Crossing the threshold : an analysis of IBRD graduation policy

According to World Bank policy, countries remain eligible to borrow from the International Bank for Reconstruction and Development until they are able to sustain long-term development without further recourse to Bank financing. Graduation from the Bank is not an automatic consequence of reaching a particular income level, but rather is supposed to be based on a determination of whether the country has reached a level of institutional development and capital-market access that enables it to sustain its own development process without recourse to Bank funding. This paper assesses how International Bank for Reconstruction and Development graduation policy operates in practice, investigating what income and non-income factors appear to have influenced graduation decisions in recent decades, based on panel data for 1982 through 2008. Explanatory variables include the per-capita income of the country, as well as measures of institutional development and market access that are cited as criteria by the graduation policy, and other plausible explanatory variables that capture the levels of economic development and vulnerability of the country. The authors find that the observed correlates of Bank graduation are generally consistent with the stated policy. Countries that are wealthier, more creditworthy, more institutionally developed, and less vulnerable to shocks are more likely to have graduated. Predicted probabilities generated by the model correspond closely to the actual graduation and de-graduation experiences of most countries (such as Korea and Trinidad and Tobago), and suggest that Hungary and Latvia may have graduated prematurely -- a prediction consistent with their subsequent return to borrowing from the Bank in the wake of the global financial crisis.Economic Theory&Research,Emerging Markets,Banks&Banking Reform,Labor Policies,Debt Markets

Drosophila EB1 is important for proper assembly, dynamics, and positioning of the mitotic spindle

EB1 is an evolutionarily conserved protein that localizes to the plus ends of growing microtubules. In yeast, the EB1 homologue (BIM1) has been shown to modulate microtubule dynamics and link microtubules to the cortex, but the functions of metazoan EB1 proteins remain unknown. Using a novel preparation of the Drosophila S2 cell line that promotes cell attachment and spreading, we visualized dynamics of single microtubules in real time and found that depletion of EB1 by RNA-mediated inhibition (RNAi) in interphase cells causes a dramatic increase in nondynamic microtubules (neither growing nor shrinking), but does not alter overall microtubule organization. In contrast, several defects in microtubule organization are observed in RNAi-treated mitotic cells, including a drastic reduction in astral microtubules, malformed mitotic spindles, defocused spindle poles, and mispositioning of spindles away from the cell center. Similar phenotypes were observed in mitotic spindles of Drosophila embryos that were microinjected with anti-EB1 antibodies. In addition, live cell imaging of mitosis in Drosophila embryos reveals defective spindle elongation and chromosomal segregation during anaphase after antibody injection. Our results reveal crucial roles for EB1 in mitosis, which we postulate involves its ability to promote the growth and interactions of microtubules within the central spindle and at the cell cortex

Beaver and Aspen: Synergy Among Keystone Species

In the West, climate change is likely to increase the frequency, intensity, and duration of drought. Restoration of soils and water storage capacity can help create resilient uplands and riverscapes (i.e., streams and the valley bottoms). Over the past two centuries, common land uses, the removal of beaver and wood, straightening of streams, and damage to riparian areas have created simplified, structurally starved, riverscapes. Degraded streams are very efficient at transporting water, sediment, and nutrients downstream. Aspen forests are also biological hotspots that have been degraded by past land uses such as overbrowsing ungulates, land clearing, fire suppression, and outright removal in favor of timber species. Loss of riverscape and aspen habitats has a disproportionate impact on biodiversity and landscape resilience. When aspen occur in or near riverscapes they are a preferred food and building material for beavers. Beaver, in-turn, can stimulate aspen regeneration, both through cutting and restoring hydrologic function in riparian areas. Adding beavers can reinstate riparian processes, increase aspen growth and diversity that extends to uplands, and buffer ecosystem sensitivity to extended drought

The impact of the UK ‘two-week rule’ on stage-on-diagnosis of oral cancer and the relationship to socio-economic inequalities

Background:The‘two-week rule’(TWR) fast-track cancer referral system for head and neck cancers was introduced by the UK government in 2000, to facilitate earlier diagnosis. However, little work has compared stage on diagnosis of cancer before and after the implementation of the system.Objectives:•Describe the presentation of oral cancer in Merseyside from 1992 to 2012.•To evaluate whether stage on presentation has improved after the introduction of the TWR using data from a clinical database in Merseyside 1992–2012.•To assess the relationship between stage on presentation and social deprivation 1992–2012.•To assess the change in presentation for different sites within the oral cavity.Method and setting:Patients were identified using the Aintree (Liverpool) head and neck oncology database,containing all diagnoses of oral squamous cell carcinoma (SCC) between 1992–2012. Cancers were clinically staged using the American Joint Committee on Cancer (AJCC) stage groupings and divided into‘early’(stage 1 and 2) and‘late’(stage 3 and 4). Index of Multiple Deprivation (IMD) 2004 data were derived from patient postcodes. Appropriate regression analyses were undertaken.Results:1485 consecutive patients diagnosed were studied. Median (IQR) age was 63 (55–73) years and 61% were male. 36% of cancers were located on anterior 2/3rds tongue, 30% floor of mouth, and 34% elsewhere.‘Late’ tumour presentation was 52% (95%CI 46.8–56.4%) for 1992–2000, and 44% (95%CI 41.4–47.5%) for 2001–2012 (P = 0.01).Join point regression analysis of‘late’presentation indicated a steady fall 1992–2012, at an annual percentage decrease of 1.27% (95% CI−2.3 to−0.2). No statistically significant change in trend was identified either overall or within deprivation groups following the TWR. For patients in‘more deprived' neighbourhoods, ‘late’ tumour presentation was: 56% and 47%; in‘less deprived’areas: 48% and 42%, before and after the introduction of the TWR, respectively.Year of diagnosis, tumour site and IMD2004 were significantly associated with‘late’presentation, and lo-cation of tumour was also associated with time period and IMD2004. Main conclusions:Stage on presentation improved between 1992–2012. Join point analysis showed no significant change in trend following the introduction of the TWR. The rate of improvement was highest for most deprived; nevertheless, deprivation inequality persists and this should be a focus of further initiatives and research

Autocatalytic plume pinch-off

A localized source of buoyancy flux in a non-reactive fluid medium creates a plume. The flux can be provided by either heat, a compositional difference between the fluid comprising the plume and its surroundings, or a combination of both. For autocatalytic plumes produced by the iodate-arsenous acid reaction, however, buoyancy is produced along the entire reacting interface between the plume and its surroundings. Buoyancy production at the moving interface drives fluid motion, which in turn generates flow that advects the reaction front. As a consequence of this interplay between fluid flow and chemical reaction, autocatalytic plumes exhibit a rich dynamics during their ascent through the reactant medium. One of the more interesting dynamical features is the production of an accelerating vortical plume head that in certain cases pinches-off and detaches from the upwelling conduit. After pinch-off, a new plume head forms in the conduit below, and this can lead to multiple generations of plume heads for a single plume initiation. We investigated the pinch-off process using both experimentation and simulation. Experiments were performed using various concentrations of glycerol, in which it was found that repeated pinch-off occurs exclusively in a specific concentration range. Autocatalytic plume simulations revealed that pinch-off is triggered by the appearance of accelerating flow in the plume conduit.Comment: 10 figures. Accepted for publication in Phys Rev E. See also http://www.physics.utoronto.ca/nonlinear/papers_chemwave.htm

Natural versus forced convection in laminar starting plumes

A starting plume or jet has a well-defined, evolving head that is driven through the surrounding quiescent fluid by a localized flux of either buoyancy or momentum, or both. We studied the scaling and morphology of starting plumes produced by a constant flux of buoyant fluid from a small, submerged outlet. The plumes were laminar and spanned a wide range of plume Richardson numbers Ri. Ri is the dimensionless ratio of the buoyancy forces to inertial effects, and is thus our measurements crossed over the transition between buoyancy-driven plumes and momentum-driven jets. We found that the ascent velocity of the plume, nondimensionalized by Ri, exhibits a power law relationship with Re, the Reynolds number of the injected fluid in the outlet pipe. We also found that as the threshold between buoyancy-driven and momentum-driven flow was crossed, two distinct types of plume head mophologies existed: confined heads, produced in the Ri > 1 regime, and dispersed heads, which are found in the Ri < 1 regime. Head dispersal is caused by a breakdown of overturning motion in the head, and a local Kelvin-Helmholtz instability on the exterior of the plume.Comment: 8 pages, 8 figures, accepted for publication in Physics of Fluids (final version with corrections

Spindle microtubules in flux

Accurate and timely chromosome segregation is a task performed within meiotic and mitotic cells by a specialized force-generating structure - the spindle. This micromachine is constructed from numerous proteins, most notably the filamentous microtubules that form a structural framework for the spindle and also transmit forces through it. Poleward flux is an evolutionarily conserved mechanism used by spindle microtubules both to move chromosomes and to regulate spindle length. Recent studies have identified a microtubule-depolymerizing kinesin as a key force-generating component required for flux. On the basis of these findings, we propose a new model for flux powered by a microtubule-disassembly mechanism positioned at the spindle pole. In addition, we use the flux model to explain the results of spindle manipulation experiments to illustrate the importance of flux for proper chromosome positioning