4,991 research outputs found

    Spatiotemporal analyses of soil moisture from point to footprint scale in two different hydroclimatic regions

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    This paper presents time stability analyses of soil moisture at different spatial measurement support scales (point scale and airborne remote sensing (RS) footprint scale 800 m × 800 m) in two different hydroclimatic regions. The data used in the analyses consist of in situ and passive microwave remotely sensed soil moisture data from the Southern Great Plains Hydrology Experiments 1997 and 1999 (SGP97 and SGP99) conducted in the Little Washita (LW) watershed, Oklahoma, and the Soil Moisture Experiments 2002 and 2005 (SMEX02 and SMEX05) in the Walnut Creek (WC) watershed, Iowa. Results show that in both the regions soil properties (i.e., percent silt, percent sand, and soil texture) and topography (elevation and slope) are significant physical controls jointly affecting the spatiotemporal evolution and time stability of soil moisture at both point and footprint scales. In Iowa, using point‐scale soil moisture measurements, the WC11 field was found to be more time stable (TS) than the WC12 field. The common TS points using data across the 3 year period (2002–2005) were mostly located at moderate to high elevations in both the fields. Furthermore, the soil texture at these locations consists of either loam or clay loam soil. Drainage features and cropping practices also affected the field‐scale soil moisture variability in the WC fields. In Oklahoma, the field having a flat topography (LW21) showed the worst TS features compared to the fields having gently rolling topography (LW03 and LW13). The LW13 field (silt loam) exhibited better time stability than the LW03 field (sandy loam) and the LW21 field (silt loam). At the RS footprint scale, in Iowa, the analysis of variance (ANOVA) tests show that the percent clay and percent sand are better able to discern the TS features of the footprints compared to the soil texture. The best soil indicator of soil moisture time stability is the loam soil texture. Furthermore, the hilltops (slope ∼0%–0.45%) exhibited the best TS characteristics in Iowa. On the other hand, in Oklahoma, ANOVA results show that the footprints with sandy loam and loam soil texture are better indicators of the time stability phenomena. In terms of the hillslope position, footprints with mild slope (0.93%–1.85%) are the best indicators of TS footprints. Also, at both point and footprint scales in both the regions, land use–land cover type does not influence soil moisture time stability

    Accelerated Simulation of P Systems on the GPU: A Survey

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    The acceleration of P system simulations is required increasingly, since they are at the core of model verification and validation processes. For this purpose, GPU computing is an alternative to more classic approaches in Parallel Computing. It provides a manycore platform with a level of high parallelism at a low cost. In this paper, we survey the developments of P systems simulators using the GPU, and analyze some performance considerations.Ministerio de Economía y Competitividad TIN2012- 37434Junta de Andalucía P08-TIC-0420

    Synthesis of bis(tert-butyl)cyclopentadienyl derivatives of titanium and zirconium. NMR spectra and dynamic behavior of the base-free [Zr(1,3-tBu2-µ5-C5H3)(CH2Ph)2]+ cation

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    Reaction of Si(1,3-tBu2-C5H3)Me3 with MCl4 (M = Ti, Zr) in toluene or hexane at room temp. affords the new trichloromonociclopentadienyl-type derivs. [M(1,3-tBu2-η5-C5H3)Cl3] [M = Ti (2), Zr (3)]. Treatment of complexes 2 and 3 with appropriate alkylating reagents in hexane gives the 1,3-di(tert-butyl)cyclopentadienyl trialkyl titanium and zirconium complexes [M(1,3-tBu2-η5-C5H3)R3] [M = Ti, R = CH3, CH2Ph; M = Zr, R = CH3, CH2Ph (7), CH2CMe2Ph]. Interestingly, when 2 reacts with 3.1 equiv of LiCH2CMe2Ph in hexane at room temp. the ring-tert-butyl-metalated complex [Ti(1-tBu-3-CMe2CH2-η5-C5H3) (CH2CMe2Ph)2] was isolated in 90% yield. The cationic mono(1,3-di-(tert-butyl)cyclopentadienyl) dibenzyl zirconium species [Zr(1,3-tBu2-η5-C5H3)(CH2Ph)2]+, generated in situ by reaction of the tribenzyl complex 7 with B(C6F5)3 or [CPh3]+[B(C6F5)4]- reagents, is reported and their dynamic NMR behavior in CD2Cl2 solns. at low temps. is studied.Financial support for this research by DGICYT (Project\ud PB92-0178-C) is gratefully acknowledged. J.I.A.\ud acknowledges Repsol Petróleo S.A. for a fellowship

    Combining Crop Models and Remote Sensing for Yield Prediction: Concepts, Applications and Challenges for Heterogeneous Smallholder Environments

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    JRC, CCAFS jointly sponsored the workshop on June 13-14, 2012, at the JRC in Ispra, Italy, to identify avenues for exploiting remote sensing information to improving crop forecasting in smallholder farming environments. The workshop’s objectives were: 1) To advance the state-of-knowledge of data assimilation for crop yield forecasting; 2) To address challenges and needs for successful applications of data assimilation in forecasting crop yields in heterogeneous, smallholder environments; and, 3) To enhance collaboration and exchange of knowledge among data assimilation and crop forecasting groups. The workshop succeeded in bringing together scientists from around the world. This has enabled discussions on research and results and has greatly enhanced collaboration and exchange of knowledge, especially about data assimilation and crop forecasting

    Basil essential oil: Composition, antimicrobial properties, and microencapsulation to produce active chitosan films for food packaging

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    The essential oil (EO) from basil—Ocimum basilicum—was characterized, microencapsu-lated by vibration technology, and used to prepare a new type of packaging system designed to extend the food shelf life. The basil essential oil (BEO) chemical composition and antimicrobial activity were analyzed, as well as the morphological and biological properties of the derived BEO microcapsules (BEOMC). Analysis of BEO by gas chromatography demonstrated that the main component was linalool, whereas the study of its antimicrobial activity showed a significant inhibitory effect against all the microorganisms tested, mostly Gram-positive bacteria. Moreover, the prepared BEOMC showed a spheroidal shape and retained the EO antimicrobial activity. Finally, chitosan-based edible films were produced, grafted with BEOMC, and characterized for their physicochemical and biological properties. Since their effective antimicrobial activity was demonstrated, these films were tested as packaging system by wrapping cooked ham samples during 10 days of storage, with the aim of their possible use to extend the shelf life of the product. It was demonstrated that the obtained active film can both control the bacterial growth of the cooked ham and markedly inhibit the pH increase of the packaged food

    Neutral and cationic di(tert-butyl) cyclopentadienyl titanium, zirconium and hafnium complexes. Dynamic NMR study of the ligand-free cations [M(1,3-tBu2-η5-C5H3)(η5-f5H5)(CH3)]+(M=Zr, Hf)

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    Group 4 metal complexes containing the di(tert-butyl)cyclopentadienyl ligand (l,3-tBu2-r/5-CsH3) have been synthesized. The\ud reaction of a mixture of 1,3- and 1,4-di(tert-butyl)cyclopentadiene isomers with KH in THF at -78°C gives the salt K+[(1,3 -\ud tBu2CsH3)]-(THF)I_3 2 as a white solid. Treatment of 2 with chlorotrimethylsilane in a 1:1 molar ratio gives the air-stable\ud trimethylsilylcyclopentadienyl derivative Si(1,3-tBu2C5H3XCH3)3 3. The silyl derivative 3 is an excellent precursor for monocyclopentadienyl\ud trichlorotitanium and zirconium compounds M(1,3 -t Bu 2-r/5-C 5 H 3)C13 [M = Ti (4), Zr (5)]. Addition of a stoichiometric amount\ud of water in the presence of NEt 3 to a toluene solution of 4 affords the oxo trimer compound [Ti(1,3-tBu2-~75 - CsH3)CI( p,-O)] 3 6. The\ud reaction of 4 with 2 equiv, of LiMe affords the chloro dimethyl derivative Ti(1,3-tBu2-'r/5-CsH3)CI(CH3)2 7. The mixed dicyclopentadienyl\ud compounds M(1,3-tBu2-r/5-CsH3XCsHs)CI2 [M = Ti (8); Zr (9)] were prepared by reaction of complexes 4 and 5 respectively with\ud TI(CsHs). Treatment of complexes (8) and (9) with the appropriate alkylating reagent and molar ratio, in hexane at -78 °C, gives the\ud chloro alkyl derivatives M(1,3-tBu2-@-C5H3XCsHs)CIR [M = Ti, R = Me (10); M = Zr, R = Me (11), Bz (12)] or the dialkyl\ud complexes M(1,3-tBu2-@-CsH3)(CsHs)Rz [M = Ti, R = Me (13); M = Zr, R = Me (14), Bz (15), Nf (16)]. When 8 reacts with 2 equiv.\ud of MgBz2(THF) 2 or LiCH2CMe2Ph the metallacyclic complexes Ti(1-tBu-3-CMe2CH~-r/5-C~Ha)(CsHs)R [R = Bz (17); Nf (18)] were\ud isolated as red oils at room temperature, with the elimination of toluene or ten-butyl benzene respectively. The previously reported\ud cationic mono 1,3-di(tert-butyl)cyclopentadienyl dibenzyl zirconium species [Zr(1,3 -t Bu 2-'05-C 5 H 3 XCH 2 Ph) 2 ] + (19) can be stabilized\ud by reaction with tBuNC or PMe 3, in CD2C12 at -78°C, and the formation of the new cationic species [Zr(1,3-tBu2-r/5-\ud CsHa)(L)(CH2Ph)2] + [L=tBuNC (20); PMe 3 (21)] was identified by NMR spectroscopy. The reaction of B(CrFs) 3 with the\ud monocyclopentadienyl trimethyl derivatives M(1,3-tBu2-r/5-CsH3XCH3)3 [M = Ti (22), Zr (23)], in the presence of PMe 3, gives the\ud cationic species [M(I,3-tBu2-@-C~H3)(PMe3)2(CH3)2] + [M = Ti (24); Zr (25)], obtained as orange-yellow solids, stable at room\ud temperature. The reaction of B(C6Fs) 3 with the metallocene dimethyl derivatives M(1,3-tBu2-r/5-CsHa)(@-CsHs)(CH3)z [M = Zr (14);\ud Hf (26)], in a 1:1 molar ratio and in hydrocarbon solvents gives the cationic derivatives [M(1,3-tBu2-@-CsH3)(@ -\ud CsHsXCH3)]+[(CH3)B(CrFs)3] - [M = Zr (27); Hf (28)] as yellow oils which can be stored for weeks under an inert atmosphere. When\ud the same reactions of (14) and (26) with B(C6Fs) 3 are carried out in a 2:1 molar ratio at room temperature, the complexes\ud {[M(1,3-tBu2-@-CsH3X@-CsH5)Me]2(/.L-Me)}[MeB(C6Fs)3] [M =Zr (29), Hf (30)] can be obtained as a mixture of syn- and\ud anti-isomers as shown by NMR spectroscopic observations. The formation of (29) and (30) implies the stabilization of the 14-electron\ud cationic intermediate by interaction with one methyl group of the neutral complexes (14) and (26). Complexes (27) and (28) undergo\ud heterolytic dissociation of the Metal-MeB(C6Fs) 3 bonds, leading to the formation of the free [M(I,3-tBu2-r/5-CsH3)(r/5-CsHs)(CH3)] +\ud 14-electron species, verified by 1H DNMR spectroscopy. When compound (27) was heated at 50°C the metallacyclic cation\ud [Zr(1-tBu-3-CMezCH2-@-C5H3)(@-CsHs)] + (31) was formed. The alkyl derivatives synthesized and reported herein, activated with MAO, B(C6Fs) 3 or [Ph3C][B(C6Fs)4], polymerize ethylene with very low activity. The molecular structure of [Ti(1,3-tBu2-r/5-\ud C5H3)C1(/x-O)] 3 6 has been determined by X-ray diffraction methods.Financial support for this research by DGICYT (Project PB92-0178C) is gratefully acknowledged. J.I.A.\ud acknowledges Repsol Petróleo S.A. for a fellowship. A.M. is grateful to Consejeria Educaci6n (CAM) for a fellowship

    Impaired hypoglycaemia awareness in early pregnancy increases risk of severe hypoglycaemia in the mid-long term postpartum irrespective of breastfeeding status in women with type 1 diabetes

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    Information regarding the postpartum period in women with type 1 diabetes (T1D) is scarce. We aim to evaluate the relation of impaired hypoglycaemia awareness (IAH) in early pregnancy and breastfeeding status (its presence and duration) with severe postpartum hypoglycaemia (SH).Retrospective cohort study of women with T1D followed during pregnancy between 2012 and 2019. Data on SH were recorded before and during pregnancy. IAH was evaluated at the first antenatal visit. Data on breastfeeding and the long-term postpartum period were collected by questionnaire and from medical records.A total of 89 women with T1D were included with a median follow-up after pregnancy of 19.2 [8.7-30.5] months. Twenty-eight (32%) women had IAH at the first antenatal visit. At discharge, 74 (83%) started breastfeeding during a median of 8 [4.4-15] months. A total of 18 (22%) women experienced ≥1 SH during postpartum. The incidence of SH significantly increased from pregestational to the gestational and post-partum period (0.09, 0.15 and 0.25 episodes/patient-year, respectively). Postpartum SH rates were comparable in breastfeeding and non-breastfeeding women (21.4% vs. 25%, respectively, p>0.05). Clarke test score at the first antenatal visit was associated with postpartum SH (for each 1-point increase: OR 1.53; 95% CI, 1.06-2.21) adjusted for confounders. No other diabetes and pregnancy-related variables were identified as predictors of SH in this period.SH are common in the long-term postpartum period independently of breastfeeding. Assessing IAH in early pregnancy could identify those at an increased risk of SH in the postpartum period.Copyright © 2022 SEEN and SED. Published by Elsevier España, S.L.U. All rights reserved

    Data on prevalence and risk factors associated with Toxocara spp infection, atopy and asthma development in Northeast Brazilian school children.

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    In the present article, we provide shortly, data on risk factors for acquiring Toxocara spp. infection and investigate possible associations between this infection with atopy and asthma in school children of a small town and its semi-rural areas of Northeast Brazil. The data set are composed by demographic, social and home environment variables. The detection of anti-Toxocara spp. IgG and specific IgE to aeroallergens was determined by ELISA and ImmunocAP/Phadiatrope systems, respectively. The data presented in this article are related to the article entitled "Risk factors for Toxocara spp. seroprevalence and its association with atopy and asthma phenotypes in school-age children in a small town and semi-rural areas of Northeast Brazil" (M.B. Silva, A.L. Amor, L.N. Santos, A.A. Galvão, A.V. Oviedo Vera, E.S. Silva et al., 2016) [1]
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