350 research outputs found

    Cost, power consumption and performance analysis in SDM ROADM architectures for uncoupled spatial channels

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    Currently optical networks are reaching their maximum transport capacity. Different solutions can be used to overcome this capacity limit, but we are going to study, in particular, space division multiplexing (SDM). To use SDM, the reconfigurable optical add/drop multiplexers (ROADMs) need to be adapted to support this multiplexing. In this paper we analyze four switching strategies used in SDM ROADMs and the respective SDM ROADM architectures. These strategies are explained and analyzed, for uncoupled scenarios, in terms of cost and power consumption. The impact of the physical layer impairments (PLIs) amplified spontaneous emission noise, non-linear interference, passband narrowing due to optical filtering and in-band crosstalk is also assessed, considering a cascade of SDM ROADMs with spatial and spatial-wavelength switching granularities. The PLI inband crosstalk, has insignificant impact, in networks with a single spatial channel or in SDM networks with spatial granularity ROADM architecture, but in a SDM network with spatial wavelength granularity this PLI can lead to an OSNR penalty of around 2 dB, when the number of spatial channels is high. The other PLIs have similar impacts in all networks studied.info:eu-repo/semantics/acceptedVersio

    Matrix gla protein in xenopus laevis: molecular cloning, tissue distribution, and evolutionary considerations

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    Matrix Gla protein (MGP) belongs to the family of vitamin K-dependent, Gla-containing proteins and in higher vertebrates, is found in the extracellular matrix of mineralized tissues and soft tissues. MGP synthesis is highly regulated at the transcription and posttranscription levels and is now known to be involved in the regulation of extracellular matrix calcification and maintenance of cartilage and soft tissue integrity during growth and development. However, its mode of action at the molecular level remains unknown. Because there is a large degree of conservation between amino,acid sequences of shark and human MGP, the function of MGP probably has been conserved throughout evolution. Given the complexity of the mammalian system, the study of MGP in a lower vertebrate might be advantageous to relate the onset of MGP expression with specific events during development. Toward this goal, MGP was purified from Xenopus long bones and its N-terminal amino acid sequence was determined and used to clone the Xenopus MGP complementary DNA (cDNA) by a mixture of reverse-transcription (RT)- and 5'- rapid amplification of cDNA ends (RACE)-polymerase chain reaction (PCR). MGP messenger RNA (mRNA) was present in all tissues analyzed although predominantly expressed in Xenopus bone and heart and its presence was detected early in development at the onset of chondrocranium development and long before the appearance of the first calcified structures and metamorphosis. These results show that in this system, as in mammals, MGP may be required to delay or prevent mineralization of cartilage and soft tissues during the early stages of development and indicate that Xenopus is an adequate model organism to further study MGP function during growth and development.NATO/CRG940751/SA5.2.05, Praxis XXI/BIA 469/94, (NIH; grant AR 25921) (Praxis XXI/BPD/18816) (Praxis XXI/BICJ-2985

    Forecasts of butterfly future richness change in the southwest Mediterranean. The role of sampling effort and non-climatic variables

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    We estimated the potential impact of Global Warming on the species richness of Iberian butterflies. First, we determined the grid size that maximized the balance between geographic resolution, area coverage and environmental representativeness. Contemporary richness was modelled in several alternative ways that differed in how sampling effort was controlled for, and in whether the non-climatic variables (physiography, lithology, position) were incorporated. The results were extrapolated to four WorldClim scenarios. Richness loss is to be expected for at least 70% of the area, with forecasts from the combined models being only slightly more optimistic than those from the purely climatic ones. Overall, the most intense losses are predicted for areas of highest contemporary species richness, while the potential slightly positive or nearly neutral changes would most often concentrate in cells of low to moderate present richness. The environmental determinants of richness might not be uniform across the geographical range of sampling effort, suggesting the need of additional data from the least intensively surveyed areas.info:eu-repo/semantics/publishedVersio

    Osmium- And Iridium-Promoted C-H Bond Activation of 2, 2'-Bipyridines and Related Heterocycles: Kinetic and Thermodynamic Preferences

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    The d2-hexahydride complex OsH6(PiPr3)2 (1) promotes the activation of C-H bonds of 2, 2'-bipyridines and related heterocycles. The study of the same reactions with the deuteride counterpart OsD6(PiPr3)2 (1-d) reveals that the activation of the C-H bonds situated in the sterically less hindered positions is kinetically preferred. However, the isolated products are the result of the thermodynamic control of the reactions. Thus, reactions of 1 with 2, 2'-bipyridine, 6-phenyl-2, 2'-bipyridine, and 6-methyl-2, 2'-bipyridine give the "rollover cyclometalation" products OsH3{¿2-C, N-[C5(R)H2N-py]}(PiPr3)2 (R = H (2), Ph (3), Me (4)), whereas 3, 5-dimethyl-6-phenyl-2, 2'-bipyridine affords OsH2{¿3-C, N, C-[C5H3N-(Me)2py-C5H4]}(PiPr3)2 (5), containing a dianionic C, N, C-pincer ligand. The behavior of substrates pyridyl-benzimidazolium and -imidazolium is similar. Reaction of 1 with 3-methyl-1-(6-phenylpyridin-2-yl)-1H-benzimidazolium tetrafluoroborate leads to OsH3{¿2-C, C-[MeBzim-C5(Ph)H2N]}(PiPr3)2 (6), bearing an anionic Cpy, CNHC-chelate. On the other hand, 3-methyl-1-(6-phenylpyridin-2-yl)-1H-imidazolium tetrafluoroborate yields [OsH2{¿3-C, N, C-(MeIm-py-C6H4)}(PiPr3)2]BF4 (7), containing a monoanionic C, N, C-pincer with a NHC-unit coordinated in an abnormal fashion. The reactivity pattern of these substrates is also observed with the d4-iridium-pentahydride IrH5(PiPr3)2 (8), which has generated IrH2{¿2-C, N-[C5(R)H2N-py]}(PiPr3)2 (R = H, (9), Ph (10)) and IrH{¿3-C, N, C-[C5H3N-(Me2)py-C5H4]}(PiPr3)2 (11). The osmium(IV)-carbon bonds display a higher degree of covalency than the iridium(III)-carbon bonds. In contrast to 2, the metalated carbon atom of 9 undergoes the addition of a proton of methanol to give [IrH2{¿2-N, N-(bipy)}(PiPr3)2]BF4 (12)

    Production of the ragworm Nereis diversicolor (O. F. Müller, 1776), fed with a diet for gilthead seabream Sparus auratus L., 1758: survival, growth, feed utilization and oogenesis

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    A 65-day experiment was conducted to determine survival, growth, feed utilization and oogenesis of Nereis diversicolor (O. F. Müller, 1776), fed with a commercial dry diet developed for gilthead seabream Sparus auratus L., 1758. Worms were reared in three replicate tanks with 50 worms per tank (255 indiv · m_2). Tetramin®, a commonly used diet for ornamental fish and polychaete laboratory experiments, was used as a control. Survival was high (95.3 %) for both treatments, and not significantly affected by diet. Specific growth rates and feed efficiency ratios did not differ significantly between worms fed with either diets, nor were there significant differences in the proportion of individuals in the oocyte size classes.La supervivencia, el crecimiento, la utilización del alimento y la oogénesis de Nereis diversicolor (O. F. Müller, 1776) alimentado con pienso de dorada Sparus auratus L., 1758 fueron estudiados durante 65 días. Los poliquetos se cultivaron en tres tanques replicados con 50 individuos en cada uno (255 indiv · m_2). Como control se utilizó Tetramin®, una dieta común para peces ornamentales y en experimentos de laboratorio con poliquetos. La supervivencia fue alta (95,3 %) en ambos tratamientos y no se vio afectada significativamente por la dieta. El aumento de peso y los cocientes de eficiencia alimentaria no variaron significativamente entre los poliquetos alimentados con ambas dietas. Entre los grupos experimentales no hubo diferencia significativa en la proporción de individuos por clases de tamaño de los oocitos.Instituto Español de Oceanografí

    Towards discard quantification of Data Limited Stocks based in on-board observers data: the case of Spanish fresh trawlers targeting black hake in NW Africa

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    Quantification of discard per unit effort rates (DPUE) has been proposed by the European Commission as a measure to manage the discarding of commercially fished organisms. In the Spanish fresh trawling fleet operating in North West Africa, both target species of black hakes, Merluccius polli and Merluccius senegalensis are data limited stocks (DLS). Hence, discards of these fleets are even more unknown but not unimportant part of the total catch (retained and discarded). Onboard observer data from commercial surveys from 2016 to 2018 provide a detailed source of scientific information about catches, discards, effort and technical factors in this fleet. This is the first quantitative analysis to model DPUE through generalised linear mixed models (GLMM), based on the explicit distinction between abundance and technical factors coming from information of observer surveys. We describe the relationship between discards and environment, catches of target and other species, effort of the fleet, spatial and temporal variation in discard accessibility, vessel characteristics, strategy of the skippers and market decisions. Unlike hake catches, discards were higher and more dispersed in shallower than in deeper waters. We identified two separate métiers for the Spanish fresh trawling fleet determined by depth and treated total discards as a stock unit susceptible of being monitored, managed and assessed. The strategy of the skipper appears to have a more important effect on discards than vessel characteristics. This study shows the importance of observer data for this fishery and identifies recommendations for the improvement in the scientific usefulness of logbook information.En prens

    Skeletal quality in Senegalese sole: characterization of fish resulting from environmental and nutritional trials

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    The Senegalese sole (Solea senegalensis) is characteristic from southern Europe and Mediterranean. It has recently been adapted for aquaculture production since it is well accepted by consumers and reaches high commercial values. After the initial description of the ontogenic events of skeletogenesis, systematic evaluation of the incidence of skeletal malformations by several groups revealed high levels of skeletal deformities reaching up to 90% of the population

    Altered bone microarchitecture in a type 1 diabetes mouse model Ins2 Akita

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    Type 1 diabetes mellitus (T1DM) has been associated to several cartilage and bone alterations including growth retardation, increased fracture risk, and bone loss. To determine the effect of long term diabetes on bone we used adult and aging Ins2(Akita) mice that developed T1DM around 3-4 weeks after birth. Both Ins2(Akita) and wild-type (WT) mice were analyzed at 4, 6, and 12 months to assess bone parameters such as femur length, growth plate thickness and number of mature and preapoptotic chondrocytes. In addition, bone microarchitecture of the cortical and trabecular regions was measured by microcomputed tomography and gene expression of Adamst-5, Col2, Igf1, Runx2, Acp5, and Oc was quantified by quantitative real-time polymerase chain reaction. Ins2(Akita) mice showed a decreased longitudinal growth of the femur that was related to decreased growth plate thickness, lower number of chondrocytes and to a higher number of preapoptotic cells. These changes were associated with higher expression of Adamst-5, suggesting higher cartilage degradation, and with low expression levels of Igf1 and Col2 that reflect the decreased growth ability of diabetic mice. Ins2(Akita) bone morphology was characterized by low cortical bone area (Ct.Ar) but higher trabecular bone volume (BV/TV) and expression analysis showed a downregulation of bone markers Acp5, Oc, and Runx2. Serum levels of insulin and leptin were found to be reduced at all-time points Ins2(Akita). We suggest that Ins2(Akita) mice bone phenotype is caused by lower bone formation and even lower bone resorption due to insulin deficiency and to a possible relation with low leptin signaling.F. R. Carvalho and S. M. Calado acknowledge the financial support from the Portuguese Foundation for Science and Technology (FCT) through Ph.D. fellowships SFRH/BD/76429/2011 and SFRH/BD/76873/2011, respectively. This study was funded in part by CCMAR funding from European Regional Development Fund (ERDF) under COMPETE Program and through FCT under PEst-C/MAR/LA0015/2011 project and through UID/Multi/04326/2013 project. GA Silva was funded by (PIRG05-GA-2009-249314-EyeSee) and Research Center Grant UID/BIM/04773/2013 to CBMR

    Preliminary results on the growth and survival of the polychaete Nereis diversicolor (O. F. Müller, 1776), when fed with faeces from the carpet shell clam Ruditapes decussatus (L., 1758)

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    The growth and survival of the polychaete Nereis diversicolor (O. F. Müller, 1776) fed on faeces of the carpet shell clam Ruditapes decussatus (L., 1758) were studied under controlled temperature and salinity conditions. Juvenile worms were fed with clam R. decussatus faeces in the presence or absence of sediment during 65 days. Starvation treatments were tested as a control. The results of the present study show that the worms were able to grow using the clam faeces in the presence or absence of sediment. However, the worms from the trials with sediment showed a higher survival rate and biomass production than those from the trials in which no sediment was used. These findings suggest that a suspension of bivalve faeces can be used in the rearing of juvenile N. diversicolor in an integrated polyculture system.El crecimiento y la supervivencia del poliqueto Nereis diversicolor (O. F. Müller, 1776) alimentado con heces de almeja Ruditapes decussatus (L., 1758) fueron estimados bajo condiciones controladas de temperatura y salinidad. Los poliquetos juveniles fueron alimentados con heces en presencia y ausencia de sedimento durante 65 días. Como control se aplicaron tratamientos de ayuno. Los resultados sugieren que los poliquetos crecieron usando las heces como única dieta en presencia y en ausencia de sedimento. Es más: los poliquetos de los ensayos con sedimiento mostraron supervivencia y producción de biomasa mayores que aquéllos en que no se utilizó sedimiento. Los resultados sugieren que se puede usar una suspensión de heces procedentes de bivalvos en el cultivo de juveniles de N. diversicolor en un sistema de policultivo integrado.Instituto Español de Oceanografí
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