2,284 research outputs found
Dissipative solitons which cannot be trapped
In this paper we study the behavior of dissipative solitons in systems with
high order nonlinear dissipation and show how they cannot survive under the
effect of trapping potentials both of rigid wall type or asymptotically
increasing ones. This provides an striking example of a soliton which cannot be
trapped and only survives to the action of a weak potential
Does functional soil microbial diversity contribute to explain within-site plant beta-diversity in an alpine grassland and a <i>dehesa</i> meadow in Spain?
Questions: Once that the effects of hydrological and chemical soil properties have been accounted for, does soil microbial diversity contribute to explain change in plant community structure (i.e. within-site beta-diversity)? If so, at which spatial scale does microbial diversity operate?
Location: La Mina in Moscosa Farm, Salamanca, western Spain (dehesa community) and Laguna Larga in the Urbión Peaks, Soria, central-northern Spain (alpine grassland).
Methods: The abundance of vascular plant species, soil gram-negative microbial functional types and soil chemical properties (pH, available phosphorus, and extractable cations) were sampled at both sites, for which hydrological models were available. Redundancy analysis (RDA) was used to partition variation in plant community structure into hydrological, chemical and microbial components. Spatial filters, arranged in scalograms, were used to test for the spatial scales at which plant community structure change.
Results: In the case of the dehesa the diversity of soil gram-negative microbes, weakly driven by soil pH, contributed to a small extent (adj-R2 = 2%) and at a relative medium spatial scale to explain change in plant community structure. The abundance of a few dehesa species, both annual (Trifolium dubium, Vulpia bromoides) and perennial (Poa bulbosa, Festuca ampla), was associated with either increasing or decreasing soil microbial diversity. In the alpine meadow the contribution was negligible.
Conclusions: Microbial diversity can drive community structure, though in the hierarchy of environmental factors structuring communities it appears to rank lower than other soil factors. Still, microbial diversity appears to promote or restrain individual plant species. This paper aims to encourage future studies to use more comprehensive and insightful techniques to assess microbial diversity and to combine this with statistical approaches such as the one used here
Rejecting abyssal thinking in the language and education of racialized bilinguals: A manifesto
Following Boaventura de Sousa Santos, the authors of this article reject the type of “abyssal thinking” that erases the existence of counter-hegemonic knowledges and lifeways, adopting instead the “from the inside out” perspective that is required for thinking constructively about the language and education of racialized bilinguals. On the basis of deep personal experience and extensive field-work research, we challenge prevailing assumptions about language, bilingualism, and education that are based on raciolinguistic ideologies with roots in colonialism. Adopting a translanguaging perspective that rejects rigid colonial boundaries of named languages, we argue that racialized bilingual learners, like all students, draw from linguistic-semiotic, cultural, and historical repertoires. The decolonial approach that guides our work reveals these students making a world by means of cultural and linguistic practices derived from their own knowledge systems. We propose that in order to attain justice and success, a decolonial education must center non-hegemonic modes of “otherwise thinking” by attending to racialized bilinguals’ knowledges and abilities that have always existed yet have continually been distorted and erased through abyssal thinking
A mesh adaptation strategy for complex wall-modeled turbomachinery LES
A mesh adaptation methodology for wall-modeled turbomachinery Large Eddy Simulation (LES) is proposed, simultaneously taking into account two quantities of interest: the average kinetic energy dissipation rate and the normalized wall distance y+. This strategy is first tested on a highly loaded transonic blade with separated flow, and is compared to wall-resolved LES results, as well as experimental data. The adaptation methodology allows to predict fairly well the boundary layer transition on the suction side and the recirculation bubble of the pressure side. The method is then tested on a real turbofan stage for which it is shown that the general operating point of the computation converges toward the experimental one. Furthermore, comparison of turbulence predictions with hot-wire anemometry show good agreement as soon as a first adaptation is performed, which confirms the efficiency of the proposed adaptation method
Synthesis, molecular structures and EPR spectra of the paramagnetic cuboidal clusters with Mo3S4Ga cores
Electron precise [Mo3(l3-S)(l-S)3(diphos)3Br3]Br (diphos = dppe,
dmpe) incomplete cuboidal clusters with six cluster skeletal electrons
(CSE) were converted into paramagnetic cuboidal [Mo3(GaBr)(l3-S)4-
(diphos)3Br3] clusters by treatment with elemental Ga. The new
heterobimetallic complexes with nine CSE possess a doublet ground
state with the unpaired electron density delocalized over the three
molybdenum atoms
Synthesis, molecular and electronic structure of an incomplete cuboidal Re3S4 cluster with an anusual quadruplet ground state
A Re(IV) cluster complex [Re3(μ3-S)(μ-S)3(dppe)3Br3]+ with nine cluster skeletal electrons (CSE) and a quadruplet ground state has been prepared by treatment of [Re3S7Br6]Br with 1,2-bis(diphenylphosphino)ethane (dppe) in MeCN
Bioactive bilayered dressing for compromised epidermal tissue regeneration with sequential activity of complementary agents
The article deals with the design, preparation, and evaluation of a new bilayered dressing for application in the healing of compromised wounds. The system is based on the sequential release of two complementary bioactive components to enhance the activation of the regeneration of dermal tissue. The internal layer is a highly hydrophilic and biodegradable film of gelatin and hyaluronic acid (HG), crosslinked with the natural compound genipin, which reacts with the amine groups of gelatin. This film is loaded with the proangiogenic, anti-inflammatory, and antibacterial peptide, proadrenomedullin N-terminal 20 peptide (PAMP), that is released slowly in the wound site. The external layer, more stable and less hydrophilic, is constituted by a biodegradable polyurethane derived from poly(caprolactone) and pluronic L61. This layer is loaded with resorbable nanoparticles of bemiparin (a fractionated low molecular weight heparin), which promotes the activation of growth factors, FGF and VEGF, and provides a good biomechanical stability and controlled permeability of the bilayered dressing. Experiments carried out in mice demonstrate the excellent angiogenic effect of the HG film in the dermal tissue. Application of the bilayered dressing in the wound healing rabbit ear model shows an improved cicatrization of the wound in both ischemic and non-ischemic defects, favoring epithelialization and reducing noticeably the contraction and the inflammation.This work was supported by the CIBER-BBN and a Grant from
Spain’s Ministry of Science and Education (SAF2009-13240-C02-01).Peer Reviewe
Rhizosphere-enhanced biosurfactant action on slowly desorbing PAHs incontaminated soil
We studied how sunflower plants affect rhamnolipid biosurfactant mobilization of slowly desorbing fractions of polycyclic aromatic hydrocarbons (PAHs) in soil froma creosote-contaminated site. Desorption kinetics of 13 individual PAHs revealed that the soil contained initially up to 50% slowly desorbing fractions. A rhamnolipid biosurfactantwas applied to the soil at the completion of the sunflower cycle (75 days in greenhouse conditions). After this period, the PAHs that remained in the soil were mainly present in a slowly desorbing form as a result of the efficient biodegradation of fast-desorbing PAHs by native microbial populations. The rhamnolipid enhanced the bioavailable fraction of the remaining PAHs by up to 30%, as evidenced by a standardized desorption extraction with Tenax, but the enhancement occurredwith only planted soils. The enhanced bioavailability did not decrease residual PAH concentrations under greenhouse conditions, possibly due to ecophysiological limitations in the biodegradation process thatwere independent of the bioavailability. However, biodegradationwas enhanced during slurry treatment of greenhouse planted soils that received the biosurfactant. The addition of rhamnolipids caused a dramatic shift in the soil bacterial community structure, which was magnified in the presence of sunflower plants. The stimulated groups were identified as fast-growing and catabolically versatile bacteria. This new rhizosphere microbial biomass possibly interacted with the biosurfactant to facilitate intra-aggregate diffusion of PAHs, thus enhancing the kinetics of slow desorption. Our results show that the usually limited biosurfactant efficiency with contaminated field soils can be significantly enhanced by integrating the sunflower ontogenetic cycle into the bioremediation design
Hypopituitarism and pregnancy : clinical characteristics, management and pregnancy outcome
Altres ajuts: Acord transformatiu CRUE-CSICAltres ajuts: Open Access Funding provided by Universitat Autonoma de Barcelona.Purpose: To describe the clinical characteristics, management and pregnancy outcome of women with prepregnancy hypopituitarism (HYPO) that received care at our center. Methods: Retrospective study describing 12 pregnancies in women with prepregnancy HYPO (two or more pituitary hormonal deficiencies under replacement treatment) that received care during pregnancy at Hospital Santa Creu i Sant Pau. Clinical characteristics, management and pregnancy outcome were systematically collected. Results: Average patients' age was 35 years and HYPO duration at the beginning of pregnancy was 19 years. The most frequent cause of HYPO was surgical treatment of a sellar mass (8 pregnancies). Eight pregnancies were in primigravid women and 10 required assisted reproductive techniques. The hormonal deficits before pregnancy were as follows: GH in 12 women, TSH in 10, gonadotropin in 9, ACTH in 5 and ADH in 2. All deficits were under hormonal substitution except for GH deficit in 4 pregnancies. During pregnancy, 4 new deficits were diagnosed. The dosage of replacement treatment for TSH, ACTH and ADH deficits was increased and GH was stopped. Average gestational age at birth was 40 weeks, gestational weight gain was excessive in 9 women, 8 patients required induction/elective delivery and cesarean section was performed in 6. Average birthweight was 3227 g. No major complications were observed. Five women were breastfeeding at discharge. Conclusions: In this group of women with long-standing HYPO, with careful clinical management (including treatment of new-onset hormonal deficits) pregnancy outcome was satisfactory but with a high rate of excessive gestational weight gain and cesarean section
Hypsometric Analysis of Rolling Pampa and its Importance as a Tool for Preventing Environmental Impacts
The region known as Rolling Pampas is crossed by multiple rivers, whose dynamics is unknown, despite their important location . This is mainly due to the lack of long-standing hydrological data on the region. Moreover, , a large number of animal feeding operations farms (AFOs) are concentrated, being a significant source of river pollution. Thus, it is impossible to predict the environmental impact of such activities and to draw up accurate good practice guidelines for rural development since the necessary hydrological information is not available. One possible way to overcome this problem is to use hypsometric analysis that is based on topographic data and so can establish similarities among different rivers in terms of their behaviour. In the area under study, it was found that all basins have very similar hypsometric curves as well as similar hypsometric integral values. These findings show its hydrological homogeneity. Furthermore, all the basins were classified as non-equilibrium basins, which indicate that erosion is the main geomorphological factor and that the free runoff process is the most significant contamination carriers.La región denominada Pampa Ondulada se halla en el centro-este de la República Argentina. Esta se encuentra surcada por múltiples ríos, cuya dinámica, a pesar del importante lugar donde se hallan, se encuentra poco estudiada. Esto se debe principalmente a la falta de datos hidrológicos de larga duración en la región. Al mismo tiempo, en esta región se concentra una gran cantidad de establecimientos ganaderos intensivos (AFOs por sus siglas en inglés) que representan una importante fuente de contaminación sobre los anteriores. Ello implica la imposibilidad de predecir el impacto ambiental de dichas actividades y de forjar lineamientos precisos de buenas prácticas para el desarrollo rural al hallarse ausente la información hidrológica necesaria. Una posible forma de salvar este problema es empleando el análisis hipsométrico, que a partir de datos topográficos es capaz de establecer, entre otras cosas, la similitud en el comportamiento de diferentes ríos. Para la región bajo estudio se encontró que todas las cuencas presentan valores de integral hipsométrica muy similares. Ello dejo en evidencia la homogeneidad hidrológica de la región. Además, todas ellas pudieron clasificarse como cuencas en estado de inequilibrio, indicativo de que la erosión es el principal factor geomorfológico actual, y los procesos de escorrentía libre los más significativos como vías de polución.Asociación de Universidades Grupo Montevide
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