A comparison of employment growth and stability before and after the Fort Worth tornado

This study examined the time series pattern of employment growth and stability in Fort Worth, Texas taking into account the March 28, 2000 tornado. The tornado is treated econometrically as an intervention and both the mean and conditional variance of employment growth were estimated. Overall, this regional labor market experienced a decline in the employment growth rate following the tornado. Among the sectors that exhibited differences in employment dynamics between the pre- and post-tornado periods, the mining sector experienced a significant increase in employment growth following the tornado while the service andwholesale, retail trade sectors experienced significant declines in employment growth in the post-tornado period. The manufacturing, service, and wholesale, retail trade sectors were characterized by greater stability (i.e., a lower level of employment growth volatility) in the post-tornado period than in the pre-tornado period. Interestingly, in several sectors, no differences in the time series dynamics of employment growth were detected between the pre- and post-tornado periods. These sectors included construction, finance, insurance, real estate, government, and transportation and public utilities.     

The role of tryptophan in don‐induced feed rejection

Abstract

Deoxynivalenol (DON, vomitoxin) commonly produced by Fusarium fungi can alter feeding behaviour of pigs and other farm animals. The effects of dietary tryptophan (TRP, precursor of brain amine serotonin) in combination with DON were examined in mice to determine if TRP can modulate DON toxicity. Results indicated that brain TRP can be influenced by dietary TRP, but no evidence of TRP potentiating DON toxicity was observed. Higher TRP levels likely induced amino acid imbalance leading to weight gain suppression.     

NITROGEN ACCUMULATION IN A CONSTRUCTED WETLAND FOR DAIRY WASTEWATER TREATMENT1

ABSTRACT: A free water surface (FWS) constructed wetland was installed at a dairy in Glendale, Arizona, to study the potential of such a wetland to remove nitrogen (N) from wastewater. The study objectives were: (1) to determine N removal from the wastewater, and (2) to evaluate N accumulation in soil and plant tissues. The system consisted of eight cells (70 × 9 × 1.5 m) planted with Typha domingensis, Scirpus validus, and Phragmites australis. The four cells in series were lined with plastic, and the four cells in a parallel series were lined with clay. Cells received approximately 180 m³/d of partially treated dairy effluent. Plant tissues and soil samples were collected above and below ground from 24 locations during one year. Total N removal from wastewater was about 17 percent. Clay‐lined cells accumulated more N in the soil and less N in plant biomass compared with plastic lined cells. Plant biomass accounted for approximately 60 percent of total N accumulated in cells with dense plant communities. Ninety percent of accumulated soil N was organic. Total N accumulated in soil reached a maximum (1,100 mg/kg) eight months after the introduction of wastewater.     

Outdoor-Indoor Levels of Six Air Pollutants

Comparisons were made of the levels of six air pollutants—total oxidant, per-oxyacetyl nitrate (PAN), nitric oxide, nitrogen dioxide, carbon monoxide, and particulate matter—outside and inside 11 buildings in the South Coast Basin of California during summer and fall.

Total oxidant levels inside depend upon how much outside air is being brought in and the residence time in the structure. With rapid intake and circulation, levels inside may be two-thirds those outside. With little intake and slow circulation, amounts inside decay to near zero. PAN is more persistent in buildings because it is more stable than ozone but also decays to low levels over an extended period. Oxides of nitrogen and CO are much more stable than oxidant or PAN and when carried into buildings remain until diluted or exhausted.

Particulate matter levels indoors depend largely upon velocity of air movement. Indoor areas where foot traffic was light or which had low ventilation rates had reduced amounts of particulate. Electrostatic precipitators were much more effective than coarse primary filters used in many buildings for removing particulate matter.     

Marijuana trajectories and associations with driving risk behaviors in Canadian youth

Objective: Research on risky driving practices involving marijuana use among youth and young adults often relies on cross-sectional data, which fail to account for longitudinal changes in substance use patterns. A better understanding of the longitudinal patterns of marijuana use and its effect on risky driving practices during young adulthood is needed in order to better inform prevention efforts. The current study examined whether different longitudinal patterns of marijuana use across the transition from adolescence to young adulthood are associated with impaired driving risks in young adulthood.

Methods: Data were from the longitudinal Victoria Healthy Youth Survey, which interviewed youth biennially on 6 occasions across 10 years (2003 to 2013).

Results: Youth who reported consistently high levels of marijuana use from adolescence to young adulthood (chronic users) and youth who reported increasing levels of use across this period (increasers) were more likely to engage in risky impaired driving behaviors compared to the other 3 user groups (occasional users, decreasers, and abstainers). Frequency of marijuana use was also predictive of impaired driving risks in young adulthood after controlling for individual characteristics (age, sex, socioeconomic status, age of onset of marijuana use), frequency of other substance use (heavy episodic drinking and illicit drug use), and simultaneous use of marijuana and other substances (alcohol and illicit drugs). By young adulthood, youth who use marijuana more than once a week are more likely to simultaneously use alcohol and engage in heavy episodic drinking. They are also more likely take driving risks.

Conclusions: Harm reduction strategies and legislative approaches targeting impaired driving risks associated with marijuana use should include approaches to target these high-risk groups and to reduce simultaneous use of alcohol.     

Effects of life‐history requirements on the distribution of a threatened reptile

Survival and reproduction are the two primary life‐history traits essential for species’ persistence; however, the environmental conditions that support each of these traits may not be the same. Despite this, reproductive requirements are seldom considered when estimating species’ potential distributions. We sought to examine potentially limiting environmental factors influencing the distribution of an oviparous reptile of conservation concern with respect to the species’ survival and reproduction and to assess the implications of the species’ predicted climatic constraints on current conservation practices. We used ecological niche modeling to predict the probability of environmental suitability for the alligator snapping turtle (Macrochelys temminckii). We built an annual climate model to examine survival and a nesting climate model to examine reproduction. We combined incubation temperature requirements, products of modeled soil temperature data, and our estimated distributions to determine whether embryonic development constrained the northern distribution of the species. Low annual precipitation constrained the western distribution of alligator snapping turtles, whereas the northern distribution was constrained by thermal requirements during embryonic development. Only a portion of the geographic range predicted to have a high probability of suitability for alligator snapping turtle survival was estimated to be capable of supporting successful embryonic development. Historic occurrence records suggest adult alligator snapping turtles can survive in regions with colder climes than those associated with consistent and successful production of offspring. Estimated egg‐incubation requirements indicated that current reintroductions at the northern edge of the species’ range are within reproductively viable environmental conditions. Our results highlight the importance of considering survival and reproduction when estimating species’ ecological niches, implicating conservation plans, and benefits of incorporating physiological data when evaluating species’ distributions.     

Transformation of a non-oestrogenic steroid metabolite to an oestrogenically active substance by minimal bacterial activity

The majority of oestrogenic material excreted from humans and wildlife, and therefore released into sewers, is in a conjugated form. However, the finding of “free” oestrogens in sewage effluent suggests that these metabolites are somehow converted back into an active form, before or during passage through a sewage treatment process. When male fathead minnows (Pimephales promelas) were continuously exposed to oestradiol-3-glucuronide, in a continuous-flow system, it demonstrated no inherent oestrogenic activity. However, when fish were exposed to effluent generated from laboratory simulations of sewage treatment processes, to which had been added oestradiol-3-glucuronide, oestrogenic activity was observed, suggesting microbial activity was capable of degrading the steroid metabolite into a more potent oestrogen. Oestrogenic potency was determined by measuring changes in plasma vitellogenin (egg yolk precursor) concentrations and gonadosomatic index. The results suggest that inactive metabolites of steroids are very readily biotransformed into biologically active oestrogens.     

Did the pre-1980 use of in-stream structures improve streams? A reanalysis of historical data.

In the 1930s, after only three years of scientific investigation at the University of Michigan Institute for Fisheries Research, cheap labor and government-sponsored conservation projects spearheaded by the Civilian Conservation Corps allowed the widespread adoption of in-stream structures throughout the United States. From the 1940s through the 1970s, designs of in-stream structures remained essentially unchanged, and their use continued. Despite a large investment in the construction of in-stream structures over these four decades, very few studies were undertaken to evaluate the impacts of the structures on the channel and its aquatic populations. The studies that were undertaken to evaluate the impact of the structures were often flawed. The use of habitat structures became an "accepted practice," however, and early evaluation studies were used as proof that the structures were beneficial to aquatic organisms. A review of the literature reveals that, despite published claims to the contrary, little evidence of the successful use of in-stream structures to improve fish populations exists prior to 1980. A total of 79 publications were checked, and 215 statistical analyses were performed. Only seven analyses provide evidence for a benefit of structures on fish populations, and five of these analyses are suspect because data were misclassified by the original authors. Many of the changes in population measures reported in early publications appear to result from changes in fishing pressure that often accompanied channel modifications. Modern evaluations of channel-restoration projects must consider the influence of fishing pressure to ensure that efforts to improve fish habitat achieve the benefits intended. My statistical results show that the traditional use of in-stream structures for channel restoration design does not ensure demonstrable benefits for fish communities, and their ability to increase fish populations should not be presumed.     

1,2,4-trichlorobenzene marine risk assessment with special emphasis on the Osparcom region North Sea

A risk assessment on 1,2,4-trichlorobenzene was carried out specifically for the marine environment according to the methodology laid down in the EU Risk Assessment Regulation 1488/94 and the Guidance Documents of the EU Existing Substances Regulation 793/93. The study consists of the collection and evaluation of data on effects and environmental concentrations from analytical monitoring programs in large rivers and estuaries in the North Sea area. The risk is indicated by comparing the predicted environmental concentration (PEC) with the predicted no-effect concentrations (PNEC) for the marine aquatic environment. A PNECwater) value of 0.3 microg/l and a PNECsed value of 38 microg/kgdw were derived from the results of toxicological studies in organisms representing three trophic levels, i.e. aquatic plants, invertebrates and fish. Based on monitoring data two situations are distinguished: a typical case and a worst case with a PECwater of <0.047 and 0.1 microg/l, respectively, and a PECsed of 40 and 90 microg/kgdw, respectively. The calculated PEC/PNEC ratios were 0.16 and 0.3 for water and 1 and 2.4 for sediment, respectively. It was concluded that no risks are expected for aquatic organisms. Based on the combination of worst-case assumptions risks to benthic organisms could not be fully excluded, but since all open uses of 1,2,4-trichlorobenzene will be ended following the EU risk assessment outcome of 2001 any potential risk is expected to be reduced accordingly. 1,2,4-trichlorobenzene is not considered toxic according to the EU criteria and the available data on persistence of 1,2,4-trichlorobenzene indicate a half-life in water of a few days and a significant biodegradation potential. The bioaccumulation potential is low to moderate with most BCF ratios for fish ranging from 600 to 1400 and one highest of 2020. Based on an extensive evaluation of persistence, biodegradation and bioaccumulation data it is concluded that 1,2,4-trichlorobenzene is not a PBT, since it does not fulfill any of the EU criteria. Biomagnification in the food chain is not expected due to the relatively high elimination rate constants.