1,721,218 research outputs found
Landslide activity in response to alpine deglaciation: the case of the Belluno Prealps (Italy)
No full textIn the Late Pleistocene, when the Piave glacier retreated from the
end moraine system areas towards the Dolomitic region, several large
landslides took place in the Belluno Prealps. The chronology of such
landslides is mainly based on spatial relationships between mass movements
and glacial or fluvial features, but poorly based on radiometric dating.
The aim of this study is improving the existing data set on landslide
chronology to clarify the relationship between deglaciation and landslides,
that is the sensitivity of an alpine environment to climatic changes.
The research is based on different types of data (geomorphological
field survey, geophysical investigations, drillings, radiometric dating and
pollen analysis) and focused on four large gravitational phenomena
(Fadalto, Madonna del Parè, Masiere di Vedana and Marziai landslides).
Different strategies were adopted in order to date mass movements, according
to the environmental conditions in which they occurred. In some
cases landslide debris reached a valley bottom free of ice and dammed
the valley, whereas in others mass movement took place during deglaciation.
Therefore investigations were addressed to define the age of landslide
deposits, of lacustrine sediments upstream of accumulation zones
and of glacial sediments of specific deglaciation phases. Obtaining
chronological information through radiocarbon method turned out a difficult
task, mainly for the scarcity of organic matter suitable for dating.
Also OSL method did not give satisfactory results. Notwithstanding such
dating problems, the use of different data and evidence (geomorphological,
stratigraphical, geophysical, and palynological) has allowed a quite
accurate definition of landslide chronology. For instance, according to
pollen types and concentration it is possible to establish that the landslides
occurred during the first phases of deglaciation. The main conclusions
are: (a) all the examined mass movements took place between
17,000 and 15,000 years BP; (b) there is a clear relationship between
landslides and the climatic changes that occurred during the last glacialinterglacial
transition; (c) reaction time of slopes to glacier retreat was relatively
short. Finally, we do not exclude the hypothesis that tectonics
could have played a role as for slope instability during a period of glacial
unloading and lithospheric rebound
Disposable label - Free immunosensor on screen - Printed electrodes for the detection of Aflatoxin B1 in food
No full textAn impedimetric label - free immunosensor on disposable screen-printed carbon electrode (SPCE) for Aflatoxin B1 detection has been developed in this work. SPCE surface was modified with gold nanoparticles and the monoclonal anti-AFB1 was immobilized on the working electrode through a cysteamine layer. After each coating step, the modified surface was characterized by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy. The charge transfer resistance (Rct) was chosen as the best parameter that describes the reproducible change in electrical properties of the electrode surface at different AFB1 concentrations and it was used to investigate the analytical parameters of the developed immunosensor. Under optimized conditions, the immunosensor showed a linear relationship between 0.01 and 4 ng/mL with a low detection limit of 0.01 ng/mL, making it suitable to detect AFB1 amount in many common food products. Lastly, the immunosensor was used to measure AFB1 in nuts samples with good results
Label-free impedimetric biosensors for the control of food safety–a review
No full textThe guarantee of food safety requires fast and accurate control for all contaminants, chemicals and bacteria, which are harmful to human health. Ensuring the safety and quality of food is the main interest both for the food industry and for consumers. In the food industry, the safety of a food product is evaluated through chemical and microbiological analysis: these procedures conventionally use the technique as chromatography, spectrophotometry and electrophoresis that are time-consuming, require highly trained personnel, are expensive and require steps of sample pretreatment, increasing the time of analysis. Consequently, among food and beverage industries, exists a growing demand in biosensing technologies as simple, rapid, accurate, low - cost and portable analytical devices for the monitoring and detection of chemical and microbiological contaminants (toxins, mycotoxins, pathogenic bacteria, pesticides and allergens) that endanger the food safety. Among biosensors, the label-free biosensors, characterised by direct detection of the analyte of interest, exploiting the advantages of an impedimetric transduction technique, seem to be the most promising devices for the future. In the last years, the potential use of Electrochemical Impedance Spectroscopy technique has been widely considered in the biosensor field; it is, in fact, a powerful, non-destructive and informative technique which can be used to study the electrical properties of the sensing device interface and to trace the reactions that occur on it. For these reasons, the application of impedimetric technique as a transduction technology has allowed the label-free detection and sensitive quantification of the bio interaction in different application and thus for the development of food hazards biosensors too. This review provides the current situation in the literature on label-free impedimetric biosensors in food safety
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Strain profiling and epidemiology of bacterial species from metagenomic sequencing
Full text linkMicrobial communities are often composed by complex mixtures of multiple strains of the same species, characterized by a wide genomic and phenotypic variability. Computational methods able to identify, quantify and classify the different strains present in a sample are essential to fully exploit the potential of metagenomic sequencing in microbial ecology, with applications that range from the epidemiology of infectious diseases to the characterization of the dynamics of microbial colonization. Here we present a computational approach that uses the available genomic data to reconstruct complex strain profiles from metagenomic sequencing, quantifying the abundances of the different strains and cataloging them according to the population structure of the species. We validate the method on synthetic data sets and apply it to the characterization of the strain distribution of several important bacterial species in real samples, showing how its application provides novel insights on the structure and complexity of the microbiota
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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