At the large watershed scale, we emphasize the effects of flow through a river network on streamflow under dry conditions. An immediate consequence of assuming dry conditions is that evapotranspiration causes flow in the river network to exhibit oscillations. When all links in the river network combine their flow patterns, the oscillations interact in ways that change the timing and amplitude of the streamflow waves at the watershed outlet. The geometric shape of the river network is particularly important, so we develop an analytic solution for streamflow which emphasizes that importance. Doing hydrology backward is a strategy recently developed by several researchers to deal with uncertainty in measurements of forcing terms applied to hydrologic models. The strategy has also been applied to resolve the assumption of homogeneity on realistic catchments that exhibit many heterogeneous properties. In this work, we demonstrate hydrology in the backward direction applied to two examples: using streamflow at the catchment scale to determine runoff at the hillslope scale and using the hillslope runoff to infer the applied evapotranspiration forcing under the assumption of dry conditions. In order to work across scales, we utilize the analytic solution for streamflow at the outlet of a river network. At the hillslope scale, we develop a soil model to create fluxes consistent with observed soil processes.

The loss of large apex predators, and their subsequent reintroduction, has been identified as a substantial driver on the structure and function of ecological communities through behavioral mediated trophic cascades (BMTCs). The reintroduction of wolves (Canis lupus) to Yellowstone National Park (YNP) has served as foundational case study of BMTCs. In our system, it has been suggested that wolves have established a ‘landscape of fear’ in which the primary prey, elk (Cervus elaphus), now avoid risky places, which ultimately led to the recovery of the vegetation community. Although this case is frequently cited as a well-understood example of a landscape of fear, researchers never quantified whether elk avoided risky places, a critical component of the BMTC hypothesis. Thus, I employed numerous quantitative approaches to evaluate the role of wolves and cougars on elk habitat selection in northern Yellowstone. The results from this work suggest that the daily activity schedule of wolves provide a temporally predictable period of risk that allows elk to use risky places during safe times. As such, diel predator activity flattened (i.e., made less risky) the landscape of fear for 16 hours per day, 7 days a week, which permitted elk to forage on deciduous woody plants despite the presence of wolves. Thus, suggests that any trophic cascade in northern Yellowstone is likely driven by the consumptive effects of wolves on elk. In addition, my results suggest that daily activity patterns are an important component of predation risk, and as such, provide a predictable avenue for elk to avoid predators despite residing in an environment spatially saturated with wolves and cougars. Thus, the ability of elk to avoid predators through fine-scale spatial decisions provides support for my findings that the current spatial distribution of prey is largely driven by the consumptive effects of predators on the prey population, rather than a landscape of fear. In combination, these results suggest that the landscape of fear, and more generally, fear effects, may be of less relevance to conservation and management than direct killing within free-living, large landscapes.

A hull-mounted 38-kHz phased-array acoustic Doppler current profiler (ADCP) was used to acoustically survey the continental margin of the northern Gulf of Mexico (GOM) during 6 cruises in 2002-2003. This is the first backscatter survey with a 38-kHz ADCP in the Gulf of Mexico. ADCPs have been used as a proxy to measure the volume backscatter return from plankton in the water column, however previous studies were restricted to the upper 200 to 300 meters due to the relatively high frequency of operation (150-300 kHz) of the transducers. In addition to measuring deep water current velocities, the 38-kHz phased-array ADCP can measure Relative Acoustic Backscatter Intensity (RABI) as deep as 1000 meters. The daytime depth of the main deep scattering layer at 400 to 500 meters was resolved, and locally high backscatter intensity can be seen down to 800 meters. The objectives were to determine how to analyze RABI from the instrument to resolve scattering layers, and then to seek secondary deep scattering layers of potential prey species below the main deep scattering layer, from 600 to 800 meters in the feeding range for Gulf of Mexico sperm whales. Based on RABI from the 38-kHz ADCP, secondary DSLs in sperm whale diving range were more commonly recorded over the continental shelf than in the deep basin region of the Gulf of Mexico. The daytime depths of migrating plankton showed variation depending on physical circulation features (cyclone, anticyclone, proximity to Mississippi river, and Loop Current) present. Vertical migrations compared between concurrently running 38 and 153-kHz ADCPs showed an overlap of acoustic scatterers recorded by the two instruments, however the 153-kHz instrument has much finer vertical resolution. Vertical migration rates were calculated and simultaneous net tow samples from one of the cruises was used to compare abundance estimates by the two methods.

Recent research has shown that groundwater flow in hyporheic zone is critical in major hydrologic, ecological, and biogeochemical processes. Quantitative analyses from the literature show that there is a strong correlation between the diel cycles in pH, water temperature, and other parameters such as trace metal concentrations. There is, however, no controlled experimental data to illustrate how water temperature influences the trace metal concentrations and other parameters. The research study presented here illustrates the mechanism of heat is transported from stream water to groundwater in the hyporheic zone on different bed form. The work will serve as the foundation of future research in understanding the relationship of heat and trace metal concentrations in the sediments. / text

Aquatic plants or macrophytes are known as conduits of Methane (CH4), Carbon dioxide (CO2) and Nitrous oxide (N2O) which contribute to the total fluxes of the Greenhouse gases emissions from lakes. Recent studies emphasized that the knowledge on plant mediated emissions calls for more systematic and comparative data especially in the areas of spatial and temporal variability. In this study I measured diel (24 hour) and diurnal(  daily hours only) plant mediated fluxes during four sampling sessions using chamber method from a  Swedish lake in summer 2012. The measurements were conducted on two macrophyte population patterns of mixed plant communities and Equisetum fluviatile (specie-specific) community. CH4 emissions were higher in darker hours and there were no diel correlation between CH4 fluxes and average diel temperature. CH4 fluxes varied between 0.42 mmol m-2d-1 and 2.3 mmol m-2d-1. The CO2 fluxes had negative fluxes in day and positive during the day which was logical due to macrophyte respiration and photosynthesis mechanisms. Occasional daily positive fluxes were seen (only) during the rainy hours and there were no correlation between temperature and diel CO2 fluxes. The total net CO2 exchange was 2.8mmol m-2d-1 indicating that there was more CO2 release in the littoral zone of that lake. N2O fluxes did not show any clear diel or monthly pattern and the fluxes ranged between positive and negative numbers. The N2O fluxes did not exceed 2µmol m-2 d-1 with the total average flux of 0.8µmol m-2 d-1.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-11-22T20:32:41Z No. of bitstreams: 1 AlcineyMirandaCabral_TESE.pdf: 9055485 bytes, checksum: 069ff7e30ae747a94ed4317fcd5f7186 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-11-23T22:39:21Z (GMT) No. of bitstreams: 1 AlcineyMirandaCabral_TESE.pdf: 9055485 bytes, checksum: 069ff7e30ae747a94ed4317fcd5f7186 (MD5) / Made available in DSpace on 2017-11-23T22:39:21Z (GMT). No. of bitstreams: 1 AlcineyMirandaCabral_TESE.pdf: 9055485 bytes, checksum: 069ff7e30ae747a94ed4317fcd5f7186 (MD5) Previous issue date: 2017-06-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / O desafio inovador deste trabalho foi aplicar o m?todo qu?mico de S?ntese por Rea??o de Combust?o adaptada ?s perovskitas multiferr?icas BiFeO3, nas suas formas monof?sicas. Inicialmente, foi realizado a s?ntese para o BFO nas temperaturas ap?s a rea??o (BFOP.C.), a 700 oC (antes da Temperatura de Curie, BFO700) e a 830oC (pr?xima a Temperatura de Curie, BFO830). Na segunda etapa da s?ntese, foi definida a temperatura de 700 oC no sistema de dopagens LaxBi1-xFeO3 (x= 0.00, 0.10, 0.20 e 0.30), formando BFO700, L0.10BFO700, L0.20BFO700 e L0.30BFO700. Os materiais sintetizados foram caracterizados por Refinamento de Rietveld (DRX ? Rietveld), Espectroscopia no Infravermelho M?dio com Transformada de Fourier (FTIR), Microscopia Eletr?nico de Varredura com Espectroscopia por Energia Dispersiva (MEV/EDS/MAPEAMENTO), An?lises T?rmicas (TG/DTA), Propriedades Magn?ticas e El?tricas (???,??,??? ? ??? ?). Os resultados das an?lises dos par?metros estruturais, el?tricos e magn?ticos das perovskita de BiFeO3 (BFO) nas fases monof?sicas, indicaram simetria/grupo espacial Rombo?drica/?3? (BFOP.C.), Rombo?drica/?3? (BFO700) e Tricl?nica/?1 (BFO830) nas cer?micas. As dopagens por La3+ nas amostras BFO700, L0.10BFO700, L0.20BFO700 e L0.30BFO700 proporcionam diferentes valores Magn?ticos de Satura??es e resultaram Romboedral/?3? - 0.011314 ??.[?.?.]?1, Ortorr?mbico/???? - 0.006516 ??.[?.?.]?1, Ortorr?mbico/???? - 0.011503 ??.[?.?.]?1e Ortorr?mbico/???? - 0.009509 ??.[?.?.]?1respectivamente. As an?lises por FTIR/DRX ? Rietveld evidenciaram vibra??es caracter?sticas em 530.34, 531.61 e 551.51cm-1 que atribu?dos s?o ?s perovskitas de BiFeO3 com distor??o octaedral (FeO6). O estudo das estruturas sintetizadas apontaram para as cer?micas antiferromagneticas com distor??o octaedral. Na faixa 0 ? 0.5 GHz a dieletricidade das cer?micas foi maior que 6 e a tangente de perdas menores que -0.13. O fator de qualidade da antena com as amostras cer?micas apresentaram valores entre -10 dB e -25dB. Os resultados indicaram o alto potencial do BFO e LBFO como substratos cer?micos qu?micos em antenas magnetoferr?icas. / The innovative challenge of this work was to apply the chemical synthesis method by combustion reaction adapted to multiferroic perovskite in the forms BiFeO3 single. Initially, the synthesis of the BFO in temperatures after the reaction (BFOP. C.), 700 oC (before to curie temperature, BFO700) and 830 oC (near to curie temperature, BFO830). Secondly, the synthesis was defined the temperature of 700 oC in the doping system LaxBi1-xFeO3 (x= 0.00, 0.10, 0.20 and 0.30), forming BFO700, L0.10BFO700, L0.20BFO700 and L0.30BFO700. The sintetized materials were characterized by Rietveld Refinement (DRX ? Rietveld), Medium Fourier Transform Infrared Spectroscopy (FT ? IR), Scanning Electron Microscopy and Energy Dispersive X ? ray Spectroscopy (SEM/EDX/MAPPING), Thermical Analysis (TG/DTA), Magnetic and Electrical Properties (???,??,??? and ??? ?). The analytical results of the structural parameters, eletrics and magnetics of the perovskites of BiFeO3 (BFO), in the single phases, indicated symmetry/space group Rhombohedral/?3? (BFOP.C.), Rhombohedral/?3? (BFO700) and Triclinic/?1 (BFO830) in the ceramics. The doping by La3+ in the samples BFO700, L0.10BFO700, L0.20BFO700 and L0.30BFO700 showed different magnetic saturation of materials, resulting in Rhombohedral/?3? - 0.011314??.[?.?.]?1, Orthorhombic/???? - 0.006516 ??.[?.?.]?1, Orthorhombic/???? - 0.011503 ??.[?.?.]?1and Orthorhombic/???? - 0.009509 ??.[?.?.]?1 respectively. The analysis by FT ? IR/XRD ? Rietveld showed vibration characteristics in 530.34, 531.61 and 551.51cm-1 that are attribute to perovskites of BiFeO3 with octahedral distortion (FeO6). The study of the sintetized structures pointed for the antiferromagnetic ceramics with an behaviour octaedral distortion. In the range 0 ? 0.5 GHz, the dielectricity of the ceramics was more that 6 and the smaller loss tangent that -0.13. The quality factor of the antenna with the ceramic samples presented value between -10 dB and -25dB. The results indicated the potential high of the BFO and LBFO as substrates chemical ceramics in magnetoferroic antennas.

The impact of fish predation on zooplankton assemblage was studied in the mesocosm experiment. Presented thesis focuses on the effect of size selective fish predation on species diversity, biomass and body sizes of zooplankton and the impact of fish occurrence on zooplankton behaviour with regard to diel horizontal migration. I also studied a change in some life history traits of zooplankton caused by fish with a special focus on keystone species of freshwater ecosystems Daphnia spp.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-07-06T19:34:30Z No. of bitstreams: 1 JoseHaroldoCavalcanteDeMorais_TESE.pdf: 8218875 bytes, checksum: 74cb32467161f10131b623d5e12e6c43 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-07-06T21:46:11Z (GMT) No. of bitstreams: 1 JoseHaroldoCavalcanteDeMorais_TESE.pdf: 8218875 bytes, checksum: 74cb32467161f10131b623d5e12e6c43 (MD5) / Made available in DSpace on 2016-07-06T21:46:11Z (GMT). No. of bitstreams: 1 JoseHaroldoCavalcanteDeMorais_TESE.pdf: 8218875 bytes, checksum: 74cb32467161f10131b623d5e12e6c43 (MD5) Previous issue date: 2015-12-01 / Esse trabalho tem como objetivo apresentar configura??es de substratos diel?tricos inovadores projetados e fabricados a partir de estruturas metamateriais. Para isso, s?o avaliados diversos fatores que podem influenciar no seu desempenho. A princ?pio, foi feito um levantamento bibliogr?fico a respeito dos temas, que est?o relacionados com as pesquisas sobre: materiais diel?tricos, metamateriais e interferometria ?ptica. S?o estudados, pesquisados e desenvolvidos dois projetos experimentais propostos, que comprovam a efici?ncia de m?todos, para se alcan?ar a permeabilidade magn?tica negativa na forma??o de metamateriais. O primeiro projeto ? a produ??o de uma nova estrutura, com u anel ressoador triangular equilateral (Split Equilateral Triangle Resonator - SETR). O segundo projeto: aplica os princ?pios da interferometria ?ptica, especialmente, com o interfer?metro de Fabry-Perot. T?cnicas para obten??o dos dispositivos que complementam a placa metamaterial como substrato foram pesquisadas na literatura e exemplificadas principalmente por meio de simula??es e medi??es. Foram feitas compara??es, simula??es e medi??es de estruturas convencionais e especiais. As experi?ncias se concentram nas evolu??es e modelagens de substratos metamateriais com aplica??es em antenas de microfita. As melhorias de alguns par?metros de desempenho de antenas tamb?m s?o relatadas. As simula??es das antenas foram feitas nos programas computacionais comerciais. Os resultados medidos foram obtidos com um analisador vetorial de redes da Rhode and Schwarz modelo ZVB 14.

Made available in DSpace on 2014-12-17T14:55:34Z (GMT). No. of bitstreams: 1 LeonardoGS_capa_ate_pag14.pdf: 8948840 bytes, checksum: 4d51d13aaf89dea78c833070223e6927 (MD5) Previous issue date: 2003-09-29 / The present work deals with the ana1ysis of microstrip patch antennas printed on tapered dielectric substrates. We investigate the influence ofthe substrate height variations on the properties of configurations such as microstrip patch antennas, microstrip patch antennas with overlay and suspende? microstrip patch antennas. The dielectric substrates can be isotropic or anisotropic ones. This accurate analysis is based on the full-wave formulation. It is carried out initially for the determination of the impedance matrix, through the use of the spectral?domain immitance approach. We use a model based on a segmentation of the considered line into uniform microstrip line subsections. Normalized phase constants and characteristic impedances are obtained by means of the Galerkin numerical technique. Then, the cascaded combination of the uniform microstrip subsections are analyzed through an interactive procedure. Numerical results are presented for the input reflection coefficient, voltage standing wave ratio, resonant frequency, and radiation pattems ofthe E_plane and H-plane diagrams. It is found that the variations in the substrate height profile produce a great influence on the bandwidth of microstrip antennas. This procedure gives bandwidth improvements without altering considerably the resonant frequency. Furthermore, the tapered microstrip antenna can be used as a lightweight altemative for bandwidth control and to eXtend the use of microstiip antenna technology to a wider variety of applications. Finally, suggestions for the continuity of this work are presented / Este trabalho consiste na an?lise de antenas de microfita sobre substratos diel?trico sem rampa. O efeito da varia??o linear na espessura do substrato ? investigado nas caracter?sticas de propaga??o de antenas patch de microfita, antenas de microfita com sobrecamada e antena de microfita sobre substratos diel?tricos suspensos em rampa. Os substratos utilizados s?o constitu?dos de materiais isotr?picos ou anisotr?picos. ? efetuada uma an?lise rigorosa utilizando o formalismo de onda completa. O m?todo da imit?ncia, no dom?nio esctral, ? empregado para a determina??o da matriz imped?ncia. O procedimento de an?lise consiste em discretizar a estrutura em se??es uniformes. As constantes de fase e as imped?ncias caracter?sticas s?o obtidas atrav?s da t?cnica num?rica de Galerkin pra cada se??o que constitui a estrutura em rampa. Da?, a caracteriza??o din?mica da combina??o em cascata de todas as se??es uniformes ? determinada atrav?s de um processo iterativo. Resultados num?ricos s?o apresentados para o coeficiente de reflex?o e para o coeficiente de onda estacion?ria na entrada da antena, para a freq??ncia de resson?ncia e para os diagramas de radia??o no plano E e no plano H. Verifica-se que as varia??es na altura do substrato em rampa afetam a largura da faixa da antena de microfita. Essa estrat?gia aumenta a largura de banda, sem que haja uma altera??o significativa na freq??ncia de resson?ncia. Assim, a antena de microfita em rampa pode ser usada em aplica??es onde se deseja uma largura de faixa maior, sem que haja uma altera??o significativa na freq??ncia de resson?ncia. Al?m disso, a antena de microfita afilada pode ser utilizada como alternativa para controle de largura de banda e para estender o uso da tecnologia de antenas de microfita e suas aplica??es. S?o apresentadas sugest?es de continuidade do trabalho

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-02-21T21:47:55Z No. of bitstreams: 1 CristovaoPorcianoDoNascimentoJunior_TESE.pdf: 27666407 bytes, checksum: 4cdfec47679082d133ed4d3182cebe76 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-02-23T20:41:29Z (GMT) No. of bitstreams: 1 CristovaoPorcianoDoNascimentoJunior_TESE.pdf: 27666407 bytes, checksum: 4cdfec47679082d133ed4d3182cebe76 (MD5) / Made available in DSpace on 2018-02-23T20:41:29Z (GMT). No. of bitstreams: 1 CristovaoPorcianoDoNascimentoJunior_TESE.pdf: 27666407 bytes, checksum: 4cdfec47679082d133ed4d3182cebe76 (MD5) Previous issue date: 2017-09-14 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / O niobato de ferro (FeNbO4) tem sido aplicado como foto?nodo em conversores de energia solar, sensores a g?s, tecnologias catal?ticas, fotodectoras e dispositivos eletr?nicos. No entanto, as descri??es de suas propriedades diel?tricas ainda s?o muito escassas. Foi preparado tr?s tipos de amostras a partir da moagem de alta energia (24h, 48h e 72h) dos precursores de: Nb2O5, ?-Fe e H2O. Depois do processo de moagem, os p?s resultantes da moagem passaram pelo processo de calcina??o por 4 horas a 1300?C. O tempo de calcina??o foi o mesmo para todas. Todas essas amostras passaram pela caracteriza??o diel?trica, mas antes elas foram prensadas a 1570 Kgf e sinterizadas ? 1000_C por 24 horas. As caracteriza??es estruturais das amostras foram realizadas atrav?s da difra??o de raios X, microscopia eletr?nica de varredura e fluoresc?ncia de raios X. Os resultados revelaram que a amostra mo?da por 24h tem 94,48 % de FeNbO4 e 5,52 % de Fe2O3, para 48h tem 97,82 % de FeNbO4 e 2,18 % de Fe2O3, para 72h tem 93,68 % de FeNbO4 e 6,32 % de Fe2O3. As propriedades diel?tricas foram analisadas atrav?s das curvas caracter?sticas I-V e da permissividade diel?trica complexa com rela??o a frequ?ncia. As curvas caracter?sticas obtidas mostraram um comportamento semelhante a dispositivos eletr?nicos semicondutores, pertencente a fam?lia dos tiristores. O nosso estudo trata de uma nova rota de s?ntese para obten??o do niobato de ferro. Os resultados indicam que as amostras t?m grande potencial para aplica??o em dispositivos eletr?nicos. / Iron niobate (FeNbO4) has been applied to the photodiode in solar energy converters, gas sensors, photo detectors, and electronic devices. However, a full description of your dielectric properties is still scarceness so. By using a high energy mill, they were prepared three kinds of samples (24, 48 and 72 hours) of the precursors of: Nb2O5, a-Fe e H2O. After milling process, the resultant powders were to calcinated for precisely 4 hours and in a temperature of 1 300 celsius. We used a hydraulic press about 1570 Kgf to produce the samples. Next, the samples were calcinated during a time considered the same for all of them and underwent to dielectric characterization. In the way to characterize the samples, the samples were submitted to X rays, scanning electronic microscopy and X rays uorescence. Results have been shown that samples milling by 24 hours, has 94.48% of FeNbO4 and 5.52% of Fe2O3, by 48h has 97.82% of FeNbO4 and 2,18% de Fe2O3, and by 72h has 93,68% of FeNbO4 and 6.32% of Fe2O3. Dielectric properties were analyzed through I-V characteristic curves and complex dielectric permitivity against frequency. The characteristic curves exhibited semiconductors electronic devices behave like thyristor class. Furthermore, the present work constitutes a fully new route to sintering iron niobate. The results indicate that the samples have great potential for application in electronic devices.