Investigation and Repair of a Leaking Earthfill Dam

This paper presents a description of the investigation performed on two leaking earthfill dams and the remedial measures undertaken to repair the dams. The dams are located at a large nursery operation that collects and stores excess irrigation water and storm water in five large on-site reservoirs. The both dams were built in 2001 and 2002 to increase the nursery’s storage capacity by 40 percent. In June 2004 water was found leaking into the outlet pipe in one of the dams through the joints and around the outside of the outlet pipe at the toe of the dam. Geosyntec was contacted to perform an investigation to find the cause of the leak and to identify potential repair options. During the initial observation, evidence of significant piping was discovered that indicated the dam may be unserviceable in its present condition. The outlet pipe was, therefore, excavated and removed. During repairs to the first dam the second dam began leaking as well. Subsequently this dam was also excavated and repaired. This paper will present the results of the investigations performed prior to and during excavation, and a discussion of the repair measures undertaken after the forensic investigation was completed

The Efficiency of Voluntary Incentive Policies for Preventing Biodiversity Loss

In this paper we analyze the efficiency of voluntary incentive-based land-use policies for biodiversity conservation. Two factors combine to make it difficult to achieve an efficient result. First, the spatial pattern of habitat across multiple landowners is important for determining biodiversity conservation results. Second, the willingness of private landowners to accept a payment in exchange for enrolling in a conservation program is private information. Therefore, a conservation agency cannot easily control the spatial pattern of voluntary enrollment in conservation programs. We begin by showing how the distribution of a landowner's willingness-to-accept a conservation payment can be derived from a parcel-scale land-use change model. Next we combine the econometric land-use model with spatial data and ecological models to simulate the effects of various conservation program designs on biodiversity conservation outcomes. We compare these results to an estimate of the efficiency frontier that maximizes biodiversity conservation at each level of cost. The frontier mimics the regulator's solution to the biodiversity conservation problem when she has perfect information on landowner willingness-to-accept. Results indicate that there are substantial differences in biodiversity conservation scores generated by the incentive-based policies and efficient solutions. The performance of incentive-based policies is particularly poor at low levels of the conservation budget where spatial fragmentation of conserved parcels is a large concern. Performance can be improved by encouraging agglomeration of conserved habitat and by incorporating basic biological information, such as that on rare habitats, into the selection criteria.

Modelling ecosystem services in terrestrial systems

Over the past few decades, a multi-disciplinary research community has documented the goods and services provided by ecosystems in specific sites scattered across the world. This research community has now begun to focus on creating methods and tools for mapping and valuing the ecosystem services produced on any landscape in the world. We describe some of these methods and tools and how they calculate and express ecosystem service provision and value on landscapes. We also describe methods for predicting landscape change. These predictions can be used by multi-ecosystem service models to assess potential changes and trade-offs in ecosystem service provision and values into the future

Handgun carrying among white youth increasing in the United States: new evidence from the national survey on drug use and health 2002–2013

The objective of the present study was to examine trends and correlates of handgun carrying among adolescents ages 12–17 in the United States. Data was derived from the National Survey on Drug Use and Health (NSDUH) involving non-Hispanic White, African American, and Hispanic respondents ages 12–17 (n = 197,313) and spanning the years 2002–2013. Logistic regression was used to examine significance of trend year and correlates of previous 12-month handgun carrying. The overall self-reported prevalence of handgun carrying was 3.4%. The prevalence of handgun carrying during 2004–2005 was significantly higher for African-Americans (4.39%) compared to non-Hispanic Whites (3.03%). However, by 2012–2013, non-Hispanic Whites (4.08%) completely diverged and reported carrying handguns significantly more than both African-American (2.96%) and Hispanic (2.82%) youth. Male gender and a number of externalizing behaviors were significant correlates of handgun carrying; however, we also found evidence of differential correlates with regard to such factors as drug selling, parental affirmation, and income by race/ethnicity. To our knowledge, this is the largest study of handgun carrying among youth in the United States. Findings indicate that although at historically low levels handgun carrying is on the rise but only among non-Hispanic Whites. Differential correlates among racial/ethnic groups suggest prevention programming and policies may need modifications depending on group and geographic locale targeted.R25 DA030310 - National Institute on Drug Abuse at the National Institutes of Healt

Trends and correlates of substance use disorders among probationers and parolees in the United States 2002–2014

BACKGROUND: Substance use and crime/recidivism are irrevocably linked. We explore the nuances of this association by highlighting the prevalence, trends, and correlates of substance use dsorders in a large group of probationers/parolees. METHODS: We examined SUDs among probationers and parolees in the United States using data from the National Study on Drug Use and Health (NSDUH). Logistic regression models were computed to examine eight distinct outcomes: alcohol abuse, illicit drug abuse, marijuana/hashish abuse, comorbid alcohol and illicit drug abuse, alcohol dependence, illicit drug dependence, marijuana/hashish dependence, and comorbid alcohol and illicit drug dependence. RESULTS: Probationers/parolees have high prevalence rates across all SUDs categories and these trends have been relatively constant. Prevalence rates for alcohol abuse and dependence are two to six times higher than for marijuana and other illicit drug abuse and dependence. Key correlates of substance abuse for probationers/parolees include: age, gender, race/ethnicity, education, income, risk propensity, crime/violence measures, and comorbid substance abuse. Similar correlates were found for substance dependence, in addition to employment and mental health treatment. CONCLUSIONS: This study indicates that SUDs are higher among probationer/parolees as compared to their non-supervised counterparts − between four and nine times higher − and these levels have changed little in recent years. Effectively responding to SUDs in this population may enhance adherence to supervision requirements, prevent recidivism, and improve public safety. We may be better served using limited funds for further development of evidence-based policies and programs, such as drug courts, which demonstrate reductions in both drug use and recidivism

Trends and correlates of marijuana use among late middle-aged and older adults in the United States, 2002–2014

BACKGROUND: Recent trend studies suggest that marijuana use is on the rise among the general population of adults ages 18 and older in the United States. However, little is known about the trends in marijuana use and marijuana-specific risk/protective factors among American adults during the latter part of adulthood. METHOD: Findings are based on repeated, cross-sectional data collected from late middle-aged (ages 50–64) and older adults (ages 65 and older) surveyed as part of the National Survey on Drug Use and Health between 2002 and 2014. RESULTS: The prevalence of past-year marijuana use among late middle-aged adults increased significantly from a low of 2.95% in 2003 to a high of 9.08% in 2014. Similarly, the prevalence of marijuana use increased significantly among older adults from a low of 0.15% in 2003 to a high of 2.04% in 2014. Notably, the upward trends in marijuana use remained significant even when accounting for sociodemographic, substance use, behavioral, and health-related factors. We also found that decreases in marijuana-specific protective factors were associated with the observed trend changes in marijuana use among late middle-aged and older adults, and observed a weakening of the association between late-middle aged marijuana use and risk propensity, other illicit drug use, and criminal justice system involvement over the course of the study. CONCLUSIONS: Findings from the present study provide robust evidence indicating that marijuana use among older Americans has increased markedly in recent years, with the most evident changes observed between 2008 and 2014

Identifying the Opportunity Cost of Critical Habitat Designation under the U.S. Endangered Species Act

We determine the effect of the US Endangered Species Act’s Critical Habitat designation on land use change from 1992 to 2011. We find that the rate of change in developed land (constructed material) and agricultural land is not significantly affected by Critical Habitat designation. Therefore, Sections 7 and 9 of the Endangered Species Act do not appear to be more heavily applied in lands designated as Critical Habitat areas versus lands within listed species’ ranges, but without critical habitat designation. Further, there does not appear to be any extraordinary conservation activity in critical habitat areas; for example, environmental non-profits and land trusts do not appear to be concentrating activity in these areas. Before we conclude that the opportunity cost of Critical Habitat designation is negligible we need to examine the land management impacts of designation

A study of the effects of pupil size on the nearpoint cross-cylinder tests

A study of the effects of pupil size on the nearpoint cross-cylinder test

Using a commercially available DNA extraction kit to obtain high quality human genomic DNA suitable for PCR and genotyping from 11-year-old saliva saturated cotton spit wads

<p>Abstract</p> <p>Background</p> <p>We sought to describe the integrity of human genomic DNA extracted from saliva saturated cotton spit wads stored at -20°C for approximately 11 years. 783 spit wad samples were collected from an ADHD sample population (Vermont Family Study) during 1996–2000. Human genomic DNA was extracted from the spit wads using a commercially available kit; QIAamp DNA Blood Midi Kit (Qiagen, Inc., Valencia, CA.) with a few modifications.</p> <p>Results</p> <p>The resulting DNA yield was more than adequate for genetic analysis and ranged from approximately 1 μg to a total of 80 μg (mean 17.3 μgs ± 11.9 μgs). A₂₆₀/A₂₈₀ratios for the human genomic DNA extracted from the spit wads was consistently within the generally acceptable values of 1.7–2.0, with the lowest purity being 1.70, and a mean value of 1.937 ± 0.226 for the 783 samples. The DNA also was suitable for PCR reactions as evidenced by the amplification of the serotonin-transporter-linked polymorphic region, 5HTTLPR. 5HTTLPR is a functional polymorphism in the promoter region of the serotonin transporter gene (<it>HTT, SLC6A4</it>, or <it>SERT</it>), consisting of two intensively studied alleles. 770 of the 783 samples (98.3%) produced fragments after PCR of the expected size with primers specific for 5HTTLPR.</p> <p>Conclusion</p> <p>High quality and abundant genomic DNA can be successfully retrieved from saliva saturated cotton spit wads using the commercially available kit, QIAamp DNA Blood Midi Kit from Qiagen, Inc. Furthermore, the DNA can be extracted in less than 3 hours and multiple samples can be processed simultaneously thus reducing processing time.</p

The 2011 Outburst of Recurrent Nova T Pyx: X-ray Observations Expose the White Dwarf Mass and Ejection Dynamics

The recurrent nova T Pyx underwent its sixth historical outburst in 2011, and became the subject of an intensive multi-wavelength observational campaign. We analyze data from the Swift and Suzaku satellites to produce a detailed X-ray light curve augmented by epochs of spectral information. X-ray observations yield mostly non-detections in the first four months of outburst, but both a super-soft and hard X-ray component rise rapidly after Day 115. The super-soft X-ray component, attributable to the photosphere of the nuclear-burning white dwarf, is relatively cool (~45 eV) and implies that the white dwarf in T Pyx is significantly below the Chandrasekhar mass (~1 M_sun). The late turn-on time of the super-soft component yields a large nova ejecta mass (>~10^-5 M_sun), consistent with estimates at other wavelengths. The hard X-ray component is well fit by a ~1 keV thermal plasma, and is attributed to shocks internal to the 2011 nova ejecta. The presence of a strong oxygen line in this thermal plasma on Day 194 requires a significantly super-solar abundance of oxygen and implies that the ejecta are polluted by white dwarf material. The X-ray light curve can be explained by a dual-phase ejection, with a significant delay between the first and second ejection phases, and the second ejection finally released two months after outburst. A delayed ejection is consistent with optical and radio observations of T Pyx, but the physical mechanism producing such a delay remains a mystery.Comment: Re-submitted to ApJ after revision