryllomorpha dalmatina strumae Andreeva, 1982, syn. n.), Petaloptila (P.) aliena (Brunner-Wattenwyl, 1882) (=Discoptila eitschbergeri Harz, 1976, syn. n.), Acheta hispanicus Rambur, 1839 (=Gryllus erythrospilus Walker, 1869, syn. n., Gryllus hispanicus var. fusculus Bolívar, 1927, syn. n.), Eumodicogryllus bordigalensis (Latreille, 1802) (=Gryllodes ferdinandi Bolívar, 1899, syn. n., Gryllus chinensis var. intermedia Bolívar, 1927, syn. n.), Eugryllodes pipiens (Dufour, 1820) (=Gryllodes pipiens var. provincialis Azam, 1901, syn. n.), y además cinco estatus nuevos y una combinación nueva. Se citan por primera vez para la Península Ibérica tres especies [Eumodicogryllus theryi (Chopard, 1943), Sciobia natalia Gorochov, 1985 y Oecanthus dulcisonans Gorochov, 1993], las dos primeras de las cuales, lo son también para Europa; para la España peninsular una (Svercus p. palmetorum Krauss, 1902) y tres para las islas Canarias [Natula averni (Costa, 1855), comb. n., Acanthogryllus acus Gorochov, 1988, bajo este nombre, y Pseudomogoplistes vicentae Gorochov, 1996], esta última además se cita por primera vez para Argelia; así como Modicogryllus (M.) algirius (Saussure, 1877), para Francia. Por otra parte, se vuelve a considerar como buena especie Eugryllodes panteli (Cazurro, 1888). Asimismo se presenta una clave de identificación acompañada de figuras para las especies del género Petaloptila. También se estudia por primera vez la genitalia del macho de varias especies. Además, se han localizado las series tipo de Gryllodes macropterus Fuente, 1894 y Gryllotalpa septemdecimchromosomica Ortiz, 1958, así como dos paratipos de Gryllomorpha adspersa merobricensis Fernandes, 1959, stat. n. Se designan lectotipos y paralectotipos de 17 taxones y se revisa la geonemia de todas las especies

Establishment of a method for determination of arsenic species in seafood by LC-ICP-MS

An analytical method for determination of arsenic species (inorganic arsenic (iAs), methylarsonic acid (MA), dimethylarsinic acid (DMA), arsenobetaine (AB), trimethylarsine oxide (TMAO) and arsenocholine (AC)) in Brazilian and Spanish seafood samples is reported. This study was focused on extraction and quantification of inorganic arsenic (iAs), the most toxic form. Arsenic speciation was carried out via LC with both anionic and cationic exchange with ICP-MS detection (LC-ICP-MS). The detection limits (LODs), quantification limits (LOQs), precision and accuracy for arsenic species were established. The proposed method was evaluated using eight reference materials (RMs). Arsenobetaine was the main species found in all samples. The total and iAs concentration in 22 seafood samples and RMs ranged between 0.27-35.2 and 0.02-0.71 mg As kg-1, respectively. Recoveries ranging from 100% to 106% for iAs, based on spikes, were achieved. The proposed method provides reliable iAs data for future risk assessment analysis

Accuracy of a method based on atomic absorption spectrometry to determine inorganic arsenic in food : Outcome of the collaborative trial IMEP-41

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