High on Life? Medical Marijuana Laws and Suicide

Using state-level data for the period 1990 through 2007, we estimate the effect of legalizing medical marijuana on suicide rates. Our results suggest that the passage of a medical marijuana law is associated with an almost 5 percent reduction in the total suicide rate, an 11 percent reduction in the suicide rate of 20- through 29-year-old males, and a 9 percent reduction in the suicide rate of 30- through 39-year-old males. Estimates of the relationship between legalization and female suicides are less precise and are sensitive to functional form.medical marijuana laws, marijuana, alcohol, suicide

Child Access Prevention Laws, Youth Gun Carrying, and School Shootings

Despite intense public interest in keeping guns out of schools, next to nothing is known about the effects of gun control policies on youth gun carrying or school violence. Using data from the Youth Risk Behavior Surveys (YRBS) for the period 1993-2013, this study is the first to examine the relationship between child access prevention (CAP) gun controls laws and gun carrying among high school students. Our results suggest that CAP laws are associated with a 13 percent decrease in the rate of past month gun carrying and an 18 percent decrease in the rate at which students reported being threatened or injured with a weapon on school property. In addition, we find that CAP laws are associated with a lagged decline in the probability that students miss school due to feeling unsafe. These results are concentrated among minors, for whom CAP laws are most likely to bind. To supplement our YRBS analysis, we collect a novel dataset on school shooting deaths for the period 1991-2013. We find that while CAP laws promote a safer school environment, they have no observable impact on school-associated shooting deaths

On sign conditions over real multivariate polynomials

We present a new probabilistic algorithm to find a finite set of points intersecting the closure of each connected component of the realization of every sign condition over a family of real polynomials defining regular hypersurfaces that intersect transversally. This enables us to show a probabilistic procedure to list all feasible sign conditions over the polynomials. In addition, we extend these results to the case of closed sign conditions over an arbitrary family of real multivariate polynomials. The complexity bounds for these procedures improve the known ones. © Springer Science+Business Media, LLC 2009.Fil:Jeronimo, G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Perrucci, D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Sabia, J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Experimental test on an RC beam equipped with embedded barometric pressure sensors for strains measurement

The current trend in structural health monitoring (SHM) is to install increasingly large numbers of distributed, heterogeneous types of sensors, for a timely and exhaustive detection of any possible damage scenario evolving in the system. These sensors should be low-cost, easy to install, robust and durable. Among others, strain remains one of the most straightforward measurands for monitoring the state of a structural element and for assessing its health condition. However, for application to reinforced concrete structures, currently available strain sensing devices, such as electric strain gauges or fibre optic sensors, do not fully satisfy the aforementioned requirements, generally proving difficult to install, fragile and expensive. In this paper, an innovative monitoring technology, called Smart Steel System (S3), is proposed that measures strains in reinforced concrete members, by incorporating commercial barometric pressure MEMS sensors in appropriate sealed cavities embedded in the reinforcing steel bars. The results of an experimental campaign are reported, in which a reinforced concrete beam, instrumented with both S3 devices and conventional electrical strain gauges, is subjected to increasing loading and unloading cycles until collapse. The tests show the superior robustness of the S3 system during construction and loading as well as its good sensing accuracy, demonstrating its potential for a massive use in SHM applications

Have U.S. Gun Buyback Programs Misfired?

There are 1.2 guns for every person in the United States, and the total number of firearms in circulation is estimated to be over 393 million. Gun violence is the leading cause of death among young men aged 15–19, and firearms are involved in 51 percent of completed suicides and 73 percent of all homicides. The link between the supply of firearms and gun violence has been the subject of intense debate among policymakers and academics studying the economics of crime. To limit the supply of firearms in circulation, a number of U.S. cities have implemented gun buyback programs (GBPs). GBPs use public funds to purchase civilians' privately owned firearms. We examined the effect of GBPs and found no evidence that they reduce gun crime