Validation of Performance-Based Specifications for Surface Asphalt Mixtures in Virginia

The Virginia Department of Transportation (VDOT), like many owner agencies, is interested in ways to facilitate the increased durability of asphalt mixes in an effort to make its roadway network more sustainable, longer lasting, and more economical. The balanced mix design (BMD) method proposes to address this through the incorporation of performance criteria into mix design and acceptance. VDOT has committed to the implementation of the BMD method in an effort to improve asphalt mix performance. The purpose of this study was to continue advancing efforts toward implementation of BMD through the evaluation of 13 asphalt mixes using performance-indicating laboratory tests, validation of the initial performance tests selected for BMD use, and validation of the initial test threshold criteria. Based on the results, the asphalt pavement analyzer (APA) rut test, indirect tensile cracking test (IDT-CT), and Cantabro test were found suitable for continued use in BMD. The current threshold criteria for all three tests were found reasonable based on additional mix testing. The study recommends that APA rut test and IDT-CT results should be compared and correlated to fundamental rutting and cracking tests, respectively, as well as to performance predictions obtained from mechanistic-empirical pavement design simulations, and to field performance for full assurance that test threshold values are appropriate. It was further recommended to evaluate the Cantabro, IDT-CT, and APA rut tests to determine acceptable variability and establish precision statements.

Clinical value of bronchodilator response for diagnosing asthma in steroid-naïve adults

Spirometry and testing for bronchodilator response have been recommended to detect asthma, and a bronchodilator response (BDR) of ≥12% and ≥200 mL has been suggested to confirm asthma. However, the clinical value of bronchodilation tests in newly diagnosed steroid-naïve adult patients with asthma remains unknown. We evaluated the sensitivity of BDR in FEV1 as a diagnostic test for asthma in a real-life cohort of participants in the Seinäjoki Adult Asthma Study (SAAS). In the diagnostic phase, 369 spirometry tests with bronchodilation were performed for 219 steroid-naïve patients. The fulfilment of each test threshold was assessed. According to the algorithm of the National Institute for Health and Care Excellence, we divided the patients into obstructive (FEV11/FVC<0.70) and non-obstructive (FEV1/FVC≥0.70) groups. Of the overall cohort, 35.6% fulfilled ΔFEV1≥12% and ≥200mL for the initial FEV1, 18.3% fulfilled ΔFEV1≥15% and ≥400 mL for the initial FEV1 and 36.1% fulfilled ΔFEV1≥9% of predicted FEV1 at least once. One-third (31%) of these steroid-naïve patients was obstructive (pre-bronchodilator FEV1/FVC<0.7). Of the obstructive patients, 55.9%, 26.5% and 48.5%, respectively, met the same thresholds. In multivariate logistic regression analysis, different thresholds recognized different kinds of asthma patients. In steroid-naïve adult patients, the current BDR threshold (ΔFEV1≥12% and ≥200 mL) has low diagnostic sensitivity (36%) for asthma. In obstructive patients, sensitivity is somewhat higher (56%) but far from optimal. If the first spirometry test with bronchodilation is not diagnostic but asthma is suspected, spirometry should be repeated, and other lung function tests should be used to confirm the diagnosis.

Merchant Card Acceptance: An Extension of the Tourist Test for Developing Countries

The paper extends the tourist test proposed by Rochet and Tirole (2011) to the situation of emerging countries which are characterized by informality (tax evasion through cash payments). We introduce a government which faces a cost associated to cash (resources to fight against crime minus seigniorage) and tax evasion in the base model. The main idea is that merchants benefit from tax evasion since they do not provide a receipt in cash transactions and thus pocket a fraction of the VAT. In the presence of informality, the tax benefit of cash reduces the merchants’ net operating benefit of accepting card sales. The tourist test aims to determine a maximum interchange fee (the fee that the acquirer pays to the issuer whenever a card transaction is done) which makes the merchant indifferent between accepting cash or card. In this new environment, the tourist test threshold now internalizes this tax benefit of accepting cash. We assess the socially optimal interchange fees in this new model setup derived from three different social maximization functions.