399 research outputs found

    Contracting decision and performance of Mexican coffee traders: The role of market institutions

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    We identified and explained the contractual choices of Mexican coffee traders in selling their product and analyzed the traders® performance. The data were obtained from personal interviews with 53 intermediaries in four coffee producing regions of the states of Oaxaca and Veracruz, Mexico. Marketing margins were used as an indicator of traders’ performance. The results indicate that being a roaster, having a wet processing plant and selling cherry coffee negatively affects the use of contracts whereas being vertically integrated has a positive effect. The results also suggest that being registered in the National Coffee System (which only a minority of the interviewed traders were) increases the margin for the trader. Selling cherry coffee, participating in a competitive environment and having a contract decreases these margins (at 5% significance) and may thus enhance the performance of the supply chain and benefit the producer

    Elastic scattering, inelastic excitation, and 1 n pick-up transfer cross sections for 10 B + 120 Sn at energies near the Coulomb barrier

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    The 10 B + 120 Sn reaction has been systematically studied at laboratory energies around the Coulomb barrier: E LAB = 31.5 , 33.5, 35.0, and 37.5 MeV. Cross sections for the elastic scattering and some reaction processes have been measured: excitation to the 1 + state of 10 B ; excitation to the 2 + and 3 − states of 120 Sn ; and the one-neutron pick-up transfer 120 Sn ( 10 B , 11 B ) 119 Sn . Coupled reaction channel (CRC) calculations have been performed in the context of the double-folding SĂŁo Paulo potential. The theoretical calculations result in a good overall description of the experimental angular distributions. The effect on the theoretical elastic-scattering angular distributions of couplings to the inelastic and transfer states (through the CRC calculations) and to the continuum states (through continuum-discretized coupled-channels calculations) has been investigated.Instituto Nacional de CiĂȘncia e Tecnologia–FĂ­sica Nuclear e AplicaçÔes (INCT-FNA) 464898/2014-5Ministerio de EconomĂ­a y Competitividad de España y el Fondo Europeo de Desarrollo Regional (FEDER) FIS2014-51941-P,Junta de AndalucĂ­a. FQM-160Programa de investigaciĂłn e innovaciĂłn de la UniĂłn Europea Horizonte 2020. 65400

    A system of three transiting super-Earths in a cool dwarf star

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    We present the detection of three super-Earths transiting the cool star LP415-17, monitored by K2 mission in its 13th campaign. High resolution spectra obtained with HARPS-N/TNG showed that the star is a mid-late K dwarf. Using spectral synthesis models we infer its effective temperature, surface gravity and metallicity and subse- quently determined from evolutionary models a stellar radius of 0.58 R Sun. The planets have radii of 1.8, 2.6 and 1.9 R Earth and orbital periods of 6.34, 13.85 and 40.72 days. High resolution images discard any significant contamination by an intervening star in the line of sight. The orbit of the furthest planet has radius of 0.18 AU, close to the inner edge of the habitable zone. The system is suitable to improve our understanding of formation and dynamical evolution of super-Earth systems in the rocky - gaseous threshold, their atmospheres, internal structure, composition and interactions with host stars.Comment: Accepted for publication in MNRAS Letter

    Machine learning based prediction of squamous cell carcinoma in ex vivo confocal laser scanning microscopy

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    Image classification with convolutional neural networks (CNN) offers an unprecedented opportunity to medical imaging. Regulatory agencies in the USA and Europe have already cleared numerous deep learning/machine learning based medical devices and algorithms. While the field of radiology is on the forefront of artificial intelligence (AI) revolution, conventional pathology, which commonly relies on examination of tissue samples on a glass slide, is falling behind in leveraging this technology. On the other hand, ex vivo confocal laser scanning microscopy (ex vivo CLSM), owing to its digital workflow features, has a high potential to benefit from integrating AI tools into the assessment and decision-making process. Aim of this work was to explore a preliminary application of CNN in digitally stained ex vivo CLSM images of cutaneous squamous cell carcinoma (cSCC) for automated detection of tumor tissue. Thirty-four freshly excised tissue samples were prospectively collected and examined immediately after resection. After the histologically confirmed ex vivo CLSM diagnosis, the tumor tissue was annotated for segmentation by experts, in order to train the MobileNet CNN. The model was then trained and evaluated using cross validation. The overall sensitivity and specificity of the deep neural network for detecting cSCC and tumor free areas on ex vivo CLSM slides compared to expert evaluation were 0.76 and 0.91, respectively. The area under the ROC curve was equal to 0.90 and the area under the precision-recall curve was 0.85. The results demonstrate a high potential of deep learning models to detect cSCC regions on digitally stained ex vivo CLSM slides and to distinguish them from tumor-free skin

    Genetic Relations Between the Aves Ridge and the Grenada Back-Arc Basin, East Caribbean Sea

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    The Grenada Basin separates the active Lesser Antilles Arc from the Aves Ridge, described as a Cretaceous‐Paleocene remnant of the “Great Arc of the Caribbean.” Although various tectonic models have been proposed for the opening of the Grenada Basin, the data on which they rely are insufficient to reach definitive conclusions. This study presents, a large set of deep‐penetrating multichannel seismic reflection data and dredge samples acquired during the GARANTI cruise in 2017. By combining them with published data including seismic reflection data, wide‐angle seismic data, well data and dredges, we refine the understanding of the basement structure, depositional history, tectonic deformation and vertical motions of the Grenada Basin and its margins as follows: (1) rifting occurred during the late Paleocene‐early Eocene in a NW‐SE direction and led to seafloor spreading during the middle Eocene; (2) this newly formed oceanic crust now extends across the eastern Grenada Basin between the latitude of Grenada and Martinique; (3) asymmetrical pre‐Miocene depocenters support the hypothesis that the southern Grenada Basin originally extended beneath the present‐day southern Lesser Antilles Arc and probably partly into the present‐day forearc before the late Oligocene‐Miocene rise of the Lesser Antilles Arc; and (4) the Aves Ridge has subsided along with the Grenada Basin since at least the middle Eocene, with a general subsidence slowdown or even an uplift during the late Oligocene, and a sharp acceleration on its southeastern flank during the late Miocene. Until this acceleration of subsidence, several bathymetric highs remained shallow enough to develop carbonate platforms
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