288 research outputs found
In search of the true nature of the rainbow : renewal of the Aristotelian tradition in the Renaissance and the De Iride
A Journey to the Centre of the Earth: Cosmology and the Centrobaric Theory from Antiquity to the Renaissance
This chapter aims to throw light on the ways in which the concept of center of gravity interacted with some of the cosmological ideas conceived in antiquity and in particular with the idea of the figure of earth as presented in Aristotle\u2019s De coelo. Developing earlier research, this study provides a better understanding of the scientific discussion that took place during the crucial first stage in the development of modern science. The origins and earliest stages in the development of the concept of center of gravity in Ancient Greece was briefly studied by Duhem, whose cursory analysis of a few texts by Pappus and Archimedes was undertaken with the specific purpose of showing the supposed faults inherent in Greek statics. The chapter will begin with a discussion of these Greek sources and attempt to follow the intellectual recovery of this key concept in the Renaissance and the first decades of the seventeenth century, relying in particular on a thorough study of textbooks used for teaching astronomy in Jesuit schools, for example, Commentaries on De sphera of Sacrobosco
Bernardino Baldi's In Mechanica Aristotelis problemata exercitationes
_In mechanica Aristotelis problemata exercitationes_ written by Bernardino Baldi is reprinted with an introduction and commentary as the third volume of the series _Sources of the Max Planck Research Library for the History and Development of Knowledge._ The volume is also freely available in electronic form as an open-access publication on the Internet at www.edition-open-access.de. The _Exercitationes_ were first published in 1621, four years after the death of the author. The work belongs to the long tradition of studies on the pseudo-Aristotelian _Mechanical Problems_ developed during the Renaissance but, unlike most other works written during the sixteenth century, it takes a critical position against the theoretical approach of the pseudo-Aristotelian text. The _Exercitationes_ display a systematic application of Archimedean principles to the explanation of the questions discussed in _Mechanical Problems_ illustrating the patchwork character of preclassical mechanics. Moreover, Baldi's work presents lengthy digressions that considerably widen the boundaries of mechanics
An immunohistochemically positive E-cadherin status is not always predictive for a good prognosis in human breast cancer
BACKGROUND:
in primary breast cancers dichotomic classification of E-cadherin expression, according to an arbitrary cutoff, may be inadequate and lead to loss of prognostic significance or contrasting prognostic indications. We aimed to assess the prognostic value of high and low E-cadherin levels in a consecutive case series (204 cases) of unilateral node-negative non-lobular breast cancer patients with a 8-year median follow-up and that did not receive any adjuvant therapy after surgery.
METHODS:
expression of E-cadherin was investigated by immunohistochemistry and assessed according to conventional score (0, 1+, 2+, 3+). Multiple correspondence analysis was used to visualise associations of both categorical and continuous variables. The impact of E-cadherin expression on patients outcome was evaluated in terms of event-free survival curves by the Kaplan-Meier method and proportional hazard Cox model.
RESULTS:
respect to intermediate E-cadherin expression values (2+), high (3+) or low (0 to 1+) E-cadherin expression levels had a negative prognostic impact. In fact, both patients with a low-to-nil (score 0 to 1+) expression level of E-cadherin and patients with a high E-cadherin expression level (score 3+) demonstrated an increased risk of failure (respectively, hazard ratio (HR)=1.71, confidence interval (CI)=0.72-4.06 and HR=4.22, CI=1.406-12.66) and an interesting association with young age.
CONCLUSIONS:
the findings support the evidence that high expression values of E-cadherin are not predictive for a good prognosis and may help to explain conflicting evidence on the prognostic impact of E-cadherin in breast cancer when assessed on dichotomic basis
Well-being and safety awareness in the context of hospital units related to work place quality
Several studies founded a positive relationship between environmental work stresses, perceived safety of work places and number of injuries. This study tested the relationship between cognitive dimensions of environmental quality, dimensions of affective quality, and perceived safety in the context of hospital units. A total of 204 hospital workers filled in a questionnaire measuring Perceived Hospital Environment Quality Indicators (PHEQIs: Fornara et al., 2006), Affective Qualities of Places (Perugini et al., 2002), and the Work Safety (WSS: Hayes et al., 1998). Results show a positive relationship between subjective indicators (both cognitive and affective) of environmental quality and specific dimensions of perceived safety in hospital units
Constitutive intestinal NF-κB does not trigger destructive inflammation unless accompanied by MAPK activation
Constitutive NF-κB activation in IECs induces inflammatory cytokines and chemokines in the lamina propria, but does not result in overt tissue damage unless acute inflammatory insults are present, causing TNF-dependent destruction and barrier disruption
Human oral isolate Lactobacillus fermentum AGR1487 induces a proinflammatory response in germ-free rat colons
Lactobacilli are thought to be beneficial for human health, with lactobacilli-associated infections being confined to immune-compromised individuals. However, Lactobacillus fermentum AGR1487 negatively affects barrier integrity in vitro so we hypothesized that it caused a pro-inflammatory response in the host. We compared germ-free rats inoculated with AGR1487 to those inoculated with another L. fermentum strain, AGR1485, which does not affect in vitro barrier integrity. We showed that rats inoculated with AGR1487 had more inflammatory cells in their colon, higher levels of inflammatory biomarkers, and increased colonic gene expression of pro-inflammatory pathways. In addition, our in vitro studies showed that AGR1487 had a greater capacity to activate TLR signaling and induce pro-inflammatory cytokines in immune cells. This study indicates the potential of strains of the same species to differentially elicit inflammatory responses in the host and highlights the importance of strain characterization in probiotic approaches to treat inflammatory disorders
Innate Immune Activation in Intestinal Homeostasis
Loss of intestinal immune regulation leading to aberrant immune responses to the commensal microbiota are believed to precipitate the chronic inflammation observed in the gastrointestinal tract of patients with inflammatory bowel diseases (IBD), Crohn's disease and ulcerative colitis. Innate immune receptors that recognize conserved components derived from the microbiota are widely expressed by both epithelial cells and leucocytes of the gastrointestinal tract and play a key role in host protection from infectious pathogens; yet precisely how pathogenic and commensal microbes are distinguished is not understood. Furthermore, aberrant innate immune activation may also drive intestinal pathology, as patients with IBD exhibit extensive infiltration of innate immune cells to the inflamed intestine, and polymorphisms in many innate immunity genes influence susceptibility to IBD. Thus, a balanced interaction between the microbiota and innate immune activation is required to maintain a healthy mutualistic relationship between the microbiota and the host, which when disturbed can result in intestinal inflammation
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