247 research outputs found
Intifada 3.0? Cyber colonialism and Palestinian resistance
Palestine âexistsâ on Google and increasingly in various other âvirtualâ ways. But are âPalestineâ on Google or the acquisition of the google.ps domain name in 2009 examples of political resistance on the internet? For Palestinian politicians, virtual presence has historical significance.
Consider, for example, the Ministry of Telecommunications and Information Technologyâs (MTIT) suggestion that âICTs information and communications technology] contribute directly to the national goal of establishing and building an independent state.â3 Within that context, Sabri Saydam, adviser to Palestinian Authority (PA) president Mahmoud Abbas and a former MTIT minister himself, posited Googleâs 2013 move as âa step towards...liberation.â 4 For Israeli politicians, as quoted above, the emergence of (a virtual) âPalestineâ poses ideological and practical dangers. Both camps ascribe power to the internet. Their only disagreement is over the ends to which the internet is a means: The internet is a threat to the existence of the state of Israel or a step toward a future state. At heart, however, both views are a form of technological determinism. They remove the internet from human, historical, and geopolitical contexts, and posit it as agent of political, social, or economic change. We contend that neither position is valid
Ozone Anomalies in Dry Intrusions Associated with Atmospheric Rivers
As a result of their important role in weather and the global hydrological
cycle, understanding atmospheric rivers' (ARs) connection to synoptic-scale
climate patterns and atmospheric dynamics has become increasingly important. In
addition to case studies of two extreme AR events, we produce a December
climatology of the three-dimensional structure of water vapor and O3 (ozone)
distributions associated with ARs in the northeastern Pacific from 2004-2014
using MERRA-2 reanalysis products. Results show that positive O3 anomalies
reside in dry intrusions of stratospheric air due to
stratosphere-to-troposphere transport (STT) behind the intense water vapor
transport of the AR. In composites, we find increased excesses of O3
concentration, as well as in the total O3 flux within the dry intrusions, with
increased AR strength. We find that STT O3 flux associated with ARs over the NE
Pacific accounts for up to 13 percent of total Northern Hemisphere STT O3 flux
in December, and extrapolation indicates that AR-associated dry intrusions may
account for as much as 32 percent of total NH STT O3 flux. This study
quantifies STT of O3 in connection with ARs for the first time and improves
estimates of tropospheric ozone concentration due to STT in the identification
of this correlation. In light of predictions that ARs will become more intense
and/or frequent with climate change, quantifying AR-related STT O3 flux is
especially valuable for future radiative forcing calculations.Comment: 26 pages, 11 main text figures, 3 appendix figures; published in JGR:
Atmosphere
Investigations of Metastable Ca\u3csub\u3e2\u3c/sub\u3eIrO\u3csub\u3e4\u3c/sub\u3e Epitaxial Thin-Films: Systematic Comparison with Sr\u3csub\u3e2\u3c/sub\u3eIrO\u3csub\u3e4\u3c/sub\u3e and Ba\u3csub\u3e2\u3c/sub\u3eIrO\u3csub\u3e4\u3c/sub\u3e
We have synthesized thermodynamically metastable Ca2IrO4 thin-films on YAlO3 (110) substrates by pulsed laser deposition. The epitaxial Ca2IrO4 thin-films are of K2NiF4-type tetragonal structure. Transport and optical spectroscopy measurements indicate that the electronic structure of the Ca2IrO4 thin-films is similar to that of Jeffâ=â1/2 spin-orbit-coupled Mott insulator Sr2IrO4 and Ba2IrO4, with the exception of an increased gap energy. The gap increase is to be expected in Ca2IrO4 due to its increased octahedral rotation and tilting, which results in enhanced electron-correlation, U/W. Our results suggest that the epitaxial stabilization growth of metastable-phase thin-films can be used effectively for investigating layered iridates and various complex-oxide systems
Evaluation of antioxidant activity of methanolic extracts and some fractions of Salvia verticillata L. using three different methods
Background: Bradykinin has effects on histaminic response,vessels seepage,cellular reproduction,causing fever, pain and coughs caused by ACE controllers (3,4,6). Noscapin has controlled Bradykinins contractional effects on guinea pigs trachea and rats vazodofran (5,6). noscapin stops the secondary effects of eskimi in brains edema, with antagonizing the responses caused by Bradykinin (3,4,8). Objective: considering that opium's alkaloids act as agonist of peptide systems like ankephalins and RAS, its interesting to know the effects of this alkaloids and among them Noscapine on B3 Bradykinin receptors on smooth muscle guinea pig trachea? Method: All variables are reported as mean and standard deviation. We have used pair test and the informations were processed by Excel, Statistical analysis with ANOVA (LSD) SPSS 9. Results: we took diagrams in to consideration and indicated that the contract ional effect of Bradykinin decreased dependent on density, in presence of three different amount of noscapines concentration. In this study we could demonstrate that noscapine interact with Bradykenin as a non competitive antagonist
Selective Growth of Epitaxial Sr\u3csub\u3e2\u3c/sub\u3eIrO\u3csub\u3e4\u3c/sub\u3e by Controlling Plume Dimensions in Pulsed Laser Deposition
We report that epitaxial Sr2IrO4 thin-films can be selectively grown using pulsed laser deposition (PLD). Due to the competition between the Ruddlesden-Popper phases of strontium iridates (Srn+1IrnO3n+1), conventional PLD methods often result in mixed phases of Sr2IrO4 (nâ=â1), Sr3Ir2O7 (nâ=â2), and SrIrO3 (nâ=ââ). We have discovered that reduced PLD plume dimensions and slow deposition rates are the key for stabilizing pure Sr2IrO4 phase thin-films, identified by real-time in-situ monitoring of their optical spectra. The slow film deposition results in a thermodynamically stable TiO2\\SrO\IrO2\SrO\SrO configuration at an interface rather than TiO2\\SrO\SrO\IrO2\SrO between a TiO2-terminated SrTiO3 substrate and a Sr2IrO4 thin film, which is consistent with other layered oxides grown by molecular beam epitaxy. Our approach provides an effective method for using PLD to achieve pure phase thin-films of layered materials that are susceptible to several energetically competing phases
Optical Signatures of Spin-Orbit Exciton in Bandwidth-Controlled Sr\u3csub\u3e2\u3c/sub\u3eIrO\u3csub\u3e4\u3c/sub\u3e Epitaxial Films via High-Concentration Ca and Ba Doping
We have investigated the electronic and optical properties of (Sr1âxCax)2IrO4 (x = 0â0.375) and (Sr1âyBay)2IrO4 (y = 0â0.375) epitaxial thin films, in which the bandwidth is systematically tuned via chemical substitutions of Sr ions by Ca and Ba. Transport measurements indicate that the thin-film series exhibits insulating behavior, similar to the Jeff = 1/2 spin-orbit Mott insulator Sr2IrO4. As the average A-site ionic radius increases from (Sr1âxCax)2IrO4 to (Sr1âyBay)2IrO4, optical conductivity spectra in the near-infrared region shift to lower energies, which cannot be explained by the simple picture of well-separated Jeff = 1/2 and Jeff = 3/2 bands. We suggest that the two-peak-like optical conductivity spectra of the layered iridates originates from the overlap between the optically forbidden spin-orbit exciton and the intersite optical transitions within the Jeff = 1/2 band. Our experimental results are consistent with this interpretation as implemented by a multiorbital Hubbard model calculation: namely, incorporating a strong Fano-like coupling between the spin-orbit exciton and intersite dâd transitions within the Jeff = 1/2 band
First Top-Down Estimates of Anthropogenic NO_x Emissions Using High-Resolution Airborne Remote Sensing Observations
A number of satelliteâbased instruments have become an essential part of monitoring emissions. Despite sound theoretical inversion techniques, the insufficient samples and the footprint size of current observations have introduced an obstacle to narrow the inversion window for regional models. These key limitations can be partially resolved by a set of modest highâquality measurements from airborne remote sensing. This study illustrates the feasibility of nitrogen dioxide (NO_2) columns from the Geostationary Coastal and Air Pollution Events Airborne Simulator (GCAS) to constrain anthropogenic NO_x emissions in the HoustonâGalvestonâBrazoria area. We convert slant column densities to vertical columns using a radiative transfer model with (i) NO_2 profiles from a highâresolution regional model (1 Ă 1 km^2) constrained by Pâ3B aircraft measurements, (ii) the consideration of aerosol optical thickness impacts on radiance at NO_2 absorption line, and (iii) highâresolution surface albedo constrained by groundâbased spectrometers. We characterize errors in the GCAS NO_2 columns by comparing them to Pandora measurements and find a striking correlation (r > 0.74) with an uncertainty of 3.5 Ă 10^(15) molecules cm^(â2). On 9 of 10 total days, the constrained anthropogenic emissions by a Kalman filter yield an overall 2â50% reduction in polluted areas, partly counterbalancing the wellâdocumented positive bias of the model. The inversion, however, boosts emissions by 94% in the same areas on a day when an unprecedented local emissions event potentially occurred, significantly mitigating the bias of the model. The capability of GCAS at detecting such an event ensures the significance of forthcoming geostationary satellites for timely estimates of topâdown emissions
Electronic and Optical Properties of La-Doped Sr\u3csub\u3e3\u3c/sub\u3eIr\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e7\u3c/sub\u3e Epitaxial Thin Films
We have investigated structural, transport, and optical properties of tensile strained (Sr1âxLax)3Ir2O7 (x = 0, 0.025, 0.05) epitaxial thin films. While high-Tc superconductivity is predicted theoretically in the system, we have observed that all of the samples remain insulating with finite optical gap energies and Mott variable-range hopping characteristics in transport. Cross-sectional scanning transmission electron microscopy indicates that structural defects such as stacking faults appear in this system. The insulating behavior of the La-doped Sr3Ir2O7 thin films is presumably due to disorder-induced localization and ineffective electron doping of La, which brings to light the intriguing difference between epitaxial thin films and bulk single crystals of the iridates
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