3,936 research outputs found
Electoral competition under the threat of political unrest
We study elections in which one party (the strong party) controls a source of political unrest; e.g., this party could instigate riots if it lost the election. We show that the strong party is more likely to win the election when there is less information about its ability to cause unrest. This is because when the weak party is better informed, it can more reliably prevent political unrest by implementing a ``centrist'' policy. When there is uncertainty over the credibility of the threat, ``posturing'' by the strong party leads to platform divergence.Electoral competition, political unrest, asymmetric information, platform divergence
Credit cycle and adverse selection effects in consumer credit markets -- evidence from the HELOC market
The authors empirically study how the underlying riskiness of the pool of home equity line of credit originations is affected over the credit cycle. Drawing from the largest existing database of U.S. home equity lines of credit, they use county-level aggregates of these loans to estimate panel regressions on the characteristics of the borrowers and their loans, and competing risk hazard regressions on the outcomes of the loans. The authors show that when the expected unemployment risk of households increases, riskier households tend to borrow more. As a consequence, the pool of households that borrow on home equity lines of credit worsens along both observable and unobservable dimensions. This is an interesting example of a type of dynamic adverse selection that can worsen the risk characteristics of new lending, and suggests another avenue by which the precautionary demand for liquidity may affect borrowing.Home equity loans ; Risk
Seasonal Habitat Use, Movement, and Exploitation of Sauger in the Arkansas River
Sauger (Sander canadensis) are a native game fish present in the Arkansas River and have an affinity for high nutrient levels, high turbidity, and deep moving water. Little is known about Sauger habitat use and movement among navigation pools in the Arkansas River. However, they aggregate below lock and dams during winter and early spring leaving them susceptible to overharvest. I caught 330 Sauger using experimental gillnets downstream from dams in two navigation pools. Fish were externally tagged with Floy Tbar anchor tags (FD94). Of the 330 fish tagged, only five were harvested resulting in a low estimation of exploitation at 3.9% adjusted for the rate of angler reporting. Another 50 adult Sauger were implanted with acoustic telemetry tags to assess habitat use and movement using both active and passive receivers. Tracking was limited to four months due to high flow and unsafe boating conditions resulting in missing important Sauger movement events. Interpool movement was detected for 22% of Sauger in both up and down stream directions traveling up to 140 km, suggesting dams may not be restrictive to the species. Sauger in the Arkansas River should be managed as a single population and the species may benefit from interjurisdictional management near state borders. Habitat was delineated based on anthropogenic influences and identified as main channel, channel edge, wing dike, dam, flats, and backwater. Second order compositional analysis of habitat use suggests channel edge is being used the most in Pool 9 and wing dike is being used the most in Pool 10. Third order compositional analysis of habitat use suggests main channel is being used the most in Pool 9 and wing dike is being used the most in Pool 10. Sauger are utilizing habitats that have heavy anthropogenic influences that typically result in fast moving water in the channel and optimal forage opportunity near wing dikes. Future studies should focus on analyzing habitats year-round on a finer scale to determine factors influencing Sauger preference for channel and wing dike habitats
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Real-time decoding of question-and-answer speech dialogue using human cortical activity.
Natural communication often occurs in dialogue, differentially engaging auditory and sensorimotor brain regions during listening and speaking. However, previous attempts to decode speech directly from the human brain typically consider listening or speaking tasks in isolation. Here, human participants listened to questions and responded aloud with answers while we used high-density electrocorticography (ECoG) recordings to detect when they heard or said an utterance and to then decode the utterance's identity. Because certain answers were only plausible responses to certain questions, we could dynamically update the prior probabilities of each answer using the decoded question likelihoods as context. We decode produced and perceived utterances with accuracy rates as high as 61% and 76%, respectively (chance is 7% and 20%). Contextual integration of decoded question likelihoods significantly improves answer decoding. These results demonstrate real-time decoding of speech in an interactive, conversational setting, which has important implications for patients who are unable to communicate
Electoral Competition under the Threat of Political Unrest
We study elections in which one party (the strong party) controls a source of political unrest; e.g., this party could instigate riots if it lost the election. We show that the strong party is more likely to win the election when there is less information about its ability to cause unrest. This is because when the weak party is better informed, it can more reliably prevent political unrest by implementing a "centrist" policy. When there is uncertainty over the credibility of the threat, "posturing" by the strong party leads to platform divergence
Experimental Study of Shock-train/Combustion Coupling and Flame Dynamics in a Heated Supersonic Flow.
Isolator/combustor interactions are measured in a direct-connect dual-mode ramjet-scramjet experiment. An operating point approach is used to create a mapping of the coupling effects between the isolator geometry, inlet flow conditions and fuel injector behavior. The resulting isolator/injector coupling map provides a description of the response of the isolator to particular injector performance, and the effective blockage it induces on the isolator flow. Existing models and correlations predicting the pressure rise across a pseudo-shock, and its resultant length, were evaluated through comparison with measurements made in a heated-flow isolator duct that is coupled to a hydrogen-air combustor. The observation of a normal-to-oblique shock-train transition mechanism has lead to the development of a revised shock-train operating regime description that takes into account the impact of Mach number and maximum pressure recovery on the shock configurations
present in the isolator.
The behavior of a ram-scram transition was examined along with pressure measurements
and high-speed laser interferometry. The work quantifies the sudden change in the wall static pressure profile and flame position that occurs as the downstream boundary condition abruptly changes when the flow becomes unchoked. Transition was studied in three ways; as a quasi-steady phenomenon, or as caused by rapid variations in either fuel flow-rate or test-section wall temperature. A regime diagram was measured that plots the ram-scram transition boundary. Under certain conditions some periodic low-frequency oscillations of the flame position occur and they are shown to be correlated with oscillations of the upstream pre-combustion pseudo-shock. A self-sustaining shear-layer instability, associated with the flameholding cavity, is identified as the mechanism perpetuating this behavior. The relevant time scales associated with the ram-scram transition and the flameshock interactions are discussed.Ph.D.Aerospace EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/91395/1/mfotia_1.pd
Peak Ventilation Reference Standards from Exercise Testing: From the FRIEND Registry
Peak Ventilation Reference Standards from Exercise Testing: From the FRIEND Registry. Med. Sci. Sports Exerc., Vol. 50, No. 12, pp. 2603–2608, 2018. Purpose: Cardiopulmonary exercise testing (CPX) provides valuable clinical information, including peak ventilation (V˙ Epeak), which has been shown to have diagnostic and prognostic value in the assessment of patients with underlying pulmonary disease. This report provides reference standards for V˙ Epeak derived from CPX on treadmills in apparently healthy individuals. Methods: Nine laboratories in the United States experienced in CPX administration with established quality control procedures contributed to the Fitness Registry and the Importance of Exercise National Database from 2014 to 2017. Data from 5232 maximal exercise tests from men and women without cardiovascular or pulmonary disease were used to create percentiles ofV˙ Epeak for both men and women by decade between 20 and 79 yr. Additionally, prediction equations were developed for V˙ Epeak using descriptive information. Results: V˙ Epeak was found to be significantly different between men and women and across age groups (P G 0.05). The rate of decline in V˙ Epeak was 8.0% per decade for both men and women. A stepwise regression model of 70% of the sample revealed that sex, age, and height were significant predictors ofV˙ Epeak. The equation was cross-validated with data from the remaining 30% of the sample with a final equation developed from the full sample (r = 0.73). Additionally, a linear regression model revealed forced expiratory volume in 1 s significantly predicted V˙ Epeak (r = 0.73). Conclusions: Reference standards were developed for V˙ Epeak for the United States population. Cardiopulmonary exercise testing laboratories will be able to provide interpretation of V˙ Epeak from these age and sex-specific percentile reference values or alternatively can use these nonexercise prediction equations incorporating sex, age, and height or with a single predictor of forced expiratory volume in 1 s
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