Optimal estimation of sea surface temperature from split-window observations

Optimal estimation (OE) improves sea surface temperature (SST) estimated from satellite infrared imagery in the “split-window”, in comparison to SST retrieved using the usual multi-channel (MCSST) or non-linear (NLSST) estimators. This is demonstrated using three months of observations of the Advanced Very High Resolution Radiometer (AVHRR) on the first Meteorological Operational satellite (Metop-A), matched in time and space to drifter SSTs collected on the global telecommunications system. There are 32,175 matches. The prior for the OE is forecast atmospheric fields from the Météo-France global numerical weather prediction system (ARPEGE), the forward model is RTTOV8.7, and a reduced state vector comprising SST and total column water vapour (TCWV) is used. Operational NLSST coefficients give mean and standard deviation (SD) of the difference between satellite and drifter SSTs of 0.00 and 0.72 K. The “best possible” NLSST and MCSST coefficients, empirically regressed on the data themselves, give zero mean difference and SDs of 0.66 K and 0.73 K respectively. Significant contributions to the global SD arise from regional systematic errors (biases) of several tenths of kelvin in the NLSST. With no bias corrections to either prior fields or forward model, the SSTs retrieved by OE minus drifter SSTs have mean and SD of − 0.16 and 0.49 K respectively. The reduction in SD below the “best possible” regression results shows that OE deals with structural limitations of the NLSST and MCSST algorithms. Using simple empirical bias corrections to improve the OE, retrieved minus drifter SSTs are obtained with mean and SD of − 0.06 and 0.44 K respectively. Regional biases are greatly reduced, such that the absolute bias is less than 0.1 K in 61% of 10°-latitude by 30°-longitude cells. OE also allows a statistic of the agreement between modelled and measured brightness temperatures to be calculated. We show that this measure is more efficient than the current system of confidence levels at identifying reliable retrievals, and that the best 75% of satellite SSTs by this measure have negligible bias and retrieval error of order 0.25 K.

Decomposition of surface electromyographic signal using Hidden Markov Model

The detection of physiological signals from the motor system (electromyographic signals) is being utilized in the practice clinic to guide the therapist in a more precise and accurate diagnosis of motor disorders. In this context, the process of decomposition of EMG (electromyographic) signals that includes the identification and classification of MUAP (Motor Unit Action Potential) of a EMG signal, is very important to help the therapist in the evaluation of motor disorders. The EMG decomposition is a complex task due to EMG features depend on the electrode type (needle or surface), its placement related to the muscle, the contraction level and the health of the Neuromuscular System. To date, the majority of researches on EMG decomposition utilize EMG signals acquired by needle electrodes, due to their advantages in processing this type of signal. However, relatively few researches have been conducted using surface EMG signals. Thus, this article aims to contribute to the clinical practice by presenting a technique that permit the decomposition of surface EMG signal via the use of Hidden Markov Models. This process is supported by the use of differential evolution and spectral clustering techniques. The developed system presented coherent results in: (1) identification of the number of Motor Units actives in the EMG signal; (2) presentation of the morphological patterns of MUAPs in the EMG signal; (3) identification of the firing sequence of the Motor Units. The model proposed in this work is an advance in the research area of decomposition of surface EMG signals.

The Maunder minimum (1645-1715) was indeed a grand minimum: a reassessment of multiple datasets

Aims. Although the time of the Maunder minimum (1645–1715) is widely known as a period of extremely low solar activity, it is still being debated whether solar activity during that period might have been moderate or even higher than the current solar cycle (number 24). We have revisited all existing evidence and datasets, both direct and indirect, to assess the level of solar activity during the Maunder minimum. Methods. We discuss the East Asian naked-eye sunspot observations, the telescopic solar observations, the fraction of sunspot active days, the latitudinal extent of sunspot positions, auroral sightings at high latitudes, cosmogenic radionuclide data as well as solar eclipse observations for that period. We also consider peculiar features of the Sun (very strong hemispheric asymmetry of the sunspot location, unusual differential rotation and the lack of the K-corona) that imply a special mode of solar activity during the Maunder minimum. Results. The level of solar activity during the Maunder minimum is reassessed on the basis of all available datasets. Conclusions. We conclude that solar activity was indeed at an exceptionally low level during the Maunder minimum. Although the exact level is still unclear, it was definitely lower than during the Dalton minimum of around 1800 and significantly below that of the current solar cycle #24. Claims of a moderate-to-high level of solar activity during the Maunder minimum are rejected with a high confidence level.

Exploring the role the brand plays in the choice of charity by UK volunteers

Charities need to understand why volunteers choose one brand rather than another in order to attract more volunteers to their organisation. There has been considerable academic interest in understanding why people volunteer generally. However, this research explores the more specific question of why a volunteer chooses one charity brand rather than another. It builds on previous conceptualisations of volunteering as a consumption decision. Seen through the lens of the individual volunteer, it considers the under-researched area of the decision-making process. The research adopts an interpretivist epistemology and subjectivist ontology. Qualitative data was collected through depth interviews and analysed using both Means-End Chain (MEC) and Framework Analysis methodology. The primary contribution of the research is to theory: understanding the role of brand in the volunteer decision-making process. It identifies two roles for brand. The first is as a specific reason for choice, an ‘attribute’ of the decision. Through MEC, volunteering for a well-known brand connects directly through to a sense of self, both self-respect but also social recognition by others. All four components of the symbolic consumption construct are found in the data: volunteers choose a well-known brand to say something about themselves. The brand brings credibility and reassurance, it reduces the risk and enables the volunteer to meet their need to make a difference and achieve a sense of accomplishment. The second closely related role for brand is within the process of making the volunteering decision. Volunteers built up knowledge about the charity brands from a variety of brand touchpoints, over time. At the point of decision-making that brand knowledge and engagement becomes relevant, enabling some to make an automatic choice despite the significant level of commitment being made. The research identifies four types of decision-making behaviour. The research also makes secondary contributions to MEC methodology and to the non-profit context. It concludes within practical implications for management practice and a rich agenda for future research.

Validation of a food frequency questionnaire for women with osteoporosis

The importance of nutrient intakes in osteoporosis prevention in treatment is widely recognized. The objective of the present study was to develop and validate a FFQ for women with osteoporosis. The questionnaire was composed of 60 items, separated into 10 groups. The relative validation was accomplished through comparison of the 3-Day Food Record (3DR) with the FFQ. The 3DR was applied to 30 elderly women with confirmed osteoporosis, and after 45 days the FFQ was administrated. Statistical analysis comprised the Kolmogorov-Smirnov, Student T test and Pearson correlation coefficient. The agreement between two methods was evaluated by the frequency of similar classification into quartiles, and by the Bland-Altman method. No significant differences between methods were observed for the mean evaluated nutrients, except for carbohydrate and magnesium. Pearson correlation coefficients were positive and statistically significant for all nutrients. The overall proportion of subjects classified in the same quartile by the two methods was on average 50.01% and in the opposite quartile 0.47%. For calcium intake, only 3% of subjects were classified in opposite extreme quartiles by the two methods. The Bland-Altman analysis demonstrated that the differences obtained by the two methods in each subject were well distributed around the mean of the difference, and the disagreement increases as the mean intake increases. These results indicates that the FFQ for elderly women with osteoporosis presented here is highly acceptable and is an accurate method that can be used in large-scale or clinical studies for evaluation of nutrient intakes in a similar population.

Vegetable Oils Deacidification by Solvent Extraction: Liquid-Liquid Equilibrium Data for Systems Containing Sunflower Seed Oil at 298.2 K

Liquid-liquid equilibrium experimental data for refined sunflower seed oil, artificially acidified with commercial oleic acid or commercial linoleic acid and a solvent (ethanol + water), were determined at 298.2 K. This set of experimental data and the experimental data from Cuevas et al.,(1) which were obtained from (283.2 to 333.2) K, for degummed sunflower seed oil-containing systems were correlated using NRTL and UNIQUAC models with temperature-dependent binary parameters. The deviation between experimental and calculated compositions presented average values of (1.13 and 1.41) % for NRTL and UNIQUAC equations, respectively, indicating that the models were able to correctly describe the behavior of compounds under different temperature and solvent hydration.

Hydrodynamical simulations of Galactic fountains - I. Evolution of single fountains

The ejection of the gas out of the disc in late-type galaxies is related to star formation and is due mainly to Type II supernovae. In this paper, we studied in detail the development of the Galactic fountains in order to understand their dynamical evolution and their influence on the redistribution of the freshly delivered metals over the disc. To this aim, we performed a number of 3D hydrodynamical radiative cooling simulations of the gas in the Milky Way where the whole Galaxy structure, the Galactic differential rotation and the supernova explosions generated by a single OB association are considered. A typical fountain powered by 100 Type II supernovae may eject material up to similar to 2 kpc which than collapses back mostly in the form of dense, cold clouds and filaments. The majority of the gas lifted up by the fountains falls back on the disc remaining within a radial distance Delta R = 0.5 kpc from the place where the fountain originated. This localized circulation of disc gas does not influence the radial chemical gradients on large scale, as required by the chemical models of the Milky Way which reproduce the metallicity distribution without invoking large fluxes of metals. Simulations of multiple fountains fuelled by Type II supernovae of different OB associations will be presented in a companion paper.

Wolf-Rayet optically thick winds with Alfven waves

The Wolf-Rayet (WR) stars are hot luminous objects which are suffering an extreme mass loss via a continuous stellar wind. The high values of mass loss rates and high terminal velocities of the WR stellar winds constitute a challenge to the theories of radiation driven winds. Several authors incorporated magnetic forces to the line driven mechanism in order to explain these characteristics of the wind. Observations indicate that the WR stellar winds may reach, at the photosphere, velocities of the order of the terminal values, which means that an important part of the wind acceleration occurs at the optically thick region. The aim of this study is to analyze a model in which the wind in a WR star begins to be accelerated in the optically thick part of the wind. We used as initial conditions stellar parameters taken from the literature and solved the energy, mass and momentum equations. We demonstrate that the acceleration only by radiative forces is prevented by the general behavior of the opacities. Combining radiative forces plus a flux of Alfven waves, we found in the simulations a fast drop in the wind density profile which strongly reduces the extension of the optically thick region and the wind becomes optically thin too close its base. The understanding how the WR wind initiate is still an open issue. (C) 2010 COSPAR. Published by Elsevier Ltd. All rights reserved.

Ablation of primary afferent neurons by neonatal capsaicin treatment reduces the susceptibility of the portal hypertensive gastric mucosa to ethanol-induced injury in cirrhotic rats

Primary sensory afferent neurons modulate the hyperdynamic circulation in Cirrhotic rats with portal hypertension.The stomach of cirrhotic rats is prone to damage induced by ethanol, a phenomenon associated with reduced gastric hyperemic response to acid-back diffusion. The aim of this study was to examine the impact of ablation of capsaicin-sensitive neurons and the tachykinin NK(1) receptor antagonist A5330 on the susceptibility of the portal hypertensive gastric mucosa, to ethanol-induced injury and its effects on gastric cyclooxygenase (COX) and nitric oxide synthase (NOS) mRNA expression. Capsaicin was administered to neonatal, male, Wistar rats and the animals were allowed to grow. Cirrhosis was then induced by bile duct ligation in adult rats while controls had sham operation. Ethanol-induced gastric damage was assessed using ex vivo gastric chamber experiments. Gastric blood flow was measured as well as COX/NOS mRNA expression. Topical application of ethanol produced significant gastric damage in cirrhotic rats compared to controls, which was reversed in capsaicin- and A5330-treated animals. Mean arterial and portal pressure was normalized in capsaicin-treated cirrhotic rats. Capsaicin and A5330 administration restored gastric blood flow responses to topical application of ethanol followed by acid in cirrhotic rats. Differential COX and NOS mRNA expression was noted in bile duct ligated rats relative to controls. Capsaicin treatment significantly modified gastric eNOS/iNOS/COX-2 mRNA expression in cirrhotic rats. Capsaicin-sensitive neurons modulate the susceptibility of the portal hypertensive gastric mucosa to injury induced by ethanol via tachykinin NK(1) receptors and signalling of prostaglandin and NO production/release. (c) 2008 Elsevier B.V. All rights reserved.

The univalent polynomial of Suffridge as a summability kernel

A positive summability trigonometric kernel {K(n)(theta)}(infinity)(n=1) is generated through a sequence of univalent polynomials constructed by Suffridge. We prove that the convolution {K(n) * f} approximates every continuous 2 pi-periodic function f with the rate omega(f, 1/n), where omega(f, delta) denotes the modulus of continuity, and this provides a new proof of the classical Jackson`s theorem. Despite that it turns out that K(n)(theta) coincide with positive cosine polynomials generated by Fejer, our proof differs from others known in the literature.

Shock wave formation in hot nuclear matter

Assuming that nuclear matter can be treated as a perfect fluid, we study the propagation of perturbations in the baryon density at high temperature. The equation of state is derived from the non-linear Walecka model. The expansion of the Euler and continuity equations of relativistic hydrodynamics around equilibrium configurations lead to the breaking wave equation for the density perturbation. We solve it numerically for this perturbation and follow the propagation of the initial pulses.

Rigidity theorems for complete spacelike hypersurfaces with constant scalar curvature in De Sitter space

In this paper we give a partially affirmative answer to the following question posed by Haizhong Li: is a complete spacelike hypersurface in De Sitter space S(1)(n+1)(c), n >= 3, with constant normalized scalar curvature R satisfying n-2/nc <= R <= c totally umbilical? (C) 2008 Elsevier B.V. All rights reserved.

Analytical Potentialities of Carbon Nanotube/Silicone Rubber Composite Electrodes: Determination of Propranolol

A new composite electrode based on multiwall carbon nanotubes (MWCNT) and silicone-rubber (SR) was developed and applied to the determination of propranolol in pharmaceutical formulations. The effect of using MWCNT/graphite mixtures in different proportions was also investigated. Cyclic voltammetry and electrochemical impedance spectroscopy were used for electrochemical characterization of different electrode compositions. Propranolol was determined using MWCNT/SR 70% (m/m) electrodes with linear dynamic ranges up to 7.0 mu molL(-1) by differential pulse and up to 5.4 mu molL(-1) by square wave voltammetry, with LODs of 0.12 and 0.078 mu molL(-1), respectively. Analysis of commercial samples agreed with that obtained by the official spectrophotometric method. The electrode is mechanically robust and presented reproducible results and a long useful life.

Electrochemical Behavior of Verapamil at Graphite-Polyurethane Composite Electrodes: Determination of Release Profiles in Pharmaceutical Samples

A solid graphite-polyurethane composite electrode has been used to determine release profiles of verapamil, a calcium-channel blocker. The electro-oxidation process was characterized by cyclic voltammetry and electrochemical impedance spectroscopy and showed no adsorption of analyte or oxidation products, unlike at other carbon-based electrodes. Quantification gave linear ranges up to 40molL-1 with cyclic voltammetry and detection limits of 0.7molL-1 by differential pulse and square-wave voltammetry. Commercial product samples were successfully analyzed with results equal to those from spectrophotometry. Because no electrode surface renewal is needed, this electrode material has many advantages.