1,348 research outputs found
The Non-Homologous Nature of Solar Diameter Variations
We show in this paper that the changes of the solar diameter in response to
variations of large scale magnetic fields and turbulence are not homologous.
For the best current model, the variation at the photospheric level is over
1000 times larger than the variation at a depth of 5 Mm, which is about the
level at which f-mode solar oscillations determine diameter variations. This
model is supported by observations that indicate larger diameter changes for
high degree f-modes than for low degree f-modes, since energy of the former are
concentrated at shallower layers than the latter.Comment: 11 pages, 3 figures, aastex style, accepted for publication by ApJ
Cholinergic cells in the nucleus basalis of mice express the N-methyl-D-aspartate-receptor subunit NR2C and its replacement by the NR2B subunit enhances frontal and amygdaloid acetylcholine levels
It is known that glutamatergic and cholinergic systems interact functionally at the level of the cholinergic basal forebrain. The N-methyl-D-aspartate receptor (NMDA-R) is a multiprotein complex composed of NR1, NR2 and/or NR3 subunits. The subunit composition of NMDA-R of cholinergic cells in the nucleus basalis has not yet been investigated. Here, by means of choline acetyl transferase and NR2B or NR2C double staining, we demonstrate that mice express both the NR2C and NR2B subunits in nucleus basalis cholinergic cells.We generated NR2C-2B mutant mice in which an insertion of NR2B cDNA into the gene locus of the NR2C gene replaced NR2C by NR2B expression throughout the brain. This NR2C-2B mutant was used to examine whether a subunit exchange in cholinergic neurons would affect acetylcholine (ACh) content in several brain structures. We found increased ACh levels in the frontal cortex and amygdala in the brains of NR2C-2B mutant mice. Brain ACh has been implicated in neuroplasticity, novelty-induced arousal and encoding of novel stimuli. We therefore assessed behavioral habituation to novel environments and objects as well as object recognition in NR2C-2B subunit exchange mice. The behavioral analysis did not indicate any gross behavioral alteration in the mutant mice compared with the wildtype mice. Our results show that the NR2C by NR2B subunit exchange in mice affects ACh content in two target areas of the nucleus basalis.
Two-dimensional Stellar Evolution Code Including Arbitrary Magnetic Fields. I. Mathematical Techniques and Test Cases
A high-precision two-dimensional stellar evolution code has been developed for studying solar variability due to structural changes produced by varying internal magnetic fields of arbitrary configurations. Specifically, we are interested in modeling the effects of a dynamo-type field on the detailed internal structure and on the global parameters of the Sun. The high precision is required to model both very small solar changes (of the order of 10-4) and short timescales (of the order of 1 yr). It is accomplished by using the mass coordinate to replace the radial coordinate, by using fixed and adjustable time steps, a realistic stellar atmosphere, and element diffusion, and by adjusting the grid points. We have also built into the code the potential to subsequently include rotation and turbulence. The current code has been tested for several cases, including its ability to reproduce the one-dimensional results
Solar variability and climate
Recent precise observations of solar global parameters are used to calibrate
an upgraded solar model which takes into account magnetic fields in the solar
interior. Historical data about sunspot numbers (from 1500 to the present) and
solar radius changes (between 1715 and 1979) are used to compute solar
variability on years to centuries timescales. The results show that although
the 11 year variability of the total irradiance is of the order of 0.1%,
additional, longer lived changes of the order of 0.1% may have occurred in the
past centuries. These could, for example, account for the occurrence of climate
excursions such as little ice ages.Comment: LaTeX, JGR preprint with AGU++ v16.b and AGUTeX 5.0, use packages
graphicx; 6 pages, 4 figures, submitted to JGR-Space physic
Estimation of Muscle Mass in the Integrated Assessment of Patients on Hemodialysis
Assessment of muscle mass (MM) or its proxies, lean tissue mass (LTM) or fat-free mass (FFM), is an integral part of the diagnosis of protein-energy wasting (PEW) and sarcopenia in patients on hemodialysis (HD). Both sarcopenia and PEW are related to a loss of functionality and also increased morbidity and mortality in this patient population. However, loss of MM is a part of a wider spectrum, including inflammation and fluid overload. As both sarcopenia and PEW are amendable to treatment, estimation of MM regularly is therefore of major clinical relevance. Whereas, computer-assisted tomography (CT) or dual-energy X-ray absorptiometry (DXA) is considered a reference method, it is unsuitable as a method for routine clinical monitoring. In this review, different bedside methods to estimate MM or its proxies in patients on HD will be discussed, with emphasis on biochemical methods, simplified creatinine index (SCI), bioimpedance spectroscopy (BIS), and muscle ultrasound (US). Body composition parameters of all methods are related to the outcome and appear relevant in clinical practice. The US is the only parameter by which muscle dimensions are measured. BIS and SCI are also dependent on either theoretical assumptions or the use of population-specific regression equations. Potential caveats of the methods are that SCI can be influenced by residual renal function, BIS can be influenced by fluid overload, although the latter may be circumvented by the use of a three-compartment model, and that muscle US reflects regional and not whole body MM. In conclusion, both SCI and BIS as well as muscle US are all valuable methods that can be applied for bedside nutritional assessment in patients on HD and appear suitable for routine follow-up. The choice for either method depends on local preferences. However, estimation of MM or its proxies should always be part of a multidimensional assessment of the patient followed by a personalized treatment strategy
Effect of the air pressure on electro-Fenton process
Electro-Fenton process is considered a very promising tool for the treatment of waste waters contaminated by organic pollutants refractant or toxic for microorganisms used in biological processes [1-6]. In these processes H2O2 is continuously supplied to an acidic aqueous solution contained in an electrolytic cell from the two-electron reduction of oxygen gas, directly injected as pure gas or bubbled air. Due to the poor solubility of O2 in aqueous solutions, two dimensional cheap graphite or carbon felt electrodes give quite slow generation of H2O2, thus resulting in a slow abatement of organics.
In this context, we report here a series of studies [7-9] on the effect of air pressure on the electro-generation of H2O2 and the abatement of organic pollutants in water by electro-Fenton process. The effect of air pressure, current density, mixing and nature of the organic pollutant was evaluated.
[1] E. Brillas, I. Sirés, M.A. Oturan, Chem. Rev., 109 (2009) 6570-6631.
[2] C.A. MartĂnez-Huitle, M.A. Rodrigo, I. SirĂ©s, O. Scialdone, Chem. Rev. 115 (2015) 13362–13407.
[3] M. Panizza, G. Cerisola, Chem. Rev. 109 (2009) 6541–6569.
[4] I. Sirés, E. Brillas, M.A. Oturan, M.A. Rodrigo, M. Panizza, Environ. Sci. Pollut. Res. 21 (2014) 8336–8367.
[5] C.A. MartĂnez-Huitle, S. Ferro, Chem. Soc. Rev. 35 (2006) 1324–1340.
[6] B.P.P. Chaplin, Environ. Sci. Process. Impacts. 16 (2014) 1182–1203.
[7] O. Scialdone, A. Galia, C. Gattuso, S. Sabatino, B. Schiavo, Electrochim. Acta, 182 (2015) 775-780.
[8] J.F. Pérez, A. Galia, M.A. Rodrigo, J. Llanos, S. Sabatino, C. Sáez, B. Schiavo, O. Scialdone, Electrochim. Acta, 248 (2017) 169-177.
[9] A.H. LtaĂŻef, S. Sabatino, F. Proietto, A. Galia, O. Scialdone, O. 2018, Chemosphere, 202, 111-118
05/18/1993 - Eastern\u27s 1993 All Student Show Winner Laura Brahos.pdf
This paper reports on the stages forming a model evaluation protocol for urban flow and dispersion models proposed within the COST Action 732 on "Quality Assurance and Improvement of Micro-Scale Meteorological Models". It discusses the different components forming model evaluation with emphasis on validation and implementation of the protocol for the test case Mock Urban Setting Test (MUST). The protocol was proposed with building-resolving models in mind, but integral models have also been included. The suggested approach can be used for further micro-scale model evaluation and for the standardisation of their applications
Quantifying co-benefits and disbenefits of Nature-based Solutions targeting Disaster Risk Reduction
Nature-based Solutions function (NBS) as an umbrella concept for ecosystem-based approaches that are an alternative to traditional engineering solutions for Disaster Risk Reduction. Their rising popularity is explained partly by their entailing additional benefits (so-called co-benefits) for the environment, society, and economy. The few existing frameworks for assessing cobenefits are lacking guidance on co-benefit pre-assessment that is required for the NBS selection and permission process. Going beyond these, this paper develops a comprehensive guidance on quantitative pre-assessment of potential co-benefits and disbenefits of NBS tackling Disaster Risk Reduction. It builds on methods and frameworks from existing NBS literature and related disciplines. Furthermore, this paper discusses the evaluation of the quantified results of the pre-assessment. In particular, the evaluation focuses on the significance of change of the estimated co-benefits and dis-benefits as well as the sustainability of the NBS. This paper will support decision-making in planning processes on suitability and sustainability of Nature-based Solutions and
assist in the preparation of Environmental Impact Assessments of projects
Protein-energy wasting and nutritional supplementation in patients with end-stage renal disease on hemodialysis
© 2016 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism Background & aims Protein-Energy Wasting (PEW) is the depletion of protein/energy stores observed in the most advanced stages of Chronic Kidney Disease (CKD). PEW is highly prevalent among patients on chronic dialysis, and is associated with adverse clinical outcomes, high morbidity/mortality rates and increased healthcare costs. This narrative review was aimed at exploring the pathophysiology of PEW in end-stage renal disease (ESRD) on hemodialysis. The main aspects of nutritional status evaluation, intervention and monitoring in this clinical setting were described, as well as the current approaches for the prevention and treatment of ESRD-related PEW. Methods An exhaustive literature search was performed, in order to identify the relevant studies describing the epidemiology, pathogenesis, nutritional intervention and outcome of PEW in ESRD on hemodialysis. Results and conclusion The pathogenesis of PEW is multifactorial. Loss of appetite, reduced intake of nutrients and altered lean body mass anabolism/catabolism play a key role. Nutritional approach to PEW should be based on a careful and periodic assessment of nutritional status and on timely dietary counseling. When protein and energy intakes are reduced, nutritional supplementation by means of specific oral formulations administered during the hemodialysis session may be the first-step intervention, and represents a valid nutritional approach to PEW prevention and treatment since it is easy, effective and safe. Omega-3 fatty acids and fibers, now included in commercially available preparations for renal patients, could lend relevant added value to macronutrient supplementation. When oral supplementation fails, intradialytic parenteral nutrition can be implemented in selected patients
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