333 research outputs found

    Phenological indicators extraction from dense time-series of Landsat data

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    Time series of remotely sensed vegetation indices are valuable data sets in various Earth science fields. In particular, they have been successfully used to map vegetation phenology. This information can be used into physically-based hydrological models to estimate crop water requirements (e.g. P\uf4\ue7as et al., 2015; Consoli & Vanella, 2014; Er-Raki et al., 2007). Most of the phenology detection studies aimed to capture single seasonal crop growth cycles per year. However, the phenological variability in agriculture, especially connected with winter crops interposed to summer crops, demonstrates the necessity of deriving more than one crop cycle per year (e.g. Patel & Oza, 2014; Li et al., 2014). Moreover, remote sensing of phenology has been largely applied using MODIS normalized difference vegetation index (NDVI) data with a spatial resolution of 250 m, which is often not sufficient to resolve highly fragmented agricultural land surfaces. The opportunities for deriving phenological indicators at high spatial resolution improved radically in 2008 when the Landsat program opened its archive (Woodcock et al. 2008). In this study, we present an approach to detect phenological indicators aimed to characterize vegetation dynamics in agricultural land surfaces. The proposed algorithm was applied to time series of bi-weekly smoothed and gapfilled Landsat Surface Reflectance Climate Data Record (CDR) data from 2012 to 2014 for a pilot area in the Marchfeld region, Lower Austria. The analytic procedure can be summarized in the following steps. First, the surface reflectance of Landsat CDR data is smoothed and gap-filled using a state-of-the art Whittaker algorithm to create a time series of 24 images per year, regularly spaced in time (Vuolo et al., in preparation). NDVI and fAPAR (fraction of Absorbed Photosynthetically Active Radiation) are then derived and used as input to calculate phenology. Using a moving window approach, the multi-temporal time series are analysed to extract local maxima and minima for each pixel. The resulting values are automatically screened to identify the absolute maxima and minima for each crop cycle. Finally, the algorithm estimates the timing of key phenological periods (i.e. green-up, maximum and senescence) for each pixel. Accuracy assessment is carried out through the visual interpretation of several crop growth curves and using a land cover/land use dataset to analyse the results. The results show that the method can successfully extract phenological indicators from dense smoothed and gapfilled time series, both for summer and winter crops. In addition, the comparison between phenologies extracted from each vegetation indices (NDVI and fAPAR) shows a good agreement (R2 = 0.70). Future effort will be dedicated to apply the proposed approach to Landsat time series for other areas of interest. Furthermore, the method will be improved by calibrating and validating the results for the pilot study based on ground truth data. The phenological indicators will be then assimilated into a hydrological model to estimate crop water requirements at basin scale

    Stress distribution in orthodontic mini-implants

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    O objetivo deste trabalho foi avaliar a distribuição de tensões na resina em contato com os filetes de roscas de mini-implantes cilíndricos e cônicos, submetidos à carga lateral e torção de inserção. Um modelo fotoelástico foi confeccionado com gelatina transparente, para simular o osso alveolar. O modelo foi observado com um polariscópio plano e fotografado antes e após a ativação dos mini-implantes com força lateral e de inserção. A aplicação de cargas laterais provocou momentos fletores nos mini-implantes, aparecimento de franjas isocromáticas ao longo dos filetes do corpo dos mini-implantes e no ápice. Quando foi aplicado o torque de inserção, verificou-se a concentração de tensões próxima ao ápice. Concluiu-se que: (1) o mini-implante cilíndrico apresentou maior concentração de tensões no ápice, e (2) o mini-implante cônico apresentou maior concentração de tensões nos filetes de rosca apicais.The objective of this study was to evaluate the stress distribution in the resin in contact with the spirals of cylindrical and conical mini-implants, when submitted to lateral load and insertion torsion. A photoelastic model was fabricated using transparent gelatin to simulate the alveolar bone. The model was observed with a plane polariscope and photographically recorded before and after activation of the two screws with a lateral force and torsion. The lateral force application caused bending moments on both mini-implants, with the uprising of fringes or isochromatics, characteristics of stresses, along the threads of the mini-implants and in the apex. When the torsion was exerted in the mini-implants, a great concentration of stress upraised close to the apex. The conclusion was that, comparing conical with cylindrical mini-implants under lateral load, the stresses were similar on the traction sides. The differences appear (1) on the apex, where the cylindrical mini-implant showed a greater concentration of stress, and (2) along the spirals, in the compression side, where the conical mini-implant showed a greater concentration of stress. The greater part of the stress produced by both mini-implants, after torsion load in insertion, were concentrated on the apex. With the cylindrical mini-implant, the greater concentration of tension was close to the apex, while with the conical one, the stresses were distributed along a greater amount of apical threads

    Giant Sigmoid Diverticulum: A Rare Presentation of a Common Pathology

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    Although colonic diverticulum is a common disease, affecting about 35% of patients above the age of 60, giant sigmoid diverticulum is an uncommon variant of which only relatively few cases have been described in the literature. We report on our experience with a patient affected by giant sigmoid diverticulum who was treated with diverticulectomy. Resection of the diverticulum is a safe surgical procedure, provided that the colon section close to the lesion presents no sign of flogosis or diverticula; in addition, recurrences are not reported after 6-year follow-up

    Effects of the antioxidant crocin on frozen-thawed buffalo (Bubalus bubalis) sperm

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    This work aimed to evaluate the effect of crocin on frozen-thawed sperm quality in buffalo. Spermatozoa were incubated in Tyrode’s Albumin Lactate Pyruvate medium supplemented with 0, 0.5, 1, and 2 mM crocin for 2 h. Sperm motility was evaluated by phase-contrast microscopy, viability and acrosome integrity by Trypan blue Giemsa staining, and membrane functional integrity by the hypoosmotic swelling test. The DNA fragmentation was evaluated by Tunel and ROS levels by spectrofluorometric analysis. The treatment with 2 mM of crocin increased (P <.05) sperm membrane functional integrity compared to the control group (59.1 ± 1.6 vs 53.3 ± 1.5) and reduced sperm DNA fragmentation, compared to the other groups (11.3 ± 1.1, 13.3 ± 1.2, 13.6 ± 1.2 and 6.0 ± 0.7, respectively in 0, 0.5, 1 and 2 mM crocin; P <.01). Finally, a dose-dependent decrease (P <.01) in superoxide anion production in the presence of crocin was observed, as indicated by Dihydroethidium values (922.6 ± 13.0, 596.8 ± 7.4, 498.9 ± 5.3 and 421.4 ± 5.0 a.u., respectively in 0, 0.5, 1 and 2 mM crocin; P <.01). The results of this study demonstrated a positive effect of 2 mM crocin on frozen-thawed buffalo sperm, as indicated by the improvement of sperm membrane integrity and the reduction of DNA fragmentation and ROS levels.Highlights Crocin improves buffalo sperm quality. Crocin improves sperm membrane integrity and reduces DNA fragmentation. Crocin decreases oxidative stress in buffalo sperm

    Climatic zone and soil properties determine the biodiversity of the soil bacterial communities associated to native plants from desert areas of north-central algeria

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    Algeria is the largest country in Africa characterized by semi-arid and arid sites, located in the North, and hypersaline zones in the center and South of the country. Several autochthonous plants are well known as medicinal plants, having in common tolerance to aridity, drought and salinity. In their natural environment, they live with a great amount of microbial species that altogether are indicated as plant microbiota, while the plants are now viewed as a \u201cholobiont\u201d. In this work, the microbiota of the soil associated to the roots of fourteen economically relevant autochthonous plants from Algeria have been characterized by an innovative metagenomic approach with a dual purpose: (i) to deepen the knowledge of the arid and semi-arid environment and (ii) to characterize the composition of bacterial communities associated with indigenous plants with a strong economic/commercial interest, in order to make possible the improvement of their cultivation. The results presented in this work highlighted specific signatures which are mainly determined by climatic zone and soil properties more than by the plant species

    Autoregulation of RCO by Low-Affinity Binding Modulates Cytokinin Action and Shapes Leaf Diversity

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    Mechanisms through which the evolution of gene regulation causes morphological diversity are largely unclear. The tremendous shape variation among plant leaves offers attractive opportunities to address this question. In cruciferous plants, the REDUCED COMPLEXITY (RCO) homeodomain protein evolved via gene duplication and acquired a novel expression domain that contributed to leaf shape diversity. However, the molecular pathways through which RCO regulates leaf growth are unknown. A key question is to identify genome-wide transcriptional targets of RCO and the DNA sequences to which RCO binds. We investigate this question using Cardamine hirsuta, which has complex leaves, and its relative Arabidopsis thaliana, which evolved simple leaves through loss of RCO. We demonstrate that RCO directly regulates genes controlling homeostasis of the hormone cytokinin to repress growth at the leaf base. Elevating cytokinin signaling in the RCO expression domain is sufficient to both transform A. thaliana simple leaves into complex ones and partially bypass the requirement for RCO in C. hirsuta complex leaf development. We also identify RCO as its own target gene. RCO directly represses its own transcription via an array of low-affinity binding sites, which evolved after RCO duplicated from its progenitor sequence. This autorepression is required to limit RCO expression. Thus, evolution of low-affinity binding sites created a negative autoregulatory loop that facilitated leaf shape evolution by defining RCO expression and fine-tuning cytokinin activity. In summary, we identify a transcriptional mechanism through which conflicts between novelty and pleiotropy are resolved during evolution and lead to morphological differences between species. Hajheidari et al. identify target genes for the RCO homeodomain protein that drove leaf shape diversity. They show that RCO regulates growth via orchestrating homeostasis for the hormone cytokinin and that it also represses its own transcription via low-affinity binding sites. This autorepression helps delimit RCO expression and shape leaf form

    Agronomical valorization of eluates from the industrial production of microorganisms: Chemical, microbiological, and ecotoxicological assessment of a novel putative biostimulant

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    Plant Biostimulants (BSs) are a valid supplement to be considered for the integration of conventional fertilization practices. Research in the BS field keeps providing alternative products of various origin, which can be employed in organic and conventional agriculture. In this study, we investigated the biostimulant activity of the eluate obtained as a by-product from the industrial production of lactic acid bacteria on bare agricultural soil. Eluates utilization is in line with the circular economy principle, creating economical value for an industrial waste product. The research focused on the study of physical, chemical, biochemical, and microbiological changes occurring in agricultural soil treated with the biowaste eluate, applied at three different dosages. The final aim was to demonstrate if, and to what extent, the application of the eluate improved soil quality parameters and enhanced the presence of beneficial soil-borne microbial communities. Results indicate that a single application at the two lower dosages does not have a pronounced effect on the soil chemical parameters tested, and neither on the biochemical proprieties. Only the higher dosage applied reported an improvement in the enzymatic activities of β-glucosidase and urease and in the chemical composition, showing a higher content of total, nitric and ammonia N, total K, and higher humification rate. On the other hand, microbial communities were strongly influenced at all dosages, showing a decrease in the bacterial biodiversity and an increase in the fungal biodiversity. Bioinformatic analysis revealed that some Operative Taxonomic Units (OTUs) promoted by the eluate application, belong to known plant growth promoting microbes. Some other OTUs, negatively influenced were attributed to known plant pathogens, mainly Fusarium spp. Finally, the ecotoxicological parameters were also determined and allowed to establish that no toxic effect occurred upon eluate applications onto soil

    Brachiopods from the Cisuralian–Guadalupian of Darvaz, Tajikistan and implications for Permian stratigraphic correlations

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    In this paper, we describe the upper Cisuralian Safetdara and Gundara formations of the Darvaz mountains, North Pamir, which were part ofthe Kunlun Arc, developed along the active Eurasian margin. The Safetdara Formation comprises massive limestones (mainly cyanobacterial,Tubiphytes and Archaeolithoporella boundstones) alternating with well-bedded bioclastic and oncoidal limestones and an interval of recessiveshales. The formation crops out above the Chelamchi Formation consisting of turbiditic siltstones and sandstones with bioclastic silty limestonesyielding massive limestone olistoliths. The Gundara Formation consists of fine sandstones at the base, followed by well-bedded marly bioclastic,oncoidal and microbial limestones, bearing a rich silicified brachiopod fauna in life-position. Two new taxa have been identified in this association:the cemented coralliform Gundaria insolita n. gen. n. sp. and the pedicle attached Hemileurus politus n. sp. The inferred environmental setting isthat of shoal deposits of warm, shallow, high energy, clear marine waters for the Safetdara Formation. The agglutinated microbial reefs to clusterreefs of the Gundara Formation were probably growing in a muddier, quieter and probably slightly deeper setting.The foraminifers of the Brevaxina Zone suggest a Bolorian age for the top of the Chelamchi Formation, the Safetdara Formation and the baseof the Gundara Formation. Kungurian conodonts have been found in the lower part of the Safetdara Formation. The biostratigraphic data from thesedimentary succession of North Pamir, integrated with those already obtained from Southeast Pamir, allow to refine the correlations between theTethyan regional scale and the International Time Scale. In particular, it seems now clear that the Bolorian and the lower part of the Kubergandiancorrelate to the Kungurian
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