Living Close to Your Neighbors: The Importance of Both Competition and Facilitation in Plant Communities

Recent work has demonstrated that competition and facilitation likely operate jointly in plant communities, but teasing out the relative role of each has proven difficult. Here we address how competition and facilitation vary with seasonal fluctuations in environmental conditions, and how the effects of these fluctuations change with plant ontogeny. We planted three sizes of pine seedlings (Pinus strobus) into an herbaceous diversity experiment and measured pine growth every two weeks for two growing seasons. Both competition and facilitation occurred at different times of year between pines and their neighbors. Facilitation was important for the smallest pines when environmental conditions were severe. This effect decreased as pines got larger. Competition was stronger than facilitation overall and outweighed facilitative effects at annual time scales. Our data suggest that both competition and the counter‐directional effects of facilitation may be more common and more intense than previously considered

Trade Facilitation Negotiations in the WTO: Implications for Bangladesh and Other Least Developed and Developing Countries

This paper provides an overview of how trade facilitation has been addressed in the WTO to date, and how this may affect Bangladesh’s negotiating strategy on trade facilitation in the upcoming Cancun Ministerial and beyond. The paper also defines the term “trade facilitation”, reviews the development of trade facilitation in the international community apart from the WTO, and examines the work that has taken place on the issue in the WTO including the current state of play in trade facilitation discussions. Apart from providing an overview of WTO provisions that are relevant to trade facilitation, as a part of the Doha Development Agenda (DDA), and summarising the proposals that various WTO members have made for enhancing trade facilitation in the WTO, the paper addresses some of the implementation issues WTO members face with respect to trade facilitation. It further examines the implications of trade facilitation negotiations on Bangladesh and other least developed and developing countries, and how these will shape the negotiating strategies and policies of these countries.Trade Facilitation, WTO, LDC, Bangladesh

Facilitation of I Kr current by some hERG channel blockers suppresses early afterdepolarizations.

Drug-induced block of the cardiac rapid delayed rectifying potassium current (I Kr), carried by the human ether-a-go-go-related gene (hERG) channel, is the most common cause of acquired long QT syndrome. Indeed, some, but not all, drugs that block hERG channels cause fatal cardiac arrhythmias. However, there is no clear method to distinguish between drugs that cause deadly arrhythmias and those that are clinically safe. Here we propose a mechanism that could explain why certain clinically used hERG blockers are less proarrhythmic than others. We demonstrate that several drugs that block hERG channels, but have favorable cardiac safety profiles, also evoke another effect; they facilitate the hERG current amplitude in response to low-voltage depolarization. To investigate how hERG facilitation impacts cardiac safety, we develop computational models of I Kr block with and without this facilitation. We constrain the models using data from voltage clamp recordings of hERG block and facilitation by nifekalant, a safe class III antiarrhythmic agent. Human ventricular action potential simulations demonstrate the ability of nifekalant to suppress ectopic excitations, with or without facilitation. Without facilitation, excessive I Kr block evokes early afterdepolarizations, which cause lethal arrhythmias. When facilitation is introduced, early afterdepolarizations are prevented at the same degree of block. Facilitation appears to prevent early afterdepolarizations by increasing I Kr during the repolarization phase of action potentials. We empirically test this prediction in isolated rabbit ventricular myocytes and find that action potential prolongation with nifekalant is less likely to induce early afterdepolarization than action potential prolongation with dofetilide, a hERG channel blocker that does not induce facilitation. Our data suggest that hERG channel blockers that induce facilitation increase the repolarization reserve of cardiac myocytes, rendering them less likely to trigger lethal ventricular arrhythmias

Analytical Solution for facilitated transport across a membrane

An analytical expression for the facilitation factor of component A across a liquid membrane is derived in case of an instantaneous reaction A(g)+B(l)AB(l) inside the liquid membrane. The present expression has been derived based on the analytical results of Olander (A.I.Ch.E. J. 6(2) (1960) 233) obtained for the enhancement factor for G–L systems with bulk. The analytical expression for the facilitation factor allows for arbitrary diffusivities of all species involved and does not contain any simplification or approximations. The facilitation factor starts from the value of unity, goes through a maximum and then reduces back to unity as the equilibrium constant is increased. The maximum facilitation factor occurs at higher values of the equilibrium constant as the ratio of the permeate-complex over carrier diffusivity is reduced whereas the maximum facilitation factor occurs at the same value of the equilibrium constant for all values of DA/DB (ratio of the permeate over carrier diffusivity). A similar behavior is seen for the flux of A as a function of the equilibrium constant. The facilitation factor remains constant with changes in the film thickness whereas the flux of A reduces with an increase in the thickness of the film. A linear increase of the facilitation factor and flux of A are seen with increasing initial carrier concentration

Trade Facilitation beyond the Doha Round of Negotiations

this paper succinctly explores three emerging (in the case of customs valuation, re-emerging) issues, drawing from recent ARTNeT working papers as well as other relevant literature: (a) trade facilitation and regional trade agreements and initiatives; (b) trade facilitation and customs valuation; and (c) trade facilitation and services.Trade, Facilitation, Doha, Negotiations

Manifestations of Dynamical Facilitation in Glassy Materials

By characterizing the dynamics of idealized lattice models with a tunable kinetic constraint, we explore the different ways in which dynamical facilitation manifests itself within the local dynamics of glassy materials. Dynamical facilitation is characterized both by a mobility transfer function, the propensity for highly-mobile regions to arise near regions that were previously mobile, and by a facilitation volume, the effect of an initial dynamical event on subsequent dynamics within a region surrounding it. Sustained bursts of dynamical activity -- avalanches -- are shown to occur in kinetically constrained models, but, contrary to recent claims, we find that the decreasing spatiotemporal extent of avalanches with increased supercooling previously observed in granular experiments does not imply diminishing facilitation. Viewed within the context of existing simulation and experimental evidence, our findings show that dynamical facilitation plays a significant role in the dynamics of systems investigated over the range of state points accessible to molecular simulations and granular experiments.Comment: 10 pages, 5 figure

Trade Facilitation in Regional Trade Agreements: Recent Trends in Asia and the Pacific

The coverage of trade facilitation is found to have become very extensive, with the details of provisions in some agreements matching that in the draft WTO agreement on trade facilitation. Trade facilitation provisions and principles are increasingly seen to apply not only to Customs procedures but more generally, as reflected in the number of recent agreements featuring separate Trade Facilitation and/or Transparency chapters (or equivalent). Other trade facilitation measures that seem to be increasingly common include those on Automation/Use of ICT, Risk Management, Advance Ruling and Single Window. The ASEAN Trade in Goods Agreement (ATIGA) and its detailed commitment to implement a Trade Facilitation Work Programme stands out as it provides a concrete and specific way forward to ensure that progress is made towards actual implementation of the many trade facilitation measures mentioned in it.trade facilitation, regional trade agreements, RTA, bilateral, free trade agreements, FTA, free trade areas, customs, WTO, Asia, Pacific, paperless, single window, ICT

The effect of spatial frequency on peripheral collinear facilitation

The detection of a Gabor patch (target) can be decreased or improved by the presence of co-oriented Gabor patches (flankers) having the same spatial frequency as the target. These phenomena are thought to be mediated by lateral interactions. Depending on the distance between target and flankers, commonly defined as a multiple of the wavelength (λ) of the carrier, flankers can increase or decrease a target's detectability. Studies with foveal presentation showed that for target-to-flankers distances 3λ contrast thresholds decrease. Earlier studies on collinear facilitation at the near-periphery of the visual field (4° of eccentricity) showed inconsistent facilitation (Shani & Sagi, 2005, Vision Research, 45, 2009-2024) whereas more recent studies showed consistent facilitation for larger separations (7-8λ) (Maniglia et al., 2011, PLoS ONE, 6, e25568; Lev & Polat, 2011, Vision Research, 51, 2488-2498). However, all of these studies used medium-to-high spatial frequencies (3-8cpd). In this study we tested lower spatial frequencies (1, 2, and 3cpd) with different target-to-flankers distances. The rationale was that near-peripheral vision is tuned for lower spatial frequencies and this could be reflected in collinear facilitation. Results show consistent collinear facilitation at 8λ for all the spatial frequencies tested, but also show collinear facilitation at shorter target-to-flanker distance (6λ) for the lowest spatial frequencies tested (1cpd). Additionally, collinear facilitation decreases as spatial frequency increases; opposite to the findings of Polat (2009, Spatial Vision, 22, 179-193) in the fovea, indicating a different spatial frequency tuning between foveal and peripheral lateral interactions

Trade Facilitation Measures under Free Trade Agreements: Are They Discriminatory against Non-Members?

Are trade facilitation measures under free trade agreements (FTAs) discriminatory? This important question has yet to be sufficiently explored by the existing literature on trade facilitation. Despite the multilateral scope and non-discriminatory objectives of trade facilitation measures, some trade facilitation measures under FTAs can be discriminatory, similar to those in preferential tariff elimination. Based on a review of FTAs in Asia and the Pacific, this study provides detailed empirical analysis on whether or not trade facilitation provisions in FTAs are exclusive to contracting FTA partners and how the measures can be discriminatory against non-members.Trade facilitation; free trade agreements (FTAs); discriminatory measures; national treatment (NT); most-favored-nation (MFN)