In this paper I analyze the work on exchange rates and external imbalances by University of Chicago faculty members during the university’s first 100 years, 1892 to 1992. Many people associate Chicago’s views with Milton Friedman’s advocacy for flexible exchange rates. But, of course, there was much more than that, including the work of J. Laurence Laughlin on bimetallism, Jacob Viner on the balance of payments, Lloyd Metzler on transfers, Harry Johnson on trade and currencies, Lloyd Mints on exchange rate regimes, Robert Mundell on optimal currency areas, and Arnold Harberger on shadow exchange rates, among others. The analysis shows that, although different scholars emphasized different issues, there was a common thread in this research, anchored on the role of relative prices’ changes during the adjustment process.

Understanding the distribution and habitat requirements of species is crucial for designing conservation actions, yet this information is not available for many plant species. We report the first confirmed wild populations of Porroglossum parsonsii, which, because of its horticultural value, is commercialized in national and international markets, from where it was first described to science. Our large-scale survey of 341 10 × 30 m plots spanning Andean forests, paramo habitats and pasturelands in Colombia suggests that P. parsonsii has a restricted geographical distribution in Andean forests with high forest cover (71.4–86.2%), where it occurs in low numbers (5–17 individuals per plot). Because of its market value (USD 18–20 per plant) there is a risk the species could be collected illegally, and therefore the habitat of the species in the Santuario de Fauna y Flora de Iguaque requires appropriate conservation.

The ‘Critically Endangered’ Red-fronted Macaw is endemic to seasonally dry, rain-shadowed valleys in the south-central Andes of Bolivia. The remoteness and inaccessibility of most of this region have hampered the rigorous collection of reliable range-wide data on the species’ global, local and breeding population sizes. Such data are imperative, however, for effective conservation and management. Estimated to number up to 5,000 birds in the early 1980s, the most recent and thorough survey to date reported a total of only 807 macaws and a breeding population fraction of about 20% in 2011, disjunctly distributed across eight breeding and six foraging areas and divided into four genetic clusters. Ten years later, we reassessed the species’ population sizes and breeding distribution with increased survey effort and geographic coverage. Six teams simultaneously surveyed different sections of the species’ entire known breeding range in four watersheds focusing on nesting sites. We estimated a global population size of 1,160 macaws, a breeding population fraction of 23.8–27.4% (138–159 nesting pairs) and discovered four new breeding areas. Watersheds and breeding areas differed widely in nesting pair and total macaw numbers. The Mizque watershed held 53% of the species’ breeding and 41.5% of its global population and had the highest breeding population fraction of 30.7–34.9%; the Pilcomayo watershed obtained the lowest values (6%, 8.5% and 14.1–18.2%, respectively). Two of the four documented genetic clusters (subpopulations) each held well over 50 breeding individuals. Two of the eight breeding areas documented in 2011 were found unoccupied in 2021. Numbers of nesting pairs per breeding area in 2011 were poorly correlated with those in 2021, and timing of breeding activities also differed between years. Our new data indicate that the Red-fronted Macaw no longer meets IUCN Red List criteria for ‘Critically Endangered’ species and that it should be downlisted to ‘Endangered.’

We analyze Milton Friedman’s two visits to Chile, in March 1975 and November 1981. We rely on a number of sources, including Friedman’s archives, press archives in Chile and the rest of the world, interviews, and the papers and recollections of some of those who accompanied Friedman during his meeting with Pinochet. Although Friedman’s 1975 visit has been widely discussed, his 1981 visit has been largely neglected. However, this visit was particularly important as it preceded a severe currency and banking crisis, stemming from an overvalued fixed exchange rate. The crisis put at risk the influence of the “Chicago Boys” and the political and economic liberalization process. We analyze Friedman’s views regarding Chile’s pegged exchange rate strategy followed between 1979 and 1982, and his position on economic and political freedom.

The role of starburst winds versus active galactic nuclei (AGN) jets/winds in the formation of the kiloparsec scale radio emission seen in Seyferts is not yet well understood. In order to be able to disentangle the role of various components, we have observed a sample of Seyfert galaxies exhibiting kpc-scale radio emission suggesting outflows, along with a comparison sample of starburst galaxies, with the EVLA B-array in polarimetric mode at 1.4 GHz and 5 GHz. The Seyfert galaxy NGC 2639, shows highly polarized secondary radio lobes, not observed before, which are aligned perpendicular to the known pair of radio lobes. The additional pair of lobes represent an older epoch of emission. A multi-epoch multi-frequency study of the starburst-Seyfert composite galaxy NGC 3079, reveals that the jet together with the starburst superwind and the galactic magnetic fields might be responsible for the well-known 8-shaped radio lobes observed in this galaxy. We find that many of the Seyfert galaxies in our sample show bubble-shaped lobes, which are absent in the starburst galaxies that do not host an AGN.

Little is known about terrestrial climate dynamics in the Levant during the penultimate interglacial-glacial period. To decipher the palaeoclimatic history of the Marine Oxygen Isotope Stage (MIS) 6 glacial period, a well-dated stalagmite (~194 to ~154 ka) from Kanaan Cave on the Mediterranean coast in Lebanon was analyzed for its petrography, growth history, and stable isotope geochemistry. A resolved climate record has been recovered from this precisely U–Th dated speleothem, spanning the late MIS 7 and early MIS 6 at low resolution and the mid–MIS 6 at higher resolution. The stalagmite grew discontinuously from ~194 to ~163 ka. More consistent growth and higher growth rates between ~163 and ~154 ka are most probably linked to increased water recharge and thus more humid conditions. More distinct layering in the upper part of the speleothem suggests strong seasonality from ~163 ka to ~154 ka. Short-term oxygen and carbon isotope excursions were found between ~155 and ~163 ka. The inferred Kanaan Cave humid intervals during the mid–MIS 6 follow variations of pollen records in the Mediterranean basins and correlate well with the synthetic Greenland record and East Asian summer monsoon interstadial periods, indicating short warm/wet periods similar to the Dansgaard-Oeschger events during MIS 4–3 in the eastern Mediterranean region.

In December 1933, John Maynard Keyes published an open letter to President Roosevelt, where he wrote: ‘The recent gyrations of the dollar have looked to me more like a gold standard on the booze than the ideal managed currency of my dreams.’ This was a criticism of the ‘gold-buying program’ launched in October 1933. In this article I use high-frequency data on the dollar–pound and dollar–franc exchange rates to investigate whether the gyrations of the dollar were unusually high in late 1933. My results show that although volatility was pronounced, it was not higher than during some other periods after 1921. Moreover, dollar volatility began to subside towards the end of the period alluded to by Keynes.

Identification of the transient snowline (TSL) from high spatial resolution Landsat imagery on Lemon Creek Glacier (LCG), southeast Alaska, USA, and Mittivakkat Gletscher (MG), southeast Greenland, is used to determine snow ablation rates, the equilibrium-line altitude (ELA) and the accumulation-area ratio (AAR). The rate of rise of the TSL during the ablation season on a glacier where the balance gradient is known provides a measure of the snow ablation rate. On both LCG and MG, snow pits were completed in regions that the TSL subsequently transects. This further provides a direct measure of the snow ablation rates for a particular year. TSL observations from multiple dates during the ablation season from 1998 to 2011 at LCG and 1999 to 2012 at MG were used to explore the consistency of the TSL rise and snow ablation rate. On LCG and MG the satellite-derived mean TSL migration rates were 3.8 ± 0.6 and 9.4 ± 9.1 m d−1, respectively. The snow ablation rates were 0.028 ± 0.004 m w.e. d−1 for LCG and 0.051 ± 0.018 m w.e. d−1 for MG estimated by applying a TSL–mass-balance-gradient method, and 0.031 ± 0.004 and 0.047 ± 0.019 m w.e. d−1 by applying a snow-pit–satellite method, illustrating significant agreement between the two different approaches for both field sites. Also, satellite-derived ELA and AAR, and estimated net mass-balance (Ba) conditions were in agreement with observed ELA, AAR and Ba conditions for LCG and MG.

We document changes for Mittivakkat Gletscher, the peripheral glacier in Greenland with the longest field-based observed mass-balance and surface velocity time series. Between 1986 and 2011, this glacier changed by −15% in mean ice thickness and −30% in volume. We attribute these changes to summer warming and lower winter snow accumulation. Vertical strain compensated for ∼60% of the elevation change due to surface mass balance (SMB) in the lower part, and ∼25% in the upper part. The annual mean ice surface velocity changed by −30%, which can be fully explained by the dynamic effect of ice thinning, within uncertainty. Mittivakkat Gletscher summer surface velocities were on average 50–60% above winter background values, and up to 160% higher during peak velocity events. Peak velocity events were accompanied by uplift of a few centimeters.

The contribution to sea level to 2200 from the grounded, mainland Antarctic Peninsula ice sheet (APIS) was calculated using an ice-sheet model initialized with a new technique computing ice fluxes based on observed surface velocities, altimetry and surface mass balance, and computing volume response using a linearized method. Volume change estimates of the APIS resulting from surface mass-balance anomalies calculated by the regional model RACMO2, forced by A1B and E1 scenarios of the global models ECHAM5 and HadCM3, predicted net negative sea-level contributions between −0.5 and −12 mm sea-level equivalent (SLE) by 2200. Increased glacier flow due to ice thickening returned ∼15% of the increased accumulation to the sea by 2100 and ∼30% by 2200. The likely change in volume of the APIS by 2200 in response to imposed 10 and 20 km retreats of the grounding line at individual large outlet glaciers in Palmer Land, southern Antarctic Peninsula, ranged between 0.5 and 3.5 mm SLE per drainage basin. Ensemble calculations of APIS volume change resulting from imposed grounding-line retreat due to ice-shelf break-up scenarios applied to all 20 of the largest drainage basins in Palmer Land (covering ∼40% of the total area of APIS) resulted in net sea-level contributions of 7–16 mm SLE by 2100, and 10–25 mm SLE by 2200. Inclusion of basins in the northern peninsula and realistic simulation of grounding-line movement for AP outlet glaciers will improve future projections.

High speed photometry of several accreting binaries was obtained using the McDonald Observatory 2.1m telescope and ARGOS CCD photometer. A broad-band filter (BVR) was used in order to maximize flux and maintain a short (1-10s) integration time on faint targets. Such observations obtained over several years allow for variability study over time scales covering many orders of magnitude. Observations and analysis for several binaries are summarized.

In this paper I use historical data to analyze the relationship between crises and growth in Latin America. I calculate by how much the region's GDP per capita has been reduced as a consequence of the recu- rrence of external crises. I also analyze the determinants of major balan- ce of payments crises. The main conclusion is that it is unlikely that Latin America will, on average, experience a major improvement in long run growth in the future. It is possible that some countries will make progress in catching up with the advanced nations. This, however, will not be the norm; most Latin American countries are likely to fall further behind in relation to the Asian countries and other emerging nations. Not everything, however, is grim. My analysis also suggests that fewer Latin America countries will be subject to the type of catastrophic crises that affected the region in the past. Latin America's future will be one of «No crises and very modest growth».

Bulk GaN sliced in bars along (11-20) and (1-100) planes from a boule grown in the [0001] direction by HVPE was confirmed as strain free material with a low dislocation density by using several characterization techniques. The high-structural quality of the material allows photoluminescence studies of free excitons, principal donor bound excitons and their two-electron satellites with regard to the optical selection rules. Raman scattering study of the bulk GaN with nonpolar orientations allows a direct access to the active phonon modes and a direct determination of their strain-free positions.

We describe a new method of three-dimensional magnetic resonance imaging of the heart that has been used to produce high quality diagnostic images in 274 patients with congenital cardiac disease, ranging in age from 1 day to 66 years. Using a steady state free precession gradient echo technique and parallel imaging, rapid acquisition of the entire cardiac volume is possible during 8 to 15 sequential breath-holds, each lasting between 8 and 15 s. We obtained high-resolution images, with a resolution of 1 mm3, at between 3 and 10 phases of the cardiac cycle.

While images of diagnostic quality were obtained in all cases, in 52 patients there was some degradation due to various factors. Children under 8 years were ventilated, and ventilation was suspended for the breath-holds. For patients breathing spontaneously a novel respiratory navigator technique was developed, using a navigator echo placed over the right hemidiaphragm. This was used successfully in 20 patients, and reduced the misalignment of images obtained during different breath-holds.

Images were analysed using multi-planar reformatting and volume rendering. Image processing took approximately five minutes for each study. End-diastolic images were processed for all patients. Systolic images were also processed in selected cases.

Further improvements in parallel imaging should reduce imaging times further, so that it is possible to obtain the full volume image in a single breath-hold. This will enable imaging of complex anatomy to be obtained using a standard imaging protocol that does not require the operator to understand the cardiac malformation, making the magnetic resonance imaging of congenital cardiac disease faster and more effective.