An Introduction to Trade and National Security: New Concepts of National Security in a Time of Economic uncertainty

Within the context of enhanced rhetoric about the need for national security measures to protect domestic economic interests, the Duke Journal of Comparative & International Law hosted a Symposium on National Security and Trade Law in which speakers raised questions as to not only what is meant by national security today, but also the significance of invoking national security exceptions in trade. This Introduction provides an overview of issues discussed as well as some reflections on the use of the national security exception in trade during a time when nations are moving away from international cooperation towards unilateralism and facing global crises such as the COVID-19 pandemic. With the World Trade Organization’s recent panel decision, Russia—Measures Concerning Traffic in Transit , the international community received some guidance as to the limited use of this exception under GATT Article XXI and the need for good faith by nations invoking it, but larger questions remained as to its applicability in the context of economic insecurity and in the context of broader global challenges such as cybersecurity and climate change. Furthermore, with the current dysfunction of the Appellate Body of the WTO, there is no central adjudicatory body to address these issues in a systematic fashion, leaving it up to the nations or ad hoc adjudicatory processes to decide, rendering the multilateral trade framework an even more fragmented system. New ways of imagining the role of trade in the context of global and economic crises are needed, as well as more resilient institutional frameworks that can adapt to future forms of insecurity and allow for varied, constructive forms of dialogue among nations

The scattering polarization of the Ly-alpha lines of H I and He II taking into account PRD and J-state interference effects

Recent theoretical investigations have pointed out that the cores of the Ly-alpha lines of H I and He II should show measurable scattering polarization signals when observing the solar disk, and that the magnetic sensitivity, through the Hanle effect, of such linear polarization signals is suitable for exploring the magnetism of the solar transition region. Such investigations were carried out in the limit of complete frequency redistribution (CRD) and neglecting quantum interference between the two upper J-levels of each line. Here we relax both approximations and show that the joint action of partial frequency redistribution (PRD) and J-state interference produces much more complex fractional linear polarization (Q/I) profiles, with large amplitudes in their wings. Such wing polarization signals turn out to be very sensitive to the temperature structure of the atmospheric model, so that they can be exploited for constraining the thermal properties of the solar chromosphere. Finally, we show that the approximation of CRD without J-state interference is however suitable for estimating the amplitude of the linear polarization signals in the core of the lines, where the Hanle effect operates.Comment: Accepted for publication in The Astrophysical Journal Letter

On the magnetic field of off-limb spicules

Determining the magnetic field related to solar spicules is vital for developing adequate models of these plasma jets, which are thought to play a key role in the thermal, dynamic and magnetic structure of the Chromosphere. Here we report on the magnetic properties of off-limb spicules in a very quiet region of the solar atmosphere, as inferred from new spectropolarimetric observations in the He I 10830 A triplet obtained with the Tenerife Infrared Polarimeter. We have used a novel inversion code for Stokes profiles caused by the joint action of atomic level polarization and the Hanle and Zeeman effects (HAZEL) to interpret the observations. Magnetic fields as strong as ~40G were detected in a very localized area of the slit, which could represent a possible lower value of the field strength of organized network spicules.Comment: Accepted for publication in ApJ, 24 pages, 5 Figure