The impacts of thresholds on risk behavior: What's wrong with index insurance?

Almost universally, implementers of index insurance for low income households have chosen to embed insurance with other interventions designed to improve productivity, with the insurance used almost entirely to make the other interventions possible. A common example is to use the insurance to allow farmers to have access to loans by reducing the probability of weather related defaults. A bundled loan/insurance implementation with overwhelming take-up rates had low insurance take-up rates when researchers unbundled the package, covering the loan default risk, so that the loans could be available without requiring insurance. If low income farmers are highly risk averse, why do they place so little value on risk reducing insurance once their access to productive inputs is secured? In general, why do index insurance implementers targeting the lowest income households nearly universally utilize insurance as a tool to increase productivity instead of using it to reduce variance? We provide a potential explanation driven by optimal risk behavior in the face of income thresholds, illustrating how models of risk aversion may not adequately represent the behavior of those with very low incomes. We show how variance reduction may not be the most important outcome for a low income farmer who lives near the poverty threshold. We show that if a farmer's goal is to avoid falling into a poverty trap, then the lower his income is, the less risk averse he becomes in the mean-variance utility maximization framework regarding the design of index insurance contracts. We begin this paper by introducing a mean-variance utility maximization framework, using a known joint distribution for the index and yield, and then we show how one's risk aversion changes when the mean-variance utility function is switched to a poverty trap avoidance utility function. We argue that one reason farmers don't always seek to minimize variance is that they may be very near a poverty trap threshold, and are therefore less willing to give up additional expected income in exchange for decreased income variance. In this case, it may be best for implementers to utilize insurance to unlock increases in productivity as opposed to variance reduction per se.Agricultural and Food Policy, Agricultural Finance, International Development, D80, O12, O16, Q14,

Bayesball: A Bayesian Hierarchical Model for Evaluating Fielding in Major League Baseball

The use of statistical modeling in baseball has received substantial attention recently in both the media and academic community. We focus on a relatively under-explored topic: the use of statistical models for the analysis of fielding based on high-resolution data consisting of on-field location of batted balls. We combine spatial modeling with a hierarchical Bayesian structure in order to evaluate the performance of individual fielders while sharing information between fielders at each position. We present results across four seasons of MLB data (2002–2005) and compare our approach to other fielding evaluation procedures

Hierarchical Bayes models for daily rainfall time series at multiple locations from heterogenous data sources

We estimate a Hierarchical Bayesian models for daily rainfall that incorporates two novelties for estimating spatial and temporal correlations. We estimate the within site time series correlations for a particular rainfall site using multiple data sources at a given location, and we estimate the across site covariance in rainfall based on location distance. Previous rainfall models have captured cross site correlations as a functions of site specific distances, but not within site correlations across multiple data sources, and not both aspects simultaneously. Further, we incorporate information on the technology used (satellite versus rain gauge) in our estimations, which is also a novel addition. This methodology has far reaching applications in providing more accurate and complex weather insurance contracts based combining information from multiple data sources from a single site, a crucial improvement in the face of climate change. Secondly, the modeling extends to many other data contexts where multiple datasources exist for a given event or variable where both within and between series covariances can be estimated over time

Weight loss, glycemic control, and cardiovascular disease risk factors in response to differential diet composition in a weight loss program in type 2 diabetes: a randomized controlled trial.

ObjectiveTo test whether a weight loss program promotes greater weight loss, glycemic control, and improved cardiovascular disease risk factors compared with control conditions and whether there is a differential response to higher versus lower carbohydrate intake.Research design and methodsThis randomized controlled trial at two university medical centers enrolled 227 overweight or obese adults with type 2 diabetes and assigned them to parallel in-person diet and exercise counseling, with prepackaged foods in a planned menu during the initial phase, or to usual care (UC; two weight loss counseling sessions and monthly contacts).ResultsRelative weight loss was 7.4% (95% CI 5.7-9.2%), 9.0% (7.1-10.9%), and 2.5% (1.3-3.8%) for the lower fat, lower carbohydrate, and UC groups (P < 0.001 intervention effect). Glycemic control markers and triglyceride levels were lower in the intervention groups compared with UC group at 1 year (fasting glucose 141 [95% CI 133-149] vs. 159 [144-174] mg/dL, P = 0.023; hemoglobin A1c 6.9% [6.6-7.1%] vs. 7.5% [7.1-7.9%] or 52 [49-54] vs. 58 [54-63] mmol/mol, P = 0.001; triglycerides 148 [134-163] vs. 204 [173-234] mg/dL, P < 0.001). The lower versus higher carbohydrate groups maintained lower hemoglobin A1c (6.6% [95% CI 6.3-6.8%] vs. 7.2% [6.8-7.5%] or 49 [45-51] vs. 55 [51-58] mmol/mol) at 1 year (P = 0.008).ConclusionsThe weight loss program resulted in greater weight loss and improved glycemic control in type 2 diabetes

Breakthrough in marine invertebrate cell culture : Sponge cells divide rapidly in improved nutrient medium

Sponges (Phylum Porifera) are among the oldest Metazoa and considered critical to understanding animal evolution and development. They are also the most prolific source of marine-derived chemicals with pharmaceutical relevance. Cell lines are important tools for research in many disciplines, and have been established for many organisms, including freshwater and terrestrial invertebrates. Despite many efforts over multiple decades, there are still no cell lines for marine invertebrates. In this study, we report a breakthrough: we demonstrate that an amino acid-optimized nutrient medium stimulates rapid cell division in 9 sponge species. The fastest dividing cells doubled in less than 1 hour. Cultures of 3 species were subcultured from 3 to 5 times, with an average of 5.99 population doublings after subculturing, and a lifespan from 21 to 35 days. Our results form the basis for developing marine invertebrate cell models to better understand early animal evolution, determine the role of secondary metabolites, and predict the impact of climate change to coral reef community ecology. Furthermore, sponge cell lines can be used to scale-up production of sponge-derived chemicals for clinical trials and develop new drugs to combat cancer and other diseases.publishedVersio

Predictors of toxicity in treating patients with neuroblastoma by radiolabeled metaiodobenzylguanidine

We searched for methods that would enable prescriptions of the maximum tolerable doses of iodine-131 metaiodobenzylguanidine (MIBG) and iodine-125 MIBG in the treatment of patients with neuroblastoma. We correlated doses, defined in different ways, with subsequent platelet levels in treated patients to determine accurate predictors of the most frequent toxicity, thrombocytopenia. Nine patients with neuroblastoma were given 131 I-MIBG (4.9–8.1 GBq or 132–220 mCi) and ten were given 125 I-MIBG (8.3-30.0 GBq or 224–809 mCi) as initial treatments. These therapies were sufficiently varied that correlations could be made between indices of the doses and the subsequent toxicity as reflected in circulating platelet levels. Predictors of toxicity were: whole-body absorbed dose of radiation (cGy) calculated from pretherapy tracer doses of 131 I-MIBG; GBq/kg of body weight; and GBq/m 2 of body surface area. Toxicity was recorded as the nadir of the platelet level and platelet/pretherapeutic level (platelet ratio). For treatments with 131 I-MIBG, the highest correlation was obtained between cGy and the logo 10 -transformed platelet ratio ( r =−0.86), but comparison of GBq/m2 and the platelet nadir ( r =−0.76) or the platelet ratio ( r =−0.74) or the log 10 − transformed platelet ratio ( r =−0.73) gave comparable and statistically significant results. For treatments with 125 I-MIBG, significant correlations were obtained between GBq/m 2 and the platelet ratio ( r =−0.81) or GBq/kg and the log 10 − -transformed platelet ratio; the correlation between cGy and any toxicity index was low. Per administered GBq, 131 I-MIBG was 2.6 times more potent than 125 I-MIBG in causing a platelet ratio of 0.1. Thus, in predicting toxicity, therapeutic doses of 131 I-MIBG expressed as GBq/m 2 performed satisfactorily and almost as well as whole-body cGy, and treatment doses of 125 I-MIBG expressed as GBq/m 2 or GBq/kg performed satisfactorily and much better than whole-body cGy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46835/1/259_2004_Article_BF00182305.pd

Ionized Gas Towards Molecular Clumps: Physical Properties of Massive Star Forming Regions

We have conducted a search for ionized gas at 3.6 cm, using the Very Large Array, toward 31 Galactic intermediate- and high-mass clumps detected in previous millimeter continuum observations. In the 10 observed fields, 35 H II regions are identified, of which 20 are newly discovered. Many of the H II regions are multiply peaked indicating the presence of a cluster of massive stars. We find that the ionized gas tends to be associated toward the millimeter clumps; of the 31 millimeter clumps observed, nine of these appear to be physically related to ionized gas, and a further six have ionized gas emission within 1'. For clumps with associated ionized gas, the combined mass of the ionizing massive stars is compared to the clump masses to provide an estimate of the instantaneous star formation efficiency. These values range from a few percent to 25%, and have an average of 7% ± 8%. We also find a correlation between the clump mass and the mass of the ionizing massive stars within it, which is consistent with a power law. This result is comparable to the prediction of star formation by competitive accretion that a power-law relationship exists between the mass of the most massive star in a cluster and the total mass of the remaining stars

Evaluation of polygenic risk scores for breast and ovarian cancer risk prediction in BRCA1 and BRCA2 mutation carriers

Background: Genome-wide association studies (GWAS) have identified 94 common single-nucleotide polymorphisms (SNPs) associated with breast cancer (BC) risk and 18 associated with ovarian cancer (OC) risk. Several of these are also associated with risk of BC or OC for women who carry a pathogenic mutation in the high-risk BC and OC genes BRCA1 or BRCA2. The combined effects of these variants on BC or OC risk for BRCA1 and BRCA2 mutation carriers have not yet been assessed while their clinical management could benefit from improved personalized risk estimates. Methods: We constructed polygenic risk scores (PRS) using BC and OC susceptibility SNPs identified through population-based GWAS: for BC (overall, estrogen receptor [ER]-positive, and ER-negative) and for OC. Using data from 15 252 female BRCA1 and 8211 BRCA2 carriers, the association of each PRS with BC or OC risk was evaluated using a weighted cohort approach, with time to diagnosis as the outcome and estimation of the hazard ratios (HRs) per standard deviation increase in the PRS. Results: The PRS for ER-negative BC displayed the strongest association with BC risk in BRCA1 carriers (HR = 1.27, 95% confidence interval [CI] = 1.23 to 1.31, P = 8.2 x 10(53)). In BRCA2 carriers, the strongest association with BC risk was seen for the overall BC PRS (HR = 1.22, 95% CI = 1.17 to 1.28, P = 7.2 x 10(-20)). The OC PRS was strongly associated with OC risk for both BRCA1 and BRCA2 carriers. These translate to differences in absolute risks (more than 10% in each case) between the top and bottom deciles of the PRS distribution; for example, the OC risk was 6% by age 80 years for BRCA2 carriers at the 10th percentile of the OC PRS compared with 19% risk for those at the 90th percentile of PRS. Conclusions: BC and OC PRS are predictive of cancer risk in BRCA1 and BRCA2 carriers. Incorporation of the PRS into risk prediction models has promise to better inform decisions on cancer risk management

Activation of Akt Signaling Reduces the Prevalence and Intensity of Malaria Parasite Infection and Lifespan in Anopheles stephensi Mosquitoes

Malaria (Plasmodium spp.) kills nearly one million people annually and this number will likely increase as drug and insecticide resistance reduces the effectiveness of current control strategies. The most important human malaria parasite, Plasmodium falciparum, undergoes a complex developmental cycle in the mosquito that takes approximately two weeks and begins with the invasion of the mosquito midgut. Here, we demonstrate that increased Akt signaling in the mosquito midgut disrupts parasite development and concurrently reduces the duration that mosquitoes are infective to humans. Specifically, we found that increased Akt signaling in the midgut of heterozygous Anopheles stephensi reduced the number of infected mosquitoes by 60–99%. Of those mosquitoes that were infected, we observed a 75–99% reduction in parasite load. In homozygous mosquitoes with increased Akt signaling parasite infection was completely blocked. The increase in midgut-specific Akt signaling also led to an 18–20% reduction in the average mosquito lifespan. Thus, activation of Akt signaling reduced the number of infected mosquitoes, the number of malaria parasites per infected mosquito, and the duration of mosquito infectivity