1,720,984 research outputs found
Escherichia coli strains isolated from retail meat products: Evaluation of biofilm formation ability, antibiotic resistance, and phylogenetic group analysis
No full textEscherichia coli is a ubiquitous organism capable of forming a biofilm. This is an important virulence factor and is critical in certain diseases and in the development of antibiotic resistance, which is increased by biofilm synthesis. In the present study, the potential health risk associated with handling and consumption of foods of animal origin contaminated with E. coliproducing biofilm was evaluated. We analyzed the ability of 182 E. coli strains isolated from pork, poultry, and beef, purchased in three different supermarkets in the area of the "Italian Food Valley" (Parma, northern Italy), to form biofilms. Positive strains were also tested for the presence of 12 biofilm-associated genes. Moreover, the 182 E. coli were characterized for antibiotic resistance, presence of multidrug resistance, extended-spectrum beta-lactamase strains, and phylogenetic diversity through PCR. Twenty-five percent of the isolates produced biofilm. The majority showed weak adherence, five were moderate, and three were strong producers. E. coli with a strong adherence capability (three of three) harbored eight biofilm-associated genes, while weak and moderate producers harbored only five (frequencies ranging from 80 to 100%). Multidrug resistance was observed in 20 biofilm-producing E. coli, and 15 of these belonged to phylogenetic group D. Among nonbiofilm producers, the percentage of strains belonging to phylogenetic groups B2 and D was approximately 40%, highlighting a potential health risk for consumers and people handling contaminated products. The present study underlines the importance of monitoring the prevalence and characteristics of E. coli contaminating retail meat in relation to the potential virulence highlighted here
Dynamic computation offloading in multi-access edge computing via ultra-reliable and low-latency communications
No full textThe goal of this work is to propose an energy-efficient algorithm for dynamic computation offloading, in a multi-access edge computing scenario, where multiple mobile users compete for a common pool of radio and computational resources. We focus on delay-critical applications, incorporating an upper bound on the probability that the overall time required to send the data and process them exceeds a prescribed value. In a dynamic setting, the above constraint translates into preventing the sum of the communication and computation queues' lengths from exceeding a given value. Ultra-reliable low latency communications (URLLC) are also taken into account using finite blocklengths and reliability constraints. The proposed algorithm, based on stochastic optimization, strikes an optimal balance between the service delay and the energy spent at the mobile device, while guaranteeing a target out-of-service probability. Starting from a long-term average optimization problem, our algorithm is based on the solution of a convex problem in each time slot, which is provided with a very fast iterative strategy. Finally, we extend the approach to mobile devices having energy harvesting capabilities, typical of Internet of Things scenarios, thus devising an energy efficient dynamic offloading strategy that stabilizes the battery level of each device around a prescribed operating level
Time-Sensitive Networking for Trajectory Tracking of an Unmanned Ground Vehicle over Wi-Fi
Full text linkThe demand for precise time synchronization is of great interest in contemporary networked systems, especially in the context of converged networks where seamless communication among devices, actuators, and sensors is imperative. This has led to the development and adoption of Time-Sensitive Networking (TSN) and Wireless TSN (WTSN) technologies, with a particular attention to the IEEE 802.1AS Generalized Precision Time Protocol (gPTP) standard. In this work, we explore the role of time synchronization in a wireless network scenario involving an Unmanned Ground Vehicle (UGV) that has to track a desired time dependent trajectory. The UGV receives trajectory waypoints from a secondary station, emphasizing the importance of precise timing in trajectory tracking. Utilizing the IEEE 802.1AS standard for wireless time synchronization, this study investigates the impact of clock synchronization errors and latency on trajectory tracking. Hence, it demonstrates the capability and benefits of IEEE 802.1AS in managing device clocks and facilitating time correction to ensure precise trajectory tracking despite synchronization errors and latency
Antibiotic Treatment Administered to Pigs and Antibiotic Resistance of Escherichia coli Isolated from Their Feces and Carcasses
No full textAntimicrobial resistance (AMR) in bacteria is a frequent and widespread phenomenon. The European Food Safety Authority (EFSA) reports that multidrug resistant (MDR) Escherichia coli is considered an important hazard to public health. The lack of data on the correlation between the administration of antibiotics to pigs and the diffusion of MDR E. coli necessitates an in-depth study. The aims of our study were first of all to determine the presence of MDR and/or extended spectrum β-lactamase (ESβL) E. coli isolated from feces and carcasses of pigs; and second, to evaluate the correlation between antibiotic resistance and the antibiotic treatment administrated to the animals considered. The examined E. coli was isolated from 100 fecal swabs and 100 carcass sponges taken from farms and slaughterhouses located in Reggio Emilia province in Italy. The MDR isolates were tested following the protocol defined by EUCAST (2015). Subsequently, a real-time PCR and an endpoint-PCR were used for the genomic analysis. Data highlighted 76.5% of MDR E. coli with a marked presence of the ampicillin (AMP)-streptomycin (STRE)-tetracycline (TETRA) pattern. Moreover, 13 isolates were ESβL producers, and the blaCTXM gene was the most frequently observed in genomic analysis. Results confirm the complexity of the AMR phenomenon showing a partial correlation between the administration of antibiotics and the resistance observed. Pigs destined to the production of Protected Designation of Origin items are colonized by bacteria resistant to a wide range of antibiotic classes even if data are encouraging for colistin and third generation cephalosporin. Furthermore, in-depth study focused on food production could be useful in a view of high safety standards for consumers
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
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