The nitrogen source as a tool for weeds management

Los resultados de producción de biomasa, tanto de parte aérea como de raíz, nos muestran las distintas preferencias por una u otra fuente [(nitrato (NO3 -) o amonio(NH4 +)] de nitrógeno (N), así como La influencia de la fuente de N en la respuesta a la dosis (2 mM vs. 0,2 mM) en la zona radicular: Amaranthus viridis y Chenopodium album prefieren el NO3- y no responden a la dosis de NH4+, Conyza bonaeriensis y Solanum nigrum también prefieren NO3- pero responden a la dosis de NH4+, mientras que Sonchus oleraceus prefiere el NH4+ y no responde a la dosis de NO3 -. Igualmente, la fuente de N, y no sólo la dosis de N, tiene una gran repercusión en la relación carbono/nitrógeno (C/N) tanto de la parte aérea como de la raíz. El conjunto de los resultados sugiere que el manejo de la fuente de N en los sistemas agrícolas podría ayudar al manejo de las malas hierbas y con ello a su control, en pro de hacer una mejor optimización de los recursos.The results of biomass production both in terms of shoot and root, show distinct plants preferences for the nitrogen source; Amaranthus viridis and Chenopodium album prefers NO3 - and does not respond to the dose of NH4 +, Conyza bonaeriensis and Solanum nigrum also prefers NO3 - but respond to the dose of NH4 +, and finally Sonchus oleraceus prefers NH4 + over NO3 - and does not respond to the dose of NO3 -. Here, we also show that the source of N has a major role in plant N and C concentration. Overall, these results indicate that N fertilization (source and dose) may be a tool for the management of weeds in agricultural system where the farmer has control over the source of N applied

Model selection for spectro-polarimetric inversions

Inferring magnetic and thermodynamic information from spectropolarimetric observations relies on the assumption of a parameterized model atmosphere whose parameters are tuned by comparison with observations. Often, the choice of the underlying atmospheric model is based on subjective reasons. In other cases, complex models are chosen based on objective reasons (for instance, the necessity to explain asymmetries in the Stokes profiles) but it is not clear what degree of complexity is needed. The lack of an objective way of comparing models has, sometimes, led to opposing views of the solar magnetism because the inferred physical scenarios are essentially different. We present the first quantitative model comparison based on the computation of the Bayesian evidence ratios for spectropolarimetric observations. Our results show that there is not a single model appropriate for all profiles simultaneously. Data with moderate signal-to-noise ratios favor models without gradients along the line-of-sight. If the observations shows clear circular and linear polarization signals above the noise level, models with gradients along the line are preferred. As a general rule, observations with large signal-to-noise ratios favor more complex models. We demonstrate that the evidence ratios correlate well with simple proxies. Therefore, we propose to calculate these proxies when carrying out standard least-squares inversions to allow for model comparison in the future.Comment: 16 pages, 2 figures, 8 tables, accepted for publication in Ap

Non-local thermodynamic equilibrium inversions from a 3D MHD chromospheric model

The structure of the solar chromosphere is believed to be governed by magnetic fields, even in quiet-Sun regions that have a relatively weak photospheric field. During the past decade inversion methods have emerged as powerful tools for analyzing the chromosphere of active regions. The applicability of inversions to infer the stratification of the physical conditions in a dynamic 3D solar chromosphere has not yet been studied in detail. This study aims to establish the diagnostic capabilities of non-local thermodynamical equilibrium (NLTE) inversion techniques of Stokes profiles induced by the Zeeman effect in the Ca II 8542 line. We computed the Ca II atomic level populations in a snapshot from a 3D radiation-MHD simulation of the quiet solar atmosphere in non-LTE using the 3D radiative transfer code Multi3d. These populations were used to compute synthetic full-Stokes profiles in the Ca II 8542 line using 1.5D radiative transfer and the inversion code Nicole. The profiles were then spectrally degraded to account for finite filter width and Gaussian noise was added to account for finite photon flux. These profiles were inverted using Nicole and the results were compared with the original model atmosphere. Our NLTE inversions applied to quiet-Sun synthetic observations provide reasonably good estimates of the chromospheric magnetic field, line-of-sight velocities and somewhat less accurate, but still very useful, estimates of the temperature. Three dimensional scattering of photons cause cool pockets in the chromosphere to be invisible in the line profile and consequently they are also not recovered by the inversions. To successfully detect Stokes linear polarization in this quiet snapshot, a noise level below 10^{-3.5} is necessary.Comment: Accepted for publication in Astronomy & Astrophysic

Influence of phase-diversity image reconstruction techniques on circular polarization asymmetries

Full Stokes filter-polarimeters are key instruments for investigating the rapid evolution of magnetic structures on the solar surface. To this end, the image quality is routinely improved using a-posteriori image reconstruction methods. We analyze the robustness of circular polarization asymmetries to phase-diversity image reconstruction techniques. We use snapshots of magneto-hydrodynamical simulations carried out with different initial conditions to synthesize spectra of the magnetically sensitive Fe I line at 5250.2 A. We degrade the synthetic profiles spatially and spectrally to simulate observations with the IMaX full Stokes filter-polarimeter. We also simulate the focused/defocused pairs of images used by the phase-diversity algorithm for reconstruction and the polarimetric modulation scheme. We assume that standard optimization methods are able to infer the projection of the wavefront on the Zernike polynomials with 10% precision. We also consider the less favorable case of 25% precision. We obtain reconstructed monochromatic modulated images that are later demodulated and compared with the original maps. Although asymmetries are often difficult to define in the quiet Sun due to the complexity of the Stokes V profiles, we show how asymmetries are degraded with spatial and spectral smearing. The results indicate that, although image reconstruction techniques reduce the spatial smearing, they can modify the asymmetries of the profiles, mainly caused by the appearance of spatially-correlated noise.Comment: 10 pages, accepted for publication in A&

Strength distribution of solar magnetic fields in photospheric quiet Sun regions

The magnetic topology of the solar photosphere in its quietest regions is hidden by the difficulties to disentangle magnetic flux through the resolution element from the field strength of unresolved structures. The observation of spectral lines with strong coupling with hyperfine structure, like the observed MnI line at 553.7 nm, allows such differentiation. The main aim is to analyse the distribution of field strengths in the network and intranetwork of the solar photosphere through inversion of the MnI line at 553.7 nm. An inversion code for the magnetic field using the Principal Component Analysis (PCA) has been developed. Statistical tests are run on the code to validate it. The code has to draw information from the small-amplitude spectral feature oppearing in the core of the Stokes V profile of the observed line for field strengths below a certain threshold, coinciding with lower limit of the Paschen-Back effect in the fine structure of the involved atomic levels. The inversion of the observed profiles, using the circular polarization (V) and the intensity (I), shows the presence of magnetic fields strengths in a range from 0 to 2 kG, with predominant weak strength values. Mixed regions with mean strength field values of 1130 and 435 Gauss are found associated with the network and intranetwork respectively. The MnI line at 553 nm probes the field strength distribution in the quiet sun and shows the predominance of weak, hectoGauss fields in the intranetwork, and strong, kiloGauss fields in the network. It also shows that both network and intranetwork are to be understood at our present spatial resolutions as field distributions of which we hint the mean properties.Comment: 10 pages, 6 figure

Interpretation of HINODE SOT/SP asymmetric Stokes profiles observed in quiet Sun network and internetwork

We present the first interpretation of the Stokes profile asymmetries measured in the FeI 630 nm lines by SOT/SP, in both quiet Sun internetwork (IN) and network regions. The inversion is carried out under the hypothesis of MISMA, where the unresolved structure is assumed to be optically thin. We analyze a 29.52"x31.70" subfield carefully selected to be representative of the properties of a 302"x162" quiet Sun field-of-view at disk center. The inversion code is able to reproduce the observed asymmetries in a very satisfactory way. The inversion code interprets 25% of inverted profiles as emerging from pixels in which both positive and negative polarities coexist. kG field strengths are found at the base of the photosphere in both network and IN; in the case of the latter, both kG fields and hG fields are admixed. When considering the magnetic properties at the mid photosphere most kG fields are gone, and the statistics is dominated by hG fields. We constrain the magnetic field of only 4.5% of the analyzed photosphere (and this percentage reduces to 1.3% when referred to all pixels, including those with low polarization not analyzed). The rest of the plasma is consistent with the presence of weak fields not contributing to the detected polarization signals. The average flux densities derived in the full subfield and in IN regions are higher than the ones derived from the same dataset by Milne-Eddington inversion. The existence of large asymmetries in SOT/SP polarization profiles is uncovered. These are not negligible in quiet Sun data. The MISMA inversion code reproduces them in a satisfactory way, and provides a statistical description of the magnetized IN and network which partly differs and complements the results obtained so far. From this it follows the importance of having a complete interpretation of the line profile shapes.Comment: 11 pages, 9 figures, 1 table - Accepted for publication on A&

A User-Centered Chatbot (Wakamola) to Collect Linked Data in Population Networks to Support Studies of Overweight and Obesity Causes: Design and Pilot Study

[EN] Background: Obesity and overweight are a serious health problem worldwide with multiple and connected causes. Simultaneously, chatbots are becoming increasingly popular as a way to interact with users in mobile health apps. Objective: This study reports the user-centered design and feasibility study of a chatbot to collect linked data to support the study of individual and social overweight and obesity causes in populations. Methods: We first studied the users' needs and gathered users' graphical preferences through an open survey on 52 wireframes designed by 150 design students; it also included questions about sociodemographics, diet and activity habits, the need for overweight and obesity apps, and desired functionality. We also interviewed an expert panel. We then designed and developed a chatbot. Finally, we conducted a pilot study to test feasibility. Results: We collected 452 answers to the survey and interviewed 4 specialists. Based on this research, we developed a Telegram chatbot named Wakamola structured in six sections: personal, diet, physical activity, social network, user's status score, and project information. We defined a user's status score as a normalized sum (0-100) of scores about diet (frequency of eating 50 foods), physical activity, BMI, and social network. We performed a pilot to evaluate the chatbot implementation among 85 healthy volunteers. Of 74 participants who completed all sections, we found 8 underweight people (11%), 5 overweight people (7%), and no obesity cases. The mean BMI was 21.4 kg/m(2) (normal weight). The most consumed foods were olive oil, milk and derivatives, cereals, vegetables, and fruits. People walked 10 minutes on 5.8 days per week, slept 7.02 hours per day, and were sitting 30.57 hours per week. Moreover, we were able to create a social network with 74 users, 178 relations, and 12 communities. Conclusions: The Telegram chatbot Wakamola is a feasible tool to collect data from a population about sociodemographics, diet patterns, physical activity, BMI, and specific diseases. Besides, the chatbot allows the connection of users in a social network to study overweight and obesity causes from both individual and social perspectives.Moreover, the authors acknowledge the funding support for this study provided by the CrowdHealth Project (Collective Wisdom Driving Public Health Policies, 727560).Asensio-Cuesta, S.; Blanes-Selva, V.; Conejero, JA.; Frigola, A.; Portolés, MG.; Merino-Torres, JF.; Rubio Almanza, M.... (2021). A User-Centered Chatbot (Wakamola) to Collect Linked Data in Population Networks to Support Studies of Overweight and Obesity Causes: Design and Pilot Study. JMIR Medical Informatics. 9(4):1-14. https://doi.org/10.2196/17503S1149

EUSKOOS (Basque Operational Oceanography System): an integrated approach to providing coastal and oceanic information

Peer Reviewe

Baixem de les tarimes i connectem: recerca en història medieval i innovació docent

We would like to introduce our group of research, [CONTRA TAEDIUM], created by professionals from different fields, that have contributed in this article. Our purpose is to expose our reflections based on our own experiences, not only in research, but also in teaching. We propose new forms of writing history in order to understand the dairy life of the women and men of the past, from birth to death. We would like to point out that interacting all types of sources is essential to understand our history. But, what really makes sense is to bring our students in the historical methodology and involve them in their education. Moreover, it is necessary to design new teaching materials using the new technologies, although it requires team-work and a great, but satisfying, effor