Trade costs, 1870–2000

What has driven trade booms and trade busts in the past century and a half? Was it changes in global output or in the costs of international trade? To address this question, we derive a micro-founded measure of aggregate bilateral trade costs based on a standard model of trade in differentiated goods. These trade costs gauge the difference between observed bilateral trade and frictionless trade in terms of an implied markup on retail prices of foreign goods. Thus, we are able to estimate the combined magnitude of tariffs, transportation costs, and all other macroeconomic frictions that impede international trade but that are inherently difficult to observe. We use this measure to examine the growth of global trade between 1870 and 1913, its retreat from 1921 to 1939, and its subsequent rise from 1950 to 2000. We find that trade cost declines explain roughly 55 percent of the pre–World War I trade boom and 33 percent of the post–World War II trade boom, while a precipitous rise in trade costs explains the entire interwar trade bust

Enhanced Gravitational Entanglement via Modulated Optomechanics

The role of entanglement in determining the non-classicality of a given interaction has gained significant traction over the last few years. In particular, as the basis for new experimental proposals to test the quantum nature of the gravitational field. Here we show that the rate of gravity mediated entanglement between two otherwise isolated optomechanical systems can be significantly increased by modulating the optomechanical coupling. This is most pronounced for low mass, high frequency systems - convenient for reaching the quantum regime - and can lead to improvements of several orders of magnitude, as well as a broadening of the measurement window. Nevertheless, significant obstacles still remain. In particular, we find that modulations increase decoherence effects at the same rate as the entanglement improvements. This adds to the growing evidence that the constraint on noise (acting on the position d.o.f) depends only on the particle mass, separation, and temperature of the environment and cannot be improved by novel quantum control. Finally, we highlight the close connection between the observation of quantum correlations and the limits of measurement precision derived via the Cram\'er-Rao Bound. An immediate consequence is that probing superpositions of the gravitational field places similar demands on detector sensitivity as entanglement verification.Comment: 31 pages, 4 figure

Hydrogeomorphic Classification for Great Lakes Coastal Wetlands

A hydrogeomorphic classification scheme for Great Lakes coastal wetlands is presented. The classification is hierarchical and first divides the wetlands into three broad hydrogeomorphic systems, lacustrine, riverine, and barrier-protected, each with unique hydrologic flow characteristics and residence time. These systems are further subdivided into finer geomorphic types based on physical features and shoreline processes. Each hydrogeomorphic wetland type has associated plant and animal communities and specific physical attributes related to sediment type, wave energy, water quality, and hydrology

Economic Feasibility of Impermeable Lagoon Covers

Environmental Economics and Policy,

Health-related quality of life improves with treatment-related GERD symptom resolution after adjusting for baseline severity

Severity and frequency of gastroesophageal reflux disease (GERD) related symptoms are associated with impaired health-related quality of life (HRQL). This study evaluated the association between baseline heartburn severity and endpoint HRQL of patients treated for heartburn and the relationship between complete resolution of heartburn symptoms and HRQL outcomes after controlling for baseline severity. We completed a secondary analysis of clinical symptom and HRQL data from three clinical trials in adult patients receiving either omeprazole or ranitidine treatment for GERD. HRQL was assessed using the Psychological General Well-Being Index (PGWB) in each of the three clinical trials, and two of the trials also included the Medical Outcomes Study Sleep disturbance scale. Gastrointestinal symptoms were evaluated using either the Gastrointestinal Symptom Rating Scale or a modified version of the scale. Baseline heartburn severity (none/minor, mild, moderate or severe) was defined based on patient-reported symptoms. Analysis of covariance (ANCOVA) models were used to compare mean HRQL scores by baseline level of heartburn symptom severity and whether or not patients experienced complete heartburn resolution. At baseline, PGWB scores were significantly worse (p < 0.05) for patients with more severe heartburn symptoms. There were no statistically significant baseline severity by symptom resolution interactions in any of the ANCOVA models. For all three trials and across all follow-up assessments, mean PGWB scores were statistically significantly higher for patients with completely resolved heartburn symptoms versus those whose symptoms were unresolved (all p-values < 0.05). Few significant effects were observed for sleep disturbance scores. While the severity of heartburn symptoms at the start of medical treatment for GERD is not associated with improvements in HRQL in subsequent weeks of treatment, complete resolution of symptoms is associated with improvements in psychological well-being

A direct empirical proof of the existence of dark matter

We present new weak lensing observations of 1E0657-558 (z=0.296), a unique cluster merger, that enable a direct detection of dark matter, independent of assumptions regarding the nature of the gravitational force law. Due to the collision of two clusters, the dissipationless stellar component and the fluid-like X-ray emitting plasma are spatially segregated. By using both wide-field ground based images and HST/ACS images of the cluster cores, we create gravitational lensing maps which show that the gravitational potential does not trace the plasma distribution, the dominant baryonic mass component, but rather approximately traces the distribution of galaxies. An 8-sigma significance spatial offset of the center of the total mass from the center of the baryonic mass peaks cannot be explained with an alteration of the gravitational force law, and thus proves that the majority of the matter in the system is unseen.Comment: Accepted for publication in ApJ

A mixed-methods evaluation using effectiveness perception surveys, social network analysis, and county-level health statistics: A pilot study of eight rural Indiana community health coalitions

Community health coalitions (CHCs) are a promising approach for addressing disparities in rural health statistics. However, their effectiveness has been variable, and evaluation methods have been insufficient and inconsistent. Thus, we propose a mixed-methods evaluation framework and discuss pilot study findings. CHCs in our pilot study partnered with Purdue Extension. Extension links communities and land grant universities, providing programming and support for community-engaged research. We conducted social network analysis and effectiveness perception surveys in CHCs in 8 rural Indiana counties during summer 2017 and accessed county-level health statistics from 2015-16. We compared calculated variables (i.e., effectiveness survey k-means clusters, network measures, health status/outcomes) using Pearson’s correlations. CHC members’ positive perceptions of their leadership and functioning correlated with interconnectedness in their partnership networks, while more centralized partnership networks correlated with CHC members reporting problems in their coalitions. CHCs with highly rated leadership and functioning developed in counties with poor infant/maternal health and opioid outcomes. Likewise, CHCs reporting fewer problems for participation developed in counties with poor infant/maternal health, poor opioid outcomes, and more people without healthcare coverage. This pilot study provides a framework for iterative CHC evaluation. As the evidence grows, we will make recommendations for best practices that optimize CHC partnerships to improve local health in rural areas

Strong and weak lensing united III: Measuring the mass distribution of the merging galaxy cluster 1E0657-56

The galaxy cluster 1E0657-56 (z = 0.296) is remarkably well-suited for addressing outstanding issues in both galaxy evolution and fundamental physics. We present a reconstruction of the mass distribution from both strong and weak gravitational lensing data. Multi-color, high-resolution HST ACS images allow detection of many more arc candidates than were previously known, especially around the subcluster. Using the known redshift of one of the multiply imaged systems, we determine the remaining source redshifts using the predictive power of the strong lens model. Combining this information with shape measurements of "weakly" lensed sources, we derive a high-resolution, absolutely-calibrated mass map, using no assumptions regarding the physical properties of the underlying cluster potential. This map provides the best available quantification of the total mass of the central part of the cluster. We also confirm the result from Clowe et al. (2004,2006a).Comment: Accepted for publication in ApJ; Version with full-resolution figures available at http://www.slac.stanford.edu/~marusa/Work/bradac_strong_weak_III.pd

Clinical and hemodynamic follow-up of left ventricular to aortic conduits in patients with aortic stenosis

To assess the long-term results of left ventricular outflow tract reconstruction utilizing an apical left ventricular to aortic valved (porcine) conduit the clinical and hemodynamic data were reviewed from 24 patients who had placement of an apico-aortic conduit. Eighteen of the patients are asymptomatic and taking no cardiac medications. Three patients were reoperated on, one patient 1.5 years after his original operation for subacute bacterial endocarditis and two patients 3 to 4 years after their original operation for severe conduit valve insufficiency. None of the patients is taking anticoagulants and no thromboembolic events have occurred. Postoperative catheterization has been performed 1 to 1.5 years (mean 1.2) after repair in 15 of 21 patients. The rest left ventricular outflow tract gradient has decreased from 102.5 ± 20 mm Hg preoperatively to 14.8 ± 9.9 mm Hg postoperatively (probability [p] < 0.001). Some degree of conduit obstruction was demonstrated by catheter passage in 11 of the 15 patients. In these 11 patients, the obstruction occurred at three distant sites: at the egress of the left ventricle in 9, at the porcine valve in 5 and at the aortic to conduit junction in 1. Isometric exercise in five and supine bicycle exercise in six patients increased the left ventricular outflow tract gradient by 2.5 ± 1.1 and 20.8 ± 11.8 mm Hg, respectively, despite an increase in cardiac index of 1 ± 0.3 and 3.7 ± 0.4 liters/min per m2, respectively. The data suggest that a left ventricular to aortic conduit is an effective form of therapy for severe left ventricular outflow tract obstruction