1,721,161 research outputs found
Mini-review : biofilm responses to oxidative stress
No full textBiofilms constitute the predominant microbial style of life in natural and engineered ecosystems. Facing harsh environmental conditions, microorganisms accumulate reactive oxygen species (ROS), potentially encountering a dangerous condition called oxidative stress. While high levels of oxidative stress are toxic, low levels act as a cue, triggering bacteria to activate effective scavenging mechanisms or to shift metabolic pathways. Although a complex and fragmentary picture results from current knowledge of the pathways activated in response to oxidative stress, three main responses are shown to be central: the existence of common regulators, the production of extracellular polymeric substances, and biofilm heterogeneity. An investigation into the mechanisms activated by biofilms in response to different oxidative stress levels could have important consequences from ecological and economic points of view, and could be exploited to propose alternative strategies to control microbial virulence and deterioration
SORVEGLIANZA DELLA CIRCOLAZIONE DI POLIOVIRUS NELLA POPOLAZIONE LOMBARDA NELL'AMBITO DEL PROGETTO DI ERADICAZIONE MONDIALE DELLA POLIOMIELITE
Full text linkPoliomyelitis is an acute, viral, infectious disease caused by the 3 poliovirus that spread from person to person, primarily via the fecal-oral route. Although approximately 90% of polio infections cause no symptoms at all, affected individuals can exhibit a range of symptoms if the virus enters the blood stream. In about 1% of cases, the virus enters the central nervous system, preferentially infecting and destroying motor neurons, leading to muscle weakness and acute flaccid paralysis.
Polio had existed for thousands of years quietly as an endemic pathogen until the 1880s, when major epidemics began to occur in Europe; soon after, widespread epidemics appeared in the United States. But following the widespread use of poliovirus vaccine in the mid-1950s, the incidence of poliomyelitis declined dramatically in many industrialized countries.
A global effort to eradicate polio began in 1988, led by the World Health Organization, UNICEF, and The Rotary Foundation. These efforts have reduced the number of annual diagnosed cases by more than 99%; from an estimated 350,000 cases in 1988 to 215 cases in 2012, the lowest ever recorded.
Stopping poliovirus transmission is pursued through a combination of high infant immunization coverage and surveillance for wild poliovirus through reporting and laboratory testing of all cases of acute flaccid paralysis (AFP) among children less than fifteen years of age.
Since 1997 in Lombardy the AFP surveillance Regional Reference Center (RCC) is located in the Department of Biomedical Sciences for Health ex Department of Microbiology-Virology-Public Health and its activity is coordinated by the National Institute of Health (ISS) and the Ministry of Health (MOH).
To conduct surveillance RCC established and still coordinates a network of hospital referents that deal with the reporting of AFP cases in children under fifteen years old even in the absence of cases. Since 1997, the number of hospitals participating has increased up to 51 in 2012.
As the RCC is provided with an accredited laboratory it also carries out the virological investigations on biological samples. Laboratory analysis mainly consists in the detection of polioviruses by isolation in cell culture (RD and L20B) of two faecal samples that must be collected within 14 days after the onset of paralysis.
The RCC also deals with the environmental monitoring which consists in the collection and analysis of sewage samples, collected at two sites (Nosedo and Peschiera Borromeo) of the center-east Lombard sewer network. The laboratory analysis is the detection of polioviruses and other non-polio enterovirus by isolation in cell culture.
During the period 2010-2012 the AFP surveillance identified 27 cases and 185 sewage samples has been collected as regards the environmental surveillance. No virological and environmental samples were tested poliovirus positive.
In none of the three years the goal of the 14 AFP expected cases was achieved and also other performance indicators are proving poor that shows cases are often not promptly and properly reported even if stool samples have been collected in almost the cases.
Instead the high percentage (79%) of non-polio enterovirus positive samples of sewage emphasizes high circulation of non-polio enterovirus in the Lombard population and confirms the good quality of the conducted investigations.
It is important to guarantee a high quality surveillance as there is a risk of importation of cases from areas where polio is endemic.
The surveillance activities will continue long after the eradication of poliomyelitis to guarantee the effective stopping of both wild and vaccine-derived poliovirus circulation
Sul comportamento di pistoni difettati per motori ad a.c. alimentati con miscela benzina-etanolo
No full textSi analizza il comportamento a fatica di pistoni per motori ad accensione comandata, alimentati con miscela
alcool-benzina, mediante prove full-scale al banco e con una macchina universale adeguatamente
attrezzata per simulare il carico di esercizio sull’articolo di prova.
I primi risultati ottenuti mostrano un’ottima resistenza del tipo di pistone esaminato all’innesco di cricche di
fatica ed alla propagazione dei difetti, anche severi, appositamente introdotti sulla superficie di testa
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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