The useful field of view assessment predicts simulated commercial motor vehicle driving safety

Objective: The Useful Field of View (UFOV) assessment, a measure of visual speed of processing, has been shown to be a predictive measure of motor vehicle collision (MVC) involvement in an older adult population, but it remains unknown whether UFOV predicts commercial motor vehicle (CMV) driving safety during secondary task engagement. The purpose of this study is to determine whether the UFOV assessment predicts simulated MVCs in long-haul CMV drivers.

Method: Fifty licensed CMV drivers (M_age = 39.80, SD = 8.38, 98% male, 56% Caucasian) were administered the 3-subtest version of the UFOV assessment, where lower scores measured in milliseconds indicated better performance. CMV drivers completed 4 simulated drives, each spanning approximately a 22.50-mile distance. Four secondary tasks were presented to participants in a counterbalanced order during the drives: (a) no secondary task, (b) cell phone conversation, (c) text messaging interaction, and (d) e-mailing interaction with an on-board dispatch device.

Results: The selective attention subtest significantly predicted simulated MVCs regardless of secondary task. Each 20 ms slower on subtest 3 was associated with a 25% increase in the risk of an MVC in the simulated drive. The e-mail interaction secondary task significantly predicted simulated MVCs with a 4.14 times greater risk of an MVC compared to the no secondary task condition. Subtest 3, a measure of visual speed of processing, significantly predicted MVCs in the email interaction task. Each 20 ms slower on subtest 3 was associated with a 25% increase in the risk of an MVC during the email interaction task.

Conclusions: The UFOV subtest 3 may be a promising measure to identify CMV drivers who may be at risk for MVCs or in need of cognitive training aimed at improving speed of processing. Subtest 3 may also identify CMV drivers who are particularly at risk when engaged in secondary tasks while driving.     

The Campus Demotechnic Index: a comparison of technological energy consumption at US colleges and universities

The Campus Demotechnic Index (CDI) was modified from the Demotechnic Index (D-Index) to serve as an index of energy use for US colleges and universities. CDI values were calculated by assessing the total campus energy used for the built and mobile environments against energy required to meet the basal metabolic demand of the total campus population. Like the D-Index, the CDI measured the scalar quantity of energy used relative to the quantity of energy required for simple survival on a per capita basis, thus providing a rational metric for comparison among institutions. For the interval 2000–2005, CDI was calculated for 64 US higher education institutions and compared using maximum, minimum, mean and median CDI values, total gigajoules used, campus population, and consumption-adjusted population. Wilcoxon signed rank test results compared pair-by-pair differences of ranked CDI values from 2000 to 2005 to determine whether CDI values were significantly increasing or decreasing over time. In general, CDI values increased over time, but increases over the 6-year interval were only significantly higher in 8 of 30 two-year comparisons; in 2005, CDI values ranged from 1.1 to 56.3 (mean = 11.9, median = 8.2, n = 64), whereas in 2000, CDI values ranged from 2.0 to 53.0 (mean = 12.6, median = 9.1, n = 22). Results suggest that the CDI may serve as a useful metric for tracking campus energy efficiency over time as well as a means of comparison of energy use among institutions.     

Community development on subtidal temperate reefs: the influences of wave energy and the stochastic recruitment of a dominant kelp

Patterns of community development on subtidal rocky reefs in Marmion Lagoon, southwest Australia, were investigated with a settlement panel experiment. We tested the hypothesis that community development would differ between outer and inner reefs lines, because exposure to swell and wave energy was significantly greater on outer reefs. Following a 14-month deployment, we recorded pronounced variability between panels and sites, but did not detect any effect of wave exposure on the structure of panel assemblages. Subsequent data exploration suggested the importance of the presence of kelp recruits (Ecklonia radiata) in structuring the overall assemblage. Panel assemblages with kelp recruits were significantly different in structure to those without, principally because of greater space coverage of encrusting coralline algae and less coverage of red turfing algae, spirorbids, and bryozoans. Mature E. radiata act as ecosystem engineers in subtidal rocky reefs in southwest Australia. Our results suggested the importance of young, recruiting kelps in determining patterns of early community development on newly available hard substrata.     

Soil and plant selenium at a reclaimed uranium mine

Selenium (Se) associated with reclaimed uranium (U) mine lands may result in increased food chain transfer and water contamination. To assess post-reclamation bioavailability of Se at a U mine site in southeastern Wyoming, we studied soil Se distribution, dissolution, speciation, and sorption characteristics and plant Se accumulation. Phosphate-extractable soil Se exceeded the critical limit of 0.5 mg/kg in all the samples, whereas total soil Se ranged from a low (0.6 mg/kg) to an extremely high (26 mg/kg) value. Selenite was the dominant species in phosphate and ammonium bicarbonate-diethylenetriamine pentaacetic acid (AB-DTPA) extracts, whereas selenate was the major Se species in hot water extracts. Extractable soil Se concentrations were in the order of KH2PO4 > AB-DTPA > hot water > saturated paste. The soils were undersaturated with respect to various Se solid phases, albeit with high levels of extractable Se surpassing the critical limit. Calcium and Mg minerals were the potential primary solids controlling Se dissolution, with dissolved organic carbon in the equilibrium solutions resulting in enhanced Se availability. Adsorption was a significant (r2 = 0.76-0.99 at P < 0.05) mechanism governing Se availability and was best described by the initial mass isotherm model, which predicted a maximum reserve Se pool corresponding to 87% of the phosphate-extractable Se concentrations. Grasses, forbs, and shrubs accumulated 11 to 1800 mg Se/kg dry weight. While elevated levels of bioavailable Se may be potentially toxic, the plants accumulating high Se may be used for phytoremediation, or the palatable forage species may be used as animal feed supplements in Se-deficient areas.     

Diel foraging patterns of the sea urchin Centrostephanus coronatus as a predator avoidance strategy

During the day, the diadematid sea urchin Centrostephanus coronatus occupies holes and crevices in shallow subtidal rocky substrata. Individuals emerge from these after sunset and forage on organisms attached to the surrounding rock surface. Each urchin travels <1 m from its shelter and returns to the same one before sunrise. The sheephead wrasse Pimelometopon pulchrum does not remove urchins from their shelters, but will attack and consume urchins placed in normal feeding locations during the daytime. The active periods of the sheephead and the urchin do not overlap; urchins begin foraging about 20 min after the diurnal sheephead retire in the evening and return to their shelters 1 to 2 h before sheephead resume feeding in the morning. We infer that the urchin's daytime crevice-dwelling and nocturnal foraging habits have evolved as a response to sheephead predation. Moreover, because shelters are limited in supply, shelter fidelity may have evolved to insure refuge from sheephead.     

Sorption of MS2 bacteriophage to layered double hydroxides: effects of reaction time, pH, and competing anions

Batch sorption and column breakthrough studies were conducted to investigate the potential of layered double hydroxides (LDHs) to remove bacteriophage MS2 from contaminated waters. All four of the LDHs evaluated in this study had very high retention capacities for MS2. Sorption results showed that MS2 could be completely removed from 5.2 x 10(2) plaque-forming units (pfu)/mL solution by Mg-Al LDH 2 (i.e., 2:1 Mg to Al ratio LDH), with the highest sorption capacity observed in this study of 1.51 x 10(10) pfu/g. Attachment of MS2 to LDHs was a rapid process and reached quasi-equilibrium after a 1-h reaction time. Within the pH range studied (pH 4-9), Mg-Al LDH 2 showed high sorption potential for MS2 at all pH values but sorption decreased slightly with increasing solution pH. Background solution anions influenced virus sorption, with SO4(2-) and HPO4(2-) decreasing sorption significantly whereas the presence of NO3- had little effect on the attachment of MS2 to Mg-Al LDH 2. The addition of another virus (phiX174) only caused a slight decrease in the retention of MS2 by Mg-Al LDH 2, suggesting that there was insignificant competitive sorption between MS2 and phiX174 on LDH surfaces. Results from column experiments indicate that there was no MS2 breakthrough from columns packed with Mg-Al LDH 2-coated sand, suggesting complete MS2 retention at the virus concentration tested. The high mass recovery by beef extract solution revealed that the removal of viruses by the LDH was due to sorption of MS2 to LDH surfaces, rather than inactivation.     

Assessment of the impact of landfill on groundwater quality: A case study of the Pirana site in western India

In present study focus has been given on estimating quality and toxicity of waste with respect to heavy metals and its impact on groundwater quality, using statistical and empirical relationships between different hydrochemical data, so that easy monitoring may be possible which in turn help the sustainable management of landfill site and municipal solid waste. Samples of solid waste, leachate and groundwater were analyzed to evaluate the impact of leachates on groundwater through the comparison of their hydrochemical nature. Results suggest the existence of an empirical relationship between some specific indicator parameters like heavy metals of all three above mentioned sample type. Further, K/Mg ratio also indicates three groundwater samples heavily impacted from leachate contamination. A good number of samples are also showing higher values for and Pb than that of World Health Organization (WHO) drinking water regulation. Predominance of Fe and Zn in both groundwater and solid waste samples may be due to metal plating industries in the area. Factor analysis is used as a tool to explain observed relation between numerous variables in term of simpler relation, which may help to deduce the strength of relation. Positive loading of most of the factors for heavy metal clearly shows landfill impact on ground water quality especially along the hydraulic gradient. Cluster analysis, further substantiates the impact of landfill. Two major groups of samples obtained from cluster analysis suggest that one group comprises samples that are severely under the influence of landfill and contaminated leachates along the groundwater flow direction while other assorted with samples without having such influence.     

Nitrate Remediation: The Importance of the Advanced Nitrogen Cycle in Remedy Selection

Nitrate has become an increased regulatory concern due to gradual deterioration of surface and groundwater quality primarily related to widespread fertilizer use. Remediation of nitrate is a relatively straightforward process; however, nitrate impacts to groundwater are often a symptom of a sustained source from another nitrogen form (e.g., ammonia, ammonium nitrate, urea), analogous to how nonaqueous phase liquid can serve as a long‐term source of volatile organic compounds in groundwater. Understanding the various nitrogen transformation reactions when selecting, implementing, or documenting a remedy associated with nitrate is therefore critical to successfully reaching remedial endpoints. Case studies are presented that highlight in situ remedial successes with nitrogen‐impacted groundwater and discuss the key considerations that should be factored into remedy application. ©2015 Wiley Periodicals, Inc.     

DYNAMICS OF ADDED NITRATE AND PHOSPHATE COMPARED IN A NORTHERN CALIFORNIA WOODLAND STREAM1

ABSTRACT: Injections of NO₃ and PO₄ were made during September 1975 into Little Lost Man Creek, a small pristine stream in Redwood National Park, California. Chloride, a conservative constituent, was added in a known ratio to the nutrients. Nutrient loss at a downstream point was calculated using concentration of added Cl as a reference. Nitrate nitrogen (NO₃-N), added for 4 h, reached 920 μg/1 (above 5 μg/1 background) just below the injection point, but increased only to 405 μg/1 at 310 m downstream. The concentration decrease was attributed to dispersion and to uptake by stream biota. Percent of NO₃-N lost decreased with increasing concentration of NO₃-N. Phosphate phosphorus (PO₄-P) was added a week after the NO₃-N for 3 h, causing a concentration increase of 296 μg/1 (above 13 μg/1 background) just below the injection point, of 161 μg/1 at 90 m downstream, and of 98 μg/1 at 310 m. Percent loss of PO₄-P at downstream sites increased with increasing PO₄-P concentration and also for a short period after peak concentration occurred, but then decreased as PO₄-P concentration continued decreasing. Differences in stream response to added NO₃-N and PO₄-P are attributed to differing rates of reaction with biota and differing degrees of interaction with abiotic stream solids.     

Modeling the impacts of temperature and precipitation changes on soil CO2 fluxes from a Switchgrass stand recently converted from cropland

Switchgrass(Panicum virgatum L.) is a perennial C_4 grass native to North America and successfully adapted to diverse environmental conditions. It offers the potential to reduce soil surface carbon dioxide(CO_2) fluxes and mitigate climate change. However, information on how these CO_2 fluxes respond to changing climate is still lacking. In this study, CO_2 fluxes were monitored continuously from 2011 through 2014 using high frequency measurements from Switchgrass land seeded in 2008 on an experimental site that has been previously used for soybean(Glycine max L.) in South Dakota, USA. DAYCENT, a process-based model, was used to simulate CO_2 fluxes. An improved methodology CPTE[Combining Parameter estimation(PEST) with "Trial and Error" method] was used to calibrate DAYCENT. The calibrated DAYCENT model was used for simulating future CO_2 emissions based on different climate change scenarios. This study showed that:(i) the measured soil CO_2 fluxes from Switchgrass land were higher for 2012 which was a drought year, and these fluxes when simulated using DAYCENT for long-term(2015–2070) provided a pattern of polynomial curve;(ii) the simulated CO_2 fluxes provided different patterns with temperature and precipitation changes in a long-term,(iii) the future CO_2 fluxes from Switchgrass land under different changing climate scenarios were not significantly different, therefore, it can be concluded that Switchgrass grown for longer durations could reduce changes in CO_2 fluxes from soil as a result of temperature and precipitation changes to some extent.