Universal dissipation scaling for non-equilibrium turbulence

It is experimentally shown that the non-classical high Reynolds number energy dissipation behaviour, $C_{\epsilon} \equiv \epsilon L/u^3 = f(Re_M)/Re_L$, observed during the decay of fractal square grid-generated turbulence is also manifested in decaying turbulence originating from various regular grids. For sufficiently high values of the global Reynolds numbers $Re_M$, $f(Re_M)\sim Re_M$.Comment: 5 pages, 6 figure

Monitoring stimulated emission at the single photon level in one-dimensional atoms

We theoretically investigate signatures of stimulated emission at the single photon level for a two-level atom interacting with a one-dimensional light field. We consider the transient regime where the atom is initially excited, and the steady state regime where the atom is continuously driven with an external pump. The influence of pure dephasing is studied, clearly showing that these effects can be evidenced with state of the art solid state devices. We finally propose a scheme to demonstrate the stimulation of one optical transition by monitoring another one, in three-level one-dimensional atoms.Comment: 4 pages, 4 figures. Improved introduction; Comments adde

Equilibrium properties of the mixed state in superconducting niobium in a transverse magnetic field: Experiment and theoretical model

Equilibrium magnetic properties of the mixed state in type-II superconductors were measured with high purity bulk and film niobium samples in parallel and perpendicular magnetic fields using dc magnetometry and scanning Hall-probe microscopy. Equilibrium magnetization data for the perpendicular geometry were obtained for the first time. It was found that none of the existing theories is consistent with these new data. To address this problem, a theoretical model is developed and experimentally validated. The new model describes the mixed state in an averaged limit, i.e. %without detailing the samples' magnetic structure and therefore ignoring interactions between vortices. It is quantitatively consistent with the data obtained in a perpendicular field and provides new insights on properties of vortices. % and the entire mixed state. At low values of the Ginzburg-Landau parameter, the model converts to that of Peierls and London for the intermediate state in type-I superconductors. It is shown that description of the vortex matter in superconductors in terms of a 2D gas is more appropriate than the frequently used crystal- and glass-like scenarios.Comment: 8 pages, 9 figure

ALDEHYDE EMISSIONS FROM A STATIONARY DIESEL ENGINE OPERATING WITH CASTOR OIL BIODIESEL – DIESEL OIL BLENDS

The presence of aldehyde in the exhaust gas of a stationary, direct injection, compression ignition engine operating with castor oil biodiesel/diesel oil blends (B5, B10, B20 and B35) is analyzed. The diesel engine was operated with constant speed of 1800 rev/min and load of 37.5 kW. The gas sample was collected directly from the exhaust. Aldehydes were identified and quantified using gas chromatography (GC) with flame ionization detector analyzer (FID). Acetaldehyde presented higher exhaust concentration than formaldehyde for all fuel blends tested. In general, the exhaust aldehyde levels were very low and did not present significant differences between the fuel blends tested

Multimedia signal processing for behavioral quantification in neuroscience

While there have been great advances in quantification of the genotype of organisms, including full genomes for many species, the quantification of phenotype is at a comparatively primitive stage. Part of the reason is technical difficulty: the phenotype covers a wide range of characteristics, ranging from static morphological features, to dynamic behavior. The latter poses challenges that are in the area of multimedia signal processing. Automated analysis of video and audio recordings of animal and human behavior is a growing area of research, ranging from the behavioral phenotyping of genetically modified mice or drosophila to the study of song learning in birds and speech acquisition in human infants. This paper reviews recent advances and identifies key problems for a range of behavior experiments that use audio and video recording. This research area offers both research challenges and an application domain for advanced multimedia signal processing. There are a number of MMSP tools that now exist which are directly relevant for behavioral quantification, such as speech recognition, video analysis and more recently, wired and wireless sensor networks for surveillance. The research challenge is to adapt these tools and to develop new ones required for studying human and animal behavior in a high throughput manner while minimizing human intervention. In contrast with consumer applications, in the research arena there is less of a penalty for computational complexity, so that algorithmic quality can be maximized through the utilization of larger computational resources that are available to the biomedical researcher

Novel methodology based on biomimetic superhydrophobic substrates to immobilize cells and proteins in hydrogel spheres for applications in bone regeneration

Cell-based therapies for regenerative medicine have been characterized by the low retention and integration of injected cells into host structures. Cell immobilization in hydrogels for target cell delivery has been developed to circumvent this issue. In this work mesenchymal stem cells isolated from Wistar rats bone marrow (rMSCs) were immobilized in alginate beads fabricated using an innovative approach involving the gellification of the liquid precursor droplets onto biomimetic superhydrophobic surfaces without the need of any precipitation bath. The process occurred in mild conditions preventing the loss of cell viability. Furthermore, fibronectin (FN) was also immobilized inside alginate beads with high efficiency in order to mimic the composition of the extracellular matrix. This process occurred in a very fast way (around 5 min), at room temperature, without aggressive mechanical strengths or particle aggregation. The methodology employed allowed the production of alginate beads exhibiting a homogenous rMSCs and FN distribution. Encapsulated rMSCs remained viable and were released from the alginate for more than 20 days. In vivo assays were also performed, by implanting these particles in a calvarial bone defect to evaluate their potential for bone tissue regeneration. Microcomputed tomography and histological analysis results showed that this hybrid system accelerated bone regeneration process. The methodology employed had a dual role by preventing cell and FN loss and avoiding any contamination of the beads or exchange of molecules with the surrounding environment. In principle, the method used for cell encapsulation could be extended to other systems aimed to be used in tissue regeneration strategies.The authors acknowledge the financial support of the Portuguese Foundation for Science and Technology (PTDC/EME-TME/103375/2008 and PTDC/EBB-BIO/114320/2009) for the PhD fellowship to Ana Catarina Lima (SFRH/BD/71395/2010), A. Sofia Silva (SFRH/BD/51584/2011), and Patricia Batista (SFRH/BD/45511/2008)

Detecting Community Structure in Dynamic Social Networks Using the Concept of Leadership

Detecting community structure in social networks is a fundamental problem empowering us to identify groups of actors with similar interests. There have been extensive works focusing on finding communities in static networks, however, in reality, due to dynamic nature of social networks, they are evolving continuously. Ignoring the dynamic aspect of social networks, neither allows us to capture evolutionary behavior of the network nor to predict the future status of individuals. Aside from being dynamic, another significant characteristic of real-world social networks is the presence of leaders, i.e. nodes with high degree centrality having a high attraction to absorb other members and hence to form a local community. In this paper, we devised an efficient method to incrementally detect communities in highly dynamic social networks using the intuitive idea of importance and persistence of community leaders over time. Our proposed method is able to find new communities based on the previous structure of the network without recomputing them from scratch. This unique feature, enables us to efficiently detect and track communities over time rapidly. Experimental results on the synthetic and real-world social networks demonstrate that our method is both effective and efficient in discovering communities in dynamic social networks

Efeito do manejo de rebrotas de espécies lenhosas da caatinga sobre o crescimento em altura das hastes.

Resumo: O experimento foi conduzido para avaliar o efeito do manejo de rebrotas de cinco espécies lenhosas da caatinga sobre o crescimento em altura das hastes. As espécies lenhosas foram submetidas aos seguintes tratamentos no delineamento inteiramente casualizado: 1 - preservação de uma haste; 2 - preservação de duas hastes; 3 - preservação de três hastes; 4 - preservação de todas as hastes. As plantas submetidas ao manejo de preservação de uma haste apresentaram maior crescimento de haste e o menor crescimento de haste foi observado para plantas submetidas ao tratamento de preservação de todas as hastes. Dentre as espécies lenhosas estudadas, a jurema preta (Mimosa hostilis) apresentou maior crescimento das hastes e a catingueira (Caesalpinia bracteosa), o menor crescimento de hastes sendo recomendada a sua preservação e uso como recurso forrageiro. A preservação de uma haste por planta propicia o maior crescimento em altura de hastes de espécies lenhosas da caatinga e, a exceção da catingueira, as demais espécies apresentam potencial para produção simultânea de lenha e forragem. [Effect of the management of the sprouts of the tree species of caating on the growth in the height of the stems]. Abstract - The experiment was carried to evaluate the effect of the management of sprouts of five woody species of caatinga on the growth in height of the stems. The woody species were assigned to a completely randomized design to the following treatments: 1-preservation of one stem; 2-preservation of two stems; 3-preservation of three stems; 4-preservation of all of the stems. Plants submitted to the management of preservation of one stem presented larger stem growth and the smallest stem growth was observed for plants submitted to the treatment of preservation of all of the stems. Among the studied woody species, the Mimosa hostilis presented larger growth of the stems and Caesalpinia bracteosa, the smallest growth of stems being recommended to preservation and use as resource forage. The preservation of one stem for plant propitiates the largest growth in height of stems of woody species of caatinga and, the exception of the Caesalpinia bracteosa, the other species present potential for simultaneous production of firewood and forage

Avaliação da aptidão agrícola das terras do campo experimental de Belterra - Estado do Pará.

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