Absolute Calibration of the Radio Astronomy Flux Density Scale at 22 to 43 GHz Using Planck

The Planck mission detected thousands of extragalactic radio sources at frequencies from 28 to 857 GHz. Planck's calibration is absolute (in the sense that it is based on the satellite's annual motion around the Sun and the temperature of the cosmic microwave background), and its beams are well characterized at sub-percent levels. Thus Planck's flux density measurements of compact sources are absolute in the same sense. We have made coordinated VLA and ATCA observations of 65 strong, unresolved Planck sources in order to transfer Planck's calibration to ground-based instruments at 22, 28, and 43 GHz. The results are compared to microwave flux density scales currently based on planetary observations. Despite the scatter introduced by the variability of many of the sources, the flux density scales are determined to 1-2% accuracy. At 28 GHz, the flux density scale used by the VLA runs 3.6% +- 1.0% below Planck values; at 43 GHz, the discrepancy increases to 6.2% +- 1.4% for both ATCA and the VLA.Comment: 16 pages, 4 figures and 4 table

The distance to the LMC cluster NGC 1866 and the surrounding field

We use the Main Sequence stars in the LMC cluster NGC 1866 and of Red Clump stars in the local field to obtain two independent estimates of the LMC distance. We apply an empirical Main Sequence-fitting technique based on a large sample of subdwarfs with accurate {\sl Hipparcos} parallaxes in order to estimate the cluster distance modulus, and the multicolor Red Clump method to derive distance and reddening of the LMC field. We find that the Main Sequence-fitting and the Red Clump distance moduli are in significant disagreement; NGC 1866 distance is equal to $\rm (m-M)_{0,NGC 1866}=18.33\pm$0.08 (consistent with a previous estimate using the same data and theoretical Main Sequence isochrones), while the field stars provide $\rm (m-M)_{0,field}=18.53\pm$0.07. This difference reflects the more general dichotomy in the LMC distance estimates found in the literature. Various possible causes for this disagreement are explored, with particular attention paid to the still uncertain metallicity of the cluster and the star formation history of the field stars.Comment: 5 pages, incl. 1 figure, uses emulateapj.sty, ApJ accepte

Upper bound for the conductivity of nanotube networks

Films composed of nanotube networks have their conductivities regulated by the junction resistances formed between tubes. Conductivity values are enhanced by lower junction resistances but should reach a maximum that is limited by the network morphology. By considering ideal ballistic-like contacts between nanotubes we use the Kubo formalism to calculate the upper bound for the conductivity of such films and show how it depends on the nanotube concentration as well as on their aspect ratio. Highest measured conductivities reported so far are approaching this limiting value, suggesting that further progress lies with nanowires other than nanotubes.Comment: 3 pages, 1 figure. Minor changes. Accepted for publication in Applied Physics Letter

Application of a statistic tool for on-line characterization of bubble population complexity in a multiphase reactor

Este resumo faz parte de: Book of abstracts of the Meeting of the Institute for Biotechnology and Bioengineering, 2, Braga, Portugal, 2010. A versão completa do livro de atas está disponível em: http://hdl.handle.net/1822/1096

As brandas de gado das Serras da Peneda e do Soajo (NW de Portugal)

Neste estudo são analisadas as brandas de gado do complexo montanhoso das Serras da Peneda e Soajo, situadas acima de 900 metros de altitude e com bom acesso, circunscritas ao Parque Nacional da Peneda-Gerês. Os resultados obtidos por análise geomorfológica e espacial, indicam que o local de edificação das brandas seguiu critérios comuns: todas têm disponibilidade de água, de pastagem espontânea, de proteção e boa exposição solar. Os cortelhos e bezerreiras enquadram-se no substrato granítico e utilizam os recursos locais sem afeiçoamento, designadamente lajes e blocos tabulares. Este é um património essencialmente cultural mas com ligações evidentes ao contexto geomorfológico, apresentando grande potencialidade no desenvolvimento territorial associado a atividades turísticas.The purpose of the study is the analys of shepherd’s shelters of the Peneda and Soajo Mountains, in the Peneda-Gerês National Park. Were selected those located above 900 meters and with good access. The results obtained from spatial and geomorphic analysis indicate that the criteria of choice for the edification of the shelters were similar. All of them have water availability, pasture spontaneous, protection, and good sun exposure. The shelters are built on the granite bedrock, mainly with slabs and blocks. They are a cultural heritage, close related with the geomorphological and geological characteristics of the area. These types of cultural and geomorphological heritage have great potential to implement tourism, having an important role to the sustainable rural development of the mountain region

Analysis and development of a localization system based on Radio Frequency

This paper presents an analysis on several strategies for location based on Radio-Frequency. The purpose of this study is to develop an infrastructure able to determine the position of a target within an area of 0.1 acres (aprox.11000 ft2 or 1000 m2) with an acceptable precision for the specific task. Along with the analysis of the many strategies and approaches on Radio- Location, this study tries to determine the best solution to implement a working system of location in an easy, secure and less expensive way, a solution able to be used in football field, without the use of large and/or expensive infrastructures like the Global Position System (G.P.S.) network

Metodologia para manuseio de Mycosphaerella musiocola em laboratório.

Introdução; Histórico da Sigatoka-amarela da bananeira; Biologia e Sintomatologia; A produção de conídios e ascósporos e sua relação com fatores climáticos; Isolamento de Mycospharella musiocola; Inoculação de Mycospharella musiocola em plantas teste; Considerações finais; Referências.bitstream/item/54426/1/Doc-198-final.pd

Relativistic O(q4)O(q^4) two-pion exchange nucleon-nucleon potential: configuration space

We have recently performed a relativistic $O(q^4)$ chiral expansion of the two-pion exchange $NN$ potential, and here we explore its configuration space content. Interactions are determined by three families of diagrams, two of which involve just $g_A$ and $f_{\pi}$, whereas the third one depends on empirical coefficients fixed by subthreshold $\pi N$ data. In this sense, the calculation has no adjusted parameters and gives rise to predictions, which are tested against phenomenological potentials. The dynamical structure of the eight leading non-relativistic components of the interaction is investigated and, in most cases, found to be clearly dominated by a well defined class of diagrams. In particular, the central isovector and spin-orbit, spin-spin, and tensor isoscalar terms are almost completely fixed by just $g_A$ and $f_{\pi}$. The convergence of the chiral series in powers of the ratio (pion mass/nucleon mass) is studied as a function of the internucleon distance and, for $r>$ 1 fm, found to be adequate for most components of the potential. An important exception is the dominant central isoscalar term, where the convergence is evident only for $r>$ 2.5 fm. Finally, we compare the spatial behavior of the functions that enter the relativistic and heavy baryon formulations of the interaction and find that, in the region of physical interest, they differ by about 5%.Comment: 27 pages, 33 figure

Piezoelectric sensor for acoustic wave detection in anisotropic systems

This paper describes a seismic wave sensor, its readout electronics and data acquisition system. The seismic sensor is based on piezoelectric materials, which show the ability of transforming mechanical into electrical signals. In particular, the present sensor is based on a piezoelectric polymer, poly(vinilidene fluoride) as its main characteristics made it suitable for detecting the amplitude and frequencies involved in seismic events. After a general background on seismic events, waves and piezoelectric materials, the main steps on the sensor design and fabrication, the data acquisition system and the first test results are presented.The authors thank the Portuguese Foundation for Science and Technology FCT (Grant PTDC/CTM/69362/2006) for financial suppor

Comparison of a retrotransposon-based marker with microsatellite markers for discriminating accessions of Vitis vinifera.

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