Signal processing of microstructure profiles: integrating turbulent spatial scales in aquatic ecological modeling

The main objective of this thesis was the integration of microstructure information in synoptic descriptors of turbulence, that reflects the mixing processes. Turbulent patches are intermittent in space and time, but they represent the dominant process for mixing. In this work, the properties of turbulent patches were considered the potential input for integrating the physical microscale measurements. The development of a method for integrating the properties of the turbulent patches required solving three main questions: a) how can we detect the turbulent patches from he microstructure measurements?; b) which are the most relevant properties of the turbulent patches?; and ) once an interval of time has been selected, what kind of synoptic parameters could better reflect the occurrence and properties of the turbulent patches? The answers to these questions were the final specific objectives of this thesis.

Initiation of deep convection at marginal instability in an ensemble of mesoscale models: a case-study from COPS

The present study investigates the initiation of precipitating deep convection in an ensemble of convection-resolving mesoscale models. Results of eight different model runs from five non-hydrostatic models are compared for a case of the Convective and Orographically-induced Precipitation Study (COPS). An isolated convective cell initiated east of the Black Forest crest in southwest Germany, although convective available potential energy was only moderate and convective inhibition was high. Measurements revealed that, due to the absence of synoptic forcing, convection was initiated by local processes related to the orography. In particular, the lifting by low-level convergence in the planetary boundary layer is assumed to be the dominant process on that day. The models used different configurations as well as different initial and boundary conditions. By comparing the different model performance with each other and with measurements, the processes which need to be well represented to initiate convection at the right place and time are discussed. Besides an accurate specification of the thermodynamic and kinematic fields, the results highlight the role of boundary-layer convergence features for quantitative precipitation forecasts in mountainous terrain.

Extended magnetic reconnection across the dayside magnetopause

The extent of where magnetic reconnection (MR), the dominant process responsible for energy and plasma transport into the magnetosphere, operates across Earth’s dayside magnetopause has previously been only indirectly shown by observations. We report the first direct evidence of X-line structure resulting from the operation of MR at each of two widely separated locations along the tilted, subsolar line of maximum current on Earth’s magnetopause, confirming the operation of MR at two or more sites across the extended region where MR is expected to occur. The evidence results from in-situ observations of the associated ion and electron plasma distributions, present within each magnetic X-line structure, taken by two spacecraft passing through the active MR regions simultaneously.

Landscape, regional and global estimates of nitrogen flux from land to sea: errors and uncertainties

Regional to global scale modelling of N flux from land to ocean has progressed to date through the development of simple empirical models representing bulk N flux rates from large watersheds, regions, or continents on the basis of a limited selection of model parameters. Watershed scale N flux modelling has developed a range of physically-based approaches ranging from models where N flux rates are predicted through a physical representation of the processes involved, through to catchment scale models which provide a simplified representation of true systems behaviour. Generally, these watershed scale models describe within their structure the dominant process controls on N flux at the catchment or watershed scale, and take into account variations in the extent to which these processes control N flux rates as a function of landscape sensitivity to N cycling and export. This paper addresses the nature of the errors and uncertainties inherent in existing regional to global scale models, and the nature of error propagation associated with upscaling from small catchment to regional scale through a suite of spatial aggregation and conceptual lumping experiments conducted on a validated watershed scale model, the export coefficient model. Results from the analysis support the findings of other researchers developing macroscale models in allied research fields. Conclusions from the study confirm that reliable and accurate regional scale N flux modelling needs to take account of the heterogeneity of landscapes and the impact that this has on N cycling processes within homogenous landscape units.

Volcanic ash layer depth: processes and mechanisms

The long duration of the 2010 Eyjafjallajökull eruption provided a unique opportunity to measure a widely dispersed volcanic ash cloud. Layers of volcanic ash were observed by the European Aerosol Research Lidar Network with a mean depth of 1.2 km and standard deviation of 0.9 km. In this paper we evaluate the ability of the Met Office's Numerical Atmospheric-dispersion Modelling Environment (NAME) to simulate the observed ash layers and examine the processes controlling their depth. NAME simulates distal ash layer depths exceptionally well with a mean depth of 1.2 km and standard deviation of 0.7 km. The dominant process determining the depth of ash layers over Europe is the balance between the vertical wind shear (which acts to reduce the depth of the ash layers) and vertical turbulent mixing (which acts to deepen the layers). Interestingly, differential sedimentation of ash particles and the volcano vertical emission profile play relatively minor roles.

Interaction of strangelets with ordinary nuclei

Strangelets (hypothetical stable lumps of strange quarkmatter) of astrophysical origin may be ultimately detected in specific cosmic ray experiments. The initial mass distribution resulting from the possible astrophysical production sites would be subject to reprocessing in the interstellar medium and in the earth`s atmosphere. In order to get a better understanding of the claims for the detection of this still hypothetic state of hadronic matter, we present a study of strangelet-nucleus interactions including several physical processes of interest (abrasion, fusion, fission, excitation and de-excitation of the strangelets), to address the fate of the baryon number along the strangelet path. It is shown that, although fusion may be important for low-energy strangelets in the interstellar medium (thus increasing the initial baryon number A), in the earth`s atmosphere the loss of the baryon number should be the dominant process. The consequences of these findings are briefly addressed.

Rock magnetism in soils of the Pampean plain. Buenos Aires province, Argentina. Linking climate and magnetic behaviour

Results of the study of Argiudolls in two localities (Zarate and Veronica) of the Pampean plain, Argentina, are presented in this contribution. This is a typical area covered by loess. The magnetic studies carried out allowed to determine the presence of detrital magnetite and titanomagnetite, as well as maghemite, pedogenic goethite and superparamagnetic particles (SP). In Veronica soils, a depletion of ferromagnetic minerals is recorded The dominant process in these soils has been the reductive loss of detrital magnetite and titanomagnetite. This is associated with a greater degree of evolution of the soil, which is determined by the concentration and type of detected clays. The higher clay concentration in these soils facilitated reducing conditions and a greater loss of detrital magnetic particles. The loss is reinforced under poor drainage conditions. In the poorly drained soil of Zarate, a concentration of magnetic particles is observed in the Bt horizon, which is associated with an illuviation process. The well drained soil of the same locality shows neoformation of SP particles. These particles would have an ephemeral life until a new wet period in the annual cycle occurs. Although some characteristics of the magnetic signal appear reinforced by the conditions of drainage, this aspect does not seem to be too significant, at least in the Pampean region with low topographic gradients.

Petrologia do plúton granitico serra verde, porção lestre do domínio seridó

The study area is located at the eastern-central portion of the Seridó Belt, on the interface between the Seridó Group Metasediments and the crystalline basement rocks of the Caicó Complex (RN). Petrographic and geochemical data allow us to define aspects related to the genesis and evolution of the Serra Verde Pluton magmas, which composes the goal of this dissertation The Serra Verde Pluton is a stock with outcropping area of about 25 km², which is intrusive into metasedimentary sequence and the basement gneisses. The pluton intrusion is sintectonic to the Brasiliano event, elongated along the NE direction, developing a cornue geometry. The rock is a monzogranite mainly composed by K-feldspar, plagioclase and quartz, which usually compose more than 85% of the modal analisys. The main mafic mineral is the biotite, while amphibole, sphene, epidote, opaque minerals, allanite, zircon and apatite occur as accessory minerals. It features still a latemagmatic paragenesis composed by chlorite, granular epidote, carbonates and muscovite, developed through the percolation of late CO2 and H2O rich fluids. Chemically, the Serra Verde Pluton rocks may be classified as metaluminous, of calc-alkaline affiliation, sometimes showing trondhjemític characteristics, with high Na2O (>4,5%), Sr (>400ppm) and Ba (>800ppm) and low K2O (≤3,0%), MgO (<1,0%), TiO2 (<0,5%), Rb (<90ppm), Y (≤16ppm) and Zr (≤13ppm). Micropetrographic evidences (mineral assembly and microtextures) indicate that the magma evolution occurred in moderated to high fO2 conditions, above the FMQ buffer. Thermo-barometric data obtained by minor elements geochemistry and the CIPW data, suggest a final/minimal pressure crystallization for the Serra Verde Pluton samples of about 3 to 5 kbar, liquidus temperature around 800o C, solidus temperature between 680o and 660o C. This data is compatible with those observed by many authors for the Neoproterozoic granites of the Seridó Belt. The group of analyzed data (Petrographic, microtextural and geochemical), suggests that the dominant process of the generation and evolution of the Serra Verde Granite magma was the fractional crystallization, probably from basement quartz-dioritic and tonalitic orthogneisses source

Dynamics of Bose-Einstein condensates with atomic pumping and dissipative processes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ageing behavior in the Cu-10 wt.%Al and Cu-10 wt.%Al-4 wt.%Ag alloys

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

EQCM study during lithium insertion/deinsertion processes in Nb2O5 films prepared by polymeric precursor method

The electrochemical quartz crystal microbalance (EQCM) technique was used to study two chemically distinct Nb2O5 electrochromic thin films (one pure and the other lithium-doped) during the lithium electroinsertion reaction. In the initial cycles, the electrode showed an irreversible mass variation greater than expected for Li+ insertion/deinsertion processes, which was attributed to the wettability effect (allied to the porous morphology) that emerged as the dominant process in apparent electrode mass changes. As the cycles progressed, the mass variation stabilized and the changes in apparent mass became reversible, showing a good correlation with the charge variations.The results generally indicated that the Li+ insertion/deinsertion process occurred more easily in the Nb2O5-doped film, which also displayed a greater capacity for Li+ insertion. However, a total mass/charge balance analysis revealed that the stoichiometry of the Li+ solid state insertion/deinsertion reaction was similar in the two electrodes under study. © 2005 Elsevier B.V. All rights reserved.

Spectroscopic properties and upconversion mechanisms in Er3+-doped fluoroindate glasses

Fluorindate glasses containing 1,2,3,4 ErF3 mol % were prepared in a dry box under argon atmosphere. Absorption, Stokes luminescence (under visible and infrared excitation), the dependence of 4S3/2, 4I11/2, and 4I13/2 lifetimes with Er concentration, and upconversion under Ti-saphire laser excitation at λ=790 nm were measured, mostly at T=77 and 300 K. The upconversion results in a strong green emission and weaker blue and red emissions whose intensity obeys a power-law behavior I∼Pn, where P is the infrared excitation power and n=1.6, 2.1, and 2.9 for the red, green, and blue emissions, respectively. The red emission exponent n=1.5 can be explained by a cross relaxation process. The green and blue emissions are due to excited state absorption (ESA) and energy transfer (ET) processes that predict a factor n=2 and n=3 for the green and blue emissions, respectively. From transient measurements we concluded that for lightly doped samples the green upconverted emission is originated due to both processes ESA and ET. However, for heavily doped samples ET is the dominant process.

Martensite aging kinetics in the Cu-10 wt.%Al and Cu-10 wt.%Al-10 wt.%Ag alloys

The martensite aging kinetics in the Cu-10 wt.%Al and Cu-10 wt.%Al-10 wt.%Ag alloys was studied using microhardness measurements, classical differential thermal analysis (DTA), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and in-situ high-temperature X-ray diffractometry (XRD). The results for the Cu-10%Al alloy indicated a process dominated by the martensite ordering assisted by migration of quenched-in vacancies and followed by the consumption of the α phase. For the Cu-10%Al-10%Ag alloy the dominant process is the consumption of the α phase associated with a decrease in the ordering degree of the martensitic phase. © 2007 Springer Science+Business Media, LLC.

The influence of niche and neutral processes on a neotropical anuran metacommunity

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Por que ainda é importante pensar como um nômade em nosso tempo

This article argues for the existence of a nomadic way of thinking, in accord with Deleuze and Guattari’s proposals throughout their “nomadology”. I will look forward to develop such an argument through of four points: the epistemological, the political, the historical and the ontological one. These four points, in set, describe what we call nomadic thought. Such reflection is defined in the observation of a dominant process that constitutes subjectivities ruled by a “capitalist axiomatic”, in our time. Such process is understood as a nomadic device involving, as its main by-product, what is called of narcissism of the difference. However, if the dominant way of becoming subjects ruled by capitalist society, in our time, is nomadic, is it still worthwhile thinking as a nomad, as pursued Deleuze and Guattari?