An automatic method for atom identification in scanning tunnelling microscopy images of Fe-chalcogenide superconductors.

We describe a computational approach for the automatic recognition and classification of atomic species in scanning tunnelling microscopy images. The approach is based on a pipeline of image processing methods in which the classification step is performed by means of a Fuzzy Clustering algorithm. As a representative example, we use the computational tool to characterize the nanoscale phase separation in thin films of the Fe-chalcogenide superconductor FeSex Te1-x , starting from synthetic data sets and experimental topographies. We quantify the stoichiometry fluctuations on length scales from tens to a few nanometres.

Thermal and electrochemical decomposition of lithium peroxide in non-catalyzed carbon cathodes for Li-air batteries.

The decomposition of lithium peroxide during the charging process of lithium-air batteries is investigated. A novel preparation method for electrodes in the discharged state, i.e., prefilled with Li2O2 using polyethylene oxide as a binder, is presented. The composition and reactivity of Li2O2-prefilled electrodes are examined by thermal analysis coupled with on-line mass spectrometry. Voltage profiles and gas evolution during the charging process of Li2O2-prefilled electrodes in battery cells are correlated with the thermal decomposition process of Li2O2 and its impact on other electrode compounds. It is found that both thermal Li2O2 decomposition and the electrochemical decomposition of Li2O2 during charging enhance the oxidation of the electrolyte, the binder, and/or carbon, which is suggested to be due to the formation of "nascent" oxygen during Li2O2 decomposition into O2 and Li2O (thermally) or into O2 and lithium ions (electrochemically).

Energy streamlines for qualitative inverse scattering in fluids and solids.

In time-harmonic acoustic fields, energy streamlines are defined as the integral curves of the power-flux density vector, averaged over a period. They provide a tool to visualize the details of propagation of energy. After reviewing the role of energy streamlines in the linear sampling method for acoustic inverse scattering, this work formulates a physical interpretation of the same qualitative method in the case of an isotropic homogeneous solid matrix. Specifically, it is shown that the linear sampling method results from conservation of energy along streamline tubes of energy flow associated with elastic waves.

A reply to "Relevant factors in the eutrophication of the Uruguay River and the Río Negro".

A recent paper by Beretta-Blanco and Carrasco-Letelier (2021) claims that agricultural eutrophication is not one of the main causes for cyanobacterial blooms in rivers and artificial reservoirs. By combining rivers of markedly different hydrological characteristics e.g., presence/absence and number of dams, river discharge and geological setting, the study speculates about the role of nutrients for modulating phytoplankton chlorophyll-a. Here, we identified serious flaws, from erratic and inaccurate data manipulation. The study did not define how erroneous original dataset values were treated, how the variables below the detection/quantification limit were numerically introduced, lack of mandatory variables for river studies such as flow and rainfall, arbitrary removal of pH > 7.5 values (which were not outliers), and finally how extreme values of other environmental variables were included. In addition, we identified conceptual and procedural mistakes such as biased construction/evaluation of model prediction capability. The study trained the model using pooled data from a short restricted lotic section of the (large) Uruguay River and from both lotic and reservoir domains of the Negro River, but then tested predictability within the (small) Cuareim River. Besides these methodological considerations, the article shows misinterpretations of the statistical correlation of cause and effect neglecting basic limnological knowledge of the ecology of harmful algal blooms (HABs) and international research on land use effects on freshwater quality. The argument that pH is a predictor variable for HABs neglects overwhelming basic paradigms of carbon fluxes and change in pH because of primary productivity. As a result, the article introduces the notion that HABs formation are not related to agricultural land use and water residence time and generate a great risk for the management of surface waterbodies. This reply also emphasizes the need for good practices of open data management, especially for public databases in view of external reproducibility.

Struma ovarii complicating pregnancy. Case report and literature review.

A 19-year-old woman at 12th week of pregnancy was referred to our hospital with severe acute abdominal pain, nausea and vomiting. Patient's abdomen was untreatable. Routine examinations, except neutrophilic leukocytosis, were normal. Ultrasound imaging showed the presence of intrauterine pregnancy corresponding to amenorrhea and a right complex ovarian mass, with well defined margins without papillary projection, 14x12 cm in diameter. No free fluid was evident. Due to untreatable abdomen and suspecting torsion of the ovarian tumor the patient underwent laparotomy under general anesthesia. The pregnant uterus was normal. The right ovary had increased volume for a cystic-solid mass of the size of 14 cm with smooth surface and twisted on the vascular peduncle. A right adnexectomy was performed. Intraoperative frozen section was negative for malignancy and postoperative histological examination revealed a struma ovarii without atypia of the follicular cells. Postoperative course was normal. The patient was discharged after three days and she delivered at term a normal baby. Mostly struma ovarii represents an incidental finding during cesarean section, but in rare case it may be cause of complications such as torsion, rupture, hypertiroidism and rarely may be a malignant tumor. The AA describe literature data on struma ovarii diagnosed in pregnancy.

Source modeling of ElectroCorticoGraphy (ECoG) data: Stability analysis and spatial filtering.

BACKGROUND: Electrocorticography (ECoG) measures the distribution of the electrical potentials on the cortex produced by the neural currents. A full interpretation of ECoG data requires solving the ill-posed inverse problem of reconstructing the spatio-temporal distribution of the neural currents. This study addresses the ECoG source modeling developing a beamformer method. NEW METHOD: We computed the lead-field matrix by using a novel routine provided by the OpenMEEG software. We performed an analysis of the numerical stability of the ECoG inverse problem by computing the condition number of the lead-field matrix for different configurations of the electrodes grid. We applied a Linear Constraint Minimum Variance (LCMV) beamformer to both synthetic data and a set of real measurements recorded during a rapid visual categorization task. RESULTS: For all considered grids the condition number indicates that the ECoG inverse problem is mildly ill-conditioned. For realistic SNR we found a good performance of the LCMV algorithm for both localization and waveforms reconstruction. COMPARISON WITH EXISTING METHOD: The flow of information reconstructed by analyzing real data seems consistent with both invasive monkey electrophysiology studies and non-invasive (MEG and fMRI) human studies. CONCLUSIONS: Despite a growing interest from the neuroscientific community, solving the ECoG inverse problem has not quite yet reached the level of systematicity found for EEG and MEG. Starting from an analysis of the numerical stability of the problem we considered the most widely utilized method for modeling neurophysiological data based on the beamformer method in the hope to establish benchmarks for future studies.

Experimental validation of a linear model for data reduction in chirp-pulse microwave CT.

Chirp-pulse microwave computerized tomography (CP-MCT) is an imaging modality developed at the Department of Biocybernetics, University of Niigata (Niigata, Japan), which intends to reduce the microwave-tomography problem to an X-ray-like situation. We have recently shown that data acquisition in CP-MCT can be described in terms of a linear model derived from scattering theory. In this paper, we validate this model by showing that the theoretically computed response function is in good agreement with the one obtained from a regularized multiple deconvolution of three data sets measured with the prototype of CP-MCT. Furthermore, the reliability of the model as far as image restoration in concerned, is tested in the case of space-invariant conditions by considering the reconstruction of simple on-axis cylindrical phantoms.

Solitary neurofibroma of the mesentery: report of a case and review of the literature.

Neurofibromas of the gastrointestinal tract are usually associated with neurofibromatosis type 1 (Nfl), or they are exclusive manifestations of the so-called "familial intestinal neurofibromatosis". Gastrointestinal neurofibromas can rarely occur as sporadic lesions in the jejunum and stomach, and only exceptionally in the mesentery. A critical review of the literature revealed that only seven cases of solitary neurofibromas (SNFs) of the mesentery (six in the ileal mesentery; one in the gastrocolic mesentery) have been reported in patients without stigmata of Nf1. We report the clinicopathologic features of an additional case of SNF of the ileal mesentery, incidentally found in a patient with an advanced gastric carcinoma. Since there is increasing evidence that some patients may have some features of Nf1, including dermal or nodular SNFs alone - limited to one or more body segments - (segmental Nf1), the possibility that SNFs of the mesentery may also represent a segmental manifestation of Nf1 is postulated.

Potential artifacts in interpretation of differential breakthrough of colloids and dissolved tracers in the context of transport in a zero-valent iron permeable reactive barrier.

Many published studies have used visual comparison of the timing of peak breakthrough of colloids versus conservative dissolved tracers (hereafter referred to as dissolved tracers or tracers) in subsurface media to determine whether they are advected differently, and to elucidate the mechanisms of differential advection. This purely visual approach of determining differential advection may have artifacts, however, due to the attachment of colloids to subsurface media. The attachment of colloids to subsurface media may shift the colloidal peak breakthrough to earlier times, causing an apparent "faster" peak breakthrough of colloids relative to dissolve tracers even though the transport velocities for the colloids and the dissolved tracers may actually be equivalent. In this paper, a peak shift analysis was presented to illustrate the artifacts associated with the purely visual approach in determining differential advection, and to quantify the peak shift due to colloid attachment. This peak shift analysis was described within the context of microsphere and bromide transport within a zero-valent iron (ZVI) permeable reactive barrier (PRB) located in Fry Canyon, Utah. Application of the peak shift analysis to the field microsphere and bromide breakthrough data indicated that differential advection of the microspheres relative to the bromide occurred in the monitoring wells closest to the injection well in the PRB. It was hypothesized that the physical heterogeneity at the grain scale, presumably arising from differences in inter- versus intra-particle porosity, contributed to the differential advection of the microspheres versus the bromide in the PRB. The relative breakthrough (RB) of microspheres at different wells was inversely related to the ionic strength of ground water at these wells, in agreement with numerous studies showing that colloid attachment is directly related to solution ionic strength.

A novel description of FDG excretion in the renal system: application to metformin-treated models.

This paper introduces a novel compartmental model describing the excretion of 18F-fluoro-deoxyglucose (FDG) in the renal system and a numerical method based on the maximum likelihood for its reduction. This approach accounts for variations in FDG concentration due to water re-absorption in renal tubules and the increase of the bladder's volume during the FDG excretion process. From the computational viewpoint, the reconstruction of the tracer kinetic parameters is obtained by solving the maximum likelihood problem iteratively, using a non-stationary, steepest descent approach that explicitly accounts for the Poisson nature of nuclear medicine data. The reliability of the method is validated against two sets of synthetic data realized according to realistic conditions. Finally we applied this model to describe FDG excretion in the case of animal models treated with metformin. In particular we show that our approach allows the quantitative estimation of the reduction of FDG de-phosphorylation induced by metformin.

Trafficking and homing of systemically administered stem cells: the need for appropriate analysis tools of radionuclide images.

AIM: Despite its enormous relevance, homing of hematopoietic stem cells (SCs) remains relatively uncertain due to the limitations of measuring small number of systemically administered cells in the different organs. Despite its high sensitivity, radionuclide detection has been relatively underutilized to this purpose since it cannot differentiate hematopietic SCs recruited by target tissues from those circulating in the blood pool. Our study aims to verify the potential of tracer kinetic approaches in estimating the recruitment of labeled SCs after their systemic administration. METHODS: Twenty-four Lewis rats underwent administration of 2 millions cells labeled with 37 MBq of 99mTc-exametazime. Animals were divided into 2 groups according to administered cells: hematopoietic SCs or cells obtained from a line of rat hepatoma. Cell injection was performed during a planar dynamic acquisition. Regions of interest were positioned to plot time activity curves on heart, lungs, liver and spleen. Blood cell clearance was evaluated according to common stochastic analysis approach. Either fraction of dose in each organ at the end of the experiment or computing the slope of regression line provided by Patlak or Logan graphical approach estimated cell recruitment. At the end of the study, animals were sacrificed and the number of cells retained in the same organs was estimated by in vitro counting. RESULTS: Cell number, documented by the dose fraction retained in each organ at imaging was consistently higher with respect to the "gold standard" in vitro counting in all experiments. An inverse correlation was observed between degree of overestimation and blood clearance of labeled cells (r=-0.56, P<0.05). Logan plot analysis consistently provided identifiable lines, whose slope values closely agreed with the "in vitro" estimation of hepatic and splenic cell recruitment. CONCLUSION: The simple evaluation of organ radioactivity concentration does not provide reliable estimates of local recruitment of systemically administered cells. Yet, the combined analysis of temporal trends of tracer (cell) tissue accumulation and blood clearance can provide quantitative estimations of cell homing in the different organs.

Highly Automated Dipole EStimation (HADES).

Automatic estimation of current dipoles from biomagnetic data is still a problematic task. This is due not only to the ill-posedness of the inverse problem but also to two intrinsic difficulties introduced by the dipolar model: the unknown number of sources and the nonlinear relationship between the source locations and the data. Recently, we have developed a new Bayesian approach, particle filtering, based on dynamical tracking of the dipole constellation. Contrary to many dipole-based methods, particle filtering does not assume stationarity of the source configuration: the number of dipoles and their positions are estimated and updated dynamically during the course of the MEG sequence. We have now developed a Matlab-based graphical user interface, which allows nonexpert users to do automatic dipole estimation from MEG data with particle filtering. In the present paper, we describe the main features of the software and show the analysis of both a synthetic data set and an experimental dataset.

Phytochemical evaluation and in vitro antioxidant and photo-protective capacity of Calendula officinalis L. leaves / Avaliação fitoquímica e capacidade antioxidante e fotoprotetora in vitro das folhas de Calendula officinalis L

ABSTRACT The plant Calendula officinalis L. is widely applied due to its medicinal properties, which are mainly dermatological and ornamental. The goal of this study is to assess the phytochemical components in a hydroethanolic extract (HECO) from the leaves of Calendula officinalis L. using UV-VIS spectrophotometry and thin layer chromatography (TLC), as well as to identify and quantify the components related to its antioxidant capacity employing high performance liquid chromatographic (HPLC). The antioxidant capacity evaluation was performed using the DPPH method for superoxide and hydroxyl radicals. The photo-protective capacity was evaluated by UVspectrophotometry in order to determine the in vitro Sun Protection Factor(SPF). The results show the plant’s strong antioxidant activity (DPPH and hydroxyl methods), which we believe to be related to the presence of flavonoids (24.67 mg/g), polyphenols (33.90 mg/g), condensed tannins (27.30 mg/g), and the amount of rutin (37.25 mg/g), and quercetin (6.09 mg/g) found during the study. The HECO presented a good antioxidant capacity, most likely due to the polyphenols, flavonoids, and tannins in its contents. However, the obtained SPF of 1.89 ± 0.05 does not allow the plant to be classified as a stand-alone sunscreen, and more studies are needed in order to test its ability to enhance sunscreens in existing cosmetic formulations.

RESUMO A Calendula officinalis L. é uma planta amplamente utilizada por suas propriedades medicinais, principalmente dermatológica e ornamental. O objetivo deste estudo é avaliar constituintes fitoquímicos do extrato hidroetanólico das folhas de Calêndula officinalis L. (HECO) por espectrofotometria UV-visível e cromatografia em camada delgada (CCD), bem como detectar e quantificar os componentes relacionados com a capacidade antioxidante por Cromatografia Líquida de Alta Eficiência (CLAE). Posteriormente, foi avaliada a capacidade antioxidante pelo método do DPPH, radicais superóxido e hidroxila. Além disso, a capacidade fotoprotetora foi avaliada através de espectrofotometria UV para determinação do Fator de Proteção Solar in vitro (FPS). Os resultados evidenciaram que a planta apresentou uma excelente atividade antioxidante para o método do DPPH e do radical hidroxila, o que pode estar relacionada com a presença de flavonoides (24,67 mg/g), polifenóis (33,90 mg/g) e taninos condensados (27,30 mg/g) e da quantidade de rutina (37,25 mg/g) e quercetina (6,09 mg/g) encontrados neste estudo. O HECO apresentou uma notável capacidade antioxidante, provavelmente devido à presença de polifenóis, flavonoides e taninos. O valor do FPS encontrado (1,89 ± 0,05), não classifica a planta como um protetor solar isolado. No entanto, mais estudos são necessários para testar a capacidade de potencializar filtros solares em formulações cosméticas.

Role of noise in image processing by the human perceptive system.

Two psychophysics experiments are described, pointing out the significant role played by stochastic resonance in recognition of capital stylized noisy letters by the human perceptive apparatus. The first experiment shows that an optimal noise level exists at which the letter is recognized for a minimum threshold contrast. A simple two-parameter model that best fits the experimental data is also discussed. In the second experiment we show that a dramatically increased ability of the visual system in letter recognition occurs in an extremely narrow range of increasing noise. Possible interesting future investigations suggested by these experimental results and based on functional imaging techniques are discussed.

Investigation of metal ions binding of humic substances using fluorescence emission and synchronous-scan spectroscopy.

The binding site interactions of IHSS humic substances, Suwannee River Humic Acid, Suwannee River Fulvic Acid, Nordic Fulvic Acid, and Aldrich Humic Acid with various metals ions and a herbicide, methyl viologen were investigated using fluorescence emission and synchronous-scan spectroscopy. The metal ions used were, Fe(III), Cr(III), Cr(VI), Pb(II), Cu(II) and Ni(II). Stern-Volmer constants, Ksv for these quenchers were determined at pH 4 and 8 using an ionic strength of 0.1 M. For all four humic substances, and at both pH studied, Fe(III) was found to be the most efficient quencher. Quenching efficiency was found to be 3-10 times higher at pH 8. The bimolecular quenching rate constants were found to exceed the maximum considered for diffusion controlled interactions, and indicate that the fluorophore and quencher are in close physical association. Synchronous-scan spectra were found to change with pH and provided useful information on binding site interactions between humic substances and these quenchers.

Mechanisms of uranium interactions with hydroxyapatite: implications for groundwater remediation.

The speciation of U(VI) sorbed to synthetic hydroxyapatite was investigated using a combination of U LIII-edge XAS, synchrotron XRD, batch uptake measurements, and SEM-EDS. The mechanisms of U(VI) removal by apatite were determined in order to evaluate the feasibility of apatite-based in-situ permeable reactive barriers (PRBs). In batch U(VI) uptake experiments with synthetic hydroxyapatite (HA), near complete removal of dissolved uranium (>99.5%) to <0.05 microM was observed over a range of total U(VI) concentrations up to equimolar of the total P in the suspension. XRD and XAS analyses of U(VI)-reacted HA at sorbed concentrations < or = 4,700 ppm U(VI) suggested that uranium(VI) phosphate, hydroxide, and carbonate solids were not present at these concentrations. Fits to EXAFS spectra indicate the presence of Ca neighbors at 3.81 A. U-Ca separation, suggesting that U(VI) adsorbs to the HA surfaces as an inner-sphere complex. Uranium(VI) phosphate solid phases were not detected in HA with 4700 ppm sorbed U(VI) by backscatter SEM or EDS, in agreement with the surface complexation process. In contrast, U(VI) speciation in samples that exceeded 7000 ppm sorbed U(VI) included a crystalline uranium(VI) phosphate solid phase, identified as chernikovite by XRD. At these higher concentrations, a secondary, uranium(VI) phosphate solid was detected by SEM-EDS, consistent with chernikovite precipitation. Autunite formation occurred at total U:P molar ratios > or = 0.2. Our findings provide a basis for evaluating U(VI) sorption mechanisms by commercially available natural apatites for use in development of PRBs for groundwater U(VI) remediation.

[Percutaneous mitral valvuloplasty and open mitral commissurotomy: comparison of 2 techniques in immediate results]. / Valvuloplastía mitral percutánea y comisurotomía mitral abierta: comparación de las dos técnicas en los resultados inmediatos.

The aim of this study was to assess the real usefulness of percutaneous mitral balloon valvuloplasty (PMV). Eighty patients aged less than 56 years old, with symptomatic pure mitral stenosis, with an hemodynamic and echocardiographic area < 1.5 cm2, without associated valvular or coronary lesions and without surgical contraindications were studied. These were randomized in two groups of similar age, sex, symptomatology, cardiac rhythm, severity of stenosis and valve anatomy, that were subjected to PMV (n = 38) using a double balloon technique or to mitral commissurotomy (n = 42) with extracorporeal circulation (MC). Mitral areas (calculated using modified Gorlin's formula) increased in 1.15 +/- 0.28 and 1.72 +/- 0.34 cm2 in patients subjected to PMV and MC respectively. No patient died, there was one technical failure with PMV and two patients subjected to MC had a surgical wound infection. Mitral regurgitation increased in more than one degree in two patients treated with PMV (5%) and in 6 patients treated with MC (15%). It is concluded that PMV and MC are highly effective and safe procedures for the treatment of mitral stenosis. Mitral areas obtained with MC are higher than with PMV, however a significant improvement of the disease is achieved with both procedures and MC produces mitral regurgitation with a higher frequency.

Structural and compositional changes attending the ultracentrifugation of very low density lipoproteins.

The effects of repetitive ultracentrifugation on the physical and chemical properties of very low density lipoproteins (VLDL) were investigated. VLDL recentrifuged one to seven times were characterized by chemical analyses, analytical ultracentrifugation and electron microscopy. The VLDL content of triglyceride was increased and the proportion of phospholipid decreased by ultracentrifugation. Recentrifugation of VLDL decreased the number of Sf-o 20-100 particles and generated particles of Sf-o greater than 400. The bulk of the material removed from VLDL by ultracentrifugation was lipoprotein having pre-beta mobility on paper electrophoresis, flotation rates of Sf-o 10-100 and a particle size of 300-400 A-O. Two ultracentrifugations separated an average of 14% of the starting VLDL protein. Characterization of the apoproteins in this material by polyacrylamide gel electrophoresis, gel chromatography, immunoprecipitation and amino acid analysis demonstrated a relatively high proportion of beta-apoprotein and relatively little C-apoproteins.

Polyvariant mutant CFTR genes in patients with chronic pancreatitis.

Several authors have reported an association between mutations of the cystic fibrosis transmembrane conductance regulator gene (CFTR) and chronic pancreatitis. CFTR gene transcription and protein efficiency are influenced by two polymorphic loci, (TG)m and M470V, other than the T5 allele, whose role is already well-established. The TG11/T5 haplotype is commonly found in healthy subjects, while the TG12/T5/V470 and TG13/T5/V470 haplotypes are present in congenital bilateral absence of the vas deferens (CBAVD) patients. While the T5 allele is a mutation that is over-represented in patients with chronic pancreatitis, no data are available concerning the possible allelic preference at the other two polymorphic loci, (TG)m and M470V, in these patients. For this reason, we screened 39 patients with chronic pancreatitis for the most common CFTR mutations found so far in the Italian population; in addition, we examined the length of the polypyrimidine (poly-T) tract in intron 8, the (TG)m length and the M or V codon at position 470. CFTR mutations were found in 3 patients. Poly-T variant typing identified genotype T5/T7 in 5 patients and T5/T9 in 1 patient. Direct sequencing of intron 8 in patients with the T5 variant revealed the TG12/T5/V470//TG11/T7/V470 genotype in 5 patients and TG10/T9//TG11,T5 genotype in 1 patient. In patients with chronic pancreatitis, the T5 allele is frequently associated with TG12 and V470, a haplotype already reported in CBAVD cases and quite uncommon in healthy subjects.