Differences between Diploid and Induced Tetraploid \u3ci\u3eLotus glaber\u3c/i\u3e Mill. (\u3ci\u3eLotus tenuis\u3c/i\u3e Waldst. & Kit.) Plants

Narrowleaf birdsfoot trefoil (Lotus glaber Mill.) is an important forage legume which has spread widely and naturalized in the grasslands of the Depressed Pampas of the Province of Buenos Aires, Argentina. L. glaber is an alogamic diploid species with a low number of chromosomes (2n=2x= 12). These features show it as a species through which induced autopolyploids by colchicine-doubling of seedlings can be obtained. In this paper, we comparatively analyze fertility and size pollen grain, stomata length, central leaflet length and width and central leaflet ratio width/length in diploid plants and induced-autotetraploid plants of L. glaber. The results show that all the characters that were evaluated are useful to differentiate tetraploid plants in this species. Among these, the length of stomata would be the most profitable since it would allow for an early tetraploid level selection

Erratum to: The study of cardiovascular risk in adolescents – ERICA: rationale, design and sample characteristics of a national survey examining cardiovascular risk factor profile in Brazilian adolescents

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Technical Note : Noise models for virtual clinical trials of digital breast tomosynthesis

Purpose: To investigate the use of an affine-variance noise model, with correlated quantum noise and spatially dependent quantum gain, for the simulation of noise in virtual clinical trials (VCT) of digital breast tomosynthesis (DBT). Methods: Two distinct technologies were considered: an amorphous-selenium (a-Se) detector with direct conversion and a thallium-doped cesium iodide (CsI(Tl)) detector with indirect conversion. A VCT framework was used to generate noise-free projections of a uniform three-dimensional simulated phantom, whose geometry and absorption match those of a polymethyl methacrylate (PMMA) uniform physical phantom. The noise model was then used to generate noisy observations from the simulated noise-free data, while two clinically available DBT units were used to acquire projections of the PMMA physical phantom. Real and simulated projections were then compared using the signal-to-noise ratio (SNR) and normalized noise power spectrum (NNPS). Results: Simulated images reported errors smaller than 4.4% and 7.0% in terms of SNR and NNPS, respectively. These errors are within the expected variation between two clinical units of the same model. The errors increase to 65.8% if uncorrelated models are adopted for the simulation of systems featuring indirect detection. The assumption of spatially independent quantum gain generates errors of 11.2%. Conclusions: The investigated noise model can be used to accurately reproduce the noise found in clinical DBT. The assumption of uncorrelated noise may be adopted if the system features a direct detector with minimal pixel crosstalk.acceptedVersionPeer reviewe