Interchange fees in various countries : developments and determinants : commentary on Weiner and Wright

Debit cards ; Credit cards

Quantum Key Distribution (QKD) and Commodity Security Protocols: Introduction and Integration

We present an overview of quantum key distribution (QKD), a secure key exchange method based on the quantum laws of physics rather than computational complexity. We also provide an overview of the two most widely used commodity security protocols, IPsec and TLS. Pursuing a key exchange model, we propose how QKD could be integrated into these security applications. For such a QKD integration we propose a support layer that provides a set of common QKD services between the QKD protocol and the security applicationsComment: 12Page

Political vs. Currency Premia in International Real Interest Differentials: A Study of Forward Rates for 24 Countries

Different approaches to quantifying the degree of capital mobility for a cross-section of currencies -- particularly saving-investment correlations and tests of real interest parity - have appeared to show a surprisingly low degree of financial market integration. We use a new data set, forward rate data for 24 countries, including many small industrialized countries and seven LDCs, to decompose the real interest differential into two parts: the covered interest differential, or political premium, and the real forward discount, or currency premium. The latter in turn can be decomposed into the exchange risk premium and expected real depreciation. We find a high degree of capital mobility across political boundaries for most of the 011 countries, plus Hong Kong and Singapore, for our sample period of 1982 to 1987. Even for most of the other LDCs and smaller industrialized countries, for which covered interest parity clearly fails, the political premium is not as big a component of the real interest differential as the currency premium. France would appear to have higher capital mobility than most by the criterion of real interest differentials, but is seen in fact to have low capital mobility by the criterion of covered interest differentials, a clear example of the superiority of the latter criterion.

Antitrust and payment technologies

Antitrust law ; Payment systems

Highly Mutable Linker Regions Regulate HIV-1 Rev Function and Stability.

HIV-1 Rev is an essential viral regulatory protein that facilitates the nuclear export of intron-containing viral mRNAs. It is organized into structured, functionally well-characterized motifs joined by less understood linker regions. Our recent competitive deep mutational scanning study confirmed many known constraints in Rev's established motifs, but also identified positions of mutational plasticity, most notably in surrounding linker regions. Here, we probe the mutational limits of these linkers by testing the activities of multiple truncation and mass substitution mutations. We find that these regions possess previously unknown structural, functional or regulatory roles, not apparent from systematic point mutational approaches. Specifically, the N- and C-termini of Rev contribute to protein stability; mutations in a turn that connects the two main helices of Rev have different effects in different contexts; and a linker region which connects the second helix of Rev to its nuclear export sequence has structural requirements for function. Thus, Rev function extends beyond its characterized motifs, and is tuned by determinants within seemingly plastic portions of its sequence. Additionally, Rev's ability to tolerate many of these massive truncations and substitutions illustrates the overall mutational and functional robustness inherent in this viral protein

HIV-1 Tat: Its Dependence on Host Factors is Crystal Clear

HIV-1 transcription is regulated at the level of elongation by the viral Tat protein together with the cellular elongation factor P-TEFb, which is composed of cyclin T1 and Cdk9 subunits. The crystal structure of a Tat:P-TEFb complex (Tahirov, T.H.; Babayeva, N.D.; Varzavand, K.; Cooper, J.J.; Sedore, S.C.; and Price, D.H. Crystal structure of HIV-1 Tat complexed with human P-TEFb. Nature 2010, 465, 747–751.) reveals molecular details of Tat and its interactions that have eluded investigators for more than two decades and provides provocative insights into the mechanism of Tat activation

Projectile Density Effects on Shield Performance

In the past, the orbital debris environment was modeled as consisting entirely of aluminum particles. As a consequence, most of the impact test database on spacecraft micro-meteoroid and orbital debris (MMOD) shields, and the resulting ballistic limit equations used to predict shielding performance, has been based on using aluminum projectiles. Recently, data has been collected from returned spacecraft materials and other sources that indicate higher and lower density components of orbital debris also exist. New orbital debris environment models such as ORDEM2008 provide predictions of the fraction of orbital debris in various density bins (high = 7.9 g/cu cm, medium = 2.8 g/cu cm, and low = 0.9-1.1 g/cu cm). This paper describes impact tests to assess the effects of projectile density on the performance capabilities of typical MMOD shields. Updates to shield ballistic limit equations are provided based on results of tests and analysis

Tailoring high precision polynomial architected material constitutive responses via inverse design

The design of specified nonlinear mechanical responses into a structure or material is a highly sought after capability, which would have a significant impact in areas such as wave tailoring in metamaterials, impact mitigation, soft robotics, and biomedicine. Here, we present a topology optimization approach to design structures for desired polynomial nonlinear behavior, wherein we formulate the problem in such a way as to decouple the nonlinear response from the stiffness. We show results across qualitatively different polynomial behaviors while achieving a high degree of precision, creating a path toward analytically tractable nonlinear dynamical systems. The approach enables access to previously difficult to design for, or hitherto unachieved, nonlinear behavior via optimized structures, which can furthermore be incorporated as unit cells of designer materials with tailored nonlinear properties