17,008 research outputs found
Non-parametric comparison of histogrammed two-dimensional data distributions using the Energy Test
When monitoring complex experiments, comparison is often made between regularly acquired histograms of data and reference histograms which represent the ideal state of the equipment. With the larger HEP experiments now ramping up, there is a need for automation of this task since the volume of comparisons could overwhelm human operators. However, the two-dimensional histogram comparison tools available in ROOT have been noted in the past to exhibit shortcomings. We discuss a newer comparison test for two-dimensional histograms, based on the Energy Test of Aslan and Zech, which provides more conclusive
discrimination between histograms of data coming from different distributions than methods provided in a recent ROOT release.The Science and Technology Facilities Council, U
Capim-Tanzânia: irrigação e adubação nitrogenada.
bitstream/item/131668/1/Comunicado-161-Capim-Tanzania-Irrigacao-e-Adubacao-Nitrogenada.pd
Irrigação e adubação nitrogenada em gramíneas forrageiras.
O objetivo deste trabalho foi avaliar o efeito de diferentes níveis de irrigação e de adubação nitrogenada sobre a produtividade média de matéria seca (MS) e o teor de proteína bruta (PB) de três gramíneas forrageiras. O trabalho foi conduzido na área experimental da Embrapa Meio-Norte em Parnaíba-PI, em Neossolo Quartzarênico Órtico Típico. As gramíneas utilizadas foram Pennisetum purpureum, cv. Pioneiro; Panicum maximum, cv. Tanzânia e Cynodon spp., cv. Tifton-85. Os níveis de irrigação aplicados foram calculados em função do fracionamento da evaporação do tanque Classe A (ECA) entre duas irrigações consecutivas: 0,2; 0,6 e 1,0. Os tratamentos de adubação foram 100, 200 e 300 kg/ha de N aplicados na forma de uréia e em cobertura. Para efeito de análise foram processados cinco cortes das gramíneas no período de avaliação. A produtividade de matéria seca (MS) da cultivar Tanzânia (24.984 kg/ha) é significativamente superior às MS das cultivares Tifton-85 (18.231 kg/ha) e Pioneiro (16.239 kg/ha). A combinação do nível de água correspondente a 0,2 ECA com o nível de adubação de 200 kg/ha de N apresenta os melhores resultados. O efeito de N sobre PB é linear e significativo (P<0,05) e o teor médio de PB da cultivar Pioneiro (15,58 %) é superior aos das cultivares Tanzânia (12,82 %) e Tifton-85 (12,85).bitstream/item/126432/1/boletim-42-Irrigacao-e-adubacao-nitrogenada-em-gramineas-forrageiras.pd
Teor de proteína bruta do Cynodon spp. cv. Tifton 85 sob irrigação e adubação nitrogenada, em Parnaíba, Piauí.
bitstream/CPAMN-2009-09/19836/1/CT171.pd
Tests of Bayesian Model Selection Techniques for Gravitational Wave Astronomy
The analysis of gravitational wave data involves many model selection
problems. The most important example is the detection problem of selecting
between the data being consistent with instrument noise alone, or instrument
noise and a gravitational wave signal. The analysis of data from ground based
gravitational wave detectors is mostly conducted using classical statistics,
and methods such as the Neyman-Pearson criteria are used for model selection.
Future space based detectors, such as the \emph{Laser Interferometer Space
Antenna} (LISA), are expected to produced rich data streams containing the
signals from many millions of sources. Determining the number of sources that
are resolvable, and the most appropriate description of each source poses a
challenging model selection problem that may best be addressed in a Bayesian
framework. An important class of LISA sources are the millions of low-mass
binary systems within our own galaxy, tens of thousands of which will be
detectable. Not only are the number of sources unknown, but so are the number
of parameters required to model the waveforms. For example, a significant
subset of the resolvable galactic binaries will exhibit orbital frequency
evolution, while a smaller number will have measurable eccentricity. In the
Bayesian approach to model selection one needs to compute the Bayes factor
between competing models. Here we explore various methods for computing Bayes
factors in the context of determining which galactic binaries have measurable
frequency evolution. The methods explored include a Reverse Jump Markov Chain
Monte Carlo (RJMCMC) algorithm, Savage-Dickie density ratios, the Schwarz-Bayes
Information Criterion (BIC), and the Laplace approximation to the model
evidence. We find good agreement between all of the approaches.Comment: 11 pages, 6 figure
Eigenfunctions of the Laplacian and associated Ruelle operator
Let be a co-compact Fuchsian group of isometries on the Poincar\'e
disk \DD and the corresponding hyperbolic Laplace operator. Any
smooth eigenfunction of , equivariant by with real
eigenvalue , where , admits an integral
representation by a distribution \dd_{f,s} (the Helgason distribution) which
is equivariant by and supported at infinity \partial\DD=\SS^1. The
geodesic flow on the compact surface \DD/\Gamma is conjugate to a suspension
over a natural extension of a piecewise analytic map T:\SS^1\to\SS^1, the
so-called Bowen-Series transformation. Let be the complex Ruelle
transfer operator associated to the jacobian . M. Pollicott showed
that \dd_{f,s} is an eigenfunction of the dual operator for the
eigenvalue 1. Here we show the existence of a (nonzero) piecewise real analytic
eigenfunction of for the eigenvalue 1, given by an
integral formula \psi_{f,s} (\xi)=\int \frac{J(\xi,\eta)}{|\xi-\eta|^{2s}}
\dd_{f,s} (d\eta), \noindent where is a -valued
piecewise constant function whose definition depends upon the geometry of the
Dirichlet fundamental domain representing the surface \DD/\Gamma
Irrigação e adubação nitrogenada em três gramíneas forrageiras no Meio-Norte do Brasil.
O objetivo deste trabalho foi avaliar o efeito de diferentes níveis de irrigação e de adubação nitrogenada sobre a produtividade média de matéria seca (MS) e o teor de proteína bruta (PB) de três gramíneas forrageiras. O trabalho foi conduzido na área experimental da Embrapa Meio-Norte, em Parnaíba-PI, em um Neossolo Quartzarênico. As gramíneas utilizadas foram Pennisetum purpureum, cv. Pioneiro; Panicum maximum, cv. Tanzânia e Cynodon sp., cv. Tifton-85. Os níveis de irrigação aplicados foram calculados em função do fracionamento da evaporação do tanque classe "A" (ECA) entre duas irrigações consecutivas: 0,2; 0,6 e 1,0. Os tratamentos de adubação foram 100; 200 e 300 kg/ha de N, aplicados na forma de uréia e em cobertura, fracionados em função do número de cortes. Para efeito de análise foram processados cinco cortes das gramíneas no período de avaliação. A produtividade de matéria seca (MS) da cultivar Tanzânia (24.984 kg/ha) foi significativamente superior às MS das cultivares Tifton-85 (18.231 kg/ha) e Pioneiro (16.239 kg/ha). A combinação do nível de água correspondente a 0,2 ECA e o nível de adubação de 200 kg/ha de N apresentou os melhores resultados. O efeito de N sobre PB foi linear e significativo (P<0,05) e o teor médio de PB da cultivar Pioneiro (15,58%) foi superior aos das cultivares Tanzânia (12,82%) e Tifton-85 (12,85%)
Bilayer graphene: gap tunability and edge properties
Bilayer graphene -- two coupled single graphene layers stacked as in graphite
-- provides the only known semiconductor with a gap that can be tuned
externally through electric field effect. Here we use a tight binding approach
to study how the gap changes with the applied electric field. Within a parallel
plate capacitor model and taking into account screening of the external field,
we describe real back gated and/or chemically doped bilayer devices. We show
that a gap between zero and midinfrared energies can be induced and externally
tuned in these devices, making bilayer graphene very appealing from the point
of view of applications. However, applications to nanotechnology require
careful treatment of the effect of sample boundaries. This being particularly
true in graphene, where the presence of edge states at zero energy -- the Fermi
level of the undoped system -- has been extensively reported. Here we show that
also bilayer graphene supports surface states localized at zigzag edges. The
presence of two layers, however, allows for a new type of edge state which
shows an enhanced penetration into the bulk and gives rise to band crossing
phenomenon inside the gap of the biased bilayer system.Comment: 8 pages, 3 fugures, Proceedings of the International Conference on
Theoretical Physics: Dubna-Nano200
Transpiration of grapevines and co-habitating cover crop and weed species in a vineyard. A “snapshot” at diurnal trends
The objective of this study was to quantify transpiration rates of two cover crops, Festuca rubra subsp. rubra (red fescue) and Medicago lupulina (black medick) and 4 weeds, Chenopodium album (fat hen), Cirsium arvense (creeping thistle), Malva neglecta (common mallow) and Taraxacum officinale (dandelion) occurring in a mixed stand in a commercial steep-slope, North-South oriented vineyard as compared to vines, cv. Riesling near Johannisberg (Rheingau), Germany. Leaf transpiration (E) was measured directly on the cover crop and weed species with a portable gas exchange measurement system. Grapevine transpiration was measured concomitantly using custommade Granier-type xylem sap flow gauges. Measurements were conducted on two days in August (15th and 22nd) in 2001 under hot and sunny conditions. All herbaceous species presented a similar diurnal pattern of E, with low values in the morning and afternoon and peak values between 12 and 15 h. In contrast E of grapevines peaked mid-morning (between 8 and 10 h) remained relatively stable until mid-afternoon (16 h) before decreasing continuously until darkness. Significant differences in E between the herbaceous species were observed throughout the day. In general transpiration rates were highest for M. neglecta and lowest for C. arvense, T. officinale and F. rubra subsp. rubra. We estimated the projected leaf area indices (leaf area per surface area covered) for each species and calculated possible transpiration rates for pure stands assuming that all leaves were well exposed. Potential transpiration rates ranged from about 1 mm d-1 (one l m-2 of soil surface) for F. rubra subsp. rubra to = 5 mm d-1 for M. neglecta as compared to only 0.9 mm d-1 for grapevine. These results underline the importance of appropriate cover crop species and the control of some weed species with respect to water use.
Electronic doping of graphene by deposited transition metal atoms
We perform a phenomenological analysis of the problem of the electronic
doping of a graphene sheet by deposited transition metal atoms, which aggregate
in clusters. The sample is placed in a capacitor device such that the
electronic doping of graphene can be varied by the application of a gate
voltage and such that transport measurements can be performed via the
application of a (much smaller) voltage along the graphene sample, as reported
in the work of Pi et al. [Phys. Rev. B 80, 075406 (2009)]. The analysis allows
us to explain the thermodynamic properties of the device, such as the level of
doping of graphene and the ionisation potential of the metal clusters in terms
of the chemical interaction between graphene and the clusters. We are also
able, by modelling the metallic clusters as perfect conducting spheres, to
determine the scattering potential due to these clusters on the electronic
carriers of graphene and hence the contribution of these clusters to the
resistivity of the sample. The model presented is able to explain the
measurements performed by Pi et al. on Pt-covered graphene samples at the
lowest metallic coverages measured and we also present a theoretical argument
based on the above model that explains why significant deviations from such a
theory are observed at higher levels of coverage.Comment: 16 pages, 10 figure
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