1,193 research outputs found
Superspace calculation of the four-loop spectrum in N=6 supersymmetric Chern-Simons theories
Using N=2 superspace techniques we compute the four-loop spectrum of single
trace operators in the SU(2) x SU(2) sector of ABJM and ABJ supersymmetric
Chern-Simons theories. Our computation yields a four-loop contribution to the
function h^2(\lambda) (and its ABJ generalization) in the magnon dispersion
relation which has fixed maximum transcendentality and coincides with the
findings in components given in the revised versions of arXiv:0908.2463 and
arXiv:0912.3460. We also discuss possible scenarios for an all-loop function
h^2(\lambda) that interpolates between weak and strong couplings.Comment: LaTeX, feynmp, 34 pages; v2: typos corrected, formulations improved,
references adde
Soilless system with supplementary LED light to obtain a high-quality out-of-season production of green beans
Green bean (Phaseolus vulgaris L.) is one of the most important sources of vegetable proteins in the world and it is cultivated all year round, but the light availability, during the dark sea-son, limited its growth. Nevertheless, recent studies conducted on greenhouse horticulture demonstrated that, with the application of light emitting diodes (LEDs) as supplementary light (SL) technology, it is possible to overcome this limitation. Consequently, during the experiment conducted, two cultivars of green bean (‘Saporro’ and ‘Maestrale’) were grown with a soilless system in a cold greenhouse during the fall-winter period. To increase the photoperiod and the daily light integral (DLI), early in the morning, four hours of red (R), blue (B) and red+blue (R+B) supplementary light were supplied by LEDs at 180 μmol·m−2·s−1 (PPFD) at plants level. Plants grown under LEDs improved the yield and the gas exchange system compared with the plants grown under natural light; when B light was supplied as a sole source of SL, it increased the dry matter content and the bright-ness (L*) of the pods. Between the cultivars, ‘Maestrale’ produced 20 g·plant−1 of pods more than ‘Saporro’ but the latter’s colour was brighter (L*) and greener (a*), and ‘Saporro’ also showed the highest photosynthetic efficiency (ΦPSII). In conclusion, ‘Maestrale’ and ‘Saporro’ obtained encouraging out-of-season yields under different LED spectra, but among those B light seems to improve overall crop performances and pods quality
Fink: early supernovae Ia classification using active learning
We describe how the Fink broker early supernova Ia classifier optimizes its
ML classifications by employing an active learning (AL) strategy. We
demonstrate the feasibility of implementation of such strategies in the current
Zwicky Transient Facility (ZTF) public alert data stream. We compare the
performance of two AL strategies: uncertainty sampling and random sampling. Our
pipeline consists of 3 stages: feature extraction, classification and learning
strategy. Starting from an initial sample of 10 alerts (5 SN Ia and 5 non-Ia),
we let the algorithm identify which alert should be added to the training
sample. The system is allowed to evolve through 300 iterations. Our data set
consists of 23 840 alerts from the ZTF with confirmed classification via
cross-match with SIMBAD database and the Transient name server (TNS), 1 600 of
which were SNe Ia (1 021 unique objects). The data configuration, after the
learning cycle was completed, consists of 310 alerts for training and 23 530
for testing. Averaging over 100 realizations, the classifier achieved 89%
purity and 54% efficiency. From 01/November/2020 to 31/October/2021 Fink has
applied its early supernova Ia module to the ZTF stream and communicated
promising SN Ia candidates to the TNS. From the 535 spectroscopically
classified Fink candidates, 459 (86%) were proven to be SNe Ia. Our results
confirm the effectiveness of active learning strategies for guiding the
construction of optimal training samples for astronomical classifiers. It
demonstrates in real data that the performance of learning algorithms can be
highly improved without the need of extra computational resources or
overwhelmingly large training samples. This is, to our knowledge, the first
application of AL to real alerts data.Comment: 8 pages, 7 figures - submitted to Astronomy and Astrophysics.
Comments are welcom
Clustering Italian medical texts: a case study on referrals
In the medical domain, there is a large amount of valuable information
that is stored in textual format. These unstructured data have long been ignored, due
to the difficulties of introducing them in statistical models, but in the last years, the
field of Natural Language Processing (NLP) has seen relevant improvements, with
models capable of achieving relevant results in various tasks, including information
extraction, classification and clustering. NLP models are typically language-specific
and often domain-specific, but most of the work to date has been focused on the
English language, especially in the medical domain. In this work, we propose a
pipeline for clustering Italian medical texts, with a case study on clinical questions
reported in referral
Avaliação do efeito cicatrizante da quitosana por aplicação tópica em ratos.
bitstream/CNPDIA-2009-09/11045/1/DOC29_2007.pd
A first approach on modelling the thermal and microstructure fields during aluminium butt welding using the HYb pinpoint extruder
Hybrid metal extrusion & bonding (HYB) is a new solid-state joining method for metals and alloys that utilizes continuous extrusion as a technique to enable aluminium filler metal additions. In the HYB case, heat is generated by friction between the rotating tool and the workpiece and by plastic deformation of the base and filler materials. To get further insight into how the PinPoint extruder behaves during aluminium butt welding, a finite element (FE) model for the HYB process has been developed by exploiting the framework provided by the numerical code WELDSIM. The model allows the thermal and microstructure fields along with the resulting HAZ hardness profile to be calculated from knowledge of the net power input. In the present investigation the FE model is used to determine the energy efficiency of the HYB process following calibration against thermal data being obtained from dedicated in-situ thermocouple measurements. In the future the FE element model will be extended to enable predictions of both residual stresses and global distortions by taking full advantage of the opportunities that the numerical code WELDSIM offers
Dislocation interactions mediated by grain boundaries
The dynamics of dislocation assemblies in deforming crystals indicate the
emergence of collective phenomena, intermittent fluctuations and strain
avalanches. In polycrystalline materials, the understanding of plastic
deformation mechanisms depends on grasping the role of grain boundaries on
dislocation motion. Here the interaction of dislocations and elastic, low angle
grain boundaries is studied in the framework of a discrete dislocation
representation. We allow grain boundaries to deform under the effect of
dislocation stress fields and compare the effect of such a perturbation to the
case of rigid grain boudaries. We are able to determine, both analytically and
numerically, corrections to dislocation stress fields acting on neighboring
grains, as mediated by grain boundary deformation. Finally, we discuss
conclusions and consequences for the avalanche statistics, as observed in
polycrystalline samples.Comment: 13 pages, 5 figure
Extraseasonal production in a soilless system and characterisation of landraces of carosello and barattiere (Cucumis melo l.)
Barattiere and Carosello are typical melon (Cucumis melo L.) landraces of Puglia’s (South-ern Italy) biodiversity. Their unripe fruits are locally consumed as an alternative to cucumbers (C. sativus L.) and are appreciated for their qualitative profile. Nevertheless, they are underutilized crops. For the high variability and confusing denominations, a morphological characterization is essential to discriminate and valorise landraces; additionally, it is fundamental to implement the agronomic technique to allow the cultivation outside the natural growth period (summer) by soilless cultivation. Two genotypes of Barattiere (‘Allungato’ and ‘Tondo’), two of Carosello (‘Scopatizzo’ and ‘Tomentoso’ (CAT)) and two of cucumber (‘Baby Star’ and ‘Modan’ hybrids) were vertically grown in the winter–spring period in a rockwool soilless system in a glasshouse with supplemental light. Lan-draces were characterized by morpho-physiological descriptors of melon; fruit biometrics and colour were analysed for all genotypes; productive parameters, leaf fluorescence, and chlorophyll content were measured. Genotypes varied in seeds, stem, leaf, fruit traits and they were andromonoecious; Carosello flowered earlier and produced more than Barattiere; CAT fruits were hairy and elongate, while other genotypes tended to rounder and glabrous fruits. Although landraces grew slower than cucumbers, both produced marketable fruits and the production of Carosello was comparable to cucumbers. In conclusion, Barattiere and Carosello have a productive potential and one vertically trained stem in a soilless system is appropriate for their extra-seasonal production
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