206 research outputs found

    A quantitative method to analyse an open-ended questionnaire: A case study about the Boltzmann Factor

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    This paper describes a quantitative method to analyse an openended questionnaire. Student responses to a specially designed written questionnaire are quantitatively analysed by not hierarchical clustering called k-means method. Through this we can characterise behaviour students with respect their expertise to formulate explanations for phenomena or processes and/or use a given model in the different context. The physics topic is about the Boltzmann Factor, which allows the students to have a unifying view of different phenomena in different contexts

    Investigating the quality of mental models deployed by undergraduate engineering students in creating explanations: The case of thermally activated phenomena

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    This paper describes a method aimed at pointing out the quality of the mental models undergraduate engineering students deploy when asked to create explanations for phenomena or processes and/or use a given model in the same context. Student responses to a specially designed written questionnaire are quantitatively analyzed using researcher-generated categories of reasoning, based on the physics education research literature on student understanding of the relevant physics content. The use of statistical implicative analysis tools allows us to successfully identify clusters of students with respect to the similarity to the reasoning categories, defined as "practical or everyday," "descriptive," or "explicative." Through the use of similarity and implication indexes our method also enables us to study the consistency in students' deployment of mental models. A qualitative analysis of interviews conducted with students after they had completed the questionnaire is used to clarify some aspects which emerged from the quantitative analysis and validate the results obtained. Some implications of this joint use of quantitative and qualitative analysis for the design of a learning environment focused on the understanding of some aspects of the world at the level of causation and mechanisms of functioning are discussed

    Exploring the Coherence of Student Reasoning when Responding to Questionnaires on Thermally Activated Phenomena

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    Many research results show that students often highlight \u201cmixed-type\u201d reasoning when tackling problematic situations and problems. This reasoning is based on the simultaneous use of common-sense and mere descriptions of facts, perceived as sufficient to build an \u201cexplanation\u201d of observed or proposed situations and problems. This fact can be interpreted as a lack of coherence. In this paper, we study the coherence of responses that a sample of undergraduate chemical engineering student give when they are asked to face real-life situations, to create explanations, and to use models in different contexts. We administered open-ended questionnaires before and after a twenty-hour Inquiry-Based workshop related to phenomena activated by a thermal overcoming of a potential barrier. Based on the Physics Education Research literature on student understanding of relevant physics contents, the student responses are analysed by using researcher-generated categories of reasoning and their coherence is studied. Finally, we discuss some implications of the results to improve the development of students' explicative skills. \ua9 2021 the authors; licensee Modestum. All Rights Reserved

    Long-term modulation of mitochondrial Ca2+ signals by protein kinase C isozymes

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    The modulation of Ca2+ signaling patterns during repetitive stimulations represents an important mechanism for integrating through time the inputs received by a cell. By either overexpressing the isoforms of protein kinase C (PKC) or inhibiting them with specific blockers, we investigated the role of this family of proteins in regulating the dynamic interplay of the intracellular Ca2+ pools. The effects of the different isoforms spanned from the reduction of ER Ca2+ release (PKCα) to the increase or reduction of mitochondrial Ca2+ uptake (PKCζ and PKCβ/PKCδ, respectively). This PKC-dependent regulatory mechanism underlies the process of mitochondrial Ca2+ desensitization, which in turn modulates cellular responses (e.g., insulin secretion). These results demonstrate that organelle Ca2+ homeostasis (and in particular mitochondrial processing of Ca2+ signals) is tuned through the wide molecular repertoire of intracellular Ca2+ transducers

    Quantum correlations beyond entanglement in a classical-channel model of gravity

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    A direct quantization of the Newtonian interaction between two masses is known to establish entanglement, which if detected would witness the quantum nature of the gravitational field. Gravitational interaction is yet compatible also with gravitational decoherence models relying on classical channels, hence unable to create entanglement. Here, we show in paradigmatic cases that, despite the absence of entanglement, a classical-channel model of gravity can still establish quantum correlations in the form of quantum discord between two masses. This is demonstrated for the Kafri-Taylor-Milburn (KTM) model and a recently proposed dissipative extension of this. In both cases, starting from an uncorrelated state, a significant amount of discord is generally created. This eventually decays in the KTM model, while it converges to a small stationary value in its dissipative extension. We also find that initial local squeezing on the state of the masses can significanlty enhance the generated discord

    Myo-inositol may prevent gestational diabetes onset in overweight women: a randomized, controlled trial

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    Objective: To evaluate whether myo-inositol supplementation may reduce gestational diabetes mellitus (GDM) rate in overweight women. Methods: In an open-label, randomized trial, myo-inositol (2 g plus 200 μg folic acid twice a day) or placebo (200 μg folic acid twice a day) was administered from the first trimester to delivery in pregnant overweight non-obese women (pre-pregnancy body mass index ≥ 25 and < 30 kg/m2). The primary outcome was the incidence of GDM. Results: From January 2012 to December 2014, 220 pregnant women were randomized at two Italian University hospitals, 110 to myo-inositol and 110 to placebo. The incidence of GDM was significantly lower in the myo-inositol group compared to the placebo group (11.6% versus 27.4%, respectively, p = 0.004). Myo-inositol treatment was associated with a 67% risk reduction of developing GDM (OR 0.33; 95% CI 0.15–0.70). Conclusions: Myo-inositol supplementation, administered since early pregnancy, reduces GDM incidence in overweight non-obese women

    Difficult evaluation of thyroid cancer due to cervical paraffin injection

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    Paraffinoma is a well known complication of previous paraffin injection into the subcutaneous layer that presents as various conditions including firm mass formation, edema, induration, ulceration, and skin necrosis. Paraffinoma can mimic neoplasm on physical examination and imaging studies and may complicate ultrasonographic diagnoses due to typical posterior shadowing and high echogenicity. When paraffinomas involve around the thyroid gland, the diagnosis of thyroid tumors is very difficult. We present a case of thyroid cancer, the evaluation of which was complicated by the presence of cervical paraffinoma

    Squamous cell carcinoma of the lower lip: FAS/FASL expression, lymphocyte subtypes and outcome.

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    Squamous cell carcinoma (SCC) of the lip is a relatively common malignancy of the head and neck region. Tumour thickness, grading and perineural invasion are significant prognostic indicators. However, there is still the need of new reliable biological markers able to predict the prognosis of the single cases with an unfavourable biological behaviour unpredictable by the classic clinical-pathological parameters. 32 cases of (SCC) of the lower lip were analysed for their clinicopathologic features, and immunohistochemical expression of Fas/FasL in neoplastic cells and in inflammatory infiltrate. Moreover the density and phenotype of tumour-infiltrating lymphocytes (TIL) were analysed. The results were related with the follow-up of the patients ranging from 2 to 6 years. The cases with over-expression of Fas/FasL in neoplastic cells and Fas+ in T cells preferentially showed a more aggressive clinical behaviour (p<0.01). Moreover we found an alteration of the normal expression of CD4 and CD8 lymphocyte types in ten cases. This data suggest that the Fas/FasL pathway is involved in the close relation between neoplastic cells and T cells and so in the biological behaviour of these tumours

    Microenvironment inflammatory infiltrate drives growth speed and outcome of hepatocellular carcinoma: a prospective clinical study

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    In HCC, tumor microenvironment, heavily influenced by the underlying chronic liver disease, etiology and stage of the tissue damage, affects tumor progression and determines the high heterogeneity of the tumor. Aim of this study was to identify the circulating and tissue components of the microenvironment immune-mediated response affecting the aggressiveness and the ensuing clinical outcome. We analyzed the baseline paired HCC and the surrounding tissue biopsies from a prospective cohort of 132 patients at the first diagnosis of HCC for immunolocalization of PD-1/PD-L1, FoxP3, E-cadherin, CLEC2 and for a panel of 82 microRNA associated with regulation of angiogenesis, cell proliferation, cell signaling, immune control and autophagy. Original microarray data were also explored. Serum samples were analyzed for a panel of 19 cytokines. Data were associated with biochemical data, histopathology and survival. Patients with a more aggressive disease and shorter survival, who we named fast-growing accordingly to the tumor doubling time, at presentation had significantly higher AFP levels, TGF-β1 and Cyphra 21-1 levels. Transcriptomic analysis evidenced a significant downregulation of CLEC2 and upregulation of several metalloproteinases. A marked local upregulation of both PD-1 and PD-L1, a concomitant FoxP3-positive lymphocytic infiltrate, a loss of E-cadherin, gain of epithelial-mesenchymal transition (EMT) phenotype and extreme poor differentiation at histology were also present. Upregulated microRNA in fast-growing HCCs are associated with TGF-β signaling, angiogenesis and inflammation. Our data show that fast HCCs are characterized not only by redundant neo-angiogenesis but also by unique features of distinctively immunosuppressed microenvironment, prominent EMT, and clear-cut activation of TGFβ1 signaling in a general background of long-standing and permanent inflammatory state
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