Was the Wealth of Nations Determined in 1000 B.C.?

We assemble a dataset on technology adoption in 1000 B.C., 0 A.D., and 1500 A.D. for the predecessors to today's nation states. We find that this very old history of technology adoption is surprisingly significant for today's national development outcomes. Although our strongest results are for 1500 A.D., we find that even technology as old as 1000 BC matters in some plausible specifications.

Income shocks and HIV in Sub-Saharan Africa:

Poverty is commonly cited as a key driver of the HIV/AIDS epidemic, yet little causal evidence exists linking economic conditions to actual disease outcomes. Using data on more than 200,000 individuals across 19 Sub-Saharan African countries, we present evidence that negative income shocks can lead to substantial increases in HIV prevalence, particularly for women in rural areas. Building on recent work showing that income shortfalls can induce some women to engage in higher-risk sex, we match data on individuals' HIV status from the Demographic and Health Surveys to data on recent variation in local rainfall, a primary (and exogenous) source of variation in income for rural households in Africa. We find that infection rates for women (men) in HIV-endemic rural areas increase significantly by 14 percent (11 percent) for every drought event experienced in the previous 10 years. Further analysis suggests that women most affected by the shocks (that is, those engaged in agriculture) are driving the women's results; these women are partnering with men least affected (those employed outside agriculture). Our findings suggest a role for formal insurance and social safety nets in tackling the HIV/AIDS epidemic.HIV/AIDS, Income shocks,

Was the Wealth of Nations Determined in 1000 B.C.?

We assemble a dataset on technology adoption in 1000 BC, 0 AD, and 1500 AD for the predecessors to today's nation states. We find that this very old history of technology adoption is surprisingly significant for today's national development outcomes. Our strong and robust results are for 1500 AD determining per capita income today. We find technological persistence across long epochs: from 1000 BC to 0 AD, from 0 AD to 1500 AD, and from 1500 AD to the present. Although the data allow only some suggestive tests of rival hypotheses to explain long?run technological persistence, we find the evidence to be most consistent with a model of endogenous technology adoption where the cost of adopting new technologies declines sufficiently with the current level of adoption. The evidence is less consistent with a dominant role for population as predicted by the semi?endogenous growth models or for country-level factors like culture, genes or institutions.Technology adoption, technology history, economic development.

Motivating Agents: How Much Does the Mission Matter?

Economic theory predicts that agents will work harder if they believe in the mission of the organization. Well-identified estimates of exactly how much harder they will work have been elusive, however, because agents select into jobs. We conduct a real effort experiment with participants who work directly for organizations with clear missions. Weeks before the experiment, we survey potential participants for their organizational preferences. At the experiment, we randomly assign workers to organizations, creating either mission matches or mismatches. We overlay performance incentives to test whether they can make up for the motivational deficit caused by a mismatch. Our estimates suggest that matched workers produce 72% more than mismatched workers and that performance pay can increase output by 35% compared to workers who only receive a base wage. Considering matches and mismatches separately, we find that performance pay has only a modest effect on matched workers (a 13% increase) while it has a large effect (a 86% increase) on mismatches, an effect that erodes much of the performance gap caused by the poor match. Our results have broad implications both for those organizations already with well-defined missions (i.e., compensation and screening policies) as well as for those organizations strategizing about strengthening or clarifying their missions

HIV Testing and Risky Sexual Behavior

Using data from a study that randomly assigns offers of HIV testing in two urban centers in East Africa, I examine the effects of testing, taking into account people's beliefs of their HIV status prior to testing. I objectively measure risky sexual behavior using sexually transmitted infections (ÒSTIsÓ) contracted during the 6 month study as proxies. Individuals surprised by an HIV-positive test are over nine times more likely to contract an STI indicating an increase in risky sexual behavior. Individuals surprised by an HIV-negative test are 84% less likely to contract an STI indicating a decrease in risky sexual behavior. Using these estimates, I simulate the effects of testing on new HIV infections. I find the overall number of HIV infections increases by 30% when people are tested compared to when they are unaware of their status - an unintended consequence of testing.HIV/AIDS; risk behavior; information; beliefs

Income Shocks and HIV in Africa

We examine how variation in local economic conditions has shaped the AIDS epidemic in Africa. Using data from over 200,000 individuals across 19 countries, we match biomarker data on individuals' HIV status to information on local rainfall shocks, a large source of variation in income for rural households. We estimate that infection rates in HIV-endemic rural areas increase by 11% for every recent drought, an effect that is statistically and economically significant. Income shocks explain up to 20% of the variation in HIV prevalence across African countries, suggesting policy approaches for HIV prevention that are distinct from existing efforts

Operation and Application of a Regional High-Frequency Radar Network in the Mid-Atlantic Bight

The Mid-Atlantic Regional Coastal Ocean Observing System (MARCOOS) High- Frequency Radar Network, which comprises 13 long-range sites, 2 medium-range sites, and 12 standard-range sites, is operated as part of the Integrated Ocean Observing System. This regional implementation of the network has been operational for 2 years and has matured to the point where the radars provide consistent coverage from Cape Cod to Cape Hatteras. A concerted effort was made in the MARCOOS project to increase the resiliency of the radar stations from the elements, power issues, and other issues that can disable the hardware of the system. The quality control and assurance activities in the Mid-Atlantic Bight have been guided by the needs of the Coast Guard Search and Rescue Office. As of May,, 2009, these quality-controlled MARCOOS High-Frequency Radar totals are being served through the Coast Guard\u27s Environmental Data Server to the Coast Guard Search and Rescue Optimal Planning System. In addition to the service to U.S. Coast Guard Search and Rescue Operations, these data support water quality, physical oceanographic, and fisheries research throughout the Mid-Atlantic Bight

Incentivising safe sex: a randomised trial of conditional cash transfers for HIV and sexually transmitted infection prevention in rural Tanzania

The authors evaluated the use of conditional cash transfers as an HIV and sexually transmitted infection prevention strategy to incentivise safe sex. An unblinded, individually randomised and controlled trial. 10 villages within the Kilombero/Ulanga districts of the Ifakara Health and Demographic Surveillance System in rural south-west Tanzania. The authors enrolled 2399 participants, aged 18-30 years, including adult spouses. Participants were randomly assigned to either a control arm (n=1124) or one of two intervention arms: low-value conditional cash transfer (eligible for $10 per testing round, n=660) and high-value conditional cash transfer (eligible for$20 per testing round, n=615). The authors tested participants every 4 months over a 12-month period for the presence of common sexually transmitted infections. In the intervention arms, conditional cash transfer payments were tied to negative sexually transmitted infection test results. Anyone testing positive for a sexually transmitted infection was offered free treatment, and all received counselling. The primary study end point was combined prevalence of the four sexually transmitted infections, which were tested and reported to subjects every 4 months: Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis and Mycoplasma genitalium. The authors also tested for HIV, herpes simplex virus 2 and syphilis at baseline and month 12. At the end of the 12-month period, for the combined prevalence of any of the four sexually transmitted infections, which were tested and reported every 4 months (C trachomatis, N gonorrhoeae, T vaginalis and M genitalium), unadjusted RR for the high-value conditional cash transfer arm compared to controls was 0.80 (95% CI 0.54 to 1.06) and the adjusted RR was 0.73 (95% CI 0.47 to 0.99). Unadjusted RR for the high-value conditional cash transfer arm compared to the low-value conditional cash transfer arm was 0.76 (95% CI 0.49 to 1.03) and the adjusted RR was 0.69 (95% CI 0.45 to 0.92). No harm was reported. Conditional cash transfers used to incentivise safer sexual practices are a potentially promising new tool in HIV and sexually transmitted infections prevention. Additional larger study would be useful to clarify the effect size, to calibrate the size of the incentive and to determine whether the intervention can be delivered cost effectively. NCT00922038 ClinicalTrials.gov

Automated Discrimination of Brain Pathological State Attending to Complex Structural Brain Network Properties: The Shiverer Mutant Mouse Case

Neuroimaging classification procedures between normal and pathological subjects are sparse and highly dependent of an expert's clinical criterion. Here, we aimed to investigate whether possible brain structural network differences in the shiverer mouse mutant, a relevant animal model of myelin related diseases, can reflect intrinsic individual brain properties that allow the automatic discrimination between the shiverer and normal subjects. Common structural networks properties between shiverer (C3Fe.SWV Mbpshi/Mbpshi, n = 6) and background control (C3HeB.FeJ, n = 6) mice are estimated and compared by means of three diffusion weighted MRI (DW-MRI) fiber tractography algorithms and a graph framework. Firstly, we found that brain networks of control group are significantly more clustered, modularized, efficient and optimized than those of the shiverer group, which presented significantly increased characteristic path length. These results are in line with previous structural/functional complex brain networks analysis that have revealed topologic differences and brain network randomization associated to specific states of human brain pathology. In addition, by means of network measures spatial representations and discrimination analysis, we show that it is possible to classify with high accuracy to which group each subject belongs, providing also a probability value of being a normal or shiverer subject as an individual anatomical classifier. The obtained correct predictions (e.g., around 91.6–100%) and clear spatial subdivisions between control and shiverer mice, suggest that there might exist specific network subspaces corresponding to specific brain disorders, supporting also the point of view that complex brain network analyses constitutes promising tools in the future creation of interpretable imaging biomarkers

Frequency drift in MR spectroscopy at 3T

Purpose: Heating of gradient coils and passive shim components is a common cause of instability in the B-0 field, especially when gradient intensive sequences are used. The aim of the study was to set a benchmark for typical drift encountered during MR spectroscopy (MRS) to assess the need for real-time field-frequency locking on MRI scanners by comparing field drift data from a large number of sites.Method: A standardized protocol was developed for 80 participating sites using 99 3T MR scanners from 3 major vendors. Phantom water signals were acquired before and after an EPI sequence. The protocol consisted of: minimal preparatory imaging; a short pre-fMRI PRESS; a ten-minute fMRI acquisition; and a long post-fMRI PRESS acquisition. Both pre- and post-fMRI PRESS were non-water suppressed. Real-time frequency stabilization/adjustment was switched off when appropriate. Sixty scanners repeated the protocol for a second dataset. In addition, a three-hour post-fMRI MRS acquisition was performed at one site to observe change of gradient temperature and drift rate. Spectral analysis was performed using MATLAB. Frequency drift in pre-fMRI PRESS data were compared with the first 5:20 minutes and the full 30:00 minutes of data after fMRI. Median (interquartile range) drifts were measured and showed in violin plot. Paired t-tests were performed to compare frequency drift pre- and post-fMRI. A simulated in vivo spectrum was generated using FID-A to visualize the effect of the observed frequency drifts. The simulated spectrum was convolved with the frequency trace for the most extreme cases. Impacts of frequency drifts on NAA and GABA were also simulated as a function of linear drift. Data from the repeated protocol were compared with the corresponding first dataset using Pearson's and intraclass correlation coefficients (ICC).Results: Of the data collected from 99 scanners, 4 were excluded due to various reasons. Thus, data from 95 scanners were ultimately analyzed. For the first 5:20 min (64 transients), median (interquartile range) drift was 0.44 (1.29) Hz before fMRI and 0.83 (1.29) Hz after. This increased to 3.15 (4.02) Hz for the full 30 min (360 transients) run. Average drift rates were 0.29 Hz/min before fMRI and 0.43 Hz/min after. Paired t-tests indicated that drift increased after fMRI, as expected (p &lt; 0.05). Simulated spectra convolved with the frequency drift showed that the intensity of the NAA singlet was reduced by up to 26%, 44 % and 18% for GE, Philips and Siemens scanners after fMRI, respectively. ICCs indicated good agreement between datasets acquired on separate days. The single site long acquisition showed drift rate was reduced to 0.03 Hz/min approximately three hours after fMRI.Discussion: This study analyzed frequency drift data from 95 3T MRI scanners. Median levels of drift were relatively low (5-min average under 1 Hz), but the most extreme cases suffered from higher levels of drift. The extent of drift varied across scanners which both linear and nonlinear drifts were observed.</p