1,576 research outputs found

    The O(3P) and N(4S) density measurement at 225 km by ultraviolet absorption and fluorescence in the Apollo-Soyuz test project

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    The densities of O(3P) and N(4S) at 225 km were determined during the Apollo Soyuz Test Project by a resonance absorption/fluorescence technique in which OI and NI line radiation produced and collimated on board the Apollo was reflected from the Soyuz back to the Apollo for spectral analysis. The two spacecraft maneuvered so that a range of observation angles of plus or minus 15 deg with respect to the normal to the orbital velocity vector was scanned. The measurements were made at night on two consecutive orbits at spacecraft separations of 150 and 500 m. The resulting relative counting rates as function of observation angle were compared to calculated values to determine the oxygen value. This value agrees with mass spectrometric measurements made under similar conditions. The nitrogen value is in good agreement with other measurements and suggests a smaller diurnal variation than is predicted by present models

    Anti-tumor activities of lipids and lipid analogues and their development as potential anticancer drugs

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    © 2015 Elsevier Inc. All rights reserved. Lipids have the potential for development as anticancer agents. Endogenous membrane lipids, such as ceramides and certain saturated fatty acids, have been found to modulate the viability of tumor cells. In addition, many tumors over-express cyclooxygenase, lipoxygenase or cytochrome P450 enzymes that mediate the biotransformation of ω-6 polyunsaturated fatty acids (PUFAs) to potent eicosanoid regulators of tumor cell proliferation and cell death. In contrast, several analogous products from the biotransformation of ω-3 PUFAs impair particular tumorigenic pathways. For example, the ω-3 17,18-epoxide of eicosapentaenoic acid activates anti-proliferative and proapoptotic signaling cascades in tumor cells and the lipoxygenase-derived resolvins are effective inhibitors of inflammatory pathways that may drive tumor expansion. However, the development of potential anti-cancer drugs based on these molecules is complex, with in vivo stability a major issue. Nevertheless, recent successes with the antitumor alkyl phospholipids, which are synthetic analogues of naturally-occurring membrane phospholipid esters, have provided the impetus for development of further molecules. The alkyl phospholipids have been tested against a range of cancers and show considerable activity against skin cancers and certain leukemias. Very recently, it has been shown that combination strategies, in which alkyl phospholipids are used in conjunction with established anticancer agents, are promising new therapeutic approaches. In future, the evaluation of new lipid-based molecules in single-agent and combination treatments may also be assessed. This could provide a range of important treatment options in the management of advanced and metastatic cancer

    Changing times in England: the influence on geography teachers’ professional practice

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    School geography in England has been characterised as a pendulum swinging between policies that emphasise curriculum and pedagogy alternately. In this paper, I illustrate the influence of these shifts on geography teacher's professional practice, by drawing on three “moments” from my experience as a student, teacher and teacher educator. Barnett's description of teacher professionalism as a continuous project of “being” illuminates how geography teachers can adapt to competing influences. It reflects teacher professionalism as an unfinished project, which is responsive, but not beholden, to shifting trends, and is informed by how teachers frame and enact policies. I argue that recognising these contextual factors is key to supporting geography teachers in “being” geography education professionals. As education becomes increasingly competitive on a global scale, individual governments are looking internationally for “solutions” to improve educational rankings. In this climate, the future of geography education will rest on how teachers react locally to international trends. Geography teacher educators can support this process by continuing to inform the field through meaningful geography education research, in particular in making the contextual factors of their research explicit. This can be supported through continued successful international collaboration in geography education research

    Probiotic Pediococcus acidilactici modulates both localised intestinal- and peripheral-immunity in tilapia (Oreochromis niloticus).

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    The application of probiotics in aquaculture has received concerted research efforts but the localised intestinal immunological response of fish to probiotic bacteria is poorly understood. Therefore, a study was conducted to evaluate the probiotic effect of Pediococcus acidilactici on Nile tilapia (Oreochromis niloticus) with specific emphasis on intestinal health and probiotic levels as well as system level responses such as growth performance, feed utilization and haemato-immunological parameters under non-challenged conditions. Fish (9.19 ± 0.04 g) were fed either a control diet or a P. acidilactici supplemented diet (at 2.81 × 10(6) CFU g(-)(1)) for six weeks. At the end of the study the probiotic was observed to populate the intestine, accounting for ca. 3% (1.59 × 10(5) CFU g(-)(1)) of the cultivable intestinal bacterial load. Real-time PCR indicated that the probiotic treatment may potentiate the immune-responsiveness of the intestine as up-regulation of the gene expression of the pro-inflammatory cytokine TNFα was observed in the probiotic fed fish (P 0.05)

    Cell-derived microparticles: New targets in the therapeutic management of disease

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    Intercellular communication is essential to maintain vital physiological activities and to regulate the organism's phenotype. There are a number of ways in which cells communicate with one another. This can occur via autocrine signaling, endocrine signaling or by the transfer of molecular mediators across gap junctions. More recently communication via microvesicular shedding has gained important recognition as a significant pathway by which cells can coordinate the spread and dominance of selective traits within a population. Through this communication apparatus, cells can now acquire and secure a survival advantage, particularly in the context of malignant disease. This review aims to highlight some of the functions and implications of microparticles in physiology of various disease states, and present a novel therapeutic strategy through the regulation of microparticle production

    Arene oxidation with malonoyl peroxides

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    Malonoyl peroxide 7, prepared in a single step from the commercially available diacid, is an effective reagent for the oxidation of aromatics. Reaction of an arene with peroxide 7 at room temperature leads to the corresponding protected phenol which can be unmasked by aminolysis. An ionic mechanism consistent with the experimental findings and supported by isotopic labeling, Hammett analysis, EPR investigations and reactivity profile studies is proposed

    Please mind the gap: students’ perspectives of the transition in academic skills between A-level and degree level geography

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    This paper explores first-year undergraduates’ perceptions of the transition from studying geography at pre-university level to studying for a degree. This move is the largest step students make in their education, and the debate about it in the UK has been reignited due to the government’s planned changes to A-level geography. However, missing from most of this debate is an appreciation of the way in which geography students themselves perceive their transition to university. This paper begins to rectify this absence. Using student insights, we show that their main concern is acquiring the higher level skills required for university learning

    PARTICLE-WATER INTERACTIONS OF HYDROPHOBIC ORGANIC MICROPOLLUTANTS IN MARINE SYSTEMS

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    An understanding of the reactivity of hydrophobic organic micropollutants (HOMs) is of paramount importance to water quality managers because of their toxicity, persistence, and liability to bioaccumulate. In this study, the role played by the main estuarine variables (organic matter, suspended particulate matter [SPM], particle type and salinity) on HOM behaviour was investigated by employing samples from estuaries with different geochemical signatures (Chupa, Russia, and the Dart, Plym, Beaulieu and Carnon, U K ) . A laboratory-based technique was developed for the determination of the solubility and sorptive behaviour of HOMs using 14C-labelled, beta-emitting organic compounds (2,2\5,5'-tetrachlorobiphenyl (2,2’5,5'-TCB), bis(2-ethylhexyl)phthalate ester (DEHP), and benzo[a]pyrene (BaP)) coupled with liquid scintillation counting. The results indicate that relative solubility is mainly dependent upon the type of dissolved organic carbon (DOC) present, not its concentration, and is reduced with increasing salinity. The uptake of 2,2’5,5'-TCB and BaP by particles is time dependent with a system response time (the time required to achieve 63% of the new equilibrium) of about 0.37 hours for 2,2',5,5’-TCB and 0.02 hours for BaP. The adsorption, expressed as particle-water partition coefficients, KDS, is to a varying extent dependent on DOC, salinity and particle characteristics (iron/manganese hydroxides, particulate carbon and specific surface area). Adsorption is best defined by a linear isotherm and is enhanced in sea water compared with river water owing to a reduction in charge on particle surfaces at high ionic strengths. This effect has been quantified using an adsorption salting constant, Gp, whose values are typically in the range 0.4-2 L mol-2 The inverse relationship between KD and SPM concentration, an effect well documented in the literature, has been defined by a simple power law (KD = a SPM-b where a and b are site and compound-specific constants). Typical values for a and b are approximately 4x10^ and 0.6 for 2,2',5,5'- TCB, 50x105 and 1.0 for DEHP, and 2x105 and 0.5 for BaP, respectively. Empirical parameterisation of these effects are extremely useful for encoding into numerical transport and distribution models, and their application is demonstrated in this thesis by calculating the retention of HOMs by estuaries.BMT Marine Information Systems Limited Southampto

    Dissolved noble gases and stable isotopes as tracers of preferential fluid flow along faults in the Lower Rhine Embayment, Germany

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    Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low δ2H and δ18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7 × 10−4 cm3 (STP) g–1 ± 2.2 % which is approximately four orders of magnitude higher than expected due to solubility equilibrium with the atmosphere. Groundwater age dating based on estimated in situ production and terrigenic flux of helium provides a groundwater residence time of ∼107 years. Although fluid exchange between the deep basal aquifer system and the upper aquifer layers is generally impeded by confining clay layers and lignite, this study’s geochemical data suggest, for the first time, that deep circulating fluids penetrate shallow aquifers in the locality of fault zones, implying  that sub-vertical fluid flow occurs along faults in the LRE. However, large hydraulic-head gradients observed across many faults suggest that they act as barriers to lateral groundwater flow. Therefore, the geochemical data reported here also substantiate a conduit-barrier model of fault-zone hydrogeology in unconsolidated sedimentary deposits, as well as corroborating the concept that faults in unconsolidated aquifer systems can act as loci for hydraulic connectivity between deep and shallow aquifers. The implications of fluid flow along faults in sedimentary basins worldwide are far reaching and of particular concern for carbon capture and storage (CCS) programmes, impacts of deep shale gas recovery for shallow groundwater aquifers, and nuclear waste storage sites where fault zones could act as potential leakage pathways for hazardous fluids

    Industrial legislation in Australia in 2018

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    © 2019, Australian Labour and Employment Relations Association (ALERA), SAGE Publications Ltd, Los Angeles, London, New Delhi, Singapore and Washington DC. It has been a quiet year like last year for the passing of federal industrial legislation (due to a number of factors, including the political turmoil of the federal coalition government and their lack of an overall labour law reform agenda). This article examines key federal industrial legislative developments including the Modern Slavery Act 2018 (Cth). The article identifies that the federal Act contains much weaker compliance measures than the counterpart New South Wales legislation also passed in 2018 – the Modern Slavery Act 2018 (NSW). Also, although the Coalition government has attempted to continue to prosecute its case for further union governance measures, this agenda has been less successful than in previous years, with key government Bills not yet passed by the Parliament. The stagnation in the federal Parliament continues to motivate certain State Parliaments to address worker exploitation, and the article goes on to examine key State industrial legislation passed in 2018 including the Victorian labour hire licensing statute. In light of the continuing dominant position of the federal Labor opposition in opinion polls and an impending federal election in 2019, the article concludes by briefly considering the federal Labor opposition's agenda for industrial legislation
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