2,902 research outputs found

    Assessing the tilt of the solar magnetic field axis through Faraday rotation observations

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    Context: Faraday rotation measurements of extragalactic radio sources during coronal occultation allow assessment of both the electron density distribution and the three-dimensional magnetic field topology in the outer solar corona. Aims: We simulate the three-dimensional structure of both the coronal magnetic field and the electron density distribution in order to reproduce the excess Faraday rotation measures (RMs) of the occulted radio sources observed during solar activity minimum. In particular, we infer the tilt of the solar magnetic axis with respect to the rotation axis. Methods: We compare the output of the model with Very Large Array (VLA) radio polarimetric measurements of a sample of extragalactic sources observed in May 1997. Information on the magnetic field geometry can be retrieved by fine-tuning the set of model free parameters that best describe the observations. Results: We find that predicted and observed Faraday rotation measures are in excellent agreement, thus supporting the model. Our best-fitting model yields a tilt angle ΞRB=3.3∘\theta_{RB}=3.3^{\circ} of the solar magnetic axis with respect to the solar rotation axis around Carrington Rotation 1923. This result is consistent with analogous but independent estimates computed from the expansion coefficients of the photospheric field observed at the Wilcox Solar Observatory (WSO).Comment: 8 pages, 5 figures, accepted for publication in A&

    YOUNG WOMEN’S NARRATIVES OF DECISION-MAKING ABOUT HUMAN PAPILLOMAVIRUS VACCINATION

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    This thesis examines young women’s decision-making regarding Human Papillomavirus (HPV) vaccination. Using a narrative approach, five young women were asked to share their stories of how they came to be or not be vaccinated. Two in-depth interviews were used to elicit participants’ stories, and an overall narrative for each young woman was constructed. The five individual narratives reveal a number of themes that capture the diversity of young women’s decision-making experiences and point to the complex ways in which young women are negotiating decisions regarding vaccination. Within this thesis, I take a critical stance on the topic of HPV vaccine decision-making in order to illuminate how young women’s decisions are embedded within broader social and discursive contexts. This critical approach to understanding participant narratives was informed by a strong sensitivity to conceptual frames of medicalization, healthism, and neo-medicalization and dominant discourses related to health risk and individual responsibility

    The radial profile of the inner heliospheric magnetic field as deduced from Faraday rotation observations

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    Faraday rotation measures (RMs) of the polarized emission from extragalactic radio sources occulted by the coronal plasma were used to infer the radial profile of the inner heliospheric magnetic field near solar minimum activity. By inverting LASCO/SOHO polarized brightness (pB) data taken during the days of observations on May 1997, we retrieved the electron density distribution along the lines of sight to the sources, thus allowing to disentangle the two plasma properties that contribute to the observed RMs. By comparing the observed RM values to those theoretically predicted by a power-law model of the radial component of the coronal magnetic field, using a best-fitting procedure, we found that the radial component of the inner heliospheric magnetic field can be nicely approximated by a power-law of the form B_r = 3.76 r^{-2.29} G in a range of heights from about 5 to 14 solar radii. Finally, our analysis suggests that the radial computation of the potential field source surface (PFSS) model from the Wilcox Solar Observatory (WSO), assuming a radial field in the photosphere and a source surface located at R_{ss} = 2.5 solar radii, is the preferred choice near solar minimum.Comment: 17 pages, 5 figures, submitted for publication in A&

    Microcephaly and macrocephaly. A study on anthropometric and clinical data from 308 subjects

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    Head circumference is the auxological parameter that most correlates with developmental anomalies in childhood. Head circumference (HC) two standard deviations (SD) below or above the mean defines microcephaly and macrocephaly, respectively. The aim of this retrospective study was to explore anthropometric parameters and clinical characteristics among subjects with abnormalities in HC who had been referred for developmental assessment. One hundred and sixty four subjects with microcephaly and 144 subjects with macrocephaly were enrolled from birth to 18 months of age. Head circumference at birth and the association with variables related to maternal health status, gestational age, growth pattern, brain imaging and clinical characteristics were analyzed. In some cases, an etiological diagnosis was made. In the two considered conditions, we found different anthropometric and clinical associations, some of which were statistically significant, with implications for ongoing neurodevelopmental surveillance

    5-(carbamoylmethylene)-oxazolidin-2-ones as a promising class of heterocycles inducing apoptosis triggered by increased ROS levels and mitochondrial dysfunction in breast and cervical cancer

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    Oxazolidinones are antibiotics that inhibit protein synthesis by binding the 50S ribosomal subunit. Recently, numerous worldwide researches focused on their properties and possible involvement in cancer therapy have been conducted. Here, we evaluated in vitro the antiproliferative activity of some 5-(carbamoylmethylene)-oxazolidin-2-ones on MCF-7 and HeLa cells. The tested compounds displayed a wide range of cytotoxicity on these cancer cell lines, measured by MTT assay, exhibiting no cytotoxicity on non-tumorigenic MCF-10A cells. Among the nine tested derivatives, four displayed a good anticancer potential. Remarkably, OI compound showed IC50 values of 17.66 and 31.10 ”M for MCF-7 and HeLa cancer cells, respectively. Furthermore, we assessed OI effect on the cell cycle by FACS analysis, highlighting a G1 phase arrest after 72 h, supported by a low expression level of Cyclin D1 protein. Moreover, mitochondrial membrane potential was reduced after OI treatment driven by high levels of ROS. These findings demonstrate that OI treatment can inhibit MCF-7 and HeLa cell proliferation and induce apoptosis by caspase-9 activation and cytochrome c release in the cytosol. Hence, 5-(carbamoylmethylene)-oxazolidin-2-ones have a promising anticancer activity, in particular, OI derivative could represent a good candidate for in vivo further studies and potential clinical use

    Teacher Retention in American Schools in the East Asia Region: Salary and Leadership Are Key

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    The purpose of this study was (a) to track teacher turnover in the East Asian Region Consortium of Schools (EARCOS) and (b) to create a model to explain teacher turnover. We received responses from 32 school heads and 744 teachers in EARCOS schools. The average turnover rate was 32% from 2009 to 2010. The most important correlates of turnover were satisfaction with salary and the perception of a supportive principal. Teachers’ age was also a significant predictor of turnover. Characteristics that defined teachers’ perceptions of supportive leadership were consistent with definitions of transformational and distributed leadership

    The Development and Validation of the Comprehensive Intellectual Humility Scale

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    A series of studies was conducted to create the 22-item Comprehensive Intellectual Humility Scale on the basis of theoretical descriptions of intellectual humility, expert reviews, pilot studies, and exploratory and confirmatory factor analyses. The scale measures 4 distinct but intercorrelated aspects of intellectual humility, including independence of intellect and ego, openness to revising one\u27s viewpoint, respect for others\u27 viewpoints, and lack of intellectual overconfidence. Internal consistency and test-retest analyses provided reliable scale and subscale scores within numerous independent samples. Validation data were obtained from multiple, independent samples, supporting appropriate levels of convergent, discriminant, and predictive validity. The analyses suggest that the scale has utility as a self-report measure for future research

    Fluvial and eolian ichnofaunas from the Lower Permian of South America (PatquĂ­a Formation, Paganzo Basin)

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    The Lower Permian PatquĂ­a Formation is the youngest unit of the Paganzo Basin, western Argentina. The lower section consists of red mudstones, and fine- and coarse-grained sandstones deposited in fluvial systems with extensive and thick floodplain deposits. These rocks contain a low-diversity and relatively abundant association of trace fossils suggesting the activity of a sub-superficial to superficial fauna. The association is characterized by Rusophycus carbonarius (Cubichnia), Cruziana problematica (Repichnia), and Palaeophycus tubularis (Domichnia) of the Scoyenia ichnofacies. Disarticulated fish remains are also present. The upper section is dominated by red, cross-bedded, medium- to fine-grained sandstones deposited in eolian systems that host a lowdiversity and low-abundance association of trace fossils that indicates the activity of a mainly superficial fauna. Tetrapod footprints (Chelichnus duncani, oval digit imprints, short parallel grooves, and sinusoidal grooves), horizontal to vertical burrows (Palaeophycus tubularis and Skolithos isp. respectively), and arthropod trackways are the typical components of these deposits. The association shows elements of the three presently proposed eolian ichnofacies (Chelichnus, Octopodichnus and Entradichnus ichnofacies) suggesting the necessity of revision and the possible integration of these separate ichnofacies into a single model. The record of fossil vertebrate tracks is uncommon in Lower Permian strata of South America. Therefore, the ichnologic record of the PatquĂ­a Formation is a significant contribution to the understanding of Lower Permian South American ichnofaunas

    Behavior of N-Doped TiO2 and N-Doped ZnO in Photocatalytic Azo Dye Degradation under UV and Visible Light Irradiation: A Preliminary Investigation

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    Abstract: N-doped TiO2 (N-TiO2) and N-doped ZnO (N-ZnO) were synthesized utilizing ammonia as a dopant source. The chemico-physical characteristics of synthesized samples were studied by Raman spectroscopy, X-ray diffraction, SEM analysis, N2 adsorption–desorption at −196 ◩C, and diffuse reflectance spectroscopy. Compared to undoped samples, the introduction of nitrogen in the semiconductor lattice resulted in a shift of band-gap energy to a lower value: 3.0 eV for N-ZnO and 2.35 eV for N-TiO2. The photocatalysts were tested for the degradation of Eriochrome Black T (EBT), which was selected as a model azo dye. Both N-doped semiconductors evidenced an improvement in photocatalytic activity under visible light irradiation (62% and 20% EBT discoloration for N-TiO2 and N-ZnO, respectively) in comparison with the undoped samples, which were inactive in the presence of visible light. Different behavior was observed under UV irradiation. Whereas N-TiO2 was more photoactive than commercial undoped TiO2, the introduction of nitrogen in ZnO wurtzite resulted in a drastic reduction in photocatalytic activity, with only 45% EBT discoloration compared to total color removal obtained with the commercial ZnO sample, suggesting intrinsic limitations for doping of this class of semiconductors
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