650 research outputs found

    On the computation of Bernstein–Sato ideals

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    AbstractIn this paper we compare the approach of Briançon and Maisonobe for computing Bernstein–Sato ideals—based on computations in a Poincaré–Birkhoff–Witt algebra—with the readily available method of Oaku and Takayama. We show that it can deal with interesting examples that have proved intractable so far

    Centennial-scale vegetation and North Atlantic Oscillation changes during the Late Holocene in the southern Iberia

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    High-reso CE to lution pollen analysis, charcoal, non-pollen palynomorphs and magnetic susceptibility have been analyzed in the sediment record of a peat bog in Sierra Nevada in southern Iberia. The study of these proxies provided the reconstruction of vegetation, climate, fire and human activity of the last ∼4500 cal yr BP. A progressive trend towards aridification during the late Holocene is observed in this record. This trend is interrupted by millennial- and centennial-scale variability of relatively more humid and arid periods. Arid conditions are recorded between ∼4000 and 3100 cal yr BP, being characterized by a decline in arboreal pollen and with a spike in magnetic susceptibility. This is followed by a relatively humid period from ∼3100 to 1600 cal yr BP, coinciding partially with the Iberian-Roman Humid Period, and is indicated by the increase of Pinus and the decrease in xerophytic taxa. The last 1500 cal yr BP are characterized by several centennial-scale climatic oscillations. Generally arid conditions from ∼450 to 1300 CE, depicted by a decrease in Pinus and an increase in Artemisia, comprise the Dark Ages and the Medieval Climate Anomaly. Since ∼ 1300 to 1850 CE pronounced oscillations occur between relatively humid and arid conditions. Four periods depicted by relatively higher Pinus coinciding with the beginning and end of the Little Ice Age are interrupted by three arid events characterized by an increase in Artemisia. These alternating arid and humid shifts could be explained by centennial-scale changes in the North Atlantic Oscillation and solar activity

    Zwitterionic Rhodium and Iridium Complexes Based on a Carboxylate Bridge-Functionalized Bis-N-heterocyclic Carbene Ligand: Synthesis, Structure, Dynamic Behavior, and Reactivity

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    A series of water-soluble zwitterionic complexes featuring a carboxylate bridge-functionalized bis-N-heterocyclic carbene ligand of formula [Cp MIIICl{(MeIm)2CHCOO}] and [MI(diene){(MeIm)2CHCOO}] (Cp* = 1, 2, 3, 4, 5-pentamethylcyclopentadienyl; M = Rh, Ir; MeIm = 3-methylimidazol-2-yliden-1-yl; diene = 1, 5-cyclooctadiene (cod), norbornadiene (nbd)) were prepared from the salt [(MeImH)2CHCOO]Br and suitable metal precursor. The solid-state structure of both types of complexes shows a boat-shaped six-membered metallacycle derived of the ¿2C, C' coordination mode of the bis-NHC ligand. The uncoordinated carboxylate fragment is found at the bowsprit position in the Cp MIII complexes, whereas in the MI(diene) complexes it is at the flagpole position of the metallacycle. The complexes [RhI(diene){(MeIm)2CHCOO}] (diene = cod, nbd) exist as two conformational isomers in dichloromethane, bowsprit and flagpole, that interconvert through the boat-to-boat inversion of the metallacycle. An inversion barrier of ~17 kcal·mol-1 was determined by two-dimensional exchange spectroscopy NMR measurements for [RhI(cod){(MeIm)2CHCOO}]. Reaction of zwitterionic Cp MIII complexes with methyl triflate or tetrafluoroboric acid affords the cationic complexes [Cp MIIICl{(MeIm)2CHCOOMe}]+ or [Cp MIIICl{(MeIm)2CHCOOH}]+ (M = Rh, Ir) featuring carboxy and methoxycarbonyl functionalized methylene-bridged bis-NHC ligands, respectively. Similarly, complexes [MI(diene){(MeIm)2CHCOOMe}]+ (M = Rh, Ir) were prepared by alkylation of the corresponding zwitterionic MI(diene) complexes with methyl triflate. In contrast, reaction of [IrI(cod){(MeIm)2CHCOO}] with HBF4·Et2O (Et = ethyl), CH3OTf, CH3I, or I2 gives cationic iridium(III) octahedral complexes [IrIIIX(cod){(MeIm)2CHCOO}]+ (X = H, Me, or I) featuring a tripodal coordination mode of the carboxylate bridge-functionalized bis-NHC ligand. The switch from ¿2C, C' to ¿3C, C', O coordination of the bis-NHC ligand accompanying the oxidative addition prevents the coordination of the anions eventually formed in the process that remain as counterions

    Efectividad de la terapia combinada a dosis fijas en una cohorte de hipertensos no controlados con monoterapia

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    ObjetivoEvaluar la efectividad de lisinoprilhidroclorotiazida a dosis fijas en el control de la presión arterial en hipertensos tratados con monoterapia y mal controlados.DiseñoEstudio observacional, prospectivo.EmplazamientoAtención primaria.ParticipantesCiento noventa y nueve médicos de atención primaria que incluyeron a 931 pacientes (56,7% mujeres), con edad media de 62,0 ± 10,3 años. Finalizaron el estudio 915 pacientes (98%) que se incluyeron en el análisis.Mediciones principalesSe siguieron las recomendaciones de la OMS/SIH en la medición de la presión arterial y el diagnóstico de mal control. Además, se evaluaron presión del pulso, índice de masa corporal y parámetros analíticos básicos. Se realizaron 4 visitas durante 6 meses de seguimiento.ResultadosLisinopril-hidroclorotiazida (20/12,5mg) disminuyó significativamente la PAS (24,6 ± 3,5mmHg) y la PAD (14,3 ± 0,7mmHg) (p < 0,001). El control de la presión arterial aumentó hasta el 52,8% (p < 0,001). La edad fue la única variable que influyó en el control de la presión arterial (OR, 0,81; IC del 95%, 0,71-0,92%; p = 0,001). La presión del pulso disminuyó 10,4 ± 4,3mmHg (p < 0,001). A las 24 semanas de tratamiento, se observó una mejoría en el perfil glucémico y lipídico, y de la HbA1c en los diabéticos.ConclusionesEn atención primaria, lisinopril-hidroclorotiazida (20/12,5mg), controló la presión arterial del 52,8% los de hipertensos mal controlados con monoterapia. Además, disminuyó la presión del pulso y mejoró el perfil lipídico y el glucémico.ObjectiveTo evaluate the effectiveness of the fixed dose of a lisinoprilhydrochlorothiazide combination treatment in the control of blood pressure, in poorly controlled high blood pressure people, treated with monotherapy.DesignProspective observational study.SettingPrimary care frame.Participants931 patients (56.7% women) with an average age of 62.0±10.3 years, were included by 199 primary care physicians. 915 patients (98%) ended the study and finally they were included for the statistical analysis.Main measurementsOMS/SIH recommendations on blood pressure measurement and diagnose of poor control were followed. Pulse pressure, body mass index and basic clinical analyses were assessed. Four continuation visits were made during six months.ResultsLisinopril–hidrochlorothiazide (20/12.5mg) reduced significantly SBP (24.6±3.5mm Hg) and DBP (14,3±0.7mm Hg) (P<.001). Blood pressure control was only influenced by age (OR, 0.81; 95% CI, 0.71-0.92; P=.001). Pulse pressure was reduced in 10.4±4.3mm Hg (P<.001). After 24 weeks of treatment, glycemic and lipidic profiles showed an improvement, as well as HbA1c in diabetic people.ConclusionsIn Primary care, a 52.8% of poorly controlled with monotherapy high blood pressure people were controlled by a combination of lisinoprilhydrochlorothiazide (20/12.5mg). In addition, pulse pressure was decreased and both lipid and glucose blood profiles improved

    Algebraic computation of some intersection D-modules

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    Let XX be a complex analytic manifold, DXD\subset X a locally quasi-homogeneous free divisor, EE an integrable logarithmic connection with respect to DD and LL the local system of the horizontal sections of EE on XDX-D. In this paper we give an algebraic description in terms of EE of the regular holonomic D-module whose de Rham complex is the intersection complex associated with LL. As an application, we perform some effective computations in the case of quasi-homogeneous plane curves.Comment: 18 page

    Transformation of light paraffins in a microwave-induced plasma-based reactor at reduced pressure

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    In this work, the effects of the plasma chemistry of an argon microwave (2.45 GHz) discharge at reduced pressure on the conversion of three different alkanes (n-pentane, n-hexane and n-heptane) have been studied. Optical emission spectroscopy has been used for identifying the species generated in the plasma and for estimating its gas temperature. Gas chromatography, mass spectrometry, X-ray diffraction and FTIR spectroscopy have been employed for identifying and analyzing all the compounds present as reaction products. Microwave power and hydrocarbon flow rate have been found critically to affect both conversion and selectivity. The main gas products have been hydrogen and ethylene. At low powers (100–150 W) the conversion to hydrogen has been quite selective. However, at high powers (>300 W) or slow hydrocarbon flow rate ethylene has resulted to be the major product. In most cases, an important fraction of a carbon deposit has been obtained which has been characterized as an amorphous hydrogenated carbon film. Some plausible mechanisms explaining the formation of the main reaction products have been discussed

    Lanthanides in granulometric fractions of Mediterranean soils. Can they be used as fingerprints of provenance?

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    Highlights Are lanthanides from fine sand and clay genetically related to the geological materials? Lanthanide concentrations of fine sand and clay fit chronofunctions Pearson's r of lanthanide couples decreases when separation increases in the periodic table Free forms of clay are scavengers of lanthanides and concentrate HREE and ceriumSample preparation and chemical analysis were conducted by Emma Humphreys-Williams and Stanislav Strekopytov (Imaging and Analysis Centre, Natural History Museum, London, UK). This work was supported by a grant from Ministerio de Economía, Industria y Competitividad de España (‘Tipologías de Suelos Mediterráneos versus Cuarzo. En la frontera del conocimiento edafogenético’; Ref. CGL2016-80308-P). The authors thank Professor Margaret A. Oliver, an anonymous editor and two anonymous reviewers for helpful comments and suggestions that improved the final manuscript. We also thank Robert Abrahams (Bsc) for revising the English language.There is geochemical interest in the lanthanides because they behave like a group that is closely related to the parent materials during surface processes, although they also undergo fractionation as a result of supergene dynamics. We analysed lanthanide concentrations (ICPms) in the granulometric fractions fine sand, clay and free forms of clay (FFclay‐CDB and FFclay‐Ox: extracted with citrate‐dithionite‐sodium bicarbonate and with ammonium oxalate, respectively) from a soil chronosequence of Mediterranean soils. There was a relative enrichment of heavy rare earth elements (HREE) in the clay fraction and its free forms with respect to fine sand. The clay free forms behaved as scavengers of lanthanides, and oxidative scavenging of cerium (Ce) in FFclay‐CDB was also detected. Lanthanide concentrations (lanthanum to gadolinium in fine sand; terbium to lutetium in clay) varied with soil age, and chronofunctions were established. There was a strong positive collinearity between most of the lanthanide concentrations. Furthermore, the value of the correlation index (Pearson's r ) of the concentrations between couples of lanthanides (r CLC) decreased significantly with increasing separation between the elements in the periodic table; this has never been described in soils. Several geochemical properties and indices in the fine sand and clay soil fractions and in the geological materials of the Guadalquivir catchment showed, on the one hand, a genetic relation between them all, enabling the lanthanides to be used as fingerprints of provenance; on the other hand, fractionation between fine sand and clay showed these are actively involved in soil lanthanide dynamics.Secretaría de Estado de Investigación, Desarrollo e Innovación. Grant Number: CGL2016‐80308‐

    El control de los criterios de higiene de los procesos en mataderos de cerdo ibérico como medio para evaluar el funcionamiento aceptable de la producción

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    La normativa vigente obliga a los mataderos de cerdo ibérico a desarrollar e implantar un plan APPCC (Análisis de Peligros y Puntos de Control Crítico). De igual modo deben comprobar el correcto funcionamiento de su proceso de producción realizando controles microbiologícos de la superficie de las canales, siguiendo un plan de muestreo diseñado de acuerdo al Reglamento 2073/2005. En el presente trabajo se expone el diseño de un plan de muestreo de un matadero de cerdo ibérico, y se muestran los resultados obtenidos en los primeros controles realizados siguiendo dicho plan
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