5,559 research outputs found

    Desarrollo de un servicio experimental de teledetección en los riegos del Porma (León) para el cálculo ajustado de necesidades hídricas y mejora en la gestión del regadío

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    El proyecto de innovación tecnológica OPTIREG Eficiencia Hídrica, impulsado por el Grupo Tragsa, tiene entre sus objetivos principales introducir el uso de la teledetección, como tecnología de apoyo a la gestión hídrica. Para ello se está desarrollando un servicio web gis experimental que servirá de repositorio único de imágenes y de sus productos derivados y que facilitará, tanto a los regantes, como a los gestores del riego, el seguimiento de los cultivos y de sus necesidades hídricas. Diversos estudios científicos han demostrado la buena relación lineal existente entre el índice de vegetación normalizado (NDVI), derivado de las imágenes de satélite, y el coeficiente de cultivo, Kc (Torres, 2010), utilizado en el cálculo de la evapotranspiración y las necesidades hídricas. Una primera evaluación de los resultados obtenidos en la campaña 2015 para los principales cultivos en regadío en la zona de estudio del Porma (León), indica que el Kc calculado a partir del NDVI, se ajusta mejor que el de FAO. Por ello, se considera un sistema muy válido como referencia para ajustar no sólo la cantidad de agua, sino también para determinar el momento más adecuado de riego, que redundará en una mayor eficiencia hídrica

    The HADES RV Programme with HARPS-N@TNG IV. Time resolved analysis of the Ca ii H&K and H{\alpha} chromospheric emission of low-activity early-type M dwarfs

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    M dwarfs are prime targets for planet search programs, particularly of those focused on the detection and characterization of rocky planets in the habitable zone. Understanding their magnetic activity is important because it affects our ability to detect small planets, and it plays a key role in the characterization of the stellar environment. We analyze observations of the Ca II H&K and H{\alpha} lines as diagnostics of chromospheric activity for low-activity early-type M dwarfs. We analyze the time series of spectra of 71 early-type M dwarfs collected for the HADES project for planet search purposes. The HARPS-N spectra provide simultaneously the H&K doublet and the H{\alpha} line. We develop a reduction scheme able to correct the HARPS-N spectra for instrumental and atmospheric effects, and to provide flux-calibrated spectra in units of flux at the stellar surface. The H&K and H{\alpha} fluxes are compared with each other, and their variability is analyzed. We find that the H and K flux excesses are strongly correlated with each other, while the H{\alpha} flux excess is generally less correlated with the H&K doublet. We also find that H{\alpha} emission does not increase monotonically with the H&K line flux, showing some absorption before being filled in by chromospheric emission when H&K activity increases. Analyzing the time variability of the emission fluxes, we derive a tentative estimate of the rotation period (of the order of a few tens of days) for some of the program stars, and the typical lifetime of chromospheric active regions (a few stellar rotations). Our results are in good agreement with previous studies. In particular, we find evidence that the chromospheres of early-type M dwarfs could be characterized by different filaments coverage, affecting the formation mechanism of the H{\alpha} line. We also show that chromospheric structure is likely related to spectral type

    Levels of Participants Satisfaction with Initial Contact and Examination Visit: The Hispanic Community Health Study/ Study of Latinos (HCHS /SOL)

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    Objective: This study examined perceived satisfaction among Hispanic/Latino individuals who participated in a baseline examination for the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), a large cohort study of 16,415 adults living in four selected communities. Method: An estimated 22% (n= 3,584) of participants completed a questionnaire regarding satisfaction with staff attention, the overall experience during the study examination, and the influence of the informed consent digital video disc (DVD). Results: The majority of participants who completed the questionnaire expressed overall satisfaction with the study. Most participants reported that staff were friendly, courteous and respectful and study test procedures were clearly explained. Participants who preferred to complete the interview in Spanish felt that the informed consent DVD positively influenced their ability to make an informed decision to enroll in the study. Participants who preferred to complete the interview in English tended to report that the baseline examination was longer than expected compared with participants who completed the interview in Spanish. Conclusion: Results demonstrate that culturally and linguistically trained staff and the use of the study’s informed consent DVD were effective in explaining study procedures and positively influenced decisions to participate in the HCHS/SOL study. These results can inform recruitment and enrollment strategies for future participation of minority groups into longitudinal cohort studies. Ethn Dis. 2016;26(3):435-442; doi:10.18865/ed.26.3.435 </p

    HADES RV Programme with HARPS-N at TNG VI. GJ 3942 b behind dominant activity signals

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    Short- to mid-term magnetic phenomena on the stellar surface of M-type stars cannot only resemble the effects of planets in radial velocity data, but also may hide them. We analyze 145 spectroscopic HARPS-N observations of GJ 3942 taken over the past five years and additional photometry to disentangle stellar activity effects from genuine Doppler signals as a result of the orbital motion of the star around the common barycenter with its planet. To achieve this, we use the common methods of pre-whitening, and treat the correlated red noise by a first-order moving average term and by Gaussian-process regression following an MCMC analysis. We identify the rotational period of the star at 16.3 days and discover a new super-Earth, GJ 3942 b, with an orbital period of 6.9 days and a minimum mass of 7.1 Me. An additional signal in the periodogram of the residuals is present but we cannot claim it to be related to a second planet with sufficient significance at this point. If confirmed, such planet candidate would have a minimum mass of 6.3 Me and a period of 10.4 days, which might indicate a 3:2 mean-motion resonance with the inner planet

    Low diversity and host specificity in the gut microbiome community of Eciton army ants (Hymenoptera: Formicidae: Dorylinae) in a Costa Rican rainforest

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    Neotropical army ants of the genus Eciton are top arthropod predators in tropical rainforests. Microbial symbionts, including Unclassified Firmicutes (UF) and Unclassified Entomoplasmatales (UE), are associated with this genus and likely play a significant role in the biology of these ants. While previous work focused on associations of army ants and gut microbes across large geographic scales, here we report a community survey of the gut microbes colonizing the six sympatric Eciton army ant species in a single Costa Rican location. Furthermore, we characterized the gut microbiota associated with different army ant castes in the swarm-raiding species Eciton burchellii. We employed a combination of 16S ribosomal RNA (rRNA) amplicon sequencing as well as fluorescence and electron microscopy to identify gut microbes and to verify their presence in ant guts. We also measured the diversity and interaction specificity of the ant-gut microbe interaction network. The two most dominant operational taxonomic unit (OTU) phylotypes in all species were related to UF and UE previously found in army ants, followed by OTUs assigned to the genus Weissella. Furthermore, the worker castes of E. burchellii shared similar gut microbiota, also dominated by UF and UE phylotypes. Overall, we found a low diversity of gut microbes and a low interaction specificity between army ants and microbes at the community level, mainly because most microbe strains were detected in various Eciton species. The fluorescence in-situ hybridization analyses documented the presence of the two dominant phylotypes within ant guts, and electron microscopy located bacterial biofilms in the hindgut near the microvilli. Their morphology suggests that these bacteria probably belong to the dominant phylotypes UF and UE. Taken together, our results confirm that the Eciton gut microbiome is consistently dominated by a few species of specialized bacteria that may improve nutrient uptake efficiency of host ants. Further research should employ multi-omics and culture-dependent strategies to fully understand the role of these potential symbionts in ant ecophysiology

    Liquid methanol Monte Carlo simulations with a refined potential which includes polarizability, nonadditivity, and intramolecular relaxation

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    Monte Carlo simulations of liquid methanol were performed using a refined ab initio derived potential which includes polarizability, nonadditivity, and intramolecular relaxation. The results present good agreement between the energetic and structural properties predicted by the model and those predicted by ab initio calculations of methanol clusters and experimental values of gas and condensed phases. The molecular level picture of methanol shows the existence of both rings and linear polymers in the methanol liquid phase

    Polarisation Patterns and Vectorial Defects in Type II Optical Parametric Oscillators

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    Previous studies of lasers and nonlinear resonators have revealed that the polarisation degree of freedom allows for the formation of polarisation patterns and novel localized structures, such as vectorial defects. Type II optical parametric oscillators are characterised by the fact that the down-converted beams are emitted in orthogonal polarisations. In this paper we show the results of the study of pattern and defect formation and dynamics in a Type II degenerate optical parametric oscillator for which the pump field is not resonated in the cavity. We find that traveling waves are the predominant solutions and that the defects are vectorial dislocations which appear at the boundaries of the regions where traveling waves of different phase or wave-vector orientation are formed. A dislocation is defined by two topological charges, one associated with the phase and another with the wave-vector orientation. We also show how to stabilize a single defect in a realistic experimental situation. The effects of phase mismatch of nonlinear interaction are finally considered.Comment: 38 pages, including 15 figures, LATeX. Related material, including movies, can be obtained from http://www.imedea.uib.es/Nonlinear/research_topics/OPO

    Binational reflections on pathways to groundwater security in the Mexico–United States borderlands

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    Shared groundwater resources between Mexico and the United States are facing unprecedented stressors. We reflect on how to improve water security for groundwater systems in the border region. Our reflection begins with the state of groundwater knowledge, and the challenges groundwater resources face from a physical, societal and institutional perspective. We conclude that the extent of ongoing cooperation frameworks, joint and remaining research efforts, from which alternative strategies can emerge, still need to be developed. The way forward offers a variety of cooperation models as the future offers rather complex, shared and multidisciplinary water challenges to the Mexico–US borderlands

    Mechanical behavior of asphalt mixtures containing silica gels as warm additives

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    This paper presents the results of a study of some compounds capable of absorbing water into their structure (silica gel), as potential foaming binders. Asphalt mixtures were manufactured at different manufacturing and compaction temperatures, using four different silica gels. Static and dynamic tests were carried out to determine their behavior in asphalt mixtures. The results were compared with those obtained using hot-mix asphalt and warm-mix asphalt manufactured with zeolite. The lab results showed a similar behavior of asphalt mixtures containing either silica gel or zeolite.The research presented herein was sponsored by the Research Office of Universidad de La Frontera (DIUFRO) under the project number DI15-0089

    Giant pulmonary artery aneurysm in a patient with vasoreactive pulmonary hypertension: a case report

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    <p>Abstract</p> <p>Background</p> <p>Pulmonary artery aneurysms are a rare condition, frequently associated with pulmonary hypertension. However, the evolution and treatment of this pathology is still not clear.</p> <p>Case Presentation</p> <p>The authors report a case of a 65-year old patient with pulmonary artery aneurysm associated with pulmonary arterial hypertension. Due to a positive vasoreactivity test, treatment with calcium channel blockers was started with near normalization of the right cardiac pressures. Nevertheless, after 20 months of treatment, the pulmonary artery aneurysm size remained unchanged with an associated severe pulmonary regurgitation and causing extrinsic compression of the main left coronary artery. Surgical correction was successfully performed.</p> <p>Conclusions</p> <p>This is the first case report of a pulmonary artery aneurysm described to be associated with vasoreactive pulmonary hypertension in a living patient. Although medical therapy for pulmonary hypertension was started, surgical correction of the aneurysm was executed in order to prevent its future complications.</p
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