116 research outputs found

    A note on quasi-Gorenstein rings

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    In this paper, after giving a criterion for a Noetherian local ring to be quasi-Gorenstein, we obtain some sufficient conditions for a quasi- Gorenstein ring to be Gorenstein. In the course, we provide a slight generalization of a theorem of Evans and Griffith.Comment: To appear in Arch. Mat

    Possible mechanism(s) for relaxant effect of aqueous and macerated extracts from Nigella sativa on tracheal chains of guinea pig

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    BACKGROUND: In previous studies, the relaxant, anticholinergic (functional antagonism) and antihistaminic effects of Nigella sativa have been demonstrated on guinea pig tracheal chains. To elucidate the other mechanisms responsible for the relaxant effect of this plant, its inhibitory effect on the calcium channel was examined in this study. RESULTS: The inhibitory effects of both concentrations of diltiazem in all three groups of experiments were significantly greater than those of saline (p < 0.01 to P < 0.001). The inhibitory of two larger concentrations of aqueous extracts in group 1 and 2 were significantly greater than those of saline (p < 0.01 to P < 0.001). The effect of two larger concentrations of macerated extract in group 1 and all concentrations of this extract in group 2 were also significantly greater than those of saline (p < 0.01 to P < 0.001). However, the extract of Nigella sativa did not show any inhibitory effect in group 3. There was a significant correlation between inhibitory effect and increasing concentrations for both extracts and diltiazem in groups 1 and 2 (p < 0.05 to p < 0.005). CONCLUSION: Although the extracts of Nigella sativa showed inhibitory effects on pre-contracted tracheal chains in the presence of both ordinary and calcium free Krebs solution, the absence of inhibitory effects of the extracts on KCl induced contraction of tracheal chains suggest that the calcium channel blocking effect of this plant dose not contribute to the relaxant effect of this plant on the tracheal chains of guinea pigs

    Scenario analysis for integrated water resources management under future land use change in the Urmia Lake region, Iran

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    Arid and semi-arid regions are particularly vulnerable to global environmental change because of their fragile climatic conditions. The rapid development of land use is expected to affect aquatic ecosystems in these regions. In this study, we focused on how land use change affects the stream flow and inflow to Urmia Lake in the Mordagh Chay basin, Iran. This case-study exemplifies dynamics found across a much larger region. We mapped changes in land use between 1993–2015 using satellite imagery and modeled future changes using the Dyna-CLUE model. We projected future land use change until 2030 under four scenarios: continuing of the current trend of water use, 40% water withdrawal reduction, and two other scenarios with 40% water withdrawal reduction and improvements of irrigation efficiency up to 50% and 85%. Between 1993–2015, 21% of the study area changed to orchard and arable land mostly at the cost of rangeland. However, upon reduction of water withdrawal our analyses showed that garden must decrease between 27% and 40%. Rainfed cropland is projected to experience a major increase in all scenarios, especially in the case of reduced water withdrawal, where it will increase by 217%. In order to achieve sustainable water resources management land use plays a major role and leads to different land use futures in this type of semi-arid regions

    Impacts of future climate and land use change on water yield in a semi‐arid basin in Iran

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    Studying the interaction between hydrology, land use and climate change is necessary to support sustainable water resources management. It is unknown how land management interventions in dry climate conditions can benefit water yield in the context of climate and land use change interactions. In this study, we assessed the effects of both land use and climate change on the Mordagh Chay basin water yield using the Integrated Valuation Ecosystem Service and Tradeoffs model (InVEST). First, we modelled the current water yield, followed by developing six combined climate‐land use scenarios until 2030 based on the CCSM4 climate model for the RCP4.5 and RCP8.5 scenarios. We used three future land use scenarios simulated by the Dyna‐CLUE model. The trend scenario of land use change, which does not include any improvements in irrigation efficiency, significantly affected basin water yield under both climate scenarios. Water yield decreases by 19.8% and 31.8% for the RCP4.5 and RCP8.5, respectively. Under all land use scenarios that included improvements in irrigation efficiency the water yield responded positively. For the RCP4.5 scenario, the water yield was projected to increase between 16.6 and 18% depending on the land use scenario. The increase in water yield under the RCP8.5 climate scenario was much lower than for the RCP4.5 scenario (about one third). Overall, the results showed that by adopting appropriate irrigation efficiency, it is possible to achieve a better balance between environmental needs, regional economic and agricultural development. The results provide insight into possible sustainable development options and also provide guidance for managing the other Urmia Lake sub‐basins while the approach of integrated assessment of climate, land use change and land management options is also applicable in other conditions to help inform sustainable management

    L-systems in Geometric Modeling

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    We show that parametric context-sensitive L-systems with affine geometry interpretation provide a succinct description of some of the most fundamental algorithms of geometric modeling of curves. Examples include the Lane-Riesenfeld algorithm for generating B-splines, the de Casteljau algorithm for generating Bezier curves, and their extensions to rational curves. Our results generalize the previously reported geometric-modeling applications of L-systems, which were limited to subdivision curves.Comment: In Proceedings DCFS 2010, arXiv:1008.127

    Comparison of the oxidative potential of primary (POA) and secondary (SOA) organic aerosols derived from α-pinene and gasoline engine exhaust precursors [version 2; referees: 2 approved]

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    Background: Primary (POA) and secondary (SOA) organic aerosols, deriving from both anthropogenic and biogenic sources, represent a major fraction of ambient particulate matter (PM) and play an important role in the etiology of respiratory and cardiovascular diseases, largely through systemic inflammation and cellular oxidative stress. The relative contributions of these species to the inhalation burden, however, are rather poorly characterized. In this study, we measured the in vitro oxidative stress response of alveolar macrophages exposed to primary and secondary PM derived from both anthropogenic and biogenic sources. Methods: POA and SOA were generated within an oxidation flow reactor (OFR) fed by pure, aerosolized α-pinene or gasoline engine exhaust, as representative emissions of biogenic and anthropogenic sources, respectively. The OFR utilized an ultraviolet (UV) lamp to achieve an equivalent atmospheric aging process of several days. Results: Anthropogenic SOA produced the greatest oxidative response (1900 ± 255 µg-Zymosan/mg-PM), followed by biogenic (α-pinene) SOA (1321 ± 542 µg-Zymosan/mg-PM), while anthropogenic POA produced the smallest response (51.4 ± 64.3 µg-Zymosan/mg-PM). Conclusions: These findings emphasize the importance of monitoring and controlling anthropogenic emissions in the urban atmosphere, while also taking into consideration spatial and seasonal differences in SOA composition. Local concentrations of biogenic and anthropogenic species contributing to the oxidative potential of ambient PM may vary widely, depending on the given region and time of year, due to factors such as surrounding vegetation, proximity to urban areas, and hours of daylight

    Comparison of the oxidative potential of primary (POA) and secondary (SOA) organic aerosols derived from α-pinene and gasoline engine exhaust precursors [version 1; referees: 2 approved]

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    Background: Primary (POA) and secondary (SOA) organic aerosols, deriving from both anthropogenic and biogenic sources, represent a major fraction of ambient particulate matter (PM) and play an important role in the etiology of respiratory and cardiovascular diseases, largely through systemic inflammation and cellular oxidative stress. The relative contributions of these species to the inhalation burden, however, are rather poorly characterized. In this study, we measured the in vitro oxidative stress response of alveolar macrophages exposed to primary and secondary PM derived from both anthropogenic and biogenic sources. Methods: POA and SOA were generated within an oxidation flow reactor (OFR) fed by pure, aerosolized α-pinene or gasoline engine exhaust, as representative emissions of biogenic and anthropogenic sources, respectively. The OFR utilized an ultraviolet (UV) lamp to achieve an equivalent atmospheric aging process of several days. Results: Anthropogenic SOA produced the greatest oxidative response (1900 ± 255 µg-Zymosan/mg-PM), followed by biogenic (α-pinene) SOA (1321 ± 542 µg-Zymosan/mg-PM), while anthropogenic POA produced the smallest response (51.4 ± 64.3 µg-Zymosan/mg-PM). Conclusions: These findings emphasize the importance of monitoring and controlling anthropogenic emissions in the urban atmosphere, while also taking into consideration spatial and seasonal differences in SOA composition. Local concentrations of biogenic and anthropogenic species contributing to the oxidative potential of ambient PM may vary widely, depending on the given region and time of year, due to factors such as surrounding vegetation, proximity to urban areas, and hours of daylight

    Identification of biomolecule mass transport and binding rate parameters in living cells by inverse modeling

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    BACKGROUND: Quantification of in-vivo biomolecule mass transport and reaction rate parameters from experimental data obtained by Fluorescence Recovery after Photobleaching (FRAP) is becoming more important. METHODS AND RESULTS: The Osborne-Moré extended version of the Levenberg-Marquardt optimization algorithm was coupled with the experimental data obtained by the Fluorescence Recovery after Photobleaching (FRAP) protocol, and the numerical solution of a set of two partial differential equations governing macromolecule mass transport and reaction in living cells, to inversely estimate optimized values of the molecular diffusion coefficient and binding rate parameters of GFP-tagged glucocorticoid receptor. The results indicate that the FRAP protocol provides enough information to estimate one parameter uniquely using a nonlinear optimization technique. Coupling FRAP experimental data with the inverse modeling strategy, one can also uniquely estimate the individual values of the binding rate coefficients if the molecular diffusion coefficient is known. One can also simultaneously estimate the dissociation rate parameter and molecular diffusion coefficient given the pseudo-association rate parameter is known. However, the protocol provides insufficient information for unique simultaneous estimation of three parameters (diffusion coefficient and binding rate parameters) owing to the high intercorrelation between the molecular diffusion coefficient and pseudo-association rate parameter. Attempts to estimate macromolecule mass transport and binding rate parameters simultaneously from FRAP data result in misleading conclusions regarding concentrations of free macromolecule and bound complex inside the cell, average binding time per vacant site, average time for diffusion of macromolecules from one site to the next, and slow or rapid mobility of biomolecules in cells. CONCLUSION: To obtain unique values for molecular diffusion coefficient and binding rate parameters from FRAP data, we propose conducting two FRAP experiments on the same class of macromolecule and cell. One experiment should be used to measure the molecular diffusion coefficient independently of binding in an effective diffusion regime and the other should be conducted in a reaction dominant or reaction-diffusion regime to quantify binding rate parameters. The method described in this paper is likely to be widely used to estimate in-vivo biomolecule mass transport and binding rate parameters
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