Magnetic resonance imaging of dense and light non-aqueous phase liquid in a rock fracture,

[1] Magnetic resonance (MR) imaging was used to observe the flow of dense (FC-75) and light (dodecane) non-aqueous phase liquids (NAPLs) through a water saturated dolomite fracture. Dynamic two-phase behavior was influenced by (1) buoyancy of the NAPL relative to the aqueous phase, (2) fracture aperture distribution, and (3) alteration of wettability by long-term presence of NAPL phase. MR imaging was capable of characterizing the fracture geometry and the fluid flow, but was limited by outlet flow conditions in the sample and acquisition times. This method permits observation of two-phase flow under natural wettability and matrix porosity, providing significant advantages over plastic or glass replicas. INDEX TERMS: 1829 Hydrology: Groundwater hydrology; 5194 Physical Properties of Rocks: Instruments and techniques; 1831 Hydrology: Groundwater quality. Citation: Becker, M. W., M. Pelc, R. V. Mazurchuk, and J. Spernyak, Magnetic resonance imaging of dense and light non-aqueous phase liquid in a rock fracture, Geophys

Searching for a Stochastic Background of Gravitational Waves with LIGO

The Laser Interferometer Gravitational-wave Observatory (LIGO) has performed the fourth science run, S4, with significantly improved interferometer sensitivities with respect to previous runs. Using data acquired during this science run, we place a limit on the amplitude of a stochastic background of gravitational waves. For a frequency independent spectrum, the new limit is $\Omega_{\rm GW} < 6.5 \times 10^{-5}$. This is currently the most sensitive result in the frequency range 51-150 Hz, with a factor of 13 improvement over the previous LIGO result. We discuss complementarity of the new result with other constraints on a stochastic background of gravitational waves, and we investigate implications of the new result for different models of this background.Comment: 37 pages, 16 figure

The Causes and Effects of Leaks in International Negotiations

International negotiations are founded on secrecy. Yet, unauthorized leaks of negotiating documents have grown common. What are the incentives behind leaks, and what are their effects on bargaining between states? Specifically, are leaks offensive or defensive: are they intended to spur parties to make more ambitious commitments, or are they more often intended to claw back commitments made? We examine these questions in the context of trade negotiations, the recurring form of which affords us rare empirical traction on an otherwise elusive issue. We assemble the first dataset of its kind, covering 120 discrete leaks from 2006 to 2015. We find that leaks are indeed rising in number. Leaks are clustered around novel legal provisions and appear to be disproportionately defensive: they serve those actors intent on limiting commitments made. The European Union (EU) appears responsible for the majority of leaks occurring worldwide. Using party manifesto data to track changing ideological positions within the EU, we find that the occurrence of leaks correlates with opposition to economic liberalization within the average EU political party. Moreover, leaks appear effective in shifting public debate. We examine trade officials' internal communications and media coverage in the wake of a specific leak of negotiations between Canada and the EU. A given negotiating text attracts more negative coverage when it is leaked than when the same text is officially released. In sum, political actors leak information strategically to mobilize domestic audiences toward their preferred negotiating outcome

Temporal Dynamics Of Nonlinear Absorption And Refraction In Crystalline And Hydrogenated Amorphous Silicon

We measure the temporal dynamics of nonlinear absorption (NLA) and refraction (NLR) in crystalline and hydrogenated-amorphous silicon at 1550 nm. The effect of relative polarization on NLA and NLR are also reported