Standard comparison test procedures for initiator output

Standard test procedures for initiators of explosive device

Rapid evolution in response to introduced predators I: rates and patterns of morphological and life-history trait divergence

BACKGROUND: Introduced species can have profound effects on native species, communities, and ecosystems, and have caused extinctions or declines in native species globally. We examined the evolutionary response of native zooplankton populations to the introduction of non-native salmonids in alpine lakes in the Sierra Nevada of California, USA. We compared morphological and life-history traits in populations of Daphnia with a known history of introduced salmonids and populations that have no history of salmonid introductions. RESULTS: Our results show that Daphnia populations co-existing with fish have undergone rapid adaptive reductions in body size and in the timing of reproduction. Size-related traits decreased by up to 13 percent in response to introduced fish. Rates of evolutionary change are as high as 4,238 darwins (0.036 haldanes). CONCLUSION: Species introductions into aquatic habitats can dramatically alter the selective environment of native species leading to a rapid evolutionary response. Knowledge of the rates and limits of adaptation is an important component of understanding the long-term effects of alterations in the species composition of communities. We discuss the evolutionary consequences of species introductions and compare the rate of evolution observed in the Sierra Nevada Daphnia to published estimates of evolutionary change in ecological timescales

Antiproton-deuteron annihilation at low energies

Recent experimental studies of the antiproton-deuteron system at low energies have shown that the imaginary part of the antiproton-deuteron scattering length is smaller than the antiproton-proton one. Two- and three-body systems with strong annihilation are investigated and a mechanism explaining this unexpected relation between the imaginary parts of the scattering lengths is proposed.Comment: 6 pages, 3 figures, to be published in The European Physical Journal

Influence of Fe2+-catalysed iron oxide recrystallization on metal cycling

Abstract Recent work has indicated that iron (oxyhydr-)oxides are capable of structurally incorporating and releasing metals and nutrients as a result of Fe 2 + -induced iron oxide recrystallization. In the present paper, we briefly review the current literature examining the mechanisms by which iron oxides recrystallize and summarize how recrystallization affects metal incorporation and release. We also provide new experimental evidence for the Fe 2 + -induced release of structural manganese from manganese-doped goethite. Currently, the exact mechanism(s) for Fe 2 + -induced recrystallization remain elusive, although they are likely to be both oxideand metal-dependent. We conclude by discussing some future research directions for Fe 2 + -catalysed iron oxide recrystallization. Metal incorporation in iron oxides Natural iron (oxyhydr-)oxides are rarely pure. Instead, they often contain structural trace metal impurities (e.g. Key words: goethite, haematite, iron oxide, magnetite, metal cycling, recrystallization. Abbreviations used: XAS, X-ray absorption spectroscopy. 1 To whom correspondence should be addressed (email [email protected]). In the present paper, we provide a brief overview of the evidence and possible mechanisms of Fe 2 + -catalysed iron oxide recrystallization in the absence of secondary transformations and summarize recent findings on metal incorporation and/or release during recrystallization. We also present some new results demonstrating Mn 2 + release from goethite in the presence of aqueous Fe 2 + and provide some closing remarks on future research directions for Fe 2 + -catalysed iron oxide recrystallization. Fe 2 + -catalysed iron oxide recrystallization of goethite, haematite and magnetite There were some clear early indications in the literature that the reaction of aqueous Fe 2 + with the more stable iron oxides, such as goethite, haematite and magnetite, was more dynamic than a simple adsorption reaction. For example, Tronc et al. [25

Stable U(IV) Complexes Form at High-Affinity Mineral Surface Sites

Uranium (U) poses a significant contamination hazard to soils, sediments, and groundwater due to its extensive use for energy production. Despite advances in modeling the risks of this toxic and radioactive element, lack of information about the mechanisms controlling U transport hinders further improvements, particularly in reducing environments where UIV predominates. Here we establish that mineral surfaces can stabilize the majority of U as adsorbed UIV species following reduction of UVI. Using X-ray absorption spectroscopy and electron imaging analysis, we find that at low surface loading, UIV forms inner-sphere complexes with two metal oxides, TiO2 (rutile) and Fe3O4 (magnetite) (at <1.3 U nm–2 and <0.037 U nm–2, respectively). The uraninite (UO2) form of UIV predominates only at higher surface loading. UIV–TiO2 complexes remain stable for at least 12 months, and UIV–Fe3O4 complexes remain stable for at least 4 months, under anoxic conditions. Adsorbed UIV results from UVI reduction by FeII or by the reduced electron shuttle AH2QDS, suggesting that both abiotic and biotic reduction pathways can produce stable UIV–mineral complexes in the subsurface. The observed control of high-affinity mineral surface sites on UIV speciation helps explain the presence of nonuraninite UIV in sediments and has important implications for U transport modeling

Comparison of bacteria found on the hands of homemakers and neonatal intensive care unit nurses

http://deepblue.lib.umich.edu/bitstream/2027.42/55404/1/a comparison of the bacteris found.pd