On the acoustic levitation stability behaviour of spherical and ellipsoidal particles

We present here an in-depth analysis of particle levitation stability and the role of the radial and axial forces exerted on fixed spherical and ellipsoidal particles levitated in an axisymmetric acoustic levitator, over a wide range of particle sizes and surrounding medium viscosities. We show that the stability behaviour of a levitated particle in an axisymmetric levitator is unequivocally connected to the radial forces: the loss of levitation stability is always due to the change of the radial force sign from positive to negative. It is found that the axial force exerted on a sphere of radius ${R}_{s}$ increases with increasing viscosity for ${R}_{s} / \lambda \lt 0. 0125$ ( $\lambda$ is the acoustic wavelength), with the viscous contribution of this force scaling with the inverse of the sphere radius. The axial force decreases with increasing viscosity for spheres with ${R}_{s} / \lambda \gt 0. 0125$ . The radial force, on the other hand, decreases monotonically with increasing viscosity. The radial and axial forces exerted on an ellipsoidal particle are larger than those exerted on a volume-equivalent sphere, up to the point where the ellipsoid starts to act as an obstacle to the formation of the standing wave in the levitator chambe

Study of the urban evolution of Brasilia with the use of LANDSAT data

The urban growth of Brasilia within the last ten years is analyzed with special emphasis on the utilization of remote sensing orbital data and automatic image processing. The urban spatial structure and the monitoring of its temporal changes were focused in a whole and dynamic way by the utilization of MSS-LANDSAT images for June 1973, 1978 and 1983. In order to aid data interpretation, a registration algorithm implemented at the Interactive Multispectral Image Analysis System (IMAGE-100) was utilized aiming at the overlap of multitemporal images. The utilization of suitable digital filters, combined with the images overlap, allowed a rapid identification of areas of possible urban growth and oriented the field work. The results obtained permitted an evaluation of the urban growth of Brasilia, taking as reference the proposed stated for the construction of the city

Sulfide toxicity kinetics of a uasb reactor

The effect of sulfide toxicity on kinetic parameters of anaerobic organic matter removal in a UASB (up-flow anaerobic sludge blanket) reactor is presented. Two lab-scale UASB reactors (10.5 L) were operated continuously during 12 months. The reactors were fed with synthetic wastes prepared daily using glucose, ammonium acetate, methanol and nutrient solution. One of the reactors also received increasing concentrations of sodium sulfide. For both reactors, the flow rate of 16 L.d-1 was held constant throughout the experiment, corresponding to a hydraulic retention time of 15.6 hours. The classic model for non-competitive sulfide inhibition was applied to the experimental data for determining the overall kinetic parameter of specific substrate utilization (q) and the sulfide inhibition coefficient (Ki). The application of the kinetic parameters determined allows prediction of methanogenesis inhibition and thus the adoption of operating parameters to minimize sulfide toxicity in UASB reactors

Exploiting a geometrically sampled grid in the steered response power algorithm for localization improvement

The steered response power phase transform (SRP-PHAT) is a beamformer method very attractive in acoustic localization applications due to its robustness in reverberant environments. This paper presents a spatial grid design procedure, called the geometrically sampled grid (GSG), which aims at computing the spatial grid by taking into account the discrete sampling of time difference of arrival (TDOA) functions and the desired spatial resolution. A SRP-PHAT localization algorithm based on the GSG method is also introduced. The proposed method exploits the intersections of the discrete hyperboloids representing the TDOA information domain of the sensor array, and projects the whole TDOA information on the space search grid. The GSG method thus allows one to design the sampled spatial grid which represents the best search grid for a given sensor array, it allows one to perform a sensitivity analysis of the array and to characterize its spatial localization accuracy, and it may assist the system designer in the reconfiguration of the array. Experimental results using both simulated data and real recordings show that the localization accuracy is substantially improved both for high and for low spatial resolution, and that it is closely related to the proposed power response sensitivity measure

Variabilidade genética de duas populações de Astyanax altiparanae da bacia do alto rio Paraná.

O presente trabalho tem como objetivo caracterizar a estrutura genética de duas populações de A. altiparanae da bacia do alto rio Paraná (Paranapanema e Tietê) através da análise de 11 marcadores moleculares do tipo microssatélite.Organizado por: Sílvio Ricardo Maurano; AQUACIÊNCIA 2012

Urban land use of the Sao Paulo metropolitan area by automatic analysis of LANDSAT data

The separability of urban land use classes in the metropolitan area of Sao Paulo was studied by means of automatic analysis of MSS/LANDSAT digital data. The data were analyzed using the media K and MAXVER classification algorithms. The land use classes obtained were: CBD/vertical growth area, residential area, mixed area, industrial area, embankment area type 1, embankment area type 2, dense vegetation area and sparse vegetation area. The spectral analysis of representative samples of urban land use classes was done using the "Single Cell" analysis option. The classes CBD/vertical growth area, residential area and embankment area type 2 showed better spectral separability when compared to the other classes

Reprodução induzida e criação de larvas de híbridos interespecíficos e intragenérico da ordem siluriforme (Pisces).

O presente trabalho tem como objetivo analisar a resposta à indução artificial da reprodução em exemplares de cachapinta, híbrido resultante do cruzamento de Pseudoplatystoma corruscans X Pseudoplatystoma reticulatum no cruzamento intergenérico entre fêmea deste produto híbrido e macho de jundiá (Leiarius marmoratus), para verificar a produção de gametas viáveis, quantidade de larvas eclodidas, percentual de sobrevivência e crescimento das larvas e consequentemente a produção de exemplares para estudos genéticos.Organizado por: Sílvio Ricardo Maurano; AQUACIÊNCIA 2012

Supporting Concurrency and Multiple Indexes in Private Access to Outsourced Data

Data outsourcing has recently emerged as a successful solution allowing individuals and organizations to delegate data and service management to external third parties. A major challenge in the data outsourcing scenario is how to guarantee proper privacy protection against the external server. Recent promising approaches rely on the organization of data in indexing structures that use encryption and the dynamic allocation of encrypted data to physical blocks for destroying the otherwise static relationship between data and the blocks in which they are stored. However, dynamic data allocation implies the need to re-write blocks at every read access, thus requesting exclusive locks that can affect concurrency. Also, these solutions only support search conditions on the values of the attribute used for building the indexing structure. In this paper, we present an approach that overcomes such limitations by extending the recently proposed shuffle index structure with support for concurrency and multiple indexes. Support for concurrency relies on the use of several differential versions of the data index that are periodically reconciled and applied to the main data structure. Support for multiple indexes relies on the definition of secondary shuffle indexes that are then combined with the primary index in a single data structure whose content and allocation is unintelligible to the server. We show how using such differential versions and combined index structure guarantees privacy, provides support for concurrent accesses and multiple search conditions, and considerably increases the performance of the system and the applicability of the proposed solution

Atropisomerism in Hindered Naphthyl Sulfoxides: Structure, Stereodynamics, and Chiral Resolution.

Barriers for the EZ interconversion of atropisomers of 1-naphthyl sulfoxides (ArSOR) having a methyl group at position 2 of the naphthalene moiety were measured by variable-temperature NMR. Their values were found to cover the range 10.6-18.4 kcal mol-1, the extreme values corresponding to derivatives 1 (R = Me) and 4 (R = Bu(t)), respectively. NOE and LIS measurements indicated that the Z atropisomer is more stable than the E but that the absence of the methyl group at position 2 of the naphthalene moiety reverses this trend, rendering E more stable than Z. Solid-state NMR and X-ray diffraction of 4 established that only the more stable atropisomer (Z) is present in the crystalline state. Molecular mechanics calculations suggest that the Z,E interconversion process might occur by a rotation pathway having an opposite direction in the case of the more hindered derivatives 3 and 4 (R = Pr(i) and Bu(t), respectively) with respect to the less hindered 1 and 2 (R = Me and Et, respectively). The enantiomers, which are due to the presence of the asymmetric sulfur atom, were resolved on a chiral stationary phase (DACH-DNB) having an SS configuration. Asymmetric oxidation reactions were employed to assign the absolute R configuration to the more retained enantiomers of alkyl aryl sulfoxides. The opposite trend (S being retained longer) was observed for diaryl sulfoxides such as 5 (R = Ph). In the case of the derivative with the largest interconversion barrier, sulfoxide 4, it was also possible to resolve (at -35-degrees-C) the two enantiomeric forms and their associated atropisomers. The use of on-line CD detection and the knowledge of the NMR assignments allowed us to unambiguously assign the elution order of the four species as ES, ER, ZS, ZR