314 research outputs found
Evaluating the Impact of Florida's "Stand Your Ground" Self-defense Law on Homicide and Suicide by Firearm: An Interrupted Time Series Study.
: In 2005, Florida amended its self-defense laws to provide legal immunity to individuals using lethal force in self-defense. The enactment of "stand your ground" laws in the United States has been controversial and their effect on rates of homicide and homicide by firearm is uncertain. : To estimate the impact of Florida's stand your ground law on rates of homicide and homicide by firearm. : Using an interrupted time series design, we analyzed monthly rates of homicide and homicide by firearm in Florida between 1999 and 2014. Data were collected from the Wide-ranging Online Data for Epidemiologic Research (WONDER) web portal at the Centers for Disease Control and Prevention. We used seasonally adjusted segmented Poisson regression models to assess whether the onset of the law was associated with changes in the underlying trends for homicide and homicide by firearm in Florida. We also assessed the association using comparison states without stand your ground laws (New York, New Jersey, Ohio, and Virginia) and control outcomes (all suicides and suicides by firearm in Florida). October 1, 2005, the effective date of the law, was used to define homicides before and after the change. : Monthly rates of homicide, firearm-related homicide, suicide, and suicide by firearm in Florida and the 4 comparison states. : Prior to the stand your ground law, the mean monthly homicide rate in Florida was 0.49 deaths per 100âŻ000 (mean monthly count, 81.93), and the rate of homicide by firearm was 0.29 deaths per 100âŻ000 (mean monthly count, 49.06). Both rates had an underlying trend of 0.1% decrease per month. After accounting for underlying trends, these results estimate that after the law took effect there was an abrupt and sustained increase in the monthly homicide rate of 24.4% (relative risk [RR], 1.24; 95%CI, 1.16-1.33) and in the rate of homicide by firearm of 31.6% (RR, 1.32; 95% CI, 1.21-1.44). No evidence of change was found in the analyses of comparison states for either homicide (RR, 1.06; 95% CI, 0.98-1.13) or homicide by firearm (RR, 1.08; 95% CI, 0.99-1.17). Furthermore, no changes were observed in control outcomes such as suicide (RR, 0.99; 95% CI, 0.94-1.05) and suicide by firearm (RR, 0.98; 95% CI, 0.91-1.06) in Florida between 2005 and 2014. : The implementation of Florida's stand your ground self-defense law was associated with a significant increase in homicides and homicides by firearm but no change in rates of suicide or suicide by firearm.<br/
Dealing with missing standard deviation and mean values in meta-analysis of continuous outcomes: a systematic review
Background: Rigorous, informative meta-analyses rely on availability of appropriate summary statistics or individual
participant data. For continuous outcomes, especially those with naturally skewed distributions, summary
information on the mean or variability often goes unreported. While full reporting of original trial data is the ideal,
we sought to identify methods for handling unreported mean or variability summary statistics in meta-analysis.
Methods: We undertook two systematic literature reviews to identify methodological approaches used to deal with
missing mean or variability summary statistics. Five electronic databases were searched, in addition to the Cochrane
Colloquium abstract books and the Cochrane Statistics Methods Group mailing list archive. We also conducted cited
reference searching and emailed topic experts to identify recent methodological developments. Details recorded
included the description of the method, the information required to implement the method, any underlying
assumptions and whether the method could be readily applied in standard statistical software. We provided a
summary description of the methods identified, illustrating selected methods in example meta-analysis scenarios.
Results: For missing standard deviations (SDs), following screening of 503 articles, fifteen methods were identified in
addition to those reported in a previous review. These included Bayesian hierarchical modelling at the meta-analysis
level; summary statistic level imputation based on observed SD values from other trials in the meta-analysis; a practical
approximation based on the range; and algebraic estimation of the SD based on other summary statistics. Following
screening of 1124 articles for methods estimating the mean, one approximate Bayesian computation approach and
three papers based on alternative summary statistics were identified. Illustrative meta-analyses showed that when
replacing a missing SD the approximation using the range minimised loss of precision and generally performed better
than omitting trials. When estimating missing means, a formula using the median, lower quartile and upper quartile
performed best in preserving the precision of the meta-analysis findings, although in some scenarios, omitting trials
gave superior results.
Conclusions: Methods based on summary statistics (minimum, maximum, lower quartile, upper quartile, median)
reported in the literature facilitate more comprehensive inclusion of randomised controlled trials with missing mean or
variability summary statistics within meta-analyses
Military veteran mortality following a survived suicide attempt
<p>Abstract</p> <p>Background</p> <p>Suicide is a global public health problem. Recently in the U.S., much attention has been given to preventing suicide and other premature mortality in veterans returning from Iraq and Afghanistan. A strong predictor of suicide is a past suicide attempt, and suicide attempters have multiple physical and mental comorbidities that put them at risk for additional causes of death. We examined mortality among U.S. military veterans after hospitalization for attempted suicide.</p> <p>Methods</p> <p>A retrospective cohort study was conducted with all military veterans receiving inpatient treatment during 1993-1998 at United States Veterans Affairs (VA) medical facilities following a suicide attempt. Deaths occurring during 1993-2002, the most recent available year at the time, were identified through VA Beneficiary and Records Locator System data and National Death Index data. Mortality data for the general U.S. adult population were also obtained from the National Center for Health Statistics. Comparisons within the veteran cohort, between genders, and against the U.S. population were conducted with descriptive statistics and standardized mortality ratios. The actuarial method was used estimate the proportion of veterans in the cohort we expect would have survived through 2002 had they experienced the same rate of death that occurred over the study period in the U.S. population having the age and sex characteristics.</p> <p>Results</p> <p>During 1993-1998, 10,163 veterans were treated and discharged at a VA medical center after a suicide attempt (mean age = 44 years; 91% male). There was a high prevalence of diagnosed alcohol disorder or abuse (31.8%), drug dependence or abuse (21.8%), psychoses (21.2%), depression (18.5%), and hypertension (14.2%). A total of 1,836 (18.1%) veterans died during follow up (2,941.4/100,000 person years). The cumulative survival probability after 10 years was 78.0% (95% CI = 72.9, 83.1). Hence the 10-year cumulative mortality risk was 22.0%, which was 3.0 times greater than expected. The leading causes overall were heart disease (20.2%), suicide (13.1%), and unintentional injury (12.7%). Whereas suicide was the ninth leading cause of death in the U.S. population overall (1.8%) during the study period, suicide was the leading and second leading cause among women (25.0%) and men (12.7%) in the cohort, respectively.</p> <p>Conclusions</p> <p>Veterans who have attempted suicide face elevated risks of all-cause mortality with suicide being prominent. This represents an important population for prevention activities.</p
Homicide and geographic access to gun dealers in the United States
<p>Abstract</p> <p>Background</p> <p>Firearms are the most commonly used weapon to commit homicide in the U.S. Virtually all firearms enter the public marketplace through a federal firearms licensee (FFL): a store or individual licensed by the federal government to sell firearms. Whether FFLs contribute to gun-related homicide in areas where they are located, in which case FFLs may be a homicide risk factor that can be modified, is not known.</p> <p>Methods</p> <p>Annual county-level data (1993â1999) on gun homicide rates and rates of FFLs per capita were analyzed using negative binomial regression controlling for socio-demographic characteristics. Models were run to evaluate whether the relation between rates of FFLs and rates of gun homicide varied over the study period and across counties according to their level of urbanism (defined by four groupings, as below). Also, rates of FFLs were compared against FS/S â which is the proportion of suicides committed by firearm and is thought to be a good proxy for firearm availability in a region â to help evaluate how well the FFL variable is serving as a way to proxy firearm availability in each of the county types of interest.</p> <p>Results</p> <p>In major cities, gun homicide rates were higher where FFLs were more prevalent (rate ratio [RR] = 1.70, 95% CI 1.03â2.81). This association increased (p < 0.01) from 1993 (RR = 1.69) to 1999 (RR = 12.72), due likely to federal reforms that eliminated low-volume dealers, making FFL prevalence a more accurate exposure measure over time. No association was found in small towns. In other cities and in suburbs, gun homicide rates were significantly lower where FFLs were more prevalent, with associations that did not change over the years of the study period. FFL prevalence was correlated strongly (positively) with FS/S in major cities only, suggesting that the findings for how FFL prevalence relates to gun homicide may be valid for the findings pertaining to major cities but not to counties of other types.</p> <p>Conclusion</p> <p>Modification of FFLs through federal, state, and local regulation may be a feasible intervention to reduce gun homicide in major cities.</p
Predicting consumer biomass, size-structure, production, catch potential, responses to fishing and associated uncertainties in the world's marine ecosystems
Existing estimates of fish and consumer biomass in the worldâs oceans are disparate. This creates uncertainty about the roles of fish and other consumers in biogeochemical cycles and ecosystem processes, the extent of human and environmental impacts and fishery potential. We develop and use a size-based macroecological model to assess the effects of parameter uncertainty on predicted consumer biomass, production and distribution. Resulting uncertainty is large (e.g. median global biomass 4.9 billion tonnes for consumers weighing 1 g to 1000 kg; 50% uncertainty intervals of 2 to 10.4 billion tonnes; 90% uncertainty intervals of 0.3 to 26.1 billion tonnes) and driven primarily by uncertainty in trophic transfer efficiency and its relationship with predator-prey body mass ratios. Even the upper uncertainty intervals for global predictions of consumer biomass demonstrate the remarkable scarcity of marine consumers, with less than one part in 30 million by volume of the global oceans comprising tissue of macroscopic animals. Thus the apparently high densities of marine life seen in surface and coastal waters and frequently visited abundance hotspots will likely give many in society a false impression of the abundance of marine animals. Unexploited baseline biomass predictions from the simple macroecological model were used to calibrate a more complex size- and trait-based model to estimate fisheries yield and impacts. Yields are highly dependent on baseline biomass and fisheries selectivity. Predicted global sustainable fisheries yield increases â4 fold when smaller individuals (< 20 cm from species of maximum mass < 1kg) are targeted in all oceans, but the predicted yields would rarely be accessible in practice and this fishing strategy leads to the collapse of larger species if fishing mortality rates on different size classes cannot be decoupled. Our analyses show that models with minimal parameter demands that are based on a few established ecological principles can support equitable analysis and comparison of diverse ecosystems. The analyses provide insights into the effects of parameter uncertainty on global biomass and production estimates, which have yet to be achieved with complex models, and will therefore help to highlight priorities for future research and data collection. However, the focus on simple model structures and global processes means that non-phytoplankton primary production and several groups, structures and processes of ecological and conservation interest are not represented. Consequently, our simple models become increasingly less useful than more complex alternatives when addressing questions about food web structure and function, biodiversity, resilience and human impacts at smaller scales and for areas closer to coasts
Short-term efficacy of physical interventions in osteoarthritic knee pain. A systematic review and meta-analysis of randomised placebo-controlled trials.
BACKGROUND: Treatment efficacy of physical agents in osteoarthritis of the knee (OAK) pain has been largely unknown, and this systematic review was aimed at assessing their short-term efficacies for pain relief. METHODS: Systematic review with meta-analysis of efficacy within 1-4 weeks and at follow up at 1-12 weeks after the end of treatment. RESULTS: 36 randomised placebo-controlled trials (RCTs) were identified with 2434 patients where 1391 patients received active treatment. 33 trials satisfied three or more out of five methodological criteria (Jadad scale). The patient sample had a mean age of 65.1 years and mean baseline pain of 62.9 mm on a 100 mm visual analogue scale (VAS). Within 4 weeks of the commencement of treatment manual acupuncture, static magnets and ultrasound therapies did not offer statistically significant short-term pain relief over placebo. Pulsed electromagnetic fields offered a small reduction in pain of 6.9 mm [95% CI: 2.2 to 11.6] (n = 487). Transcutaneous electrical nerve stimulation (TENS, including interferential currents), electro-acupuncture (EA) and low level laser therapy (LLLT) offered clinically relevant pain relieving effects of 18.8 mm [95% CI: 9.6 to 28.1] (n = 414), 21.9 mm [95% CI: 17.3 to 26.5] (n = 73) and 17.7 mm [95% CI: 8.1 to 27.3] (n = 343) on VAS respectively versus placebo control. In a subgroup analysis of trials with assumed optimal doses, short-term efficacy increased to 22.2 mm [95% CI: 18.1 to 26.3] for TENS, and 24.2 mm [95% CI: 17.3 to 31.3] for LLLT on VAS. Follow-up data up to 12 weeks were sparse, but positive effects seemed to persist for at least 4 weeks after the course of LLLT, EA and TENS treatment was stopped. CONCLUSION: TENS, EA and LLLT administered with optimal doses in an intensive 2-4 week treatment regimen, seem to offer clinically relevant short-term pain relief for OAK
What Goes Around Comes Around: Learning Sentiments in Online Medical Forums
Currently 19%-28% of Internet users participate in online health discussions. A 2011 survey of the US population estimated that 59% of all adults have looked online for information about health topics such as a specific disease or treatment. Although empirical evidence strongly supports the importance of emotions in health-related messages, there are few studies of the relationship between a subjective lan-guage and online discussions of personal health. In this work, we study sentiments expressed on online medical forums. As well as considering the predominant sentiments expressed in individual posts, we analyze sequences of sentiments in online discussions. Individual posts are classified into one of five categories. We identified three categories as sentimental (encouragement, gratitude, confusion) and two categories as neutral (facts, endorsement). 1438 messages from 130 threads were annotated manually by two annotators with a strong inter-annotator agreement (Fleiss kappa = 0.737 and 0.763 for posts in se-quence and separate posts respectively). The annotated posts were used to analyse sentiments in consec-utive posts. In four multi-class classification problems, we assessed HealthAffect, a domain-specific af-fective lexicon, as well general sentiment lexicons in their ability to represent messages in sentiment recognition
Decadal to monthly timescales of magma transfer and reservoir growth at a caldera volcano
International audienceCaldera-forming volcanic eruptions are low-frequency, highimpact events capable of discharging tens to thousands of cubic kilometres of magma explosively on timescales of hours to days, with devastating effects on local and global scales1. Because no such eruption has been monitored during its long build-up phase, the precursor phenomena are not well understood. Geophysical signals obtained during recent episodes of unrest at calderas such as Yellowstone, USA, and Campi Flegrei, Italy, are difficult to interpret, and the conditions necessary for large eruptions are poorly constrained2,3. Here we present a study of pre-eruptive magmatic processes and their timescales using chemically zoned crystals from the 'Minoan' caldera-formingeruption of Santorini volcano,Greece4, which occurred in the late 1600s BC. The results provide insights into how rapidly large silicic systems may pass from a quiescent state to one on the edge of eruption5,6. Despite the large volume of erupted magma4 (40-60 cubic kilometres), and the 18,000-year gestation period between the Minoan eruption and the previous major eruption, most crystals in the Minoan magma record processes that occurred less than about 100 years before the eruption. Recharge of the magma reservoir by large volumes of silicic magma (and some mafic magma) occurred during the century before eruption, and mixing between different silicicmagmabatches was still taking place during the final months. Final assembly of large silicic magma reservoirs may occur on timescales that are geologically very short by comparison with the preceding repose period, with major growth phases immediately before eruption. These observations have implications for the monitoring of long-dormant, but potentially active, caldera systems
Fermi surface instability at the hidden-order transition of URu2Si2
Solids with strong electron correlations generally develop exotic phases of
electron matter at low temperatures. Among such systems, the heavy-fermion
semi-metal URu2Si2 presents an enigmatic transition at To = 17.5 K to a `hidden
order' state whose order parameter remains unknown after 23 years of intense
research. Various experiments point to the reconstruction and partial gapping
of the Fermi surface when the hidden-order establishes. However, up to now, the
question of how this transition affects the electronic spectrum at the Fermi
surface has not been directly addressed by a spectroscopic probe. Here we show,
using angle-resolved photoemission spectroscopy, that a band of heavy
quasi-particles drops below the Fermi level upon the transition to the
hidden-order state. Our data provide the first direct evidence of a large
reorganization of the electronic structure across the Fermi surface of URu2Si2
occurring during this transition, and unveil a new kind of Fermi-surface
instability in correlated electron systemsComment: 15 pages, 5 figure
The search for transient astrophysical neutrino emission with IceCube-DeepCore
We present the results of a search for astrophysical sources of brief transient neutrino emission using IceCube and DeepCore data acquired between 2012 May 15 and 2013 April 30. While the search methods employed in this analysis are similar to those used in previous IceCube point source searches, the data set being examined consists of a sample of predominantly sub-TeV muon-neutrinos from the Northern Sky (-5 degrees < delta < 90 degrees) obtained through a novel event selection method. This search represents a first attempt by IceCube to identify astrophysical neutrino sources in this relatively unexplored energy range. The reconstructed direction and time of arrival of neutrino events are used to search for any significant self-correlation in the data set. The data revealed no significant source of transient neutrino emission. This result has been used to construct limits at timescales ranging from roughly 1 s to 10 days for generic soft-spectra transients. We also present limits on a specific model of neutrino emission from soft jets in core-collapse supernovae
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