Hexagonal Tilings: Tutte Uniqueness

We develop the necessary machinery in order to prove that hexagonal tilings are uniquely determined by their Tutte polynomial, showing as an example how to apply this technique to the toroidal hexagonal tiling.Comment: 12 figure

Hexagonal Tilings and Locally C6 Graphs

We give a complete classification of hexagonal tilings and locally C6 graphs, by showing that each of them has a natural embedding in the torus or in the Klein bottle. We also show that locally grid graphs are minors of hexagonal tilings (and by duality of locally C6 graphs) by contraction of a perfect matching and deletion of the resulting parallel edges, in a form suitable for the study of their Tutte uniqueness.Comment: 14 figure

Mortalidad atribuible al alcohol en Cataluña y sus provincias

ObjetivoEstimar la contribución del consumo de alcohol en la mortalidad de Cataluña en 1997, su impacto sobre la mortalidad prematura y evaluar si existen diferencias entre provincias.DiseñoEstudio ecológico, descriptivo.EmplazamientoCataluña.PacientesDefunciones de residentes en Cataluña en 1997 por una causa relacionada con el consumo excesivo de alcohol.Mediciones y resultados principalesLos datos de las causas de muerte en Cataluña en 1997 fueron facilitados por el Registre de Mortalitat de Catalunya y se usaron las fracciones poblacionales atribuibles al alcohol recomendadas por los Centers for Disease Control de Estados Unidos en 1987. Se estimó la mortalidad atribuible al alcohol (MAA) y los años potenciales de vida perdidos (APVP) para el conjunto de Cataluña y desagregada por provincias.Un 4,8% de la mortalidad de Cataluña en 1997 estuvo relacionada con el consumo excesivo de alcohol. La mortalidad fue más elevada en varones (6,0%) que en mujeres (3,5%). Por grupos diagnósticos, las neoplasias malignas (29,9%) contribuyeron con un mayor número de MAA, mientras que los accidentes no intencionales presentaron la mayor mortalidad prematura (50,9%). Por causa específica, el mayor número de APVP correspondió a los accidentes de vehículos a motor. Por provincias, se observó mayor MAA por accidentes no intencionales en todas las provincias respecto a Barcelona y menor riesgo de muerte por enfermedades digestivas.ConclusiónEste estudio pone de manifiesto la importante implicación del alcohol en la mortalidad, así como su contribución en la mortalidad prematura y la existencia de importantes diferencias según la provincia de residencia, especialmente para accidentes no intencionales.ObjectivesTo calculate the contribution of alcohol consumption to mortality in Catalonia in 1997, and its impact on premature mortality. To evaluate whether inter-provincial differences exist.DesignDescriptive ecological study.SettingCatalonia.PatientsDeaths of residents of Catalonia in 1997 for a cause related to excess alcohol consumption.Measurements and main resultsThe data on the causes of death in Catalonia in 1997 were provided by the Catalonia Death Register. The population fractions attributable to alcohol used were those recommended by the United States Centers for Disease Control in 1987. Mortality attributable to alcohol and the potential years of life lost were calculated for Catalonia as a whole and province by province. 4.8% of mortality in Catalonia in 1997 was related to excessive alcohol consumption. Mortality was higher in men (6.0%) than in women (3.5%). By diagnostic groups, malignant neoplasms (29.9%) contributed to the greatest number of deaths attributable to alcohol, whereas non-intentional accidents was the greatest cause of premature death (50.9%). As a specific cause, the greatest number of potential years of life lost was due to motor vehicle accidents. The highest mortality rate due to alcohol in non-intentional accidents and the lowest risk of death from digestive diseases were in all the provinces rather than in Barcelona.ConclusionThis study highlighted the importance of alcohol in the mortality figures, its contribution to premature death and the existence of major differences depending on the province of residence, especially in non-intentional accidents

Origin of the Rubian carbonate-hosted magnesite deposit, Galicia, NW Spain: mineralogical, REE, fluid inclusion and isotope evidence)

The Rubian magnesite deposit (West Asturian—Leonese Zone, Iberian Variscan belt) is hosted by a 100-m-thick folded and metamorphosed Lower Cambrian carbonate/siliciclastic metasedimentary sequence—the Cándana Limestone Formation. It comprises upper (20-m thickness) and lower (17-m thickness) lens-shaped ore bodies separated by 55 m of slates and micaceous schists. The main (lower) magnesite ore body comprises a package of magnesite beds with dolomite-rich intercalations, sandwiched between slates and micaceous schists. In the upper ore body, the magnesite beds are thinner (centimetre scale mainly) and occur between slate beds. Mafic dolerite dykes intrude the mineralisation. The mineralisation passes eastwards into sequence of bedded dolostone (Buxan) and laminated to banded calcitic marble (Mao). These show significant Variscan extensional shearing or fold-related deformation, whereas neither Rubian dolomite nor magnesite show evidence of tectonic disturbance. This suggests that the dolomitisation and magnesite formation postdate the main Variscan deformation. In addition, the morphology of magnesite crystals and primary fluid inclusions indicate that magnesite is a neoformed hydrothermal mineral. Magnesite contains irregularly distributed dolomite inclusions (<50 μm) and these are interpreted as relics of a metasomatically replaced dolostone precursor. The total rare earth element (REE) contents of magnesite are verysimilar to those of Buxan dolostone but are depleted in light rare earth elements (LREE); heavy rare earth element concentrations are comparable. However, magnesite REE chondrite normalised profiles lack any characteristic anomaly indicative of marine environment. Compared with Mao calcite, magnesite is distinct in terms of both REE concentrations and patterns. Fluid inclusion studies show that the mineralising fluids were MgCl2–NaCl–CaCl2–H2O aqueous brines exhibiting highly variable salinities (3.3 to 29.5 wt.% salts). This may be the result of a combination of fluid mixing, migration of pulses of variable-salinity brines and/or local dissolution and replacement processes of the host dolostone. Fluid inclusion data and comparison with other N Iberian dolostone-hosted metasomatic deposits suggest that Rubian magnesite probably formed at temperatures between 160 and 200°C. This corresponds, at hydrostatic pressure (500 bar), to a depth of formation of ∼5 km. Mineralisation- related Rubian dolomite yields δ18O values (δ18O: 12.0–15.4‰, mean: 14.4±1.1‰) depleted by around 5‰ compared with barren Buxan dolomite (δ18O: 17.1– 20.2‰, mean: 19.4±1.0‰). This was interpreted to reflect an influx of 18O-depleted waters accompanied by a temperature increase in a fluid-dominated system. Overlapping calculated δ18Ofluid values (∼+5‰ at 200°C) for fluids in equilibrium with Rubian dolomite and magnesite show that they were formed by the same hydrothermal system at different temperatures. In terms of δ13C values, Rubian dolomite (δ13C: −1.4 to 1.9‰, mean: 0.4±1.3‰) and magnesite (δ13C: −2.3 to 2.4‰, mean: 0.60±1.0‰) generally exhibit more negative δ13C values compared with Buxan dolomite (δ13C: −0.2 to 1.9‰, mean: 0.8± 0.6‰) and Mao calcite (δ13C: −0.3 to 1.5‰, mean: 0.6± 0.6‰), indicating progressive odification to lower δ13C values through interaction with hydrothermal fluids. 87Sr/86Sr ratios, calculated at 290 Ma, vary from 0.70849 to 0.70976 for the Mao calcite and from 0.70538 to 0.70880 for the Buxan dolostone. The 87Sr/86Sr ratios in Rubian magnesite are more radiogenic and range from 0.71123 to 0.71494. The combined δ18O–δ13C and 87Sr/86Sr data indicate that the magnesite-related fluids were modified basinal brines that have reacted and equilibrated with intercalated siliciclastic rocks. Magnesite formation is genetically linked to regional hydrothermal dolomitisation associated with lithospheric delamination, late-Variscan high heat flow and extensional tectonics in the NW Iberian Belt. A comparison with genetic models for the Puebla de Lillo talc deposits suggests that the formation of hydrothermal replacive magnesite at Rubian resulted from a metasomatic column with magnesite forming at higher fluid/rock ratios than dolomite. In this study, magnesite generation took place via the local reaction of hydrothermal dolostone with the same hydrothermal fluids in very high permeability zones at high fluid/rock ratios (e.g. faults). It was also possibly aided by additional heat from intrusive dykes or sub-cropping igneous bodies. This would locally raise isotherms enabling a transition from the dolomite stability field to that of magnesite

Mutual optical injection in coupled DBR laser pairs

We report an experimental study of nonlinear effects, characteristic of mutual optical coupling, in an ultra-short coupling regime observed in a distributed Bragg reflector laser pair fabricated on the same chip. Optical feedback is amplified via a double pass through a common onchip optical amplifier, which introduces further nonlinear phenomena. Optical coupling has been introduced via back reflection from a cleaveended fibre. The coupling may be varied in strength by varying the distance of the fibre from the output of the chip, without significantly affecting the coupling time. © 2008 Optical. Society of America

Unprecedented pathway of reducing equivalents in a diflavin-linked disulfide oxidoreductase

Flavoproteins participate in a wide variety of physiologically relevant processes that typically involve redox reactions. Within this protein superfamily, there exists a group that is able to transfer reducing equivalents from FAD to a redox-active disulfide bridge, which further reduces disulfide bridges in target proteins to regulate their structure and function. We have identified a previously undescribed type of flavin enzyme that is exclusive to oxygenic photosynthetic prokaryotes and that is based on the primary sequence that had been assigned as an NADPH-dependent thioredoxin reductase (NTR). However, our experimental data show that the protein does not transfer reducing equivalents from flavins to disulfides as in NTRs but functions in the opposite direction. High-resolution structures of the protein from Gloeobacter violaceus and Synechocystis sp. PCC6803 obtained by X-ray crystallography showed two juxtaposed FAD molecules per monomer in redox communication with an active disulfide bridge in a variant of the fold adopted by NTRs. We have tentatively named the flavoprotein “DDOR” (diflavin-linked disulfide oxidoreductase) and propose that its activity is linked to a thiol-based transfer of reducing equivalents in bacterial membranes. These findings expand the structural and mechanistic repertoire of flavoenzymes with oxidoreductase activity and pave the way to explore new protein engineering approaches aimed at designing redox-active proteins for diverse biotechnological applications

Cerebral state index during propofol anesthesia:A Comparison with the Bispectral Index and the A-Line ARX Index

Background: The objective of this study was to prospectively test the Cerebral State Index designed for measuring the depth of anesthesia. The Cerebral State Index is calculated using a fuzzy logic combination of four subparameters of the electroencephalographic signal. The performance of the Cerebral State index was compared with that of the Bispectral Index and the A-Line ARX Index. Methods: This study applied raw data from two previously published clinical protocols. The patients in protocol 1 were given a continuous propofol infusion, 300 ml/h, until 80% of burst suppression occurred. In protocol 2, a stepwise increased target-controlled infusion of propofol was administered to patients until loss of response to noxious stimuli while the Observer's Assessment of Alertness and Sedation was registered every 4 min. The Cerebral State index was calculated off-line from the recorded electroencephalographic data. The Spearman rank correlation coefficient between electronic indices and the effect site concentration of propofol was calculated along with the prediction probability of each index to predict the Observer's Assessment of Alertness and Sedation level. Results: The Spearman rank correlation coefficients between the Cerebral State Index, Bispectral Index, and A-Line ARX Index and the propofol effect site concentration were -0.94, -0.89, and -0.82, respectively, in protocol 1, whereas the prediction probability values between the Cerebral State Index, Bispectral Index, and A-Line ARX Index and the Observer's Assessment of Alertness and Sedation score in protocol 2 were 0.92, 0.93, and 0.91, respectively. Conclusion: The Cerebral State Index detects well the graduated levels of propofol anesthesia when compared with the propofol effect site concentration and the Observer's Assessment of Alertness and Sedation score

Stability of schizophrenia diagnosis in a ten-year longitudinal study on first episode of non-affective psychosis: conclusions from the PAFIP cohort

OBJECTIVE: To evaluate the ten-year stability of schizophrenia diagnosis in a cohort of first-episode psychosis (FEP) patients and the factors associated with it. METHODS: Changes in diagnosis of 209 FEP patients were described during ten years of follow-up. Related factors with maintenance or change of schizophrenia diagnosis were evaluated in prospective and retrospective approaches through Binary Logistic Regressions, ROC and survival curves. RESULTS: Out of the 209 patients, 126 were diagnosed of schizophrenia six months after their inclusion in the clinical program. Prospective analyses showed that eight of those 126 schizophrenia patients had changed to a different diagnosis after ten years, and predictors of change were better childhood premorbid adjustment, less severity of clinical global impression at baseline, and diagnosis of comorbid personality disorder during follow-up. Retrospectively, out of the 154 patients with schizophrenia in the ten-year assessment, 36 had a different diagnosis at baseline, and those factors related with a different prior diagnosis than schizophrenia were better socioeconomic status and shorter duration of untreated psychosis (DUP). A survival analysis on the timing of schizophrenia diagnosis showed that male gender and longer DUP were predictors of earlier definite diagnosis. CONCLUSIONS: Diagnostic stability of schizophrenia in our FEP sample is high, especially prospective stability, and the group of patients with diagnostic change corresponded to a milder psychopathological profile before and at the onset of disease. Moreover, we observed a cautious attitude in the diagnosis of schizophrenia in patients with shorter DUP who had schizophrenia diagnosis after ten years