No abstract

T o alleviate poverty in developing countries, governments and non-governmental organizations disseminate two types of information: (i) agricultural advice to enable farmers to improve their operations (cost reduction, quality improvement, and process yield increase); and (ii) market information about future price/demand to enable farmers to make better production planning decisions. This information is usually disseminated free of charge. While farmers can use the market information to improve their production plans without incurring any (significant) cost, adopting agricultural advice to improve operations requires upfront investment, for example, equipment, fertilizers, pesticides, and higher quality seeds. In this study, we examine whether farmers should use market information to improve their production plans (or adopt agricultural advice to improve their operations) when they engage in Cournot competition under both uncertain market demand and uncertain process yield. Our analysis indicates that both farmers will use the market information to improve their profits in equilibrium. Hence, relative to the base case in which market information is not available, the provision of market information can improve the farmers' total welfare (i.e., total profit for both farmers). Moreover, when the underlying process yield is highly uncertain or when the products are highly heterogeneous, the provision of market information is welfare-maximizing in the sense that the maximum total welfare of farmers is attained when both farmers utilize market information in equilibrium. Furthermore, in equilibrium, whether a farmer adopts the agricultural advice depends on the size of the requisite upfront investment. More importantly, we show that agricultural advice is not always welfare improving unless the upfront investment is sufficiently low. This result implies that to improve farmers' welfare, governments should consider offering farmer subsidies.

Background and Purpose: Intracranial atherosclerosis is one of the main causes of stroke, and high-resolution magnetic resonance imaging provides useful imaging biomarkers related to the risk of ischemic events. This study aims to evaluate differences in histogram features between culprit and nonculprit intracranial atherosclerosis using high-resolution magnetic resonance imaging. Methods: Two hundred forty-seven patients with intracranial atherosclerosis who underwent high-resolution magnetic resonance imaging sequentially between January 2015 and December 2016 were recruited. Quantitative features, including stenosis, plaque burden, minimum luminal area, intraplaque hemorrhage, enhancement ratio, and dispersion of signal intensity (coefficient of variation), were analyzed based on T2-, T1-, and contrast-enhanced T1-weighted images. Step-wise regression analysis was used to identify key determinates differentiating culprit and nonculprit plaques and to calculate the odds ratios (ORs) with 95% CIs. Results: In total, 190 plaques were identified, of which 88 plaques (37 culprit and 51 nonculprit) were located in the middle cerebral artery and 102 (57 culprit and 45 nonculprit) in the basilar artery. Nearly 90% of culprit lesions had a degree of luminal stenosis of <70%. Multiple logistic regression analyses showed that intraplaque hemorrhage (OR, 16.294 [95% CI, 1.043–254.632]; P =0.047), minimum luminal area (OR, 1.468 [95% CI, 1.032–2.087]; P =0.033), and coefficient of variation (OR, 13.425 [95% CI, 3.987–45.204]; P <0.001) were 3 significant features in defining culprit plaques in middle cerebral artery. The enhancement ratio (OR, 9.476 [95% CI, 1.256–71.464]; P =0.029), intraplaque hemorrhage (OR, 2.847 [95% CI, 0.971–10.203]; P =0.046), and coefficient of variation (OR, 10.068 [95% CI, 2.820–21.343]; P <0.001) were significantly associated with plaque type in basilar artery. Coefficient of variation was a strong independent predictor in defining plaque type for both middle cerebral artery and basilar artery with sensitivity, specificity, and accuracy being 0.79, 0.80, and 0.80, respectively. Conclusions: Features characterized by high-resolution magnetic resonance imaging provided complementary values over luminal stenosis in defined lesion type for intracranial atherosclerosis; the dispersion of signal intensity in histogram analysis was a particularly effective predictive parameter.

Background: Patients with intracranial atherosclerotic disease (ICAD) have a high frequency of stroke recurrence. However, there has been little investigation into the prognostic value of higher-resolution magnetic resonance imaging (HR-MRI). Purpose: To investigate the use of intracranial atherosclerotic plaques features in predicting risk of recurrent cerebrovascular ischemic events using HR-MRI. Study Type: Prospective. Population: Fifty-eight patients with acute/subacute stroke (N = 46) or transient ischemic attack (N = 12). Field Strength/Sequence: A 3.0 T, 3D time-of-flight gradient echo sequence and T1-and T2-weighted fast spin echo sequences with 0.31 x 0.39 mm 2 in-plane resolution, twice (with >3 months between scans) following the initial event. Assessment: Patients were also followed clinically for recurrent ischemic events for up to 48 months or until a subsequent event occurred. The degree of stenosis, plaque burden (PB), minimal lumen area (MLA), and contrast enhancement ratio were assessed at each scanning session and the percentage change of each over time was calculated. Statistical Tests: Univariable and multivariable Cox regression analyses were used to calculate the hazard ratio (HR) and 95% confidence interval (CI) for predicting recurrent events. Results: The mean time interval between baseline and follow-up MRI scans was 6.2 ± 4.1 months. After the second MRI scan, 20.7% of patients (N = 12) had experienced ipsilateral recurrent TIA/stroke within 10.9 ± 9.2 months. Univariable analyses showed that baseline triglyceride, percentage change of PB, and progression of PB were significantly associated with recurrent events (all P < 0.05). Multivariable Cox regression indicated that progression of PB (HR, 6.293; 95% CI, 1.620-24.444; P < 0.05) was a significant independent imaging feature for recurrent ischemic events. Data Conclusion: Progression of PB was independently associated with recurrent ischemic cerebrovascular events. HR-MRI may help risk stratification of patients at risk of recurrent stroke. Level of Evidence: 2 Technical Efficacy: Stage 4

This paper examines the impact of two reimbursement schemes, Fee-for-Service and Bundled Payment, on the social welfare, the patient revisit rate, and the patient waiting time in a public healthcare system. The two schemes differ on the payment mechanism: under the fee-for-service scheme, the healthcare provider receives the payment each time a patient visits (or revisits) whereas, under the bundled payment scheme, the healthcare provider receives a lump sum payment for the entire episode of care regardless of how many revisits a patient incurs. By considering the quality-speed tradeoff (i.e., a higher service speed reduces service quality, resulting in a higher revisit rate), we examine a three-stage Stackelberg game to determine the patients' initial visit rate, the service provider's service rate (which affects the revisit rate), and the funder's reimbursement rate. This analysis enables us to compare the equilibrium outcomes (social welfare, revisit rate and waiting time) associated with the two payment schemes. We find that when the patient pool size is large, the bundled payment scheme dominates the fee-for-service scheme in terms of higher social welfare and a lower revisit rate, whereas the fee-for-service scheme prevails in terms of shorter waiting time. When the patient pool is small, the bundle payment scheme dominates the fee-for-service scheme in all three performance measures.