1,720,990 research outputs found
Dynamic properties of bovine Cu,Zn superoxide dismutase from crystallographic data
No full textThe Cu,Zn superoxide dismutase (SOD) enzyme from bovine erythrocytes has been the subject of several crystallographic studies over the last fifteen years. Nine crystal structures in space groups C2, P2(1)2(1)2(1) and C222(1), have been refined at high resolution and are available from the Protein Data Bank and our laboratory. We have performed a comparative analysis based on the experimentally determined structural variability in order to study the dynamics of the enzyme in terms of molecular flexibility. We have been able to show that information on molecular motions of different types occurring on different timescales may be obtained from the data by comparing thermal motion analysis with that of backbone C alpha fluctuations. We have found that the most mobile parts of Cu,Zn SOD are located in turns and loops and that there is a strict correlation between thermal motion and flexibility of the molecule, with the only exception of the two residues Asp11 and Glu38. The analysis of crystal polymorphism established the existence of a quite strict correlation between crystal contacts and mobility in space group C2, while in P2(1)2(1)2(1) and C222(1) the opposite was observed. Comparison with the results of molecular dynamics simulation revealed a good agreement between the two approaches although some differences emerge when active site residues are considered. The results of this work indicate the feasibility of an 'experimental' approach to the study of protein dynamics. (C) 1998 Elsevier Science S.A. All rights reserved
Low power wide area networks (LPWAN) at sea: Performance analysis of offshore data transmission by means of loRaWAN connectivity for marine monitoring applications
Full text linkIn this paper the authors discuss the realization of a Long Range Wide Area Network (LoRaWAN) network infrastructure to be employed for monitoring activities within the marine environment. In particular, transmission ranges as well as the assessment of parameters like Signal to Noise Ratio (SNR) and Received Signal Strength Indicator (RSSI) are analyzed in the specific context of an aquaculture industrial plant, setting up a transmission channel from an offshore monitoring structure provided with a LoRaWAN transmitter, to an ashore receiving device composed of two LoRaWAN Gateways. A theoretical analysis about the feasibility of the transmission is provided. The performances of the system are then measured with different network parameters (in particular the Spreading Factor-SF) as well as with two different heights for the transmitting antenna. Test results prove that efficient data transmission can be achieved at a distance of 8.33 km even using worst case network settings: this suggests the effectiveness of the system even in harsher environmental conditions, thus entailing a lower quality of the transmission channel, or for larger transmission ranges
An IoT System for the Measurement and the Interpretation of the Photosynthesis-Related CO2 Fluxes
No full textThe estimation of the CO2 concentration variations due to plants photosynthesis has become a topic of outstanding interest in view of evaluating the carbon footprint of greenhouses and farms. In this framework, distributed sensing solutions can be an alternative to expensive and power-consuming gas analyzers. In this paper, a low-cost sensor node thought for the accurate monitoring of photosynthesis-related quantities (i.e., temperature, pressure, water vapor concentration and CO2 concentration) is presented. The system is validated through measurement campaigns involving plants enclosed in an accumulation chamber in the presence of artificial light with controlled intensity, photoperiod and spectral composition. A simplified preliminary model is also proposed to interpret the obtained results from the point of view of the kinetics of the gas exchanges, achieving the estimation of the CO2 uptake and release rates ascribable to the plants activit
A LoRaWAN network infrastructure for the remote monitoring of offshore sea farms
No full textFish farming is nowadays a crucial sector for food industry all around the world. While the total amount of captured fish production has remained almost constant in the last 30 years (around 90 millions tonnes according to the Food and Agriculture Organization (FAO) of the United States), in the same span of time the quantity of bred fish has increased tenfold, almost reaching the quantity of the captured one. What was once little more than a hand-crafted production, is now an actual industrial sector, employing around 60 million workers all around the world. Like all industrial sectors, aquaculture can considerably benefit by the introduction of Internet of Things (IoT) technologies, thus adopting them within the context of Industry 4.0 to optimize fish farming processes. In this context, this paper proposes a real-time monitoring infrastructure based on the use of Fixed Nodes and Mobile Sinks for the remote, real-time control of offshore sea farms. The proposed architecture exploits a LoRaWAN network infrastructure for data transmission: different configurations are tested on the field, proving the reliability of the communication channel in a worst case scenario up to a 8.33 km offshore distance. A complete real-time monitoring system is presented, allowing to measure in real time several parameters about the quality of water in the fish cages as well as their maintenance status
Designing a Reliable and Low-Latency LoRaWAN Solution for Environmental Monitoring in Factories at Major Accident Risk
Full text linkIn this article, we propose a reliable and low-latency Long Range Wide Area Network (LoRaWAN) solution for environmental monitoring in factories at major accident risk (FMAR). In particular, a low power wearable device for sensing the toxic inflammable gases inside an industrial plant is designed with the purpose of avoiding peculiar risks and unwanted accidents to occur. Moreover, the detected data have to be urgently and reliably delivered to remote server to trigger preventive immediate actions so as to improve the machine operation. In these settings, LoRaWAN has been identified as the most proper communications technology to the needs owing to the availability of off the shelf devices and software. Hence, we assess the technological limits of LoRaWAN in terms of latency and reliability and we propose a fully LoRaWAN compliant solution to overcome these limits. The proposed solution envisages coordinated end device (ED) transmissions through the use of Downlink Control Packets (DCPs). Experimental results validate the proposed method in terms of service requirements for the considered FMAR scenario
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
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
- …
