Experimental demonstration of digital predistortion for orthogonal frequency-division multiplexing-radio over fibre links near laser resonance

Radio over fibre (RoF), an enabling technology for distribution of wireless broadband service signals through analogue optical links, suffers from non-linear distortion. Digital predistortion has been demonstrated as an effective approach to overcome the RoF non-linearity. However, questions remain as to how the approach performs close to laser resonance, a region of significant dynamic non-linearity, and how resilient the approach is to changes in input signal and link operating conditions. In this work, the performance of a digital predistortion approach is studied for directly modulated orthogonal frequency-division multiplexing RoF links operating from 2.47 to 3.7 GHz. It extends previous works to higher frequencies, and to higher quadrature amplitude modulation (QAM) levels. In addition, the resilience of the predistortion approach to changes in modulation level of QAM schemes, and average power levels are investigated, and a novel predistortion training approach is proposed and demonstrated. Both memoryless and memory polynomial predistorter models, and a simple off-line least-squares-based identification method, are used, with excellent performance improvements demonstrated up to 3.0 GHz

Disordered hyperuniformity in superconducting vortex lattices

The current carrying capability of type II superconductors under magnetic fields is determined to a large extent by the interaction of superconducting vortices with pinning centers. Vortices are arranged in lattices with varying degrees of disorder depending on the balance between the intervortex interactions and the pinning strength. We analyze here vortex arrangements in disordered vortex lattices of different superconducting systems, single crystals (Co-doped NbSe2, LiFeAs, and CaKFe4As4), and amorphous W- based thin films (with critical temperatures T-c from 4 K to 35 K and critical fields from 3.4 T to more than 90 T). We calculate for each case the structure factor and number variance and compare to calculations on an interacting set of partially pinned particles. We find that random density fluctuations appear when pinning overcomes interactions and show that the suppression of density fluctuations is correlated to the presence of interactions. We discuss the results within the framework of hyperuniform distributions and find that all studied lattices follow a similar increase of the number variance with the defect density

Effect of dietary grape pomace on fattening rabbit performance, fatty acid composition, and shelf life of meat

The use of agroindustry by-products in animal diets allows the use of residues that are not fit for human consumption. In this study, it was investigated whether fattening commercial rabbits during 30 days with a non-medicated feed, with 20% addition of grape pomace (GPD), affected production traits and the fatty acid composition, antioxidants properties, and the shelf life of the meat compared to a conventional strategy (CON). Furthermore, it was tested, by chromatographic analysis, whether this alternative diet allowed the transfer of phenolic compounds to the meat. Thirty-six weaned rabbits were allotted to the two treatments. In each treatment, 18 rabbits were fattened in three indoor cages, each housing three males and three female rabbits. No significant differences were found in live weights (p > 0.05), but the feed conversion rate and carcass weight and yield were found to be impaired in the GPD group (p = 0.05). The GPD group had a higher intramuscular fat percentage (2.01 vs. 1.54), improved polyunsaturated/saturated fatty acids ratio (0.75 vs. 0.66), and better atherogenicity (0.71 vs. 0.83) and thrombogenicity (1.14 vs. 1.24) indexes, while the n-6/n-3 ratio was higher (25.4 vs. 20.3). Total volatile basic nitrogen in meat was lower in the GPD group (p = 0.01), suggesting a delayed spoilage. However, no improvements in total phenolic content, antioxidant capacity, reducing power, and lipid oxidation (p > 0.05) were found in the meat. Even though the GPD pellets offered to the animals had several grape-derived phenolic compounds, and higher antioxidant properties compared to the CON diet, none of the phenolic compounds detected in feeds were detected in the meat samples. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Description Of The Hemipenial Morphology Of Tupinambis Quadrilineatus Manzani And Abe, 1997 (squamata, Teiidae) And New Records From Piauí, Brazil

Few data are available on the morphology of the hemipenis of teiid lizards, especially those of the recentlydefined genus Tupinambis, a widely-distributed group of large-bodied lizards. This study provides an illustrated description of the hemipenis of Tupinambis quadrilineatus, which is similar to that of other representatives of the Tupinambinae subfamily. New records of the species from the state of Piauí, in northeastern Brazil, are also presented. © Marcélia Basto da Silva et al.3616172Avila-Pires, T.C.S., (1995) Lizards of Brazilian Amazonia (Reptilia: Squamata), p. 706. , Zoologische VerhandelingenBarreto, L., Arzabe, C., Lima, Y.C.C., Herpetofauna da região de Balsas (2007) Cerrado Norte do Brasil, pp. 221-229. , In: Barreto L (Ed), USEB, PelotasBöhme, W., Zur Genitalmorphologie der Sauria: Funktionelle und stammesgeschichtliche Aspekte (1988) Bonner Zoologische Monographien, 27, pp. 1-176Colli, G.R., Péres Jr., A.K., Cunha, H.J., A new species of Tupinambis (Squamata: Teiidae) from Central Brazil, with an analysis of morphological and genetic variation in the genus (1998) Herpetologica, 54 (4), pp. 477-492Cope, E.D., On the hemipenes of the Sauria (1896) Proceedings of the Academy of Natural Sciences of Philadelphia, 48, pp. 461-467Costa, H.C., São Pedro, V.A., Péres, A.K., Feio, N.R., Reptilia, Squamata, Teiidae, Tupinambis longilineus: Distribution extension (2008) Check List, 4, pp. 267-268Dal Vechio, F., Recoder, R., Rodrigues, M.T., Zaher, H., The herpetofauna of the Estação Ecológica de Uruçuí-Una, state of Piauí, Brazil (2013) Papéis Avulsos de Zoologia, 53 (16), pp. 225-243. , doi: 10.1590/S0031-10492013001600001Dowling, H.G., Duellman, W.E., (1978) Systematic Herpetology: A Synopsis of Families and Higher Categories, p. 118. , HISS Publications, New YorkFerreira, L.V., Pereira, J.L.G., Avila-Pires, T.C.S., Chaves, P.P., Cunha, D.A., Furtado, C.S., Primeira ocorrência de Tupinambis quadrilineatus Manzani, Abe, 1997 (Squamata: Teiidae) no bioma Amazônia (2009) Boletim do Museu Paraense Emílio Goeldi Ciências Naturais, 4 (3), pp. 355-361Fitzgerald, L.A., Cook, J.A., Aquino, A.J., Molecular phylogenetics and conservation of Tupinambis (Sauria: Teiidae) (1999) Copeia, pp. 894-905. , doi: 10.2307/1447965Guimarães, T.C.S., Figueiredo, G.B., Salmito, W.E., Geographic distribution: Tupinambis quadrilineatus (2007) Herpetological Review, 38 (3), pp. 353-354Harvey, M.B., Ugueto, G.N., Gutberlet, R.L., Review of Teiid Morphology with a Revised Taxonomy and Phylogeny of the Teiidae (Lepidosauria: Squamata) (2012) Zootaxa, pp. 1-156. , http://zoobank.org/References/457C2AD0-E5CF-4A41-B6CB-11722700BC5FLangstroth, R.P., Adiciones probables y confirmadas para la saurofauna boliviana (2005) Kempffiana, 1 (1), pp. 101-128Levington, A.E., McDiarmid, R., Moody, S., Nickerson, M., Rosado, J., Sokol, O., Voris, H., Museum acronyms (1980) Second edition, Herpetological Review, 11, pp. 93-102Lima, A.C., Pimenta, F.E., Reptilia, Squamata, Teiidae, Tupinambis longilineus: Distribution extension (2008) Check List, 4, pp. 240-243Manzani, P.R., Abe, A., A new species of Tupinambis Daudin, 1802 (Squamata: Teiidae) from Brazil (1997) Boletim do Museu Nacional, Nova Série, Zoologia, 382, pp. 1-10Manzani, P.R., Abe, A., Sobre dois novos métodos de preparação de hemipênis de serpentes (1988) Memórias do Instituto Butantan, 50 (1), pp. 15-20Manzani, P.R., Abe, A.S., A new species of Tupinambis Daudin, 1803 from southeastern Brazil (Squamata, Teiidae) (2002) Arquivos do Museu Nacional, Rio de Janeiro, 60, pp. 295-302Mesquita, D.O., Colli, G.R., França, F.G.R., Vitt, L.J., Ecology of a Cerrado lizard assemblage in the Jalapão region of Brazil (2006) Copeia 2006, (3), pp. 460-471. , doi: 10.1643/0045-8511(2006)2006[460:EOACLA]2.0.CO;2Moreira, L.A., Fenolio, D.B., Silva, H.L.R., Silva Jr., N.J., A preliminary list of the Herpetofauna from termite mounds of the cerrado in the Upper Tocantins river valley (2009) Papéis Avulsos de Zoologia, 49 (15), pp. 183-189. , http://www.scielo.br/scielo.php?pid=S0031-10492009001500001&script=sci_arttextMyers, C.H., Williams, E.E., McDiarmid, R.W., A new anoline lizard (Phenacosaurus) from the highland of Cerro de la Neblina, Southern Venezuela (1993) American Museum Novitates 3070, pp. 1-15Pesantes, O.S., A method for preparing the hemipenis of preserved snakes (1994) Journal of Herpetology, 28, pp. 93-95. , doi: 10.2307/1564686Recoder, R., Nogueira, C., Composição e diversidade de répteis na região sul do Parque Nacional Grande Sertão Veredas, Brasil Central (2007) Biota Neotropica, 7 (3), pp. 267-278. , doi: 10.1590/S1676-06032007000300029Recoder, R.S., Junior, M.T., Camacho, A., Nunes, P.M.S., Mott, T., Valdujo, P.H., Ghellere, J.M., Rodrigues, M.T., Répteis da Estação Ecológica Serra Geral do Tocantins, Brasil Central (2011) Biota Neotropica, 11 (1), pp. 263-282. , doi: 10.1590/S1676-06032011000100026Savage, J.M., On terminology for the description of the hemipenis of squamate reptiles (1997) Herpetological Journal, 7, pp. 23-25. , doi: 10.1590/S1984-46702011000400005Silva Jr., N.J., Silva, H.L.R., Rodrigues, M.T., Valle, N.C.U., Costa, M.C., Castro, S.P., Linder, E.T., Sites Jr., J.W., A fauna de vertebrados do vale do alto rio Tocantins em áreas de usinas hidrelétricas (2005) Estudos, 32, pp. 57-101Silveira, A.L., Reptilia, Squamata, Teiidae, Tupinambis quadrilineatus: Distribution extension and geographic distribution map (2009) Check List, 5 (3), pp. 442-445Taylor, J.F., Genus Tupinambis, Tegus (2003) Reptilia, 27, pp. 43-49Vitt, L.J., Cadwell, J.P., Colli, G.R., Garda, A.A., Mesquita, D.O., França, F.G.R., Shepard, D.B., Silva, V.N., Uma atualização do guia fotográfico dos répteis e anfíbios da região do Jalapão no Cerrado brasileiro (2005) Special Publications in Herpetology, San Noble Oklahoma Museum of Nature History, 2, pp. 1-24Werneck, F.P., Colli, G.R., The lizard assemblage from seasonally dry tropical forest enclaves in the Cerrado biome, Brazil, and its association with the pleistocenic arc (2006) Journal of Biogeography, 33, pp. 1983-1992. , doi: 10.1111/j.1365-2699.2006.01553.xZaher, H., Prudente, A.L.C., Hemipenis of Siphlophis (Serpentes, Xenodontinae) and Techniques of Hemipenial Preparation in Snakes: A Response to Dowling (2003) Herpetological Review, 34, pp. 302-30

Can power spectrum observations rule out slow-roll inflation?

The spectral index of scalar perturbations is an important observable that allows us to learn about inflationary physics. In particular, a detection of a significant deviation from a constant spectral index could enable us to rule out the simplest class of inflation models. We investigate whether future observations could rule out canonical single-field slow- roll inflation given the parameters allowed by current observational constraints. We find that future measurements of a constant running (or running of the running) of the spectral index over currently available scales are unlikely to achieve this. However, there remains a large region of parameter space (especially when considering the running of the running) for falsifying the assumed class of slow-roll models if future observations accurately constrain a much wider range of scales

New WC-Cu composites for the divertor in fusion reactors

ABSTRACT: The requirements for the divertor components of future fusion reactors are challenging and therefore a stimulus for the development of new materials. In this paper, WC-Cu composites are studied for use as thermal barrier between the plasma facing tungsten tiles and the copper-based heat sink of the divertor. Composite materials with 50% vol. WC were prepared by hot pressing and characterized in terms of microstructure, density, expansion coefficient, elastic modulus, Young's modulus and thermal diffusivity. The produced materials consisted of WC particles homogeneously dispersed in a Cu matrix with densifications between 88% and 98%. The sample with WC particles coated with Cu evidenced the highest densification. The thermal diffusivity was significantly lower than that of pure copper or tungsten. The sample with higher densification exhibits a low value of Young's modulus (however, it is higher compared to pure copper), and an average linear thermal expansion coefficient of 13.6 x 10(-6) degrees C-1 in a temperature range between 100 degrees C and 550 degrees C. To estimate the behaviour of this composite in actual conditions, a monoblock of the divertor in extreme conditions was modelled. The results predict that while the use of WC-Cu interlayer leads to an increase of 190 degrees C on the temperature of the upper part of the monoblock when compared to a pure Cu interlayer, the composite will improve and reduce significantly the cold-state stress between this interlayer and the tungsten.info:eu-repo/semantics/publishedVersio

Effects of α-tocopherol and ternatin antioxidants on morphology and activation of goat preantral follicles in vitro cultured

Os efeitos do α-tocoferol e da ternatina sobre morfologia, ativação e crescimento de folículos pré-antrais caprinos cultivados in vitro, por um ou cinco dias, foram avaliados. Os fragmentos ovarianos foram imediatamente fixados (controle não-cultivado) ou cultivados in vitro, por um ou cinco dias, em Meio Essencial Mínimo (MEM) com ou sem suplementação com α-tocoferol ou ternatina nas concentrações de 5, 10 ou 15M, formando os tratamentos MEM, TOC5, TOC10, TOC 15, TER5, TER10, TER15. O percentual de folículos pré-antrais normais no controle não-cultivado foi de 73,2%, depois de cinco dias de cultivo, houve redução desse percentual em todos os tratamentos, quando comparados com o controle não-cultivado (P<0,05). O cultivo por cinco dias aumentou a ativação folicular em todos os tratamentos (P<0,05). A análise ultra-estrutural não mostrou folículos pré-antrais íntegros após cinco dias de cultivo em meio contendo antioxidantes. Concluiu-se que o α -tocoferol e a ternatina podem promover a ativação folicular, no entanto a adição desses antioxidantes nas concentrações testadas reduziu a viabilidade folicular após o cultivo in vitro. ______________________________________________________________________________________________________________ ABSTRACTThe effects of α-tocopherol and ternatin on the morphology, activation, and growth of goat preantral follicles in vitro cultured, for one or five days, were evaluated. Ovarian fragments were immediately fixed (non-cultured control) or in vitro cultured for one or five days in Minimum Essential Medium (MEM) with or without α-tocopherol or ternatin supplementation, both at concentrations of 5, 10, or 15M, corresponding to the following treatments: MEM, TOC5, TOC10, TOC 15, TER5, TER10, and TER15. The percentages of morphologically normal preantral follicles in non-cultured ovarian tissue (control) was 73.2% and after five days of culture, there was a decrease on these percentages in all treatments (P<0.05) when compared with non-cultured control. Culture of ovarian cortex for five days increased the percentages of follicular activation in all treatments (P<0.05). Ultrastructural analysis did not confirm the integrity of caprine preantral follicles cultured for five days in medium containing antioxidants. This study demonstrated that α-tocopherol and ternatin can promote follicular activation; however, addition of these antioxidants in the tested concentrations reduced the follicular viability after in vitro culture