Galois representations, embedding problems and modular forms

To an odd irreducible 2-dimensional complex linear representation of the absolute Galois group of the field Q of rational numbers, a modular form of weight 1 is associated (modulo Artin's conjecture on the L-series of the representation in the icosahedral case). In addition, linear liftings of 2-dimensional projective Galois representations are related to solutions of certain Galois embedding problems. In this paper we present some recent results on the existence of liftings of projective representations and on the explicit resolution of embedding problems associated to orthogonal Galois representations, and explain how these results can be used to construct modular forms.

Animal Tissue Response To Mid-Term Electronic Modular Artificial Sphincter Implantation

Introduction and objectives: The AMS 800TM is considered the gold standard for sphincter replacement. However, the one-ring design can erode the urethra and lead to severe complications. A mechanism that could alternatively compress successive segments of the urethra would limit such deleterious outcome. We report 12 weeks animal urethral tissue analysis following implantation of a new modular artificial sphincter. METHODS: The device is composed by three parts: the contractile unit, two rings and an integrated microprocessor. The contractile unit is made of Nitinol fibers. The rings are placed around the urethra to control the flow of urine by squeezing the urethra. They work in a sequential alternative mode and are controlled by a microprocessor connected to an external computer. The computer can reveal specific failure of device components. The device was impkanted in eight male sheep. The rings were positioned around the urethra and the control unit was placed 5cm away. The device was working twenty hours per day; it was open 10min. per hour to allow urination. The animals were sacrificed after 12 weeks. The urethra and the tissues surrounding the control unit were macroscopically and microscopically examined. Two transversal sections crossing the sphincter and two transversal sections crossing the urethra alone were obtained and stained with modified Paragon after resin embedding. Urethra was also embedded in paraffin. The first section was stained with safranin-hematoxylin-eosin, the second section was stained with Masson's Trichrome and the remaining eight sections were available for immunolabelling of the macrophages.Results: The chronic study went uneventful. No clinical infection or pain was observed. The computer registered no specific failure in ring function, Nitinol wires and tube connectors. At explantation, except for a slight grade of lymphocytes in two out of eight specimens, no urethral stricture or atrophy could be observed. Immunohistochemistry confirmed the absence of macrophages. Tissue structure and organization of the urethra with and without artificial sphincter were similar. No migration of the device was observed.Conclusions: The study clearly showed no tissue damage or inflammation of the urethra. Electronic design, preservation of urethral vascularisation and adjustability after implantation are the key ideas to improve the actual AUS. Further studies will be carried out to evaluate this potential.

Arithmetical problems in number fields, abelian varieties and modular forms

Number theory, a fascinating area in mathematics and one of the oldest, has experienced spectacular progress in recent years. The development of a deep theoretical background and the implementation of algorithms have led to new and interesting interrelations with mathematics in general which have paved the way for the emergence of major theorems in the area. This report summarizes the contribution to number theory made by the members of the Seminari de Teoria de Nombres (UB-UAB-UPC) in Barcelona. These results are presented in connection with the state of certain arithmetical problems, and so this monograph seeks to provide readers with a glimpse of some specific lines of current mathematical research.

A modular magnetic anastomotic device for minimally invasive digestive anastomosis: proof of concept and preliminary data in the pig model.

BACKGROUND: The aim of our study was to assess the feasibility of minimally invasive digestive anastomosis using a modular flexible magnetic anastomotic device made up of a set of two flexible chains of magnetic elements. The assembly possesses a non-deployed linear configuration which allows it to be introduced through a dedicated small-sized applicator into the bowel where it takes the deployed form. A centering suture allows the mating between the two parts to be controlled in order to include the viscerotomy between the two magnetic rings and the connected viscera. METHODS AND PROCEDURES: Eight pigs were involved in a 2-week survival experimental study. In five colorectal anastomoses, the proximal device was inserted by a percutaneous endoscopic technique, and the colon was divided below the magnet. The distal magnet was delivered transanally to connect with the proximal magnet. In three jejunojejunostomies, the first magnetic chain was injected in its linear configuration through a small enterotomy. Once delivered, the device self-assembled into a ring shape. A second magnet was injected more distally through the same port. The centering sutures were tied together extracorporeally and, using a knot pusher, magnets were connected. Ex vivo strain testing to determine the compression force delivered by the magnetic device, burst pressure of the anastomosis, and histology were performed. RESULTS: Mean operative time including endoscopy was 69.2 ± 21.9 min, and average time to full patency was 5 days for colorectal anastomosis. Operative times for jejunojejunostomies were 125, 80, and 35 min, respectively. The postoperative period was uneventful. Burst pressure of all anastomoses was ≥ 110 mmHg. Mean strain force to detach the devices was 6.1 ± 0.98 and 12.88 ± 1.34 N in colorectal and jejunojejunal connections, respectively. Pathology showed a mild-to-moderate inflammation score. CONCLUSIONS: The modular magnetic system showed enormous potential to create minimally invasive digestive anastomoses, and may represent an alternative to stapled anastomoses, being easy to deliver, effective, and low cost.

Comparative modular analysis of gene expression in vertebrate organs.

ABSTRACT: BACKGROUND: The degree of conservation of gene expression between homologous organs largely remains an open question. Several recent studies reported some evidence in favor of such conservation. Most studies compute organs' similarity across all orthologous genes, whereas the expression level of many genes are not informative about organ specificity. RESULTS: Here, we use a modularization algorithm to overcome this limitation through the identification of inter-species co-modules of organs and genes. We identify such co-modules using mouse and human microarray expression data. They are functionally coherent both in terms of genes and of organs from both organisms. We show that a large proportion of genes belonging to the same co-module are orthologous between mouse and human. Moreover, their zebrafish orthologs also tend to be expressed in the corresponding homologous organs. Notable exceptions to the general pattern of conservation are the testis and the olfactory bulb. Interestingly, some co-modules consist of single organs, while others combine several functionally related organs. For instance, amygdala, cerebral cortex, hypothalamus and spinal cord form a clearly discernible unit of expression, both in mouse and human. CONCLUSIONS: Our study provides a new framework for comparative analysis which will be applicable also to other sets of large-scale phenotypic data collected across different species.

Nickel incorporation in Fe(II, III) hydroxysulfate Green Rust: effect on crystal lattice spacing and oxidation products

Ni(II)-Fe(II)-Fe(III) layered double hydroxides (LDH) or Ni-containing sulfate green rust (GR2) samples were prepared from Ni(II), Fe(II) and Fe(III) sulfate salts and analyzed with X ray diffraction. Nickel is readily incorporated in the GR2 structure and forms a solid solution between GR2 and a Ni(II)-Fe(III) LDH. There is a correlation between the unit cell a-value and the fraction of Ni(II) incorporated into the Ni(II)-GR2 structure. Since there is strong evidence that the divalent/trivalent cation ratio in GR2 is fixed at 2, it is possible in principle to determine the extent of divalent cation substitution for Fe(II) in GR2 from the unit cell a-value. Oxidation forms a mixture of minerals but the LDH structure is retained if at least 20 % of the divalent cations in the initial solution are Ni(II). It appears that Ni(II) is incorporated in a stable LDH structure. This may be important for two reasons, first for understanding the formation of LDHs, which are anion exchangers, in the natural environment. Secondly, this is important for understanding the fate of transition metals in the environment, particularly in the presence of reduced Fe compounds.

Occupational respiratory exposures to irritating and sensitizing volatile compounds deriving from cleaning products

Recent findings suggest an association between exposure to cleaning products and respiratory dysfunctions including asthma. However, little information is available about quantitative airborne exposures of professional cleaners to volatile organic compounds deriving from cleaning products. During the first phases of the study, a systematic review of cleaning products was performed. Safety data sheets were reviewed to assess the most frequently added volatile organic compounds. It was found that professional cleaning products are complex mixtures of different components (compounds in cleaning products: 3.5 ± 2.8), and more than 130 chemical substances listed in the safety data sheets were identified in 105 products. The main groups of chemicals were fragrances, glycol ethers, surfactants, solvents; and to a lesser extent phosphates, salts, detergents, pH-stabilizers, acids, and bases. Up to 75% of products contained irritant (Xi), 64% harmful (Xn) and 28% corrosive (C) labeled substances. Hazards for eyes (59%), skin (50%) and by ingestion (60%) were the most reported. Monoethanolamine, a strong irritant and known to be involved in sensitizing mechanisms as well as allergic reactions, is frequently added to cleaning products. Monoethanolamine determination in air has traditionally been difficult and air sampling and analysis methods available were little adapted for personal occupational air concentration assessments. A convenient method was developed with air sampling on impregnated glass fiber filters followed by one step desorption, gas chromatography and nitrogen phosphorous selective detection. An exposure assessment was conducted in the cleaning sector, to determine airborne concentrations of monoethanolamine, glycol ethers, and benzyl alcohol during different cleaning tasks performed by professional cleaning workers in different companies, and to determine background air concentrations of formaldehyde, a known indoor air contaminant. The occupational exposure study was carried out in 12 cleaning companies, and personal air samples were collected for monoethanolamine (n=68), glycol ethers (n=79), benzyl alcohol (n=15) and formaldehyde (n=45). All but ethylene glycol mono-n-butyl ether air concentrations measured were far below (<1/10) of the Swiss eight hours occupational exposure limits, except for butoxypropanol and benzyl alcohol, where no occupational exposure limits were available. Although only detected once, ethylene glycol mono-n-butyl ether air concentrations (n=4) were high (49.5 mg/m3 to 58.7 mg/m3), hovering at the Swiss occupational exposure limit (49 mg/m3). Background air concentrations showed no presence of monoethanolamine, while the glycol ethers were often present, and formaldehyde was universally detected. Exposures were influenced by the amount of monoethanolamine in the cleaning product, cross ventilation and spraying. The collected data was used to test an already existing exposure modeling tool during the last phases of the study. The exposure estimation of the so called Bayesian tool converged with the measured range of exposure the more air concentrations of measured exposure were added. This was best described by an inverse 2nd order equation. The results suggest that the Bayesian tool is not adapted to predict low exposures. The Bayesian tool should be tested also with other datasets describing higher exposures. Low exposures to different chemical sensitizers and irritants should be further investigated to better understand the development of respiratory disorders in cleaning workers. Prevention measures should especially focus on incorrect use of cleaning products, to avoid high air concentrations at the exposure limits. - De récentes études montrent l'existence d'un lien entre l'exposition aux produits de nettoyages et les maladies respiratoires telles que l'asthme. En revanche, encore peu d'informations sont disponibles concernant la quantité d'exposition des professionnels du secteur du nettoyage aux composants organiques volatiles provenant des produits qu'ils utilisent. Pendant la première phase de cette étude, un recueil systématique des produits professionnels utilisés dans le secteur du nettoyage a été effectué. Les fiches de données de sécurité de ces produits ont ensuite été analysées, afin de répertorier les composés organiques volatiles les plus souvent utilisés. Il a été mis en évidence que les produits de nettoyage professionnels sont des mélanges complexes de composants chimiques (composants chimiques dans les produits de nettoyage : 3.5 ± 2.8). Ainsi, plus de 130 substances listées dans les fiches de données de sécurité ont été retrouvées dans les 105 produits répertoriés. Les principales classes de substances chimiques identifiées étaient les parfums, les éthers de glycol, les agents de surface et les solvants; dans une moindre mesure, les phosphates, les sels, les détergents, les régulateurs de pH, les acides et les bases ont été identifiés. Plus de 75% des produits répertoriés contenaient des substances décrites comme irritantes (Xi), 64% nuisibles (Xn) et 28% corrosives (C). Les risques pour les yeux (59%), la peau (50%) et par ingestion (60%) était les plus mentionnés. La monoéthanolamine, un fort irritant connu pour être impliqué dans les mécanismes de sensibilisation tels que les réactions allergiques, est fréquemment ajouté aux produits de nettoyage. L'analyse de la monoéthanolamine dans l'air a été habituellement difficile et les échantillons d'air ainsi que les méthodes d'analyse déjà disponibles étaient peu adaptées à l'évaluation de la concentration individuelle d'air aux postes de travail. Une nouvelle méthode plus efficace a donc été développée en captant les échantillons d'air sur des filtres de fibre de verre imprégnés, suivi par une étape de désorption, puis une Chromatographie des gaz et enfin une détection sélective des composants d'azote. Une évaluation de l'exposition des professionnels a été réalisée dans le secteur du nettoyage afin de déterminer la concentration atmosphérique en monoéthanolamine, en éthers de glycol et en alcool benzylique au cours des différentes tâches de nettoyage effectuées par les professionnels du nettoyage dans différentes entreprises, ainsi que pour déterminer les concentrations atmosphériques de fond en formaldéhyde, un polluant de l'air intérieur bien connu. L'étude de l'exposition professionnelle a été effectuée dans 12 compagnies de nettoyage et les échantillons d'air individuels ont été collectés pour l'éthanolamine (n=68), les éthers de glycol (n=79), l'alcool benzylique (n=15) et le formaldéhyde (n=45). Toutes les substances mesurées dans l'air, excepté le 2-butoxyéthanol, étaient en-dessous (<1/10) de la valeur moyenne d'exposition aux postes de travail en Suisse (8 heures), excepté pour le butoxypropanol et l'alcool benzylique, pour lesquels aucune valeur limite d'exposition n'était disponible. Bien que détecté qu'une seule fois, les concentrations d'air de 2-butoxyéthanol (n=4) étaient élevées (49,5 mg/m3 à 58,7 mg/m3), se situant au-dessus de la frontière des valeurs limites d'exposition aux postes de travail en Suisse (49 mg/m3). Les concentrations d'air de fond n'ont montré aucune présence de monoéthanolamine, alors que les éthers de glycol étaient souvent présents et les formaldéhydes quasiment toujours détectés. L'exposition des professionnels a été influencée par la quantité de monoéthanolamine présente dans les produits de nettoyage utilisés, par la ventilation extérieure et par l'emploie de sprays. Durant la dernière phase de l'étude, les informations collectées ont été utilisées pour tester un outil de modélisation de l'exposition déjà existant, l'outil de Bayesian. L'estimation de l'exposition de cet outil convergeait avec l'exposition mesurée. Cela a été le mieux décrit par une équation du second degré inversée. Les résultats suggèrent que l'outil de Bayesian n'est pas adapté pour mettre en évidence les taux d'expositions faibles. Cet outil devrait également être testé avec d'autres ensembles de données décrivant des taux d'expositions plus élevés. L'exposition répétée à des substances chimiques ayant des propriétés irritatives et sensibilisantes devrait être investiguée d'avantage, afin de mieux comprendre l'apparition de maladies respiratoires chez les professionnels du nettoyage. Des mesures de prévention devraient tout particulièrement être orientées sur l'utilisation correcte des produits de nettoyage, afin d'éviter les concentrations d'air élevées se situant à la valeur limite d'exposition acceptée.

Extractants to assess zinc phytoavailability in mineral fertilizer and industrial by-products

Efficient analytical methods for the quantification of plant-available Zn contained in mineral fertilizers and industrial by-products are fundamental for the control and marketing of these inputs. In this sense, there are some doubts on the part of the scientific community as well as of the fertilizer production sector, whether the extractor requested by the government (Normative Instruction No. 28, called 2nd extractor), which is citric acid 2 % (2 % CA) (Brasil, 2007b), is effective in predicting the plant availability of Zn via mineral fertilizers and about the agronomic significance of the required minimal solubility of 60 % compared to the total content (HCl) (Brasil, 2007a). The purpose of this study was to evaluate the alternative extractors DTPA, EDTA, neutral ammonium citrate (NAC), buffer solution pH 6.0, 10 % HCl, 10 % sulfuric acid, 1 % acetic acid, water, and hot water to quantify the contents of Zn available for maize and compare them with indices of agronomic efficiency of fertilizers and industrial by-products when applied to dystrophic Clayey Red Latosol and Dystrophic Alic Red Yellow Latosol with medium texture. The rate of Zn applied to the soil was 5 mg kg-1, using the sources zinc sulfate, commercial granular zinc, ash and galvanic sludge, ash and two brass slags. Most Zn was extracted from the sources by DTPA, 10 % HCl, NAC, 1% acetic acid, and 10 % sulfuric acid. Recovery by the extractors 2 % CA, EDTA, water, and hot water was low. The agronomic efficiency index was found to be high when using galvanic sludge (238 %) and commercial granular zinc (142 %) and lower with brass slag I and II (67 and 27 %, respectively). The sources galvanizing ash and brass ash showed solubility lower than 60 % in 2 % CA, despite agronomic efficiency indices of 78 and 125 %, respectively. The low agronomic efficiency index of industrial by-products such as brass slag I and galvanizing ash can be compensated by higher doses, provided there is no restriction, as well as for all other sources, in terms of contaminant levels of arsenic, cadmium, chromium, lead, and mercury as required by law (Normative Instruction No 27/2006). The implementation of 2nd extractor 2 % CA and the requirement of minimum solubility for industrial by-products could restrict the use of alternative sources as potential Zn sources for plants.

Analysis of the role of mobility-lifetime products in the performance of amorphous silicon p-i-n solar cells

An analytical model of an amorphous silicon p-i-n solar cell is presented to describe its photovoltaic behavior under short-circuit conditions. It has been developed from the analysis of numerical simulation results. These results reproduce the experimental illumination dependence of short-circuit resistance, which is the reciprocal slope of the I(V) curve at the short-circuit point. The recombination rate profiles show that recombination in the regions of charged defects near the p-i and i-n interfaces should not be overlooked. Based on the interpretation of the numerical solutions, we deduce analytical expressions for the recombination current and short-circuit resistance. These expressions are given as a function of an effective ¿¿ product, which depends on the intensity of illumination. We also study the effect of surface recombination with simple expressions that describe its influence on current loss and short-circuit resistance.

PHYTOAVAILABILITY OF COPPER IN INDUSTRIAL BY-PRODUCTS AND MINERAL FERTILIZERS

Alternative copper (Cu) sources could be used in fertilizer production, although the bioavailability of copper in these materials is unknown. The objective of this study was to evaluate the extractants neutral ammonium citrate (NAC), 2 % citric acid, 1 % acetic acid, 10 % HCl, 10 % H2SO4, buffer solution pH 6.0, DTPA, EDTA, water, and hot water in the quantification of available Cu content in several sources, relating them to the relative agronomic efficiency (RAE) of wheat grown in a clayey Latossolo Vermelho eutrófico (Oxisol) and Neossolo Quartzarênico (Typic Quartzipsamment). Copper was applied at the rate of 1.5 mg kg-1 as scrap slag, brass slag, Cu ore, granulated copper, and copper sulfate. The extractants 10 % HCl, 10 % H2SO4, and NAC extracted higher Cu concentrations. The RAE values of brass slag and Cu ore were similar to or higher than those of Cu sulfate and granulated Cu. Solubility in the 2nd NAC extractant, officially required for mineral fertilizers with Cu, was lower than 60 % for the scrap slag, Cu ore, and granulated copper sources. This fact indicates that adoption of the NAC extractant may be ineffective for industrial by-products, although no extractant was more efficient in predicting Cu availability for wheat fertilized with the Cu sources tested.