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Palestinian suicide terrorism has been a key feature in the latest phase of the Israeli–Palestinian conflict. During the past decade, and particularly since September 2000, there has been a substantial increase in the use of this type of warfare. Recent studies suggest that, contrary to common belief, suicide terrorism is highly rational and driven by strategic considerations. This article explores the rationality of Palestinian suicide terrorism from a geographical perspective. It is argued that suicide terrorism works along two parallel paths: rationality and randomness. It complies with geographical fundamentals, and target selection is highly rational, subject to spatial considerations such as distance, agglomeration, and accessibility. As the permeability to Israel became more difficult, suicide bombers and their organizers had to adopt more flexible practices which emphasized other spatial considerations. Timing is of importance both for strategic and tactical reasoning. Obstructing negotiations and peace talks has been a salient objective, but the exact timing of suicide bombings has been influenced by tactical considerations, which aim at maximizing casualties. 相似文献
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Ultrasonic longitudinal acoustic velocities in oxidized silicate liquids indicate that the pressure derivative of the partial-molar
volume of Fe2O3 is the same in iron-rich alkali-, alkaline earth- and natural silicate melt compositions at 1 bar. The dV/dP for multicomponent silicate liquids can be expressed as a linear combination of partial-molar constants plus a positive excess
term for Na2O−Al2O3 mixing. Partial-molar properties for FeO and Fe2O3 components allow extension of the empirical expression of Sack et al. (1980) to permit the calculation of Fe-redox equilibrium
in a natural silicate liquid as a function of composition, temperature, fo2 and pressure; a more formal thermodynamic expression is presented in the Appendix. The predicted equilibrium fo2 of natural silicate melts, of fixed oxygen content, closely parallels that defined by the metastable assemblage fayalite+magnetite+β-quartz
(FMQ), in pressure-temperature space. A silicate melt initially equilibrated at 3 GPa and FMQ, will remain within approximately
0.5 log10 units of FMQ during its closed-system ascent. Thus, for magmas closed to oxygen, iron-redox equilibrium in crystal-poor pristine
glassy lavas represents an excellent probe of the relative oxidation state of their source regions. 相似文献
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The Mount Wilson synoptic magnetic data for the period September 1987 through March 1996 are completely revised and used to provide polar plots of the solar magnetic fields for both hemispheres. This period, from Carrington rotations 1793 to 1906, covers the reversals of the polar magnetic fields in cycle 22. Comparison of our plots with the presently available H filtergrams for this period shows that the polarity boundaries are consistent in these two data sets where they overlap. The Mount Wilson plots show that the polar field reversals involve a complex sequence of events. Although the details differ slightly, the basic patterns are similar in each hemisphere. First the old polarity becomes isolated at the pole, then shortly thereafter, the isolation is broken, and the polar field includes unipolar regions of both polarities. The old polarity then reclaims the polar region, but when the isolation of this field is established for a second time, it declines in both area and strength. We take the reversal to be complete when the old polarity field is no longer observed in the Mount Wilson plots. With this criterion we find that the polar field reversal is completed in the north by CR 1836, i.e., by December 1990, and in the south by CR 1853, i.e., March 1992. 相似文献
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The objective of this study was to examine whether dissolved inorganic phosphate (DIP) is removed from the Eastern Mediterranean Sea by adhering to atmospherically deposited loess particles sinking through the water column. In a series of radiolable experiments, loess from the Negev Desert, treated in various ways, was added to surface (SSW) and deep (DSW) seawater spiked with 32PO4−3. It was shown that when fresh loess reaches the Mediterranean SSW approximately 1.3 μmol P/g are released (11% of the total P concentration). Biological activity and inorganic particles removed similar amounts of the tracer (30–40%) from SSW. It was estimated that about 0.2 μmol P/g of ‘aged loess' (proxy of particles sinking into DSW), were removed from poisoned SSW and DSW, while there was minor adsorption when either nothing or quartz powder was added. The adsorbed DIP accounts for approximately 15% of the released P and is equivalent to about 2% of the remaining P (11.17 μmol P/g loess). Therefore, the process of DIP removal by atmospherically derived particles exists, but due to the higher release of P, the result is a net addition of dissolved atmospheric phosphorus in seawater. It is postulated that in actual SSW where dust concentrations are much lower, biological uptake out-competes inorganic adsorption, although it was demonstrated that the decrease in loess particle concentrations tends to increase their adsorption capacity. As the loess descends into the DSW it continues to remove DIP and thus transports phosphate from the water column to the sediments. A preliminary quantitative estimate suggests that the process of DIP removal by loess particles cannot explain the phosphate ‘deficit' in the Eastern Mediterranean DSW characterized by unusually high DIN/DIP ratios (27) reported by others. 相似文献
7.
Nurit Hildebrand-Mittlefehldt 《Tectonophysics》1980,64(3-4)
In a previous paper, the strain field in the vicinity of the termination of an experimentally induced fault in clay was described. The present study deals with the strain field associated with the termination of a natural normal fault, and a comparison of the two is made.Samples were taken near the termination of a steeply dipping fault in the Green River Formation, Utah. The preferred orientation of basal planes of clay minerals was measured at 80 points in a three-dimensional array, using an X-ray pole-figure goniometer. From the preferred orientation data, strain was calculated according to the theory of March (1932). Strain remote from the fault, due to compaction alone, was determined bed by bed and subtracted from the strain observed near the fault. In this way the finite strain, presumably associated with faulting only, was determined.The displacement field was found by unstraining and superposing the unstrained and strained configurations. The displacement field, patterns of magnitudes of the second invariant of the strain tensor (being a measure of the shear strain), and those of the principal strains were found. They resemble analogous fields and patterns near strike-slip faults observed in experiments, deduced theoretically, and inferred from field observations on active natural faults, after coordinates are rotated so as to bring the fault planes and slip directions into coincidence. 相似文献
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Dr. Waltraud Kress 《Meteorology and Atmospheric Physics》1967,16(4):301-313
Zusammenfassung Aus der 300mb-Fläche der täglichen Wetterkarte des deutschen Wetterdienstes wurden für den Zeitraum von 1955 bis 1963 Lage, Richtung und Geschwindigkeit der hochtroposphärischen Strahlströme bestimmt. Die jahreszeitlichen Änderungen der Positionen, Intensitäten und Richtungen des Polarfront-Jet (PFJ) und des Subtropen-Jet (STJ) werden für den Bereich von 20° W bis 20° E und von 35° N bis 70° N angegeben und diskutiert.
Mit 6 Textabbildungen 相似文献
Summary The position, direction and speed of the high-tropospheric jet-streams in the years 1955 to 1963 were determined from the 300 mb chart of the Daily Weather Map of the German Weather Service. The seasonal variations of the positions, intensities and directions of the polarfront jet (PFJ) and subtropic jet (STJ) in the region between 20° W and 20° E and between 35° N and 70° N have been evaluated and are discussed here.
Résumé En partant des cartes journalières de la surface de 300 mb éditées par le service météorologique de la République fédérale d'Allemagne, on a déterminé la position, la direction et la vitesse des courants jets de la troposphère supérieure et cela pour la période 1955 à 1963. On indique et on discute les variations saisonnières de la position, de l'intensité et de la direction du jet accompagnant le front polaire (PFJ) et du Jet subtropical (STJ). La zone étudiée s'étend entre le 20ème méridien E et le 20ème méridien W, respectivement entre les 35ème et 70ème paralèlles N.
Mit 6 Textabbildungen 相似文献
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Summary Since early experiments by Renard and Clarke in 1965 there has been until now no essential progress in numerical frontal analysis. To overcome the frequent lack of agreement of frontal analysis between different analysts and weather bureau centers an objective frontal analysis model seems to be necessary. Therefore an attempt will be made to develop an algorithm to analyse fronts in relation to their location, type and activity by a numerical method.With 12 Fugures 相似文献
10.
V. Kress 《Contributions to Mineralogy and Petrology》2000,139(3):316-325
We present a new formulation to describe the thermodynamics of liquids in the system O-S-Fe. The model is based on an associated
regular solution formulation. According to this model, liquids in the O-S-Fe ternary are made up of an equilibrium solution
of the six melt species S, Fe, FeO, FeO1.5, FeS and FeOS. The model presented here represents oxygen and sulfur fugacities as well as phase equilibria with stoichiometric
solid phases better than models from the literature on O-Fe and S-Fe binaries. Furthermore, this model represents a substantial
improvement on the model of Kress (1997), which is the only other thermodynamic model available in the ternary system. Asymmetric
regular solution parameters are required along the FeO join in order to reproduce experimental data with the chosen list of
species. Symmetric regular solution parameters are required along the Fe-S binary. Mixing between any of the species considered
and FeOS close to ideal. The associated solution model presented here will serve as a more solid foundation for future models
in O-S-Fe- Ni-Cu liquids. Efficient and robust strategies for calculating equilibrium speciation and estimating model parameters
are presented.
Received: 15 June 1999 / Accepted: 5 February 2000 相似文献