43,250 research outputs found
Quantification of the effects of ocean acidification on sediment microbial communities in the environment: the importance of ecosystem approaches
No full textTo understand how ocean acidification (OA) influences sediment microbial communities, naturally CO2-rich sites are increasingly being used as OA analogues. However, the characterization of these naturally CO2-rich sites is often limited to OA-related variables, neglecting additional environmental variables that may confound OA effects. Here, we used an extensive array of sediment and bottom water parameters to evaluate pH effects on sediment microbial communities at hydrothermal CO2seeps in Papua New Guinea. The geochemical composition of the sediment pore water showed variations in the hydrothermal signature at seep sites with comparable pH, allowing the identification of sites that may better represent future OA scenarios. At these sites, we detected a 60% shift in the microbial community composition compared with reference sites, mostly related to increases inChloroflexisequences. pH was among the factors significantly, yet not mainly, explaining changes in microbial community composition. pH variation may therefore often not be the primary cause of microbial changes when sampling is done along complex environmental gradients. Thus, we recommend an ecosystem approach when assessing OA effects on sediment microbial communities under natural conditions. This will enable a more reliable quantification of OA effects via a reduction of potential confounding effect
The evolution of bacterial genome assemblies - where do we need to go next?
No full textAltermann E, Tegetmeyer H, Chanyi RM. The evolution of bacterial genome assemblies - where do we need to go next? Microbiome Research Reports. 2022;1(3): 15.Genome sequencing has fundamentally changed our ability to decipher and understand the genetic blueprint of life and how it changes over time in response to environmental and evolutionary pressures. The pace of sequencing is still increasing in response to advances in technologies, paving the way from sequenced genes to genomes to metagenomes to metagenome-assembled genomes (MAGs). Our ability to interrogate increasingly complex microbial communities through metagenomes and MAGs is opening up a tantalizing future where we may be able to delve deeper into the mechanisms and genetic responses emerging over time. In the near future, we will be able to detect MAG assembly variations within strains originating from diverging sub-populations, and one of the emerging challenges will be to capture these variations in a biologically relevant way. Here, we present a brief overview of sequencing technologies and the current state of metagenome assemblies to suggest the need to develop new data formats that can capture the genetic variations within strains and communities, which previously remained invisible due to sequencing technology limitations. © The Author(s) 2022
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
On site analysis of bacterial communities of the ultra-oligotrophic South Pacific Gyre.
No full textReintjes G, Tegetmeyer H, Burgisser M, et al. On site analysis of bacterial communities of the ultra-oligotrophic South Pacific Gyre. Applied and environmental microbiology. 2019;85(14): UNSP e00184-19.The South Pacific Gyre (SPG) covers 10% of the ocean's surface and is often regarded as a marine biological desert. To gain an on-site overview of the remote, ultra-oligotrophic microbial community of the SPG we developed a novel on-board analysis pipeline, which combines next-generation sequencing with fluorescence in situ hybridisation and automated cell enumeration. We tested the pipeline during the SO245 "UltraPac" cruise from Chile to New Zealand and found that the overall microbial community of the SPG was highly similar to that of other oceanic gyres. The SPG was dominated by 20 major bacterial clades, including SAR11, SAR116, AEGEAN-169 marine group, SAR86, Prochlorococcus, SAR324, SAR406, and SAR202. Most of the bacterial clades showed a strong vertical (20 m - 5000 m), but only a weak longitudinal (80°W - 160°W), distribution pattern. Surprisingly, in the central gyre Prochlorococcus, the dominant photosynthetic organism, had only low cellular abundances in the upper waters (20 - 80 m) and were more frequent around the 1% irradiance zone (100 - 150 m). Instead, the surface waters of the central gyre were dominated by SAR11, SAR86, and SAR116 clades known to harbour light-driven proton pumps. The alphaproteobacterial AEGEAN-169 marine-group was particularly abundant in the surface waters of the central gyre indicating a potentially interesting adaptation to ultraoligotrophic waters and high solar irradiance. In the future, the newly developed community analysis pipeline will allow for on-site insights into a microbial community within 35 hours of sampling, which will permit more targeted sampling efforts and hypothesis-driven research.ImportanceThe South Pacific Gyre is due to its vast size and remoteness one of the least studied oceanic regions on earth. However, both remote sensing and in situ measurements indicated that the activity of its microbial community contributes significantly to global biogeochemical cycles. Presented here is an unparalleled investigation of the microbial community of the SPG from 20 - 5000 m depth covering a geographic distance of 7000 km. This insight was achieved through the development of a novel on-board analysis pipeline, which combines next-generation sequencing with fluorescence in situ hybridisation and automated cell enumeration. The pipeline is well comparable to on-shore systems based on the Illumina platforms and yields microbial community data in less than 35 hours after sampling. Going forward the ability to gain on-site knowledge of a remote microbial community will permit hypothesis-driven research, through the generation of novel scientific questions and subsequent additional targeted sampling efforts. Copyright © 2019 American Society for Microbiology
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Control and Filtering for Discrete Linear Repetitive Processes with H infty and ell 2--ell infty Performance
No full textRepetitive processes are characterized by a series of sweeps, termed passes, through a set of dynamics defined over a finite duration known as the pass length. On each pass an output, termed the pass profile, is produced which acts as a forcing function on, and hence contributes to, the dynamics of the next pass profile. This can lead to oscillations which increase in amplitude in the pass to pass direction and cannot be controlled by standard control laws. Here we give new results on the design of physically based control laws for the sub-class of so-called discrete linear repetitive processes which arise in applications areas such as iterative learning control. The main contribution is to show how control law design can be undertaken within the framework of a general robust filtering problem with guaranteed levels of performance. In particular, we develop algorithms for the design of an H? and dynamic output feedback controller and filter which guarantees that the resulting controlled (filtering error) process, respectively, is stable along the pass and has prescribed disturbance attenuation performance as measured by and – norms
Microbial nitrate respiration - Genes, enzymes and environmental distribution
No full textKraft B, Strous M, Tegetmeyer H. Microbial nitrate respiration - Genes, enzymes and environmental distribution. Journal of Biotechnology. 2011;155(1):104-117.Nitrate is a key node in the network of the assimilatory and respiratory nitrogen pathways. As one of the 'fixed' forms of nitrogen, nitrate plays an essential role in both nature and industry. For bacteria, it is both a nitrogen source and an electron acceptor. In agriculture and wastewater treatment, nitrate respiration by microorganisms is an important issue with respect to economics, greenhouse gas emission and public health. Several microbial processes compete for nitrate: denitrification, dissimilatory nitrate reduction to ammonium and anaerobic ammonium oxidation. In this review we provide an up to date overview of the organisms, genes and enzymes involved in nitrate respiration. We also address the molecular detection of these processes in nature. We show that despite rapid progress in the experimental and genomic analyses of pure cultures, knowledge on the mechanism of nitrate reduction in natural ecosystems is still largely lacking. (C) 2011 Elsevier B. V. All rights reserved
Conservatismo en el simbolismo de Oaxaca: un breve informe.. Anales del Instituto Nacional de Antropología e Historia. Num. 49 Tomo I (1967-1968) Séptima Época (1967-1976)
No full textCaso, A. 1928 Las Estelas Zapotecas. Monografías del Museo Nacional de Arqueología, Historia y Etnografía. México.Caso, A. y Bernal, l. 1952 Urnas de Oaxaca. Memorias del Instituto Nacional de Antropología e Historia, II. México.Boos, Frank H. 1964 Las Urnas Zapotecas en el Museo Real de Ontario. Corpus Antiquitatum Americanensium, vol. l. Instituto Nacional de Antropología e Historia. México.Boos, Frank H. 1965 The Oaxacan Urn of the Zapotec God One Z and the Urn of his Feminine Companion. Wadsworth Athenaeum Bulletin. Sixth series, vol. 1. No. 2. Hartford, Connecticut.Boos, Frank H. 1966 The Ceramic Sculptures of Ancient Oaxaca. A. S. Barnes & Co., New York y Thomas Yoseloff Ltd., London.Leigh, H. 1958 An Identification of Zapotec Day Names. Boletín de Estudios Oaxaqueños, No. 6. Mexico City College, México.Paddock, J. 1966 Ancient Oaxaca. Stanford University Press
Contribution of Information and Communication Technology (ICT) in Country’S H-Index
No full textThe aim of this study is to examine the effect of Information and Communication Technology (ICT) development on country’s scientific ranking as measured by H-index. Moreover, this study applies ICT development sub-indices including ICT Use, ICT Access and ICT skill to find the distinct effect of these sub-indices on country’s H-index. To this purpose, required data for the panel of 14 Middle East countries over the period 1995 to 2009 is collected. Findings of the current study show that ICT development increases the H-index of the sample countries. The results also indicate that ICT Use and ICT Skill sub-indices positively contribute to higher H-index but the effect of ICT access on country’s H-index is not clear
. 49 Tomo I (1967-1968) Séptima Época (1967-1976). Anales del Instituto Nacional de Antropología e Historia
No full textPublicación que recopila y difunde cien años de trabajo de la antropología en México (1877-1977), integrada por documentos y manuscritos arqueológicos, antropológicos, históricos, geológicos, botánicos y lingüísticos.- Información general de las actividades del Instituto Nacional de Antropología e Historia durante los años 1967-1968 por Ignacio Bernal. - Dos elementos de uso ritual en el arte olmeca por María Antonieta Cervantes. - Las ruinas del Rancho de San Pablo, Becanchén, Yucatán por William J. Folan. - Reconocimiento del sitio Varejonal, municipio de Jiquipilas, Chiapas por Pierre Agrinier. - Conservatismo en el simbolismo de Oaxaca: un breve informe por Frank H. Boos. - La lengua de Huehuetán (Maliwi) por Carlos Robles Uribe y Roberto D. Bruce S. - Términos de parentesco del náhuatl. Dialecto del norte de Puebla por Earl Brockway. - Un nexo prehistórico entre quechua y tarasco por Mauricio Swadesh. - El tuzanteco y su posición dentro de la familia mayense por Otto Schummann. - Noticia del mame de Tuxtla Chico por Roberto H. Escalante. - Differential Pueblos specialization in fetishes and shrines por Florence Hawley Ellis. - Una leyenda mixteca por Jorge Poulat Legorreta. - Los pimas bajos de la Sierra Madre Occidental por Margarita Nolasco Armas. - Los choloques y los cholultecas. Apuntes sobre las relaciones étnicas en Cholula hasta el siglo XVI por Mercedes Olivera y Cayetano Reyes. - Fray Servando Teresa de Mier y la Sociadad Lautaro por José R. Guzmán. - Casas en que vivió el capitán don Juan de Chavarría Valera por Pedro Álvarez y Gasca
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