130,665 research outputs found
Giant axonal neuropathy: acceleration of neurofilament transport in optic axons.
No full textGiant axonal neuropathies are a group of acquired and inherited human diseases morphologically characterized by accumulation of neurofilaments (NF) in enlargements of preterminal regions of central and peripheral axons. Slow axonal transport was studied in the optic systems of rats treated with 2,5-hexanedione, a toxic compound that produces an experimental model of giant axonal neuropathy. The transport rate of NF and of two other polypeptides of M(r) 64,000 and 62,000 were selectively increased. Other components of the slow axonal transport were not affected. Acceleration of labeled NF was also observed when 2,5-hexanedione was given after [35S]methionine administration. Morphometric analysis revealed that the number of NF and the axon size were decreased in regions of optic axons proximal to the enlargements. It is suggested that acceleration of NF transport leads to a longitudinal redistribution of NF: NF decrease proximally and increase distally, forming NF-containing enlargements. Evidence was obtained that polypeptides of M(r) 64,000 and 62,000 are cytoskeletal components related to intermediate filaments, normally migrating with the component a of the slow axonal transport. The 2,5-hexanedione axon may provide insight into the pathogenesis of inherited and acquired giant axonal neuropathies and offers a model to investigate the relationship between number of NF and axonal size in central axons
Status spongiosus of rat central nervous system induced by actinomycin D
No full textThe effect on central myelin of Actinomycin D, an RNA--and, secondarily, a protein-synthesis inhibitor, has been studied by light and electron microscopy. The intracranial injection of this drug produced an extensive status spongiosus of the white matter in the cerebrum, cerebellum, brain stem and optic nerve within 48 h. The status spongiosus was due to vacuole formation within the myelin sheath and to enlargement of the extracellular space. Three types of vacuoles were observed: (a) the most common varieties formed between the inner tongue and the remainder of the myelin sheath; (b) a second variety formed by enlargement of the periaxonal space with separation of the axon from its myelin sheath, and (c) a less common type of vacuolization was due to splitting of the myelin lamellae at the interperiod line to form large intramyelinic vacuoles. Myelinic vacuoles were preceded by nuclear and cytoplasmic changes in oligodendrocytes, which included nucleolar segregation, disaggregation, and diminution in number of ribosomes. These changes were similar to those previously reported in a variety of cells exposed to Actinomycin D. It is suggested that myelin vacuoles result secondarily from the Actinomycin D inhibitory effect on oligodendroglial RNA--and protein-synthesis, rather than from a direct effect of this drug on the myelin sheath
Asymmetric Effects of Monetary Policy Easing and Tightening
No full textMonetary policy easing and tightening have asymmetric effects: a policy easing has large effects on prices but small effects on real activity variables. The opposite is found for a policy tightening: large real effects but small effects on prices. Nonlinearities are estimated using a new and simple procedure based on linear Strutural Vector Autoregressions with exogenous variables (SVARX). We rationalize the result through the lens of a simple model with downward nominal wage rigidities
Pathogenesis-targeted preventive strategies for multidrug resistant ventilator-associated pneumonia: A narrative review
No full textVentilator-associated pneumonia (VAP) is the most common hospital-acquired infection in the intensive care unit (ICU), accounting for relevant morbidity and mortality among critically ill patients, especially when caused by multidrug resistant (MDR) organisms. The rising problem of MDR etiologies, which has led to a reduction in treatment options, have increased clinician’s attention to the employment of effective prevention strategies. In this narrative review we summarized the evidence resulting from 27 original articles that were identified through a systematic database search of the last 15 years, focusing on several pathogenesis-targeted strategies which could help preventing MDR-VAP. Oral hygiene with Chlorhexidine (CHX), CHX body washing, selective oral decontamination (SOD) and/or digestive decontamination (SDD), multiple decontamination regimens, probiotics, subglottic secretions drainage (SSD), special cuff material and shape, silver-coated endotracheal tubes (ETTs), universal use of gloves and contact isolation, alcohol-based hand gel, vaporized hydrogen peroxide, and bundles of care have been addressed. The most convincing evidence came from interventions directly addressed against the key factors of MDR-VAP pathogenesis, especially when they are jointly implemented into bundles. Further research, however, is warranted to identify the most effective combination
Eudaimonia: the sociocultural value of consumers’ social labor
No full textConsumers participate in social media producing value through social labor. So far scholars
approached social labor through a Marxist lens focusing on the economic aspects of its value and the
potential risks related to consumers’ exploitation. We build a sociocultural conceptualization of
social labor actualizing the Aristotelian idea of virtuous action that realizes a life well lived with
others. Following this approach, we identify Eudaimonia as a theoretical construct to capture the
sociocultural value of social labor, and we elaborate how social labor in social media enables the
achievement of a eudaimonic state of living. We support our conceptualization with empirical
evidence in the social media context of amateur cooking practices that illustrates how Eudaimonia
is achieved through social labor practices of cultural performativity. Our perspective extends
previous theory related to three research domains of consumers’ social labor: (1) Marxist and
technocapitalist critique, (2) neoliberalist perspective, and (3) networked consumer collectives
Il castagno da frutto. Progetto castagno
No full textIdentifica le norme teniche e opportunità di reddito per i produttori dell'Appennino Centro Settentrional
Using hydrophone measurements to monitor incipient cavitation in variable displacement pendulum-slider pumps
No full textThe present work proposes an experimental methodology for monitoring the inception and the subsequent development of cavitation and aeration in variable displacement pendulum-slider pumps. These two phenomena may affect volumetric machines when the working condition requires high values of working speed and specific displacement, often causing undesired broadband noise. Since these pumps find their most common application in automotive auxiliary systems and powertrain lubricating circuits, the abnormal noise caused by this phenomenon is often unacceptable. Based on these considerations, an experimental cavitation detection method based on hydrophone measurements is proposed and assessed through direct comparison with a non-cavitating machine. Cavitation is promoted by increasing the pump working speed, as it happens in actual automotive applications. The effective presence of cavitation is further checked with the help of durability tests and efficiency measurements, made possible by the capability to control the pump working eccentricity. Measurements are repeated for different values of both specific flow rate and oil temperature, showing that these operational parameters have a consistent interaction in the definition of the inception of the phenomenon and its intensity
Cook, click, share and be happy! Eudaimonic self-presentation in consumer cooking practices in contemporary technocultures
No full textThis chapter describes consumers’ cooking and self-presentation practices on social media as means for pursuing happiness. This chapter draws from a concept of happiness as a core dimension of individual wellbeing that relies on both hedonic and eudaimonic fulfilment. While hedonic fulfilment has been extensively investigated in consumer research, eudaimonic fulfilment has received scarce attention. Hedonic pleasure is pursued through enjoying life in a basically passive way, while eudaimonia is associated to pursuing one’s own life project, growing as an individual and integrating into a given social setting. Rooted in the digital consumer culture of the current Italian amateur cooking tradition, this chapter claims that consumers pursue happiness by engaging in self-presentation of their cooking practices in social media. These practices reveal an eudaimonic tension toward wellbeing according to which consumers spread their pictures and videos into the network of their peers in order to engage them in a collective project of emancipation and self-realization. While illustrating the empirical evidence of a recent netnographic study, this chapter will critically discuss in a simple and straightforward style how happiness in contemporary consumption is not only or primarily a psychological state. Beyond that, it has evolved into a technocultural process where eudaimonic wellbeing, digital self-presentation, production and networked sociality are subtly interwoven
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
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
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