Performance of Lotus corniculatus L. genotypes submitted to cutting interval: subsidies to a breeding program

The objective of this work was to evaluate the response of five birdsfoot trefoil populations (Lotus corniculatus L.), selected under severe and intense grazing (P38, P37, P9 and P3) or cutting (population Corte), one rhizomatous population from Morocco and two cultivars, São Gabriel (Brazil) and ARS 2620 (USA), to different cutting intervals (20 and 40 days). The trial was carried out in a greenhouse for 224 days. The plants were submitted to the treatments during four months, when it was made four and two cuttings for the 20 and 40 day intervals, respectively. In the following months, aerial part of the plants was totally removed and after 70 days of regrowth, evaluation of roots and aerial section were performed. Analysis of variance and multivariate analysis was performed, obtaining the Mahalanobis distance (Md), dendogram by UPGMA method and the relative contribution of the characters for genetic divergence. There was no genotype × cutting interval interaction and the genotypes presented a reduction on dry matter yield of roots, crown and aerial sections, number of stems and plant height when submitted to frequent cuttings. The most divergent genotypes were Marrocos and P9 (Md = 108.7) and the most similar ones were São Gabriel and P37 (Md = 7.8). The results suggest exclusion of the population P9 because of its weak performance and the utilization of the populations Corte and P37 as progenitors in the birdsfoot trefoil breeding program. Root dry matter accumulation and plant height were the characters that contributed most to genetic divergence and they can be used for selection works

In Situ Observations of the Deformation Behavior and Fracture Mechanisms of Ti-45Al-2Nb-2Mn+0.8 vol pct TiB₂

The deformation and fracture mechanisms of a nearly lamellar Ti-45Al-2Nb-2Mn (at. pct) + 0.8 vol pct TiB₂ intermetallic, processed into an actual low-pressure turbine blade, were examined by means of in situ tensile and tensile-creep experiments performed inside a scanning electron microscope (SEM). Low elongation-to-failure and brittle fracture were observed at room temperature, while the larger elongations-to-failure at high temperature facilitated the observation of the onset and propagation of damage. It was found that the dominant damage mechanisms at high temperature depended on the applied stress level. Interlamellar cracking was observed only above 390 MPa, which suggests that there is a threshold below which this mechanism is inhibited. Failure during creep tests at 250 MPa was controlled by intercolony cracking. The in situ observations demonstrated that the colony boundaries are damage nucleation and propagation sites during tensile creep, and they seem to be the weakest link in the microstructure for the tertiary creep stage. Therefore, it is proposed that interlamellar areas are critical zones for fracture at higher stresses, whereas lower stress, high-temperature creep conditions lead to intercolony cracking and fracture.The authors are grateful to Industria de Turbo Propulsores, S.A. for supplying the intermetallic blades. Funding from the Spanish Ministry of Science and Innovation through projects MAT2009-14547-C02-01 and MAT2009-14547-C02-02 is acknowledged. The Madrid Regional Government supported this project partially through the ESTRUMAT grant P2009/MAT-1585. C.J.B. acknowledges the support from Grant SAB2009-0045 from the Spanish Ministry of Education for his sabbatical stage in Madrid.Publicad

An improved method for measuring muon energy using the truncated mean of dE/dx

The measurement of muon energy is critical for many analyses in large Cherenkov detectors, particularly those that involve separating extraterrestrial neutrinos from the atmospheric neutrino background. Muon energy has traditionally been determined by measuring the specific energy loss (dE/dx) along the muon's path and relating the dE/dx to the muon energy. Because high-energy muons (E_mu > 1 TeV) lose energy randomly, the spread in dE/dx values is quite large, leading to a typical energy resolution of 0.29 in log10(E_mu) for a muon observed over a 1 km path length in the IceCube detector. In this paper, we present an improved method that uses a truncated mean and other techniques to determine the muon energy. The muon track is divided into separate segments with individual dE/dx values. The elimination of segments with the highest dE/dx results in an overall dE/dx that is more closely correlated to the muon energy. This method results in an energy resolution of 0.22 in log10(E_mu), which gives a 26% improvement. This technique is applicable to any large water or ice detector and potentially to large scintillator or liquid argon detectors.Comment: 12 pages, 16 figure

All-particle cosmic ray energy spectrum measured with 26 IceTop stations

We report on a measurement of the cosmic ray energy spectrum with the IceTop air shower array, the surface component of the IceCube Neutrino Observatory at the South Pole. The data used in this analysis were taken between June and October, 2007, with 26 surface stations operational at that time, corresponding to about one third of the final array. The fiducial area used in this analysis was 0.122 km^2. The analysis investigated the energy spectrum from 1 to 100 PeV measured for three different zenith angle ranges between 0{\deg} and 46{\deg}. Because of the isotropy of cosmic rays in this energy range the spectra from all zenith angle intervals have to agree. The cosmic-ray energy spectrum was determined under different assumptions on the primary mass composition. Good agreement of spectra in the three zenith angle ranges was found for the assumption of pure proton and a simple two-component model. For zenith angles {\theta} < 30{\deg}, where the mass dependence is smallest, the knee in the cosmic ray energy spectrum was observed between 3.5 and 4.32 PeV, depending on composition assumption. Spectral indices above the knee range from -3.08 to -3.11 depending on primary mass composition assumption. Moreover, an indication of a flattening of the spectrum above 22 PeV were observed.Comment: 38 pages, 17 figure

Prospects for dark matter detection with IceCube in the context of the CMSSM

We study in detail the ability of the nominal configuration of the IceCube neutrino telescope (with 80 strings) to probe the parameter space of the Constrained MSSM (CMSSM) favoured by current collider and cosmological data. Adopting conservative assumptions about the galactic halo model and the expected experiment performance, we find that IceCube has a probability between 2% and 12% of achieving a 5sigma detection of dark matter annihilation in the Sun, depending on the choice of priors for the scalar and gaugino masses and on the astrophysical assumptions. We identify the most important annihilation channels in the CMSSM parameter space favoured by current constraints, and we demonstrate that assuming that the signal is dominated by a single annihilation channel canlead to large systematic errors in the inferred WIMP annihilation cross section. We demonstrate that ~ 66% of the CMSSM parameter space violates the equilibrium condition between capture and annihilation in the center of the Sun. By cross-correlating our predictions with direct detection methods, we conclude that if IceCube does detect a neutrino flux from the Sun at high significance while direct detection experiments do not find a signal above a spin-independent cross section sigma_SI^p larger than 5x10^{-9} pb, the CMSSM will be strongly disfavoured, given standard astrophysical assumptions for the WIMP distribution. This result is robust with respect to a change of priors. We argue that the proposed low-energy DeepCore extension of IceCube will be an ideal instrument to focus on relevant CMSSM areas of parameter space.Comment: 32 pages, 12 figures. Updated discussion of comparison with direct detection. References added. Main results unchanged. Matches version accepted by JCA

Deal or no deal? Some reflections on the ‘Baker-Thompson rule,’ ‘matching,’ and ‘market design’

This article raises the issue of why the idea of a ‘deal’ has become so prevalent in the discussion of political matters and policy proposals associated with future economic developments. It does this by linking the deal with several features of market design. Principal amongst these are game theory and matching algorithms. The Barker-Thompson Rule is presented as an example of a particular type of market construction operating in a game theoretic context, while the ‘matching engine’ is explored in a variety of contexts where it is argued to have become a standardized technique indicating to a possible reshaping of the economic terrain more generally. The consequences of these developments and trends are the emergence of a ‘dealing culture’ that threatens to overwhelm other forms of decision-making and consume the policy-making environment with the immediacy of its dealing logic

Experimental study of sheet flow regime of sediment transport in a laboratory flume.

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