1,845 research outputs found
Homological Epimorphisms and Hochschild-Mitchell Cohomology
In this work, we study the Hochschild-Mitchell Cohomology of triangular
matrix categories. Given a triangular matrix category , we investigate the relationship of the
Hochschild-Mitchell cohomologies and of
and respectively; and we show that they can be
connected by a long exact sequence. This result extend the well-known result of
Michelana-Platzeck given in [S. Michelena, M. I. Platzeck. {\it{Hochschild
cohomology of triangular matrix algebras}}. J. Algebra 233, (2000) 502-525].Comment: In this new version, the title of the article has been changed and a
new section has been adde
Evidence of microhabitat overlap between juvenile of introduced salmon Oncorhynchus tshawytscha and the native fish Trichomycterus areolatus in the Allipén River, Chile
Juveniles del salmón Chinook (Oncorhynchus tshawytscha) introducido en el sur de Chile han sido observados co-ocurriendo con peces nativos en el río Allipén, Chile. Con objeto de identificar las potenciales implicancias ecológicas de esta invasión sobre la fauna íctica nativa, durante el verano y otoño de los años 2007-2008, se determinaron las
preferencias y grado de solapamiento de microhábitat entre el salmón Chinook y el pez nativo bagre, Trichomycterus areolatus. Las preferencias y grado de solapamiento de microhábitat entre el salmón Chinook y el bagre se determinaron utilizando el método incremental para la asignación de caudales mínimos y el índice Pianka. En ambas especies, las preferencias de microhábitat variaron estacionalmente mostrando además un alto grado de similitud y solapamiento
(mayor al 80%). Los resultados obtenidos sugieren una potencial interacción negativa entre el salmón Chinook y el bagre a través de una segregación interactiva por hábitat. De este modo, el actual proceso de invasión del salmón Chinook en el sur de Chile representaría una amenaza para la estabilidad de las poblaciones de bagre en el río Allipén
Emergence of a small-scale magnetic flux tube and the response of the solar atmosphere
Cutting-edge observations with the 1.6-meter telescope at Big Bear Solar Observatory (BBSO) in California have
taken research into the activity of the Sun to new levels of understanding of the structure and evolution of the
solar atmosphere at high-resolution spatial and temporal scales. On August 7, 2013 the NST observed active region
NOAA 11810 in photospheric and chromospheric wavelengths. The observations were performed as part of a program
conducted jointly with NASA\u27s Interface Region Imaging Spectrograph (IRIS) mission, Solar Dynamics Observatory (SDO)
and Hinode satellite. These observations provided a unique view on the emergence of a buoyant small-scale magnetic-flux
rope in the solar photosphere. The event is accompanied by response of the solar atmosphere once the newly emerged field
interacts with the pre-existing overlying one. The reconnection process that takes place in the region produces jet
emission and high-temperature points in the chromosphere and corona
Taxa de aplicação máxima anual de lodo de esgoto higienizado pelo processo de estabilização alcalina: estudo comparativo de curvas de pH de solos
Objetivou-se avaliar a taxa de aplicação máxima anual de lodo de esgoto higienizado porprocesso de estabilização alcalina prolongada (EAP) em dois solos da RegiãoMetropolitana de Curitiba (Lapa e Pinhais). Obteve-se curvas de neutralização do pH,incubando-se os solos com doses crescentes de dois dos três corretivos de acidezutilizados: dois lodos EAP (obtido em condições controladas e da estação) e um calcário.Concluiu-se que três toneladas de lodo EAP higienizado sob condições controladas foiequivalente a uma tonelada de calcário; houve interação entre lodo e tipo de solo, sendoa capacidade tampão dos solos importante para determinação da taxa de aplicaçãomáxima anual
Healthcare Worker Occupation and Immune Response to Pneumocystis jirovecii
Humans may be a reservoir for this pathogen and transmit it from person to person
Potential of Native Microalgae from the Peruvian Amazon on the Removal of Pollutants
Environmental pollution is a severe and common problem in all the countries worldwide. Various physicochemical technologies and organisms (e.g., plants, microorganisms, etc.) are used to address these environmental issues, but low-cost, practical, efficient, and effective approaches have not been available yet. Microalgae offer an attractive, novel, and little-explored bioremediation alternative because these photosynthetic organisms can eliminate pathogenic microorganisms and remove heavy metals and toxic organic compounds through processes still under study. Our research team has conducted some experiments to determine the bioremediation potential of native microalgae on some pollutant sources (i.e., leachate and wastewater) and its ability to remove hazardous chemical compounds. Therefore, in this chapter, we provide the results of our research and updated information about this exciting topic. Experiments were conducted under controlled culture conditions using several native microalgae species, variable time periods, different pollutant sources, and hazardous chemicals such as ethidium bromide. The results indicated that native microalgae can remove pollutants (i.e., phosphorus, ammonia, etc.) of wastewater, leachate, and some hazardous chemical compounds such as ethidium bromide. In conclusion, native microalgae have an excellent potential for removing several pollutants and, consequently, could be used to develop bioremediation technologies based on native microalgae from the Peruvian Amazon
Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis
BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London
Environmental regulation of carbon isotope composition and crassulacean acid metabolism in three plant communities along a water availability gradient
Expression of crassulacean acid metabolism (CAM) is characterized by extreme variability within and between taxa and its sensitivity to environmental variation. In this study, we determined seasonal fluctuations in CAM photosynthesis with measurements of nocturnal tissue acidification and carbon isotopic composition (δ13C) of bulk tissue and extracted sugars in three plant communities along a precipitation gradient (500, 700, and 1,000 mm year−1) on the Yucatan Peninsula. We also related the degree of CAM to light habitat and relative abundance of species in the three sites. For all species, the greatest tissue acid accumulation occurred during the rainy season. In the 500 mm site, tissue acidification was greater for the species growing at 30% of daily total photon flux density (PFD) than species growing at 80% PFD. Whereas in the two wetter sites, the species growing at 80% total PFD had greater tissue acidification. All species had values of bulk tissue δ13C less negative than −20‰, indicating strong CAM activity. The bulk tissue δ13C values in plants from the 500 mm site were 2‰ less negative than in plants from the wetter sites, and the only species growing in the three communities, Acanthocereus tetragonus (Cactaceae), showed a significant negative relationship between both bulk tissue and sugar δ13C values and annual rainfall, consistent with greater CO2 assimilation through the CAM pathway with decreasing water availability. Overall, variation in the use of CAM photosynthesis was related to water and light availability and CAM appeared to be more ecologically important in the tropical dry forests than in the coastal dune
The CARMENES search for exoplanets around M dwarfs High-resolution optical and near-infrared spectroscopy of 324 survey stars
The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520–1710 nm at a resolution of at least R >80 000, and we measure its RV, Hα emission, and projected rotation velocity. We present an atlas of high-resolution M-dwarf spectra and compare the spectra to atmospheric models. To quantify the RV precision that can be achieved in low-mass stars over the CARMENES wavelength range, we analyze our empirical information on the RV precision from more than 6500 observations. We compare our high-resolution M-dwarf spectra to atmospheric models where we determine the spectroscopic RV information content, Q, and signal-to-noise ratio. We find that for all M-type dwarfs, the highest RV precision can be reached in the wavelength range 700–900 nm. Observations at longer wavelengths are equally precise only at the very latest spectral types (M8 and M9). We demonstrate that in this spectroscopic range, the large amount of absorption features compensates for the intrinsic faintness of an M7 star. To reach an RV precision of 1 m s−1 in very low mass M dwarfs at longer wavelengths likely requires the use of a 10 m class telescope. For spectral types M6 and earlier, the combination of a red visual and a near-infrared spectrograph is ideal to search for low-mass planets and to distinguish between planets and stellar variability. At a 4 m class telescope, an instrument like CARMENES has the potential to push the RV precision well below the typical jitter level of 3–4 m s−1
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