2,082 research outputs found

    Magneto-Dielectric Effect in the S = 1/2 Quasi-Two Dimensional Antiferromagnet K2V3O8

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    We report the optical and magneto-optical properties of K2V3O8, an S=1/2 quasi-two-dimensional Heisenberg antiferromagnet. Local spin density approximation electronic structure calculations are used to assign the observed excitations and analyze the field dependent features. Two large magneto-optical effects, centered at ~1.19 and 2.5 eV, are attributed to field-induced changes in the V 4+ d to d on-site excitations due to modification of the local crystal field environment of the VO5 square pyramids with applied magnetic field. Taken together, the evidence for a soft lattice, the presence of vibrational fine structure on the sharp 1.19 eV magneto-optical feature,and the fact that these optical excitations are due to transitions from a nearly pure spin polarized V d state to hybridized states involving both V and O, suggest that the magneto-dielectric effect in K2V3O8 is driven by strong lattice coupling.Comment: Zipped file containing 8 pages, 12 figures, in press PR

    Assessing gender mainstreaming in the education sector: depoliticised technique or a step towards women's rights and gender equality?

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    In 1995 the Beijing Conference on Women identified gender mainstreaming as a key area for action. Policies to effect gender mainstreaming have since been widely adopted. This special issue of Compare looks at research on how gender mainstreaming has been used in government education departments, schools, higher education institutions, international agencies and NGOs .1 In this introduction we first provide a brief history of the emergence of gender mainstreaming and review changing definitions of the term. In the process we outline some policy initiatives that have attempted to mainstream gender and consider some difficulties with putting ideas into practice, particularly the tensions between a technical and transformative interpretations . Much of the literature about experiences with gender mainstreaming tends to look at organizational processes and not any specificities of a particular social sector. However, in our second section, we are concerned to explore whether institutional forms and particular actions associated with education give gender mainstreaming in education sites some distinctive features. In our last section we consider some of the debates about global and local negotiations in discussions of gender policy and education and the light this throws on gender mainstreaming. In so doing, we place the articles that follow in relation to contestations over ownership, political economy, the form and content of education practice and the social complexity of gender equality

    The origin of aubrites: Evidence from lithophile trace element abundances and oxygen isotope compositions

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    We report the abundances of a selected set of “lithophile” trace elements (including lanthanides, actinides and high field strength elements) and high-precision oxygen isotope analyses of a comprehensive suite of aubrites. Two distinct groups of aubrites can be distinguished: (a) the main-group aubrites display flat or light-REE depleted REE patterns with variable Eu and Y anomalies; their pyroxenes are light-REE depleted and show marked negative Eu anomalies; (b) the Mount Egerton enstatites and the silicate fraction from Larned display distinctive light-REE enrichments, and high Th/Sm ratios; Mount Egerton pyroxenes have much less pronounced negative Eu anomalies than pyroxenes from the main-group aubrites. Leaching experiments were undertaken to investigate the contribution of sulfides to the whole rock budget of the main-group aubrites. Sulfides contain in most cases at least 50% of the REEs and of the actinides. Among the elements we have analyzed, those displaying the strongest lithophile behaviors are Rb, Ba, Sr and Sc. The homogeneity of the Δ17O values obtained for main-group aubrite falls [Δ17O = +0.009 ± 0.010‰ (2σ)] suggests that they originated from a single parent body whose differentiation involved an early phase of large-scale melting that may have led to the development of a magma ocean. This interpretation is at first glance in agreement with the limited variability of the shapes of the REE patterns of these aubrites. However, the trace element concentrations of their phases cannot be used to discuss this hypothesis, because their igneous trace-element signatures have been modified by subsolidus exchange. Finally, despite similar O isotopic compositions, the marked light-REE enrichments displayed by Mount Egerton and Larned suggest that they are unrelated to the main-group aubrites and probably originated from a distinct parent body

    Transformation and scattering activities of the receptor tyrosine kinase RON/Stk in rodent fibroblasts and lack of regulation by the jaagsiekte sheep retrovirus receptor, Hyal2

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    BACKGROUND: The envelope (Env) protein of jaagsiekte sheep retrovirus (JSRV) can transform cells in culture and is likely to be the main factor responsible for lung cancer induction by JSRV in animals. A recent report indicates that the epithelial-cell transforming activity of JSRV Env depends on activation of the cell-surface receptor tyrosine kinase Mst1r (called RON for the human and Stk for the rodent orthologs). In the immortalized line of human epithelial cells used (BEAS-2B cells), the virus receptor Hyal2 was found to bind to and suppress the activity of RON. When Env was expressed it bound to Hyal2 causing its degradation, release of RON activity from Hyal2 suppression, and activation of pathways resulting in cell transformation. METHODS: Due to difficulty with reproducibility of the transformation assay in BEAS-2B cells, we have used more tractable rodent fibroblast models to further study Hyal2 modulation of RON/Stk transforming activity and potential effects of Hyal2 on RON/Stk activation by its natural ligand, macrophage stimulating protein (MSP). RESULTS: We did not detect transformation of NIH 3T3 cells by plasmids expressing RON or Stk, but did detect transformation of 208F rat fibroblasts by these plasmids at a very low rate. We were able to isolate 208F cell clones that expressed RON or Stk and that showed changes in morphology indicative of transformation. The parental 208F cells did not respond to MSP but 208F cells expressing RON or Stk showed obvious increases in scattering/transformation in response to MSP. Human Hyal2 had no effect on the basal or MSP-induced phenotypes of RON-expressing 208F cells, and human, mouse or rat Hyal2 had no effect on the basal or MSP-induced phenotypes of Stk-expressing 208F cells. CONCLUSIONS: We have shown that RON or Stk expression in 208F rat fibroblasts results in a transformed phenotype that is enhanced by addition of the natural ligand for these proteins, MSP. Hyal2 does not directly modulate the basal or MSP-induced RON/Stk activity, although it is possible that adaptor proteins might mediate such signaling in other cell types

    "Can't live willingly": A thematic synthesis of qualitative evidence exploring how early marriage and early pregnancy affect experiences of pregnancy in South Asia.

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    In South Asia, early marriage has been associated with a range of adverse outcomes during pregnancy and infancy. This may partly be explained by early marriage leading to a younger maternal age, however it remains unclear which other factors are involved. This review aimed to synthesise the qualitative evidence on experiences of pregnancy following early marriage or early pregnancy in South Asia, to inform our understanding of the mechanisms between early marriage and adverse pregnancy outcomes. We searched MEDLINE, EMBASE, Scopus, Global Index Medicus, CINAHL, PsycINFO, Web of Science, and grey literature on 29/11/2022 to identify papers on experiences of pregnancy among those who married or became pregnant early in South Asia (PROSPERO registration number: CRD42022304336, funded by an MRC doctoral training grant). Seventy-nine papers from six countries were included after screening. We appraised study quality using an adapted version of the Critical Appraisal Skills Programme tool for qualitative research. Reporting of reflexivity and theoretical underpinnings was poor. We synthesised findings thematically, presenting themes alongside illustrative quotes. We categorised poor pregnancy experiences into: care-seeking challenges, mental health difficulties, and poor nutritional status. We identified eight inter-connected themes: restrictive social hierarchies within households, earning social position, disrupted education, social isolation, increased likelihood of and vulnerability to abuse, shaming of pregnant women, normalisation of risk among younger women, and burdensome workloads. Socioeconomic position and caste/ethnic group also intersected with early marriage to shape experiences during pregnancy. While we found differences between regions, the heterogeneity of the included studies limits our ability to draw conclusions across regions. Pregnancy experiences are largely determined by social hierarchies and the quality of relationships within and outside of the household. These factors limit the potential for individual factors, such as education and empowerment, to improve experiences of pregnancy for girls married early

    Lung adenocarcinoma originates from retrovirus infection of proliferating type 2 pneumocytes during pulmonary post-natal development or tissue repair

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    Jaagsiekte sheep retrovirus (JSRV) is a unique oncogenic virus with distinctive biological properties. JSRV is the only virus causing a naturally occurring lung cancer (ovine pulmonary adenocarcinoma, OPA) and possessing a major structural protein that functions as a dominant oncoprotein. Lung cancer is the major cause of death among cancer patients. OPA can be an extremely useful animal model in order to identify the cells originating lung adenocarcinoma and to study the early events of pulmonary carcinogenesis. In this study, we demonstrated that lung adenocarcinoma in sheep originates from infection and transformation of proliferating type 2 pneumocytes (termed here lung alveolar proliferating cells, LAPCs). We excluded that OPA originates from a bronchioalveolar stem cell, or from mature post-mitotic type 2 pneumocytes or from either proliferating or non-proliferating Clara cells. We show that young animals possess abundant LAPCs and are highly susceptible to JSRV infection and transformation. On the contrary, healthy adult sheep, which are normally resistant to experimental OPA induction, exhibit a relatively low number of LAPCs and are resistant to JSRV infection of the respiratory epithelium. Importantly, induction of lung injury increased dramatically the number of LAPCs in adult sheep and rendered these animals fully susceptible to JSRV infection and transformation. Furthermore, we show that JSRV preferentially infects actively dividing cell in vitro. Overall, our study provides unique insights into pulmonary biology and carcinogenesis and suggests that JSRV and its host have reached an evolutionary equilibrium in which productive infection (and transformation) can occur only in cells that are scarce for most of the lifespan of the sheep. Our data also indicate that, at least in this model, inflammation can predispose to retroviral infection and cancer

    An observational review of accretion-driven millisecond X-ray pulsars

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    I present an observational review of the five currently known accretion-driven millisecond X-ray pulsars. A prominent place in this review is given to SAX J1808.4-3658; it was the first such system discovered and currently four outbursts have been observed from this source. This makes SAX J1808.4-3658 the best studied example of the group. Its most recent outburst in October 2002 is of particular interest because of the discovery of two simultaneous kilohertz quasi-periodic oscillations and nearly coherent oscillations during type-I X-ray bursts. This is the first time that such phenomena are observed in a system for which the neutron star spin frequency is exactly known. The other four systems were discovered within the last two years and only limited results have been published. Since new exiting results are to be expected in the future for all five sources, this review will only represent a snap-shot of the current observational knowledge of accretion-driven millisecond X-ray pulsars. A more extended and fully up-to-date review can be found at http://zon.wins.uva.nl/~rudy/admxp/.Comment: To appear in the Proceedings of the Symposium "The Restless High-Energy Universe", 5-8 May 2003, Amsterdam, The Netherlands, E.P.J. van den Heuvel, J.J.M. in 't Zand, and R.A.M.J. Wijers Eds. A more extended and always fully-up-to-date version of this review can be found at http://zon.wins.uva.nl/~rudy/admxp

    Does Hypercapnic Acidosis, induced by Adding CO2 to Inspired Gas, Have Protective Effect in a Ventilator-induced Lung Injury?

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    To investigate whether hypercapnic acidosis, induced by adding CO2 to inspired gas, would be protective effect against ventilator-induced lung injury (VILI), we ventilated 55 normal white rabbits for 6 hr or until PaO2/FIO2 <200 mmHg. Control group (n=15) was ventilated with peak inspiratory pressure (PIP) of 15 cm H2O, positive end-expiratory pressure (PEEP) of 3 cm H2O, an inspiration-to-expiration ratio of 1:2, and an inspired oxygen fraction (FIO2) of 0.40. High pressure hypercapnic group (HPHC; n=20) was ventilated with PIP of 30 cm H2O, PEEP of 0 cm H2O, and FIO2 of 0.40. Carbon dioxide was introduced into the inspiratory limb of the ventilator circuit, as necessary to maintain hypercapnia (PaCO2, 65 to 75 mmHg). High pressure normocapnic group (HPNC; n=20) was ventilated with same setting of HPHC, except normocapnia (PaCO2, 35 to 45 mmHg). Bronchoalveolar lavage fluid (BALF) lactate dehydrogenase, aspartate aminotransferase, interleukin-8 were significantly higher in high pressure ventilator group than control group (p<0.05). Wet weight to dry weight (WW/DW) and histologic scores were significantly higher in high pressure ventilator group than control group (p<0.05). However, there were no significant differences in oxygenation, BALF inflammatory markers, WW/DW and histologic scores between HPHC and HPNC groups. These findings suggest that hypercapnic acidosis at least induced by CO2 insufflation would not be protective effect against VILI in this model

    Rand Patents and Exclusion Orders: Submission of 19 Economics and Law Professors to the International Trade Commission

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    In this comment to ITC Investigation 337-TA-745 (Certain Wireless Communication Devices, Motorola v. Apple) we, as teachers and scholars of economics, antitrust and intellectual property, remedies, administrative, and international intellectual property law, former Department of Justice lawyers and chief economists, a former executive official at the Patent and Trademark Office, a former counsel at the ITC Office of the General Counsel, and a former Member of the President’s Council of Economic Adviser take the position that ITC exclusion orders generally should not be granted under § 1337(d)(1) on the basis of patents subject to obligations to license on “reasonable and non-discriminatory” (RAND) terms. Doing so would undermine the significant pro-competitive and pro-consumer benefits that RAND promises produce and the investments they enable. A possible exception may arise if district court jurisdiction is lacking, the patent is valid and infringed, and the public interest favors issuing an exclusion order. We explain our position in the comment

    Assessment of macro-micro element accumulation capabilities of Elodea nuttallii under gradient redox statuses with elevated NH4-N concentrations

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    Aquatic plants often encounter various redox conditions in their natural environment. Elodea nuttallii (Planch.), a submerged aquatic macrophyte, has a flexile ability to use different nutrient sources from various environments. In the present study, Elodea nuttallii was subjected to various redox conditions (+400 mV to –180 mV) at both normal (2.5 ppm) and high (10 ppm) ammonium concentrations and evaluated for macro and micro element accumulation. A reduced environment was prepared by adding glucose to growth medium and nitrogen gas bubbling, while an oxic environment was executed by atmospheric air bubbling. Plants in oxygen-deprived conditions manifested heavy metal (HM) toxicity, such as reduction of biomass and photosynthetic pigments, excess generation of reactive oxygen species (ROS), lipid peroxidation and reduction of major macro elements. In reduced treatments, the bioaccumulation sequence for micro elements was Cu>Mn>Zn>Al>Cd>Fe>Pb at both normal and high NH4-N concentrations. The combined effect of low redox state and high ammonium concentration had a strong physiological impact on the submerged macrophyte. However, macro- and micronutrient accumulation was more significantly affected by reduced environment than by a high NH4-N concentratio
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