1,396 research outputs found
Flower development and pollen vitality of moringa oleifera lam. Grown in a humid temperate climatic condition
Moringa oleifera is a tropical tree cultivated in many countries. This species has acquired a great importance in human nutrition and it was recently indicated as a “novel food” by the European Commission. Recently, moringa plants have been introduced in humid temperate climatic areas, among which Moreno (Buenos Aires Province-Argentina). In such area, the cultivation is possible for the production of leaves, but plants need protection during winter time in order to overcome damages due to low temperatures and hence to produce capsules and seeds. The main objective of this research was to study flower morphology and anatomy of M. oleifera, as well as microsporogenesis and viability of pollen grains of plants cultivated in Moreno in comparison with those produced in a humid sub-tropical climatic area of Argentina (San Miguel de Tucumán). Flowers grown in the temperate environment resulted similar for morphological parameters to those observed in the sub-tropical environment. Nevertheless, pollen grain fertility depended directly on air temperature and it was negatively affected by the lower temperatures registered in the temperate site. According to the observed results, pollen viability increases with mean monthly temperatures above 16°C.Fil: Radice, Silvia. Universidad de Moron. Facultad de Agronomia y Ciencias Agroalimentarias. Laboratorio de Investigaciones En Fisiología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Giordani, Edgardo. Università degli Studi di Firenze; Itali
Neutrino-driven Turbulent Convection and Standing Accretion Shock Instability in Three-Dimensional Core-Collapse Supernovae
We conduct a series of numerical experiments into the nature of
three-dimensional (3D) hydrodynamics in the postbounce stalled-shock phase of
core-collapse supernovae using 3D general-relativistic hydrodynamic simulations
of a - progenitor star with a neutrino leakage/heating scheme. We
vary the strength of neutrino heating and find three cases of 3D dynamics: (1)
neutrino-driven convection, (2) initially neutrino-driven convection and
subsequent development of the standing accretion shock instability (SASI), (3)
SASI dominated evolution. This confirms previous 3D results of Hanke et al.
2013, ApJ 770, 66 and Couch & Connor 2014, ApJ 785, 123. We carry out
simulations with resolutions differing by up to a factor of 4 and
demonstrate that low resolution is artificially favorable for explosion in the
3D convection-dominated case, since it decreases the efficiency of energy
transport to small scales. Low resolution results in higher radial convective
fluxes of energy and enthalpy, more fully buoyant mass, and stronger neutrino
heating. In the SASI-dominated case, lower resolution damps SASI oscillations.
In the convection-dominated case, a quasi-stationary angular kinetic energy
spectrum develops in the heating layer. Like other 3D studies, we
find in the "inertial range," while theory and
local simulations argue for . We argue that
current 3D simulations do not resolve the inertial range of turbulence and are
affected by numerical viscosity up to the energy containing scale, creating a
"bottleneck" that prevents an efficient turbulent cascade.Comment: 24 pages, 15 figures. Accepted for publication in The Astrophysical
Journal. Added one figure and made minor modifications to text according to
suggestions from the refere
VALUTAZIONE DELL'ATTIVITA' E DELLE COMPLICANZE DELLA MALATTIA DI CROHN PERIANALE: CONFRONTO TRA ECOANGIOGRAFIA PERFUSIONALE, ELASTOGRAFIA ECOGRAFICA E RISONANZA MAGNETICA NUCLEARE.
Abstract
Assessing perianal disease activity is important for the treatment and prognosis of Crohn\u2019s disease (CD) patients. Transperineal ultrasound in a simple, painless, non invasive method to define the morphological features of fistulas and abscess and probably also to evaluate activity. TPUS results could be optimized using e.v. contrast enhancement and sonoelastography.
Purpose The aim of this study was to determine the agreement of clinical scores, the Fistula Drainage Assessment (FDA) and Perianal Disease Activity Index (PDAI), pelvic MRI and transperineal ultrasound (TPUS) with contrast enhancement (CEUS) ad elastography, in defining the activity of perianal CD.
Methods Thirty consecutive patients with CD and perianal fistulae underwent clinical, FDA and PDAI; only 28 underwent TPUS evaluation (traditional, with e.v. contrast enhancement and with elastography), and 23 pelvic MRI.
Results MRI finding correlate with both PDAI (p=0.02) and PDAI (p=0.059) in defining active/inactive perianal fistulas. CEUS parameters show great variability and poor concordance with clinical index and MRI. Elastography TPUS correlate with FDA (p=0.039) but not with PDAI.
Conclusions MRI still represents the gold standard in defining perianal CD activity. TPUS is an emerging technique in the study of perianal CD, with promising results in association with elastography. CEUS does not seem to provide additional advantages
Robust fitting for generalized additive models for location, scale and shape
The validity of estimation and smoothing parameter selection for the wide class of generalized additive models for location,
scale and shape (GAMLSS) relies on the correct specification of a likelihood function. Deviations from such assumption
are known to mislead any likelihood-based inference and can hinder penalization schemes meant to ensure some degree of
smoothness for nonlinear effects. We propose a general approach to achieve robustness in fitting GAMLSSs by limiting the
contribution of observations with low log-likelihood values. Robust selection of the smoothing parameters can be carried out
either by minimizing information criteria that naturally arise from the robustified likelihood or via an extended Fellner–Schall
method. The latter allows for automatic smoothing parameter selection and is particularly advantageous in applications with
multiple smoothing parameters. We also address the challenge of tuning robust estimators for models with nonlinear effects by
proposing a novel median downweighting proportion criterion. This enables a fair comparison with existing robust estimators
for the special case of generalized additive models, where our estimator competes favorably. The overall good performance
of our proposal is illustrated by further simulations in the GAMLSS setting and by an application to functional magnetic
resonance brain imaging using bivariate smoothing splines
Flexible Causal Inference for Political Science
Measuring the causal impact of state behavior on outcomes is one of the biggest methodological challenges in the field of political science, for two reasons: behavior is generally endogenous, and the threat of unobserved variables that confound the relationship between behavior and outcomes is pervasive. Matching methods, widely considered to be the state of the art in causal inference in political science, are generally ill-suited to inference in the presence of unobserved confounders. Heckman-style multiple-equation models offer a solution to this problem; however, they rely on functional-form assumptions that can produce substantial bias in estimates of average treatment effects. We describe a category of models, flexible joint likelihood models, that account for both features of the data while avoiding reliance on rigid functional-form assumptions. We then assess these models’ performance in a series of neutral simulations, in which they produce substantial (55% to
90%) reduction in bias relative to competing models. Finally, we demonstrate their utility in a reanalysis of Simmons’ (2000) classic study of the impact of Article VIII commitment on compliance with the IMF’s currency-restriction regime
The synergistic effect of prebiotics, probiotics and antioxidants on dogs with chronic kidney disease
The use of probiotics, prebiotics and antioxidants could be found beneficial for dogs with chronic kidney disease (CKD). The aim of our case-control study is to evaluate the synergistic effect of a diet integrated with a supplement containing probiotics (Lactobacillus acidophilus), prebiotics (fructoligosaccharides) and antioxidants (Olea Europaea extract) on the nutritional status and on serum and urinary parameters of dogs with CKD. A total of 30 dogs classified with IRIS CKD stage 3 were enrolled and randomly assigned to a control (CG, n = 15) and a treated (TG n = 15) group. The trial consisted in a 7-days adaptation period, followed by 90 days where animals in the TR group received the supplement, while in the CG group the placebo. No significant changes in body weight and body condition score were recorded. We recorded a significant improvement of the protein plasmatic level and a decrease in blood phosphorus, systolic pressure, BUN, proteinuria and urine protein-to-creatinine ratio throughout the trial in the TG compared to the CG group. Furthermore, the parameters related to inflammation and oxidative stress (C-reactive protein and Reactive Oxygen Metabolite- derived compound, respectively) were lower in the TG than in the CG group throughout the study. Our results showed that the supplement allows to maintain the correct nutritional status and to improve blood and kidney parameters in dogs with advance stage of CKD. This supplement could be considered as a new nutritional approach for treating this condition.HIGHLIGHTS Diet supplemented with prebiotics, probiotics and antioxidants is safe for dogs with CKD. The synergic effect of prebiotics, probiotics and antioxidants included in the supplement under study shows the maintenance of a good nutritional status and the improvement of blood and urinary parameters in dogs with CKD
Assessment of Natural Resources Use for Sustainable Development - DPSIR Framework for Case Studies in Portsmouth and Thames Gateway, U.K.
This chapter reports on the uses of the DPSIR framework to assess the sustainability of the intertidal environments within the two UK case study areas, Portsmouth and Thames Gateway. It focuses on statutory conservation areas dominated by intertidal habitats. Two are located in Portsmouth (Portsmouth and Langstone Harbours) and four in the Thames Gateway (Benfleet Marshes, South Thames Estuary, Medway Estuary and the Swale in the Thames Gateway). Based on the reduction of a number of pressures and impacts observed in recent decades and the improvement of overall environmental quality, all six SSSIs are considered to be sustainable in the short and medium term. In the future, it is possible that the impacts of climate change, especially sea-level rise, might result in further reduction in the area and/or quality of intertidal habitats. Further integration between conservation and planning objectives (both for urban development and management of flood risk) at local level is needed to support the long-term sustainability of intertidal habitats
Consequences of asteroid fragmentation during impact hazard mitigation
The consequences of the fragmentation of an Earth-threatening asteroid due to an attempted deflection are examined in this paper. The minimum required energy for a successful impulsive deflection of a threatening object is computed and compared to the energy required to break up a small size asteroid. The results show that the fragmentation of an asteroid that underwent an impulsive deflection, such as a kinetic impact or a nuclear explosion, is a very plausible event.Astatistical model is used to approximate the number and size of the fragments as well as the distribution of velocities at the instant after the deflection attempt takes place. This distribution of velocities is a function of the energy provided by the deflection attempt, whereas the number and size of the asteroidal fragments is a function of the size of the largest fragment. The model also takes into account the gravity forces that could lead to a reaggregation of the asteroid after fragmentation. The probability distribution of the pieces after the deflection is then propagated forward in time until the encounter with Earth. A probability damage factor (i.e., expected damage caused by a given size fragment multiplied by its impact probability) is then computed and analyzed for different plausible scenarios, characterized by different levels of deflection energies and lead times
Modelling the extremes of seasonal viruses and hospital congestion: The example of flu in a Swiss hospital
Viruses causing flu or milder coronavirus colds are often referred to as ‘seasonal viruses’ as they tend to subside in warmer months. In other words, meteorological conditions tend to impact the activity of viruses, and this information can be exploited for the operational management of hospitals. In this study, we use 3 years of daily data from one of the biggest hospitals in Switzerland and focus on modelling the extremes of hospital visits from patients showing flu-like symptoms and the number of positive flu cases. We propose employing a discrete generalized Pareto distribution for the number of positive and negative cases. Our modelling framework allows for the parameters of these distributions to be linked to covariate effects, and for outlying observations to be dealt with via a robust estimation approach. Because meteorological conditions may vary over time, we use meteorological and not calendar variations to explain hospital charge extremes, and our empirical findings highlight their significance. We propose a measure of hospital congestion and a related tool to estimate the resulting CaRe (Charge-at-Risk-estimation) under different meteorological conditions. The relevant numerical computations can be easily carried out using the freely available GJRM R package. The empirical effectiveness of the proposed method is assessed through a simulation study
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