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Different Signs (different + sign)
Selected AbstractsPan Evaporation Trends and the Terrestrial Water Balance.GEOGRAPHY COMPASS (ELECTRONIC), Issue 2 2009Declines in pan evaporation have been reported across the USA, former Soviet Union, India, China, Australia, New Zealand and Canada, among other places. The trend is large , approximately an order of magnitude larger than model-based estimates of top of the atmosphere radiative forcing. The pan evaporation trend also has a different sign (i.e. decline) from commonly held conceptions. These are a remarkably interesting set of observations. In the first article of this two-part series, we discussed the measurements themselves and then presented summaries of the worldwide observations. In this, the second article, we outline the use of energy balance methods to attribute the observed changes in pan evaporation to changes in the underlying physical variables, namely, radiation, temperature, vapour pressure deficit and wind speed. We find that much of the decline in pan evaporation can be attributed to declines in radiation (i.e. dimming) and/or wind speed (i.e. stilling). We then discuss the interpretation of changes in the terrestrial water balance. This has been an area of much misunderstanding and confusion, most of which can be rectified through use of the familiar and longstanding supply/demand framework. The key in using the pan evaporation data to make inferences about changes in the terrestrial water balance is to distinguish between water- and energy-limited conditions where different interpretations apply. [source] , -model and cooling flows in X-ray clusters of galaxiesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2000Stefano Ettori The spatial emission from the core of cooling-flow clusters of galaxies is inadequately described by a , -model. Spectrally, the central region of these clusters is well approximated with a two-temperature model, where the inner temperature represents the multiphase status of the core and the outer temperature is a measure of the ambient gas temperature. Following this observational evidence, I extend the use of the , -model to a two-phase gas emission, where the two components coexist within a boundary radius rcool and the ambient gas alone fills the volume shell at a radius above rcool. This simple model still provides an analytic expression for the total surface brightness profile (Note in the first term the different sign with respect to the standard , -model.) Based upon a physically meaningful model for the X-ray emission, this formula can be used (i) to improve significantly the modelling of the surface brightness profile of cooling flow clusters of galaxies when compared to the standard , -model results, (ii) to constrain properly the physical characteristics of the intracluster plasma in the outskirts, like, e.g., the ambient gas temperature. [source] Background magnetic fields during last three cycles of solar activityASTRONOMISCHE NACHRICHTEN, Issue 6 2008O.A. Andryeyeva Abstract This paper describes our studies of evolution of the solar magnetic field with different sign and field strength in the range from ,100 G to 100 G. The structure and evolution of large-scale magnetic fields on the Sun during the last 3 cycles of solar activity is investigated using magnetograph data from the Kitt Peak Solar Observatory. This analysis reveals two groups of the large-scale magnetic fields evolving differently during the cycles. The first group is represented by relatively weak background fields, and is best observed in the range of 3,10 Gauss. The second group is represented by stronger fields of 75,100 Gauss. The spatial and temporal properties of these groups are described and compared with the total magnetic flux. It is shown that the anomalous behaviour of the total flux during the last cycle can be found only in the second group. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Calculated Raman Optical Activity Signatures of Tryptophan Side ChainsCHEMPHYSCHEM, Issue 15 2008Christoph R. Jacob Dr. Raman optical activity: The different local chirality of an adjacent group can cause a different sign of the ROA intensity of an amino-acid side chain (here tryptophan, see picture centre), even though the normal mode is unchanged. Calculated spectra clearly confirm that ROA spectroscopy can be utilized to determine the absolute conformation of tryptophan side chains in proteins (see figure, left and right). [source] Metacommunity patterns of highly diverse stream midges: gradients, chequerboards, and nestedness, or is there only randomness?ECOLOGICAL ENTOMOLOGY, Issue 5 2005Jani Heino Abstract., 1.,Several non-random patterns in the distribution of species have been observed, including Clementsian gradients, Gleasonian gradients, nestedness, chequerboards, and evenly spaced gradients. Few studies have examined these patterns simultaneously, although they have often been studied in isolation and contrasted with random distribution of species across sites. 2.,This study examined whether assemblages of chironomid midges exhibit any of the idealised distribution patterns as opposed to random distribution of species across sites within the metacommunity context in a boreal drainage system. Analyses were based on stream surveys conducted during three consecutive years. Analytical approaches included ordinations, cluster analysis, null models, and associated randomisation methods. 3.,Midge assemblages did not conform to Clementsian gradients, which was evidenced by the absence of clearly definable assemblage types with numerous species exclusive to each assemblage type. Rather, there were signs of continuous Gleasonian variability of assemblage composition, as well as significant nested subset patterns of species distribution. 4.,Midge assemblages showed only weak relationships with any of the measured environmental variables, and even these weak environmental relationships varied among years. 5.,Midge assemblages did not appear to be structured by competition. This finding was somewhat problematic, however, because the two indices measuring co-occurrence provided rather different signs of distribution patterns. This was probably a consequence of how they actually measure co-occurrence. 6.,Although midge assemblages did not show a perfect match with any of the idealised distribution patterns, they nevertheless showed a resemblance to the empirical patterns found previously for several plant and animal groups. [source] A laboratory study of seismic velocity and attenuation anisotropy in near-surface sedimentary rocksGEOPHYSICAL PROSPECTING, Issue 5 2007Angus I. Best ABSTRACT The laboratory ultrasonic pulse-echo method was used to collect accurate P- and S-wave velocity (±0.3%) and attenuation (±10%) data at differential pressures of 5,50 MPa on water-saturated core samples of sandstone, limestone and siltstone that were cut parallel and perpendicular to the vertical borehole axis. The results, when expressed in terms of the P- and S-wave velocity and attenuation anisotropy parameters for weakly transversely isotropic media (,, ,, ,Q, ,Q) show complex variations with pressure and lithology. In general, attenuation anisotropy is stronger and more sensitive to pressure changes than velocity anisotropy, regardless of lithology. Anisotropy is greatest (over 20% for velocity, over 70% for attenuation) in rocks with visible clay/organic matter laminations in hand specimens. Pressure sensitivities are attributed to the opening of microcracks with decreasing pressure. Changes in magnitude of velocity and attenuation anisotropy with effective pressure show similar trends, although they can show different signs (positive or negative values of ,, ,Q, ,, ,Q). We conclude that attenuation anisotropy in particular could prove useful to seismic monitoring of reservoir pressure changes if frequency-dependent effects can be quantified and modelled. [source] Effects of uniaxial stress on the magnetic properties of thin films and GMR sensors prepared on polyimide substratesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2008Berkem Özkaya Abstract The effects of externally applied uniaxial stress on the magnetic properties of Co thin films and pseudo-spin-valve (PSV) structures on flexible polyimide substrates were investigated. The advantage of the polyimide substrate is its flexibility and high elasticity (,1%), which cannot be achieved using conventional crystalline substrates. The Co layers exhibit a macroscopic easy axis induced by the preparation process. When the stress is applied perpendicular to the induced in-plane easy axis, the magnetic domains in the film rotate towards the applied stress direction, which was confirmed using Kerr microscopy and magneto-optical Kerr effect (MOKE) magnetometer measurements. A Co/Cu/Ni PSV system was prepared on polyimide substrate with dc magnetron sputtering. Applying uniaxial stress leads to opposite rotation of the magnetisation directions in both layers to each other due to different signs of the magnetostriction coefficients of Co and Ni. The magnetisation and giant magnetoresistance (GMR) curves under applied stress were recorded using in situ MOKE and current in-plane four-point probe techniques, respectively. When the stress is applied perpendicular to the external magnetic field (Hext), the operating range of the GMR sensor increases, whereas the sensitivity decreases. Anisotropy energies and saturation magnetostriction values of the Co and Ni layer were determined by fitting the GMR and magnetisation curves using a micromagnetic model. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Equatorial magnetic helicity flux in simulations with different gaugesASTRONOMISCHE NACHRICHTEN, Issue 1 2010D. Mitra Abstract We use direct numerical simulations of forced MHD turbulence with a forcing function that produces two different signs of kinetic helicity in the upper and lower parts of the domain. We show that the mean flux of magnetic helicity from the small-scale field between the two parts of the domain can be described by a Fickian diffusion law with a diffusion coefficient that is approximately independent of the magnetic Reynolds number and about one third of the estimated turbulent magnetic diffusivity. The data suggest that the turbulent diffusive magnetic helicity flux can only be expected to alleviate catastrophic quenching at Reynolds numbers of more than several thousands. We further calculate the magnetic helicity density and its flux in the domain for three different gauges. We consider the Weyl gauge, in which the electrostatic potential vanishes, the pseudo-Lorenz gauge, where the speed of light is replaced by the sound speed, and the ,resistive gauge' in which the Laplacian of the magnetic vector potential acts as a resistive term. We find that, in the statistically steady state, the time-averaged magnetic helicity density and the magnetic helicity flux are the same in all three gauges (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] 1333: OCT: from single use to combined use in macular degenerationACTA OPHTHALMOLOGICA, Issue 2010C CREUZOT Purpose Optical Coherence Tomography (OCT) plays a key role in the diagnosis and the treatment of Age Macular Degeneration (AMD). Authors will present the different signs observed in OCT in exudative AMD. Methods Authors will present clinical cases to illustrate the place of the OCT in AMD diagnosis. OCT has progressively replaced the first-line tool played by angiography especially for the following of the patient once the treatment initiated. The different schemas currently proposed emphasize the role of the OCT combined with visual acuity measurement and fundus examination. Results However, the role of fluorescein and indocyanin green angiography remained essential especially to precise the clinical form before treatment. The combination of OCT and angiography remained a "key association" especially when there is some discrepancy between results or in case of treatment failure to consider another option. It is also the only opportunity for us to understand better the prognosis of these cases under treatment. Conclusion OCT has dramatically changed the supervision of exudative AMD especially during treatment. However, the combination with fluorescein and indocyanin angiograms is highly recommended not only for initial diagnosis but also in difficult cases during follow-up. [source] Infection with Fasciola hepaticaCLINICAL MICROBIOLOGY AND INFECTION, Issue 11 2005D. Y. Aksoy Abstract Fascioliasis, caused by the liver fluke Fasciola hepatica, is an infection that occurs worldwide, although humans are accidental hosts. F. hepatica infection comprises two stages, hepatic and biliary, with different signs and symptoms. Stool examination and ELISA can be used for the initial diagnosis. Radiographic techniques, such as computerised tomography and ultrasonography, as well as magnetic resonance imaging, are used widely for confirmation and follow-up of the disease. Invasive techniques, such as percutaneous cholangiography, endoscopic retrograde cholangiography and liver biopsy, may aid in the diagnosis but are not essential. Triclabendazole is recommended as the first-line agent for the treatment of F. hepatica infection, with bithionol as an alternative. [source] |