Ranking and clustering of nodes in networks with smart teleportation

Random teleportation is a necessary evil for ranking and clustering directed networks based on random walks. Teleportation enables ergodic solutions, but the solutions must necessarily depend on the exact implementation and parametrization of the teleportation. For example, in the commonly used PageRank algorithm, the teleportation rate must trade off a heavily biased solution with a uniform solution. Here we show that teleportation to links rather than nodes enables a much smoother trade-off and effectively more robust results. We also show that, by not recording the teleportation steps of the random walker, we can further reduce the effect of teleportation with dramatic effects on clustering.Comment: 10 pages, 7 figure

Crescimento e desenvolvimento de pessegueiros 'Chimarrita' e 'Maciel' sobre diferentes porta-enxertos e locais de cultivo.

Objetivou-se com o presente trabalho avaliar a influência dos porta-enxertos no que se refere ao crescimento vegetativo e desenvolvimento dos pessegueiro 'Chimarrita' e 'Maciel' em três locais de cultivo. O experimento foi desenvolvido em três locais de cultivo: 1 (Embrapa Uva e Vinho), 2 (EEA UFRGS) e 3 (CAP UFPel), em três anos. As cultivares de pessegueiro utilizadas foram: 'Chimarrita' e 'Maciel' enxertadas sobre seis porta-enxertos ('Aldrighi', 'Capdeboscq', 'Flordaguard', 'Nemaguard', 'Okinawa' e Umezeiro), no espaçamento 1,5 X 5,0m e conduzidas no sistema em ?V?. Foram avaliados: volume de copa, diâmetro de tronco, massa fresca da poda, produção por planta acumulada, comprimento, espessura, gemas floríferas e densidade florífera do ramo produtivo. Também foi avaliado de forma visual o ponto de enxertia. O porta-enxerto Umezeiro induziu menor vigor nos três locais de cultivo estudados e na média dos três anos. Ele pode ser indicado para utilização sob 'Maciel' nas condições edafoclimáticas do local 3. No local 1 o porta-enxerto, 'Nemaguard' possui alto vigor e maior produção acumulada, sendo o mais indicado. Já para o local 2, os porta-enxertos 'Capdeboscq', 'Okinawa' e 'Flordaguard' são os mais indicados. Os porta-enxertos afetam as características de crescimento e desenvolvimento das cultivares 'Chimarrita' e 'Maciel', o vigor destas é menor sobre o portaenxerto Umezeiro nos três locais de cultivo. Todos os portaenxertos podem ser indicados para os três locais de cultivo, com exceção do Umezeiro, que somente pode ser indicado em combinação com a cultivar 'Maciel' no local 3

Accessibility and Conservation in Contemporary Cities: A(n) (Im)possible Coupling

Cities are built by and for able-bodied people and are often composed of a range of elements that make them partially (or not) accessible to disabled people. Architectural barriers within and around buildings can limit disabled people’s access to structures and services, precluding their full participation in a social life. It is not possible to talk about making further social progress until disabled people are no longer victims of marginalisation caused by our urban architecture. In order to identify some specific problems and possible solutions, a qualitative research study was carried out in a city in northern Italy, involving people with sensory and physical impairments. Findings indicate that cities in general, and the oldest ones in particular, can present an important problem: some historic centres and buildings are not (or cannot be) restored to become more accessible. This lack of accessibility will increase the exclusion of disabled people by imposing limitations and restrictions, from mobilising around urban centres, to use of pavements, entry into shops or workplaces, through to accessing treatment and health services. Moreover, this research demonstrates that, in many cases, relatively inexpensive and simple measures and arrangements might be enough to help tackle and solve many of these problems. This paper argues that a first, fundamental step in looking to improve access should be to involve disabled people in participatory planning. These users will be the best experts of their own needs and some of the best informed about the attributes and particularities of any alterations or adaptations needed to help them negotiate, manage and plan the areas in which they live

Organogenesis and embryogenesis in several hypericum perforatum genotypes

St John’s wort (Hypericum perforatum) is a valuable plant used as a herbal remedy or in phytopharmaceutical drugs to treat a variety of physical ailments. Much research has been performed to study the biochemical production of secondary metabolites of in vitro cultured plants or organs. However, all of these studies have looked at the regeneration of plants from explants in only one genotype. In addition, no study has revealed the mechanism of plant regeneration in H. perforatum, i.e. organogenesis or somatic embryogenesis. We found that different genotypes Helos, Topas, Elixir, and Numi responded similarly to regeneration medium. The regeneration responses (i.e. callus, root, or shoot production) of identical explants from different genotypes were similar. However, the source of explant material (leaves, hypocotyls, and roots) from the same genotype had significant effects on the response to media and plant regeneration frequency. Using scanning electron microscopy and light microscopy, the progress of organogenesis and embryogenesis under similar culture conditions was recorded. Root segments were the most responsive explants, producing the maximum number of shoots per explant of all the genotypes.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/AGR/40 283/2001, SFRH/BPD/17102/2004

Automated determination of the end time of junk radiation in binary black hole simulations

When numerically solving Einstein's equations for the evolution of binary black holes, physical imperfections in the initial data manifest as a transient, high-frequency pulse of ''junk radiation.'' This unphysical signal must be removed before the waveform can be used. Improvements in the efficiency of numerical simulations now allow waveform catalogs containing thousands of waveforms to be produced. Thus, an automated procedure for identifying junk radiation is required. To this end, we present a new algorithm based on the empirical mode decomposition (EMD) from the Hilbert-Huang transform. This approach allows us to isolate and measure the high-frequency oscillations present in the measured irreducible masses of the black holes. The decay of these oscillations allows us to estimate the time from which the junk radiation can be ignored. To make this procedure more precise, we propose three distinct threshold criteria that specify how small the contribution of junk radiation has to be before it can be considered negligible. We apply this algorithm to 3403 BBH simulations from the SXS catalog to find appropriate values for the thresholds in the three criteria. We find that this approach yields reliable decay time estimates, i.e., when to consider the simulation physical, for over 98.6% of the simulations studied. This demonstrates the efficacy of the EMD as a suitable tool to automatically isolate and characterize junk radiation in the simulation of binary black hole systems

Design of a hydraulic servo-actuation fed by a regenerative braking system

Many conventional truck and working machines are equipped with additional hydraulic tooling or manipulation systems which are usually fed through a mechanical connection with the internal combustion engine, involving a poor efficiency. In particular, this is a common situation for industrial vehicles whose mission profiles involves a relevant consumption of energy by the on board hydraulic systems, respect to the one really needed for only traction purpose. In this work it is proposed an innovative solution based on the adoption of a system aimed to recover braking energy in order to feed an efficient on board hydraulic actuation system. The proposed system is then adopted to a real application, an Isuzu truck equipped with a hydraulic tooling for garbage collection. A prototype of the system has been designed, assembled and tested showing a relevant improvement of system efficiency and the feasibility of the proposed approach. In the paper the proposed solution is presented, showing the simulation models and preliminary validation results including experimental devices assembled to perform the tests

A comparison of charcoal- and slag-based constructed wetlands for acid mine drainage remediation

Subsurface-flow constructed wetlands (CW) with charcoal- or slag-based bed matrices were investigated for their potential use in remediating acid mine drainage (AMD). A CW is effectively a reactor in which some components of the wastewater are broken down by the organisms occurring within the CW, whilst others may be degraded by physico-chemical processes or a combination thereof. Two 200 ℓ small-scale CWs were built at the University. Commercially available charcoal and <19 mm basic oxygen furnace (BOF) slag were used as the bed matrices and the units were planted with a variety of plants. The units were exposed to an artificial AMD. The results showed that the systems removed almost all soluble iron and more than 75% of the sulphate. Both CWs were able to increase the pH of the AMD.Keywords: AMD, charcoal, slag, constructed wetlands, remediatio