Search

Lehman Caves is an extensively decorated high desert cave that represents one of the main tourist attractions in Great Basin National Park, Nevada. Although traditionally considered a water table cave, recent studies identified abundant speleogenetic features consistent with a hypogenic and, potentially, sulfuric acid origin. Here, we characterized white mineral deposits in the Gypsum Annex (GA) passage to determine whether these secondary deposits represent biogenic minerals formed during sulfuric acid corrosion and explored microbial communities associated with these and other mineral deposits throughout the cave. Powder X-ray diffraction (pXRD), scanning electron microscopy with electron dispersive spectroscopy (SEM-EDS), and electron microprobe analyses (EPMA) showed that, while most white mineral deposits from the GA contain gypsum, they also contain abundant calcite, silica, and other phases. Gypsum and carbonate-associated sulfate isotopic values of these deposits are variable, with δ 34 S V-CDT between +9.7‰ and +26.1‰, and do not reflect depleted values typically associated with replacement gypsum formed during sulfuric acid speleogenesis. Petrographic observations show that the sulfates likely co-precipitated with carbonate and SiO 2 phases. Taken together, these data suggest that the deposits resulted from later-stage meteoric events and not during an initial episode of sulfuric acid speleogenesis. Most sedimentary and mineral deposits in Lehman Caves have very low microbial biomass, with the exception of select areas along the main tour route that have been impacted by tourist traffic. High-throughput 16S rRNA gene amplicon sequencing showed that microbial communities in GA sediments are distinct from those in other parts of the cave. The microbial communities that inhabit these oligotrophic secondary mineral deposits include OTUs related to known ammonia-oxidizing Nitrosococcales and Thaumarchaeota, as well as common soil taxa such as Acidobacteriota and Proteobacteria. This study reveals microbial and mineralogical diversity in a previously understudied cave and expands our understanding of the geomicrobiology of desert hypogene cave systems., (© 2024 John Wiley & Sons Ltd.)

Here, we report on new data (75 analyses) of plutonium (Pu) isotopes to elucidate activity concentrations, inventories, sources, and their transport from the ocean surface to the seafloor from a collection of six deep-sea sediment cores (depths ranging from 257 to 3739 m) in the southern Gulf of Mexico. Sediment cores collected from the continental shelf and upper slope region of the Gulf of Mexico showed 240 Pu/ 239 Pu ratios of 0.15 to 0.26, and 239+240 Pu-inventories ranging from 14.7 to 33.0 Bq m -2 . Inventories and ratios are consistent with global fallout Pu for this tropical region. In contrast, sediment cores collected from the lower slope region and abyssal plain showed low 240 Pu/ 239 Pu ratios of 0.07 to 0.13 and much lower 239+240 Pu inventories below 6.8 Bq m -2 . This implies that only a small fraction of the expected global fallout Pu has reached the deep-sea sediments. The low 240 Pu/ 239 Pu isotope ratios indicate that fallout from the Nevada testing site was an important source of Pu in deep-sea sediments, and that this Pu was likely more efficiently scavenged from the water column than Pu from global fallout. We estimated that up to 44% of the total inventory of 239+240 Pu in deep-sea sediments is due to the Nevada source. Low values and a progressive decrease of 240 Pu/ 239 Pu ratios and 239+240 Pu inventories with increasing water depth have been previously reported for the Gulf of Mexico. Analysis of Pu isotopes in two sediment traps from the upper slope regions shows 240 Pu/ 239 Pu ratios comparable to those observed in global fallout. These results indicate that global fallout Pu is currently the main source of Pu in sinking particles in the water column. Therefore, a significant fraction of global fallout Pu must still be present, either in a dissolved phase, or as biologically recycled material in the water column, or scavenged on the shelf and shelf break. Our results bring to light important questions on the application of Pu isotopes to establish sediment chronologies in deep-sea sediments, since global fallout features such as the 1963 maximum are not available., (© 2022. The Author(s).)

Micro-organisms have long been implicated in the construction of stromatolites. Yet, establishing a microbial role in modern stromatolite growth via molecular analysis is not always straightforward because DNA in stromatolites can have multiple origins. For example, the genomic material could represent the microbes responsible for the construction of the stromatolite (i.e., "builders"), microbes that inhabited the structure after it was built (i.e., "tenants"), or microbes/organic matter that were passively incorporated after construction from the water column or later diagenetic fluids (i.e., "squatters"). Disentangling the role of micro-organisms in stromatolite construction, already difficult in modern systems, becomes more difficult as organic signatures degrade, and their context is obscured. To evaluate our ability to accurately decipher the role of micro-organisms in stromatolite formation in geologically recent settings, 16/18S SSU rRNA gene sequences were analyzed from three systems where the context of growth was well understood: (a) an actively growing stromatolite from a silicic hot spring in Yellowstone National Park, Wyoming, where the construction of the structure is controlled by cyanobacteria; (b) a mixed carbonate and silica precipitate from Little Hot Creek, a hot spring in the Long Valley Caldera of California that has both abiogenic and biogenic components to accretion; and (c) a near-modern lacustrine carbonate stromatolite from Walker Lake, Nevada that is likely abiogenic. In all cases, the largest percentage of recovered DNA sequences, especially when focused on the deeper portions of the structures, belonged to either the tenant or squatter communities, not the actual builders. Once removed from their environmental context, correct interpretation of biology's role in stromatolite morphogenesis was difficult. Because high-throughput genomic analysis may easily lead to incorrect assumptions even in these modern and near-modern structures, caution must be exercised when interpreting micro-organismal involvement in the construction of accretionary structures throughout the rock record., (© 2021 John Wiley & Sons Ltd.)

Morphologically complex trace fossils, recording the infaunal activities of bilaterian animals, are common in Phanerozoic successions but rare in the Ediacaran fossil record. Here, we describe a trace fossil assemblage from the lower Dunfee Member of the Deep Spring Formation at Mount Dunfee (Nevada, USA), over 500 m below the Ediacaran-Cambrian boundary. Although millimetric in scale and largely not fabric-disruptive, the Dunfee assemblage includes complex and sediment-penetrative trace fossil morphologies that are characteristic of Cambrian deposits. The Dunfee assemblage records one of the oldest documented instances of sediment-penetrative infaunalization, corroborating previous molecular, ichnologic, and paleoecological data suggesting that crown-group bilaterians and bilaterian-style ecologies were present in late Ediacaran shallow marine ecosystems. Moreover, Dunfee trace fossils co-occur with classic upper Ediacaran tubular body fossils in multiple horizons, indicating that Ediacaran infauna and epifauna coexisted and likely formed stable ecosystems., (© 2020 John Wiley & Sons Ltd.)

This study investigates concentrations of toxic and potentially toxic elements (PTEs) in organic and conventional wheat flour and grains marketed in Las Vegas. Geographic origins of the samples were evaluated using Linear Discriminant Analysis (LDA). Monte Carlo Simulation technique was also employed to evaluate non-carcinogenic risk in four life stages. Concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sr, and Zn were determined using inductively coupled plasma mass spectrometry (ICP-MS) following hot block-assisted digestion. Obtained results showed non-significant differences in contents of toxic and PTEs between conventional and organic wheat grains/flour. Using LDA, metal (loid)s were found to be indicative of geographical origin. The LDA produced a total correct classification rate of 95.8% and 100% for US and West Pacific Region samples, respectively. The results of the present study indicate that the estimated non-carcinogenic risk associated with toxic element intakes across the four life stages were far lower than the threshold value (Target Hazard Quotient (THQ) > 1). However, the probability of exceeding the threshold value for Mn is approximately 32% in children aged between 5 and 8 years. The findings of this study can aid in understanding dietary Mn exposure in children in Las Vegas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

A more comprehensive understanding of how recreational values and forest visitation rates vary across different activities enables forest managers to tailor conservation and management strategies to align with preferences among visitors, ensuring more effective allocation of budgetary resources. However, current research often focuses on only a few recreational activities, resulting in limited insights for forest managers. This study aims to expand the nature-based activities considered so that management can better serve the broader public. We conduct a travel cost analysis using a large survey-based dataset to estimate the value of nature-based recreation in national forests in the Sierra Nevada region and assess how these values differ across main activities. We categorize recreational activities into five broad groups (Passive, Active, Camping, Winter, and Other) to offer a comprehensive view of recreational preferences. A truncated negative binomial regression accounting for endogenous stratification is used to analyze the relationship between the number of trips to the forests, travel cost, activity categories, and socio-demographic variables. Our results suggest a mean consumer surplus (CS) of $65 per visit per person to national forests in the Sierra Nevada. Aggregated over annual per person visits, the total CS is approximately $313.3 million per year. Our findings reveal variations in CS across activity groups, with winter activities (e.g., skiing, snowboarding) and active activities (e.g., hiking, fishing) attracting the highest number of visits, and the highest total CS. Our results provide valuable insights for national forest managers, facilitating the strategic allocation of limited resources to recreational activities that maximize societal welfare., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The COVID-19 pandemic highlighted the value of wastewater surveillance in providing unbiased assessments of incidence/prevalence for infectious disease targets, ultimately leading to the development of local, state, and national programs across the United States. To address the growing epidemic of drug abuse, there have been calls to extend these programs to high risk substances (HRS) and metabolites, while leveraging the experience gained during the pandemic and from ongoing efforts in other countries. This study further advances the science of wastewater surveillance for HRS by (1) highlighting analytical and sewer transport considerations, (2) proposing sucralose normalization to adjust for varying human urine/fecal load and confounded population estimates (e.g., high tourism areas), and (3) characterizing temporal and geographic trends in HRS use. This one-year study across eight sewersheds in Southern Nevada (208 total samples) monitored concentrations of 17 pharmaceuticals and personal care products (PPCPs) and 22 HRS and metabolites, including natural, semi-synthetic, and synthetic opioids. The data indicated a ∼200 % increase in heroin and methamphetamine use since 2010, a stark increase in fentanyl consumption beginning in October 2022, and statistically significant differences in HRS consumption patterns between sewersheds and on certain dates. Notably, the latter outcome highlights the potential for wastewater surveillance data to be strategically translated into public health action to reduce and/or more rapidly respond to overdoses., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

This study reports a new case of acanthocephalan (thorny-headed worm) eggs in a coprolite from Bonneville Estates Rockshelter in eastern Nevada and uses archaeological and ethnographic data to better understand long-term relationships between people and acanthocephalans. Acanthocephalans are parasitic worms that use arthropods as intermediate hosts in their multi-host life cycles. Though acanthocephaliasis is rare among humans today, cases have increased in the last decade, and the discovery of acanthocephalan eggs in coprolites from archaeological sites in the Great Basin suggests a deep, shared history. At Bonneville Estates Rockshelter, 9 acanthocephalan eggs were recovered using a modified rehydration-homogenization-micro-sieving protocol on a coprolite that was radiocarbon dated to 6,040 ± 60 14C BP (7,160-6,730 cal BP), pushing back the oldest evidence of human acanthocephalan infection by 3 millennia. Researchers have proposed that the paleoepidemiology of acanthocephalans may relate to subsistence practices due to overlap in locations of infection and areas where insects are part of traditional foodways. This paper considers the paleoepidemiology of acanthocephalan infection through the first combined review of paleoparasitological, ethnographic, and archaeological records in western North America. Ethnographic and archaeological records support the hypothesis that archaeological cases of human acanthocephaliasis may be linked to entomophagy. Additional parasitological analyses are advised to determine whether this distribution is the result of dietary practices, host ecology, taphonomic issues, sampling biases, or a combination of factors., (© American Society of Parasitologists 2023.)

The dominant source of drinking water in rural Nevada, United States, is privately-owned domestic wells. Because the water from these wells is unregulated with respect to government guidelines, it is the owner's responsibility to test their groundwater for heavy metals and other contaminants. Arsenic, lead, cadmium, and uranium have been previously measured at concentrations above Environmental Protection Agency (EPA) guidelines in Nevada groundwater. This is a public health concern because elevated levels of these metals are known to have negative health effects. We recruited individuals through a population health study, the Healthy Nevada Project, to submit drinking water samples from domestic wells for testing. Water samples were returned from 174 households with private wells. We found 22 % had arsenic concentrations exceeding the EPA maximum contaminant level (MCL) of 10 μg/L. Additionally, federal, state, or health-based guidelines were exceeded for 8 % of the households for uranium and iron, 6 % for lithium and manganese, 4 % for molybdenum, and 1 % for lead. The maximum observed concentrations of arsenic, uranium, and lead were ∼80, ∼5, and ∼1.5 times the EPA guideline values, respectively. 41 % of households had a treatment system and submitted both pre- and post-treatment water samples from their well. The household treatments were shown to reduce metal concentrations, but concentrations above guideline values were still observed. Many treatment systems cannot reduce the concentration below guideline values because of water chemistry, treatment failure, or improper treatment techniques. These results show the pressing need for continued education and outreach on regular testing of domestic well waters, proper treatment types, and health effects of metal contamination. These findings are potentially applicable to other arid areas where groundwater contamination of naturally occurring heavy metals occurs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Subsurface microbial community distribution patterns are influenced by biogeochemical and groundwater fluxes and may inform hydraulic connections along groundwater-flow paths. This study examined the regional-scale microbial community of the Death Valley Regional Flow System and evaluated whether subsurface communities can be used to identify groundwater-flow paths between recharge and discharge areas. Samples were collected from 36 sites in three groundwater basins: Pahute Mesa-Oasis Valley (PMOV), Ash Meadows (AM), and Alkali Flat-Furnace Creek Ranch (AFFCR). Microbial diversity within and between communities varied by location, and communities were separated into two overall groups that affiliated with the AM and PMOV/AFFCR basins. Network analysis revealed patterns between clusters of common microbes that represented groundwaters with similar geochemical conditions and largely corroborated hydraulic connections between recharge and discharge areas. Null model analyses identified deterministic and stochastic ecological processes contributing to microbial community assemblages. Most communities were more different than expected and governed by dispersal limitation, geochemical differences, or undominating processes. However, certain communities from sites located within or near the Nevada National Security Site were more similar than expected and dominated by homogeneous dispersal or selection. Overall, the (dis)similarities between the microbial communities of DVRFS recharge and discharge areas supported previously documented hydraulic connections between: (1) Spring Mountains and Ash Meadows; (2) Frenchman and Yucca Flat and Amargosa Desert; and (3) Amargosa Desert and Death Valley. However, only a portion of the flow path between Pahute Mesa and Oasis Valley could be supported by microbial community analyses, likely due to well-associated artifacts in samples from the two Oasis Valley sites. This study demonstrates the utility of combining microbial data with hydrologic, geologic, and water-chemistry information to comprehensively characterize groundwater systems, highlighting both strengths and limitations of this approach., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier B.V.)

Housing is a key health determinant. Habitability laws set minimum standards for adequate housing. However, accessing them to ensure adequate housing may be a challenge for many tenants. This paper explores the need for rental housing policy that would better support adequate and safe housing, particularly for low-income renters. A mixed-methods approach assessed residential tenant habitability concerns in Clark County, Nevada, through calls relayed to the Clark County Landlord-Tenant Hotline (CCLTH). Of the 2865 calls, 74.3% were from ZIP codes that were 80% of the median income and below. There was a significant relationship between the ZIP code-level income and the reporting of at least one essential habitability concern. Of the 266 participants that responded to a follow-up call, 34.6% reported that their complaint was resolved and there was no association between resolution and income. Qualitative data analysis from phone interviews revealed two central themes: (1) resources to navigate landlord-tenant laws are limiting and (2) housing policies need to be strengthened to help tenants and keep people housed. Understanding tenant concerns regarding substandard housing and related inequities can help inform rental housing policy and its implementation to promote healthy homes and improve health outcomes for communities burdened by poor rental housing conditions.

The State of Nevada, USA Administrative Code requires a 12-log enteric virus reduction/inactivation, 10-log Giardia cyst reduction, and 10-log Cryptosporidium oocyst reduction for Category A+ reclaimed water suitable for indirect potable reuse (IPR) based on raw wastewater to potable reuse water. Accurately demonstrating log 10 reduction values (LRVs) through secondary biological treatment prior to an advanced water treatment train enables redundancy and resiliency for IPR projects while maintaining a high level of public confidence. LRVs for Cryptosporidium and Giardia resulting from secondary biological treatment are not fully established due to a wide range of performance variabilities resulting from different types of secondary biological treatment processes employed in water reclamation. A one-year investigation of two full-scale northern Nevada (e.g. ≤4 mgd; 1.5 × 10 7 L/day) water reclamation facilities (WRFs) was conducted to monitor Cryptosporidium oocysts and Giardia cysts in untreated wastewater and secondary effluent. This study aimed at establishing secondary treatment LRVs, monitor WRF performance and attempted to correlate performance to protozoan reduction. California's IPR regulations, in which Nevada IPR regulations were modeled after, were based on a maximum concentration of 5-logs (cysts/L) of Giardia and 4-logs (oocysts/L) of Cryptosporidium. The recovery-corrected Giardia and Cryptosporidium concentrations measured in untreated influent (20 samples each at each WRF) were below 5-log cysts/L at the 99th percentile (maximum 4.4-log cysts/L) and 4-log oocysts/L (maximum 2.7 log oocysts/L), respectively. Both secondary treatment WRFs produced secondary effluent that is consistently better than federal and the State of Nevada requirements and perform within an operating envelop for other secondary facilities. Given the results, it appears that a minimum conservative estimate for LRVs for well-operated secondary activated sludge treatment plants (at the 5th percentile) of 0.5 LRV credit for Cryptosporidium and 2.0 LRV for Giardia is warranted. These minimum LRVs are consistent with a conservative review of the available literature., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Bisphenols are massively used in several manufacture processes such that bisphenol A (BPA) is ubiquitous in environment worldwide. After the implementation of regulations about BPA use, manufacturers have moved their production toward alternative substances structurally similar to it. Unfortunately, BPA analogues, given their structural similarity, exert also similar adverse effects. This review aims to investigate the occurrence of bisphenols (BPs) in bivalve molluscs. In this way, valuable information on the amount of BPs released into the environment in different areas are given. The current research indicates that BPA presence in bivalve molluscs has been investigated in Asia (Indian Ocean and Pacific Ocean), Europe (Mediterranean Sea, Baltic Sea and Atlantic Ocean) and America (Lake Mead, Nevada) with the highest amount of studies reported in bivalves harvested in Asian Coasts. BPA analogues are frequently detected in several matrices and their levels will continuously increase in the environment. Nevertheless, there is a current lack of studies analysing BPs other than BPA in bivalves. Further investigations should be conducted in this direction, in order to assess environmental distribution and the hazard for animals and human health given that seafood consumption could be an important pathway of bisphenols intake., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Increasing frequency and severity of droughts have motivated natural resource managers to mitigate harmful ecological and hydrological effects of drought, but drought mitigation is an emerging science and evaluating its effectiveness is difficult. We examined ecohydrological responses of drought mitigation actions aimed at conserving populations of the Columbia spotted frog (Rana luteiventris) in a semi-arid valley in Nevada, USA. Abundance of this rare frog had declined precipitously after multiple droughts. Mitigation included excavating ponds to increase available surface water and installing earthen dams to raise water tables. We assessed responses of riparian vegetation to mitigation using a 30-year time series of satellite-derived Normalized Difference Vegetation Index (NDVI) and gridded weather data. We then analyzed a 23-year mark-recapture dataset to evaluate the effects of drought mitigation and NDVI on the probability of frog survival and rates of recruitment. After accounting for interannual precipitation variability, we found that NDVI increased significantly from before to after drought mitigation, suggesting that mitigation influenced the hydrology and vegetation of the meadows. Frog survival increased with NDVI, but mitigation had a stronger effect than NDVI suggesting that excavated mitigation ponds were particularly important for frog survival during drought. In contrast, frog recruitment was associated with NDVI more than mitigation, but only in meadows where NDVI was dependent on precipitation. At meadows with available groundwater, recruitment was associated with mitigation ponds. These findings suggest that mitigation ponds are critical for juvenile frogs to recruit into the adult population, but recruitment can also be increased by raising water tables in meadows lacking groundwater sources. Lagged recruitment (i.e., effects on larvae and juveniles) was negatively associated with NDVI. This study illustrates the ecohydrological complexity of drought mitigation and demonstrates novel ways to assess the effectiveness of drought mitigation using time series of readily available satellite imagery and organismal data., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

Introductions of dreissenid mussels in North America have been a significant concern over the last few decades. This study assessed the distribution of synthetic organic compounds (SOCs) in the food web of Lake Mead, Nevada/Arizona, USA and how this distribution was influenced by the introduction of invasive quagga mussels. A clear spatial gradient of SOC concentrations in water was observed between lake basins downstream of populated areas and more rural areas. Within the food web, trophic magnification factors (TMF) indicated statistically significant biomagnification for nine, and biodilution for two, of 22 SOCs examined. The highest value recorded was for PCB 118 (TMF, 5.14), and biomagnification of methyl triclosan (TMF, 3.85) was also apparent. Biodilution was observed for Tonalide® (0.06) and Galaxolide® (0.38). Total SOC concentration in quagga mussels was higher than in three pelagic fishes. Also, 19 of 20 SOC examined in Largemouth Bass (Micropterus salmoides) had substantially lower concentrations in 2013, when quagga mussels had become well established, than in 2007/08, soon after quagga mussels were introduced. Estimates of SOC concentrations in the water column and quagga mussels suggest that a considerable portion (~10.5%) of the SOC mass in the lake has shifted from the pelagic to the benthic environments due to quagga mussel growth. These observations suggest that benthic species, such as the endangered Razorback Sucker, may be experiencing increased risk of SOC exposure. In addition, stable isotope analysis (carbon and nitrogen) indicated a decrease in the nutritional value of zooplankton to consumers (e.g., Razorback Sucker larvae) since quagga mussels became established. These changes could affect Razorback Sucker larval survival and recruitment. Results from this study strongly suggest that the introduction of quagga mussels has greatly altered the dynamics of SOCs and other processes in the food web of Lake Mead., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier B.V.)

Tungsten (W) occurrence and speciation was investigated in sediments collected from Fallon, Nevada where previous studies have linked elevated W levels in human body fluids to an unusual cluster of childhood leukemia cases. The speciation of sedimentary W was determined by μ-XRF mapping and μ-XANES. The W content of the analyzed surface sediments ranged between 81 and 25,908 mg/kg, which is significantly higher than the W content in deeper sediments which ranged from 37 to 373 mg/kg at 30 cm depth. The μ-XANES findings reveal that approximately 20-50% of the total W in the shallow sediment occurs in the metallic form (W 0 ); the rest occurs in the oxide form (W VI O 3 ). Because W 0 does not occur naturally, its elevated concentrations in surface sediments point toward a possible local anthropogenic origin. The oxidation of metallic W 0 with meteoric waters likely leads to the formation of W VI O 3 . The chief water-soluble W species was identified as WO 4 2- by chromatographic separation and speciation modeling. These results led us to postulate that W 0 particles from a currently unknown but local source(s) is (are) deposited onto the soils and/or surface sediments. The W 0 in interaction with meteoric water is oxidized to W VI O 3 , and as these sediment-water interactions progress, WO 4 2- is formed in the water at pH ∼7. Under pH < 7, and sufficient W concentrations, tungstate tends to polymerize, and polymerized species are less likely to adsorb onto sediments. Polymerized species have lower affinity than monomers, which leads to enhanced mobility of W., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Most of the state governments in United States (U.S.) issued lockdown or business restrictions amid the COVID-19 pandemic in March 2020, which created a unique opportunity to evaluate the air quality response to reduced economic activities. Data acquired from 28 long-term air quality stations across the U.S. revealed widespread but nonuniform reductions of nitrogen dioxide (NO 2 ) and carbon monoxide (CO) during the first phase of lockdown (March 15-April 25, 2020) relative to a pre-lockdown reference period and historical baselines established in 2017-2019. The reductions, up to 49% for NO 2 and 37% for CO, are statistically significant at two thirds of the sites and tend to increase with local population density. Significant reductions of particulate matter (PM 2.5 and PM 10 ) only occurred in the Northeast and California/Nevada metropolises where NO 2 declined the most, while the changes in ozone (O 3 ) were mixed and relatively minor. These findings are consistent with lower transportation and utility demands that dominate NO 2 and CO emissions, especially in major urban areas, due to the lockdown. This study provides an insight into potential public health benefits with more aggressive air quality management, which should be factored into strategies to reopen the U.S. and global economy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

We investigated the interaction between soil water supply and atmospheric evaporative demand for driving the seasonal pattern of transpiration in sky-island high-elevation forest ecosystems. Sap flow measurements were collected at 10-minute intervals for five consecutive years (2013-2017) on two co-occurring subalpine conifers, i.e. limber pine (Pinus flexilis) and bristlecone pine (Pinus longaeva). Our study site is part of the Nevada Climate-ecohydrological Assessment Network (NevCAN), and is located at 3355 m a.s.l. within an undisturbed mixed-conifer stand. We found that seasonal changes in soil moisture regulated transpiration sensitivity to atmospheric conditions. Sap flow density was mainly limited by evaporative demands under non-water limiting conditions, but was influenced only by soil moisture when water availability decreased. Daily sap flow density increased with radiation and soil moisture in June and July when soil moisture was generally above 10%, but correlated only with soil moisture in August and September when soil drought occurred. Sap flow sensitivity to vapor pressure deficit and solar radiation was therefore reduced under decreasing soil moisture conditions. Transpiration peaked in mid-to-late June during both dry and wet years, with a lower peak in late summer during wet years. Normalized mean daily canopy conductance of both species declined with decreasing soil moisture (i.e., increasing soil drought). Severe soil drying (i.e., soil moisture <7% at 20 cm depth), which was rarely detected in wet summers (2013-2014) but occurred more frequently in dry summers (2015-2017), induced a minimum in crown conductance with unchanged low-level sap flow, which might potentially trigger hydraulic failure. The minimum sap flow level under severe soil drought was higher for limber pine than bristlecone pine, possibly because of wider tracheids in limber compared to bristlecone pine. Our findings provide insights into physiological mechanisms of drought-induced stress for iconic sky-island five-needle pines located at high elevation in xeric environments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Dental students need to be equipped as clinicians to treat diverse communities and to recognize oral health disparities that are rooted in the social determinants of health. Library instruction is frequently focused on information literacy topics. Within the health sciences this might include critical appraisal or evidence synthesis, and instruction centered on locating and using library resources. This paper details the unique experiences of two liaison librarians to the School of Dental Medicine who taught the topics of cultural competence and cultural humility to first-year dental medicine students. While the authors do not discuss typical information literacy instruction in this paper, they share strategies used to design the instruction sessions, reflections on teaching these themes, lessons learned, and suggestions for other liaison librarians who might have an interest in teaching about cultural competence or cultural humility.

Long duration tree-ring records with annual precision allow for the reconstruction of past growing conditions. Investigations limited to the most common tree-ring proxy of ring width can be difficult to interpret, however, because radial growth is affected by multiple environmental processes. Furthermore, studies of living trees may miss important effects of drought on tree survival and forest changes. Stable carbon isotopes can help distinguish drought from other environmental factors that influence tree-ring width and forest stand condition. We quantified tree-ring radial expansion and stable carbon isotope ratios (δ 13 C) in riparian cottonwoods (Populus angustifolia and P. angustifolia x P.trichocarpa) along Snake Creek in Nevada, USA. We investigated how hydrological drought affected tree growth and death at annual to half-century scales in a partially dewatered reach (DW) compared to reference reaches immediately upstream and downstream. A gradual decline in tree-ring basal area increment (BAI) began at DW concurrent to streamflow diversion in 1961. BAI at DW diverged from one reference reach immediately but not from the other until nearly 50 years later. In contrast, tree-ring δ 13 C had a rapid and sustained increase following diversion at DW only, providing the stronger and clearer drought signal. BAI and δ 13 C were not significantly correlated prior to diversion; after diversion they both reflected drought and were correlated for DW trees only. Cluster analyses distinguished all trees in DW from those in reference reaches based on δ 13 C, but BAI patterns left trees intermixed across reaches. Branch and tree mortality were also highest and canopy vigor was lowest in DW. Results indicate that water scarcity strongly limited cottonwood photosynthesis following flow diversion, thus reducing carbon assimilation, basal growth and survival. The dieback was not sudden, but occurred over decades as carbon deficits mounted and depleted streamflow left trees increasingly vulnerable to local meteorological drought., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier B.V.)

Improving predictive models for noble gas transport through natural materials at the field-scale is an essential component of improving US nuclear monitoring capabilities. Several field-scale experiments with a gas transport component have been conducted at the Nevada National Security Site (Non-Proliferation Experiment, Underground Nuclear Explosion Signatures Experiment). However, the models associated with these experiments have not treated zeolite minerals as gas adsorbing phases. This is significant as zeolites are a common alteration mineral with a high abundance at these field sites and are shown here to significantly fractionate noble gases during field-scale transport. This fractionation and associated retardation can complicate gas transport predictions by reducing the signal-to-noise ratio to the detector (e.g. mass spectrometers or radiation detectors) enough to mask the signal or make the data difficult to interpret. Omitting adsorption-related retardation data of noble gases in predictive gas transport models therefore results in systematic errors in model predictions where zeolites are present.Herein is presented noble gas adsorption data collected on zeolitized and non-zeolitized tuff. Experimental results were obtained using a unique piezometric adsorption system designed and built for this study. Data collected were then related to pure-phase mineral analyses conducted on clinoptilolite, mordenite, and quartz. These results quantify the adsorption capacity of materials present in field-scale systems, enabling the modeling of low-permeability rocks as significant sorption reservoirs vital to bulk transport predictions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background : Electronic platform surveys are ideal for self-administration in adolescent populations, as nearly all adolescents in the US report using or having access to smartphones. This technology-savvy population seems prepared to graduate away from paper surveys. Despite predicted advantages of using smartphones for data collection, there is a surprising lack of data regarding the use of this mode for surveillance of substance use trends among adolescent populations. Objectives : The objective of this study was to evaluate completion rates, times, and responses of high school students taking the Secondary Student Life Survey: Nevada (SSLS:NV) on their own personal smartphones compared to provided computers or tablets. Methods: The SSLS:NV is a web-based survey designed to assess adolescent beliefs, attitudes, and use-trends surrounding substance use. The SSLS:NV was self-administered via self-selected device (personal vs. provided) within one class period to approximately one thousand 9th-12th grade students in December 2016. Data was collected and analyzed to compare outcomes by computer, tablet, or smartphone. Statistical analysis was performed in SPSS 23.0 using χ 2 or Fisher's exact test for categorical data and one-way ANOVA for continuous data. Results : SSLS:NV completion times averaged 21 min overall ( p  = .193). Differences were seen with completion rates of 86% smartphone 94% tablet, and 95% computer ( p  < .001), while responses to lifetime substance use were similar across all groups. Conclusions/Importance : The current study provides proof of concept that personal smartphones are effective in achieving more comprehensive adolescent substance use surveillance within a relatively short amount of time, while retaining robust response rates.

Background: Comorbidity rates and service needs are high among people living with HIV/AIDS (PLWHA). The effects of service utilization and unmet service needs on antiretroviral therapy (ART) adherence are not well understood. The purpose of this study was to investigate associations among PLWHA's service utilization, unmet service needs, and ART adherence., Methods: PLWHA (N=162) 18 years or older were recruited from a Nevada statewide needs assessment project in 2016. Participants completed a self-administered questionnaire on paper or online. The independent variables were service utilization and unmet service needs. The outcome variable was ART adherence. Multivariable logistic regression analyses were conducted to examine associations between the amount of utilized services and unmet service needs with ART adherence., Results: Only 12 (7.5%) participants reported they received all the needed services. The ART nonadherence group showed significantly higher unmet medical service needs compared to the ART adherence group (p=0.007). Unmet medical service needs (Adjusted Odds Ratio (AOR) 0.69, CI 0.53-0.90) and unmet support service needs (AOR 0.68, CI 0.48-0.97) were negatively associated with ART adherence. However, utilizing medical services (AOR 1.06, CI 0.87-1.30) and support services (AOR 0.88, CI 0.74-1.04) in the current year were not significantly associated with ART adherence., Conclusion: The results of this study indicate that health promotion programming should focus not only on introducing new services at the community level, but also work to optimize the availability and awareness of current services. Furthermore, health promotion programs should focus on filling service coverage gaps and improving the facilitation of services., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The purpose of this paper is to describe the development, actions, and evaluation of a university-based, transdisciplinary coalition so that the model may be replicated in other university or multidisciplinary systems. The University of Nevada Las Vegas (UNLV) Mental and Behavioral Health Coalition addresses Nevada's workforce shortages through multi-disciplinary faculty collaboration among seven training programs at UNLV that produce mental health professionals. The coalition's collaborative approach to solution-generating work has served as a catalyst for professional integration in the community as a whole.

Objectives: In January 2014, Nevada became 1 of the 32 states that have expanded Medicaid under the Affordable Care Act. As a result of the expansion, 276,400 additional Nevada residents received Medicaid insurance. The objectives of this paper were to examine the impact of Nevada's Medicaid expansion on changes in rates of hospital admissions for ambulatory care-sensitive conditions (ACSCs), which are potentially preventable with good access to outpatient medical care, and to examine the racial/ethnic disparities in such rates., Study Design: We used complete inpatient discharge data (for the years 2012, 2013, and 2014, and the first 3 quarters of 2015) from all nonfederal acute care community hospitals in Nevada., Methods: We employed pooled cross-sectional design with a difference-in-differences approach to identify overall and race/ethnicity-specific changes in admissions for ACSCs, adjusted for secular trends unrelated to expansion. We examined admissions for ACSCs among adults aged 18 to 64 years (those most likely to have been affected by the reform) admitted for overall, acute, and chronic ACSC composites in the 24 months before and 21 months after the date on which expansion was implemented., Results: After adjusting for confounders, we found that Hispanic patients with Medicaid were more likely to be admitted for ACSCs after Nevada's Medicaid expansion (overall quality composite: odds ratio [OR], 1.20; P = .05; chronic quality composite: OR, 1.34; P = .02)., Conclusions: This analysis provides evidence that Medicaid expansion may have limited potential to reduce the disparities in rates of hospital admissions for ACSCs. In Nevada, additional efforts might be needed to improve access to outpatient care and reduce preventable admissions.

Background: In the United States, about 38,000 cases of nonfatal workplace injuries were reported in 2015, in the category of 'mechanical work' (plumbing, heating, and air conditioning); this is nearly identical to the number of cases reported under 'building construction'., Objective: This paper analyzes the types and rates of injuries and illnesses of mechanical contractors of southern Nevada, including the nature of the injuries and illnesses, body parts affected by injuries, causes of injuries, and factors affecting the injury rates., Methods: To obtain data, a survey consisting of questions regarding the number of injuries and types of injuries was conducted with 31 mechanical contractors of southern Nevada involved in plumbing, piping, heating, refrigeration, and air conditioning., Results: The injury rate for larger mechanical contractors (n = 16), in terms of number of employees and annual revenue, was significantly lower than for smaller mechanical contractors (n = 15). Mechanical contractors who worked on residential buildings (n = 13) had significantly higher rates of injuries than those involved with industrial (n = 7) or commercial buildings (n = 10). Results showed that sprains and strains (31%) were dominant injuries, and the major causes were from parts and materials (39%), hand tools (16%), contact with objects (14%), and falls (7%)., Conclusions: The study concluded that the injury rate for these mechanical contractors was found to be higher than that reported by the Occupational Safety and Health Administration for specialty trade contractors.

In order to obtain the cellulolytic bacterial consortia, sediments from Great Basin hot springs (Nevada, USA) were sampled and enriched with cellulosic biomass as the sole carbon source. The bacterial composition of the resulting anaerobic ethanol-producing celluloytic bacterial consortium, named SV79, was analyzed. With methods of the full-length 16S rRNA librarybased analysis and denaturing gradient gel electrophoresis, 21 bacteria belonging to eight genera were detected from this consortium. Clones with closest relation to the genera Acetivibrio, Clostridium, Cellulosilyticum, Ruminococcus, and Sporomusa were predominant. The cellulase activities and ethanol productions of consortium SV79 using different agricultural residues (sugarcane bagasse and spent mushroom substrate) and energy crops (Spartina anglica, Miscanthus floridulus, and Pennisetum sinese Roxb) were studied. During cultivation, consortium SV79 produced the maximum filter paper activity (FPase, 9.41 U/ml), carboxymethylcellulase activity (CMCase, 6.35 U/ml), and xylanase activity (4.28 U/ml) with sugarcane bagasse, spent mushroom substrate, and S. anglica, respectively. The ethanol production using M. floridulus as substrate was up to 2.63 mM ethanol/g using gas chromatography analysis. It has high potential to be a new candidate for producing ethanol with cellulosic biomass under anoxic conditions in natural environments.

This paper provides a safety evaluation of a special protected/permitted left turn signal control (Las Vegas LT Display) that has been implemented in the urbanized area of Las Vegas, Nevada. The Las Vegas LT Display eliminates the yellow trap condition for leading approach in lead/lag operation. It provides protected only left turns during certain times of day by suppressing the permitted green ball and yellow ball displays. Before and after studies were conducted using the crash data from 10 intersections. Results from the analyses indicated that no obvious safety concerns due to use of the special display., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Several closely related, thermophilic and cellulolytic bacterial strains, designated JKG1(T), JKG2, JKG3, JKG4 and JKG5, were isolated from a cellulolytic enrichment (corn stover) incubated in the water column of Great Boiling Spring, NV. Strain JKG1(T) had cells of diameter 0.7-0.9 µm and length ~2.0 µm that formed non-branched, multicellular filaments reaching >300 µm. Spores were not formed and dense liquid cultures were red. The temperature range for growth was 45-65 °C, with an optimum of 55 °C. The pH range for growth was pH 5.6-9.0, with an optimum of pH 7.5. JKG1(T) grew as an aerobic heterotroph, utilizing glucose, sucrose, xylose, arabinose, cellobiose, CM-cellulose, filter paper, microcrystalline cellulose, xylan, starch, Casamino acids, tryptone, peptone, yeast extract, acetate, citrate, lactate, pyruvate and glycerol as sole carbon sources, and was not observed to photosynthesize. The cells stained Gram-negative. Phylogenetic analysis using 16S rRNA gene sequences placed the new isolates in the class Chloroflexia, but distant from other cultivated members, with the highest sequence identity of 82.5 % to Roseiflexus castenholzii. The major quinone was menaquinone-9; no ubiquinones were detected. The major cellular fatty acids (>5 %) were C18 : 0, anteiso-C17 : 0, iso-C18 : 0, iso-C17 : 0, C16 : 0, iso-C16 : 0 and C17 : 0. The peptidoglycan amino acids were alanine, ornithine, glutamic acid, serine and asparagine. Whole-cell sugars included mannose, rhamnose, glucose, galactose, ribose, arabinose and xylose. Morphological, phylogenetic and chemotaxonomic results suggest that JKG1(T) is representative of a new lineage within the class Chloroflexia, which we propose to designate Kallotenue papyrolyticum gen. nov., sp. nov., Kallotenuaceae fam. nov., Kallotenuales ord. nov. The type strain of Kallotenue papyrolyticum gen. nov., sp. nov. is JKG1(T) ( = DSM 26889(T) = JCM 19132(T)).

Introduction: Burning Man is a large weeklong outdoor arts festival held annually in the rugged and austere Black Rock Desert in northern Nevada. The 2011 event presented several unusual challenges in terms of emergency medical services (EMS) and medical care provision., Objective: This paper details the planning and subsequent emergency medical care for Burning Man 2011., Methods: This was a retrospective, observational review of the preparation, management, and medical care at Burning Man 2011., Results: Attendance at Burning Man 2011 was 53,735. Of these attendees, 2,307 were treated in the field hospital. While most patients had minor injuries, 33 were subsequently transported to a hospital (28 by ambulance and five by helicopter). The most common conditions treated were soft-tissue injuries, dehydration, eye problems, and urinary tract infections. There was one death (subarachnoid hemorrhage) and one patient in cardiac arrest (thoracic aortic dissection) who was successfully resuscitated and transferred. Burning Man 2011 presented numerous challenges in provision of EMS and medical care because of attendance size, the austere environment, and significant distance (150 miles) to definitive medical care. EMS operations included six dedicated ambulances, three quick-response vehicles, two first-aid stations, and a physician-staffed field hospital. The hospital had limited diagnostic capabilities (e.g., x-ray, ultrasound, basic laboratory analysis) and a limited formulary. We found that the use of physicians was necessary because much of the care provided was beyond the scope of paramedics., Conclusions: We describe the preparation and medical care for a large outdoor mass-gathering event held in a remote and austere environment. We met the stated goals of providing needed medical care while minimizing the need to transport attendees offsite for additional care. Our experience with Burning Man 2011 may aid planners with similar events.

Between 1997 and 2002, 16 cases of acute childhood leukemia were diagnosed in children who either lived in Churchill County, Nevada at the time of diagnosis or had lived in the county before their diagnosis. The cases were characterized as a cluster of like illnesses and the probability of having such a cluster occur by chance was estimated to be very small (approximately one in 2.33×10(8)). This suggested that the cluster could be linked to one or more physical, limnological, chemical, or biological agents. This review discusses the setting in which the cluster took place, the epidemiological investigations carried out by the Nevada Bureau of Health Protection Services, the National Center for Environmental Health Centers for Disease Control and Prevention and the Agency for Toxic Substances and Disease Registry, and subsequent investigations supported by a special allocation of federal funds through the US Environmental Protection Agency's Region IX office in San Francisco, CA. This review is meant as background for the papers in this special issue that report results from multi- and interdisciplinary research into environmental and biological factors potentially related to the Churchill County leukemia cluster., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

While the mechanism of biological phosphorus removal (BPR) and the need for volatile fatty acids (VFA) have been well researched and documented to the point where it is now possible to design a plant with a very reliable phosphorus removal process using formal flow sheets, BPR is still observed in a number of plants that have no designated anaerobic zone, which was considered essential for phosphorus removal. Some examples are given in this paper. A theory is proposed and then applied to solve problems with a shortage of VFA in the influent of the Henderson NV plant. Mixed liquor was fermented in the anaerobic zone, which resulted in phosphorus removal to very low levels. This paper will discuss some of the background, and some case histories and applications, and present a simple postulation as to the mechanism and efforts at modelling the results.

This paper describes the development and evolution of the Electric Power Research Institute's (EPRI) post-closure dose assessment for potential releases of radionuclides from the proposed High Level Waste repository at Yucca Mountain. The starting point for this work was the 1995 publication of Technical Bases for Yucca Mountain Standards by the Commission on Geosciences, Environment and Resources of the National Research Council. This report proposed the development and application of an individual risk-based standard for releases from the repository to replace the existing one, which was based on radionuclide release limits. This in turn implied the development and application of methods to assess radiation doses to humans. Accordingly, EPRI produced a methodology for such dose assessment as part of its Total System Performance Assessment program for the proposed Yucca Mountain repository site. The methodology initially addressed releases via groundwater and then releases associated with extrusive igneous events. The methodology was updated and applied over the following years to take account of regulatory developments, changes in estimates of the source term to the biosphere, peer review through international model comparison exercises, new site generic data, and new data concerning conditions at the point of compliance in Amargosa Valley. The main outputs were Biosphere Dose Conversion Factors, which relate radionuclide levels in environmental media to the annual individual doses to a member of a hypothetical critical group and to the regulator-defined Reasonably Maximally Exposed Individual. Most recently, consideration has been given to uncertainty in the dose estimates based on a probabilistic analysis. The paper provides a perspective on the evolution of the dose assessments in response to the developments listed above.

In this research, the impact of several water conservation policies and return flow credits on the fate of water used outdoors in an arid region is evaluated using system dynamics modeling approach. Return flow credits is a strategy where flow credits are obtained for treated wastewater returned to a water body, allowing for the withdrawal of additional water equal to the amount returned as treated wastewater. In the return credit strategy, treated wastewater becomes a resource. This strategy creates a conundrum in which conservation may lead to an apparent decrease in water supply because less wastewater is generated and returned to water body. The water system of the arid Las Vegas Valley in Nevada, USA is used as basis for the dynamic model. The model explores various conservation scenarios to attain the daily per capita demand target of 752 l by 2035: (i) status quo situation where conservation is not implemented, (ii) conserving water only on the outdoor side, (iii) conserving water 67% outdoor and 33% indoor, (iv) conserving equal water both in the indoor and outdoor use (v) conserving water only on the indoor side. The model is validated on data from 1993 to 2008 and future simulations are carried out up to 2035. The results show that a substantial portion of the water used outdoor either evapo-transpires (ET) or infiltrates to shallow groundwater (SGW). Sensitivity analysis indicated that seepage to groundwater is more susceptible to ET compared to any other variable. The all outdoor conservation scenario resulted in the highest return flow credits and the least ET and SGW. A major contribution of this paper is in addressing the water management issues that arise when wastewater is considered as a resource and developing appropriate conservation policies in this backdrop. The results obtained can be a guide in developing outdoor water conservation policies in arid regions., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Mercury (Hg) may be naturally associated with the rock units hosting precious and base metal deposits. Active gold mines are known to have point source releases of Hg associated with ore processing facilities. The nonpoint source release of Hg to the air from the large area (hundreds to thousands of hectares) of disturbed and processed material at industrial open pit gold mines has not been quantified. This paper describes the field data collected as part of a project focused on estimating nonpoint source emissions of Hg from two active mines in Nevada, USA. In situ Hg flux data were collected on diel and seasonal time steps using a dynamic flux chamber from representative mine surfaces. Hg fluxes ranged from <1500 ng m(-2) day(-1) for waste rock piles (0.6-3.5 μg g(-1)) to 684,000 ng m(-2) day(-1) for tailings (2.8-58 μg g(-1)). Releases were positively correlated with material Hg concentrations, surface grain size, and moisture content. Highest Hg releases occurred from materials under active cyanide leaching and from tailings impoundments containing processed high-grade ore. Data collected indicate that as mine sites are reclaimed and material disturbance ceases, emissions will decline. Additionally local cycling of atmospheric Hg (deposition and re-emission) was found to occur., (Copyright © 2010 Elsevier B.V. All rights reserved.)

This paper presents a study of solute transport through ground water in the saturated zone and the resulting breakthrough curves (BTCs), using a field-scale numerical model that incorporates the processes of advection, dispersion, matrix diffusion in fractured volcanic formations, sorption, and colloid-facilitated transport. Such BTCs at compliance boundaries are often used as performance measures for a site. The example considered here is that of the saturated zone study prepared for the Yucca Mountain license application. The saturated zone at this site occurs partly in volcanic, fractured rock formations and partly in alluvial formations. This paper presents a description of the site and the ground water flow model, the development of the conceptual model of transport, model uncertainties, model validation, and the influence of uncertainty in input parameters on the downstream BTCs at the Yucca Mountain site., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)

Context: The challenge of providing meaningful health care services to veterans living in rural communities is a major public health concern that involves redefining the traditional facility-based model of care delivery employed in urban areas., Purpose: This paper describes the steps of a demonstration project, the Elko Telehealth Outreach Clinic. The clinic, located in Elko, Nevada, was created to meet the health care needs of veterans who expressed a desire for greater access to VA services., Methods: The Elko Telehealth Outreach Clinic is a specific example of the real-life implementation of the community-as-partner model as an operational framework for coordinating local, regional, and VA resources. The Elko Clinic provides a limited set of health care services including medication management, health education, prescription refills, routine lab tests, and specialty services through telehealth., Findings: From December 2006 to December 2007, a total of 84 unique veterans received health care services through the Elko Clinic., Conclusions: Our findings support the usefulness of an expanded community-as-partner model to guide a process for addressing the health care needs of veterans in Elko, Nevada, and they have implications for the development and maintenance of outreach clinics in other rural settings., (© 2010 National Rural Health Association.)

The NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory Model (HYSPLIT) was evaluated as a research tool to simulate the dispersion and deposition of radioactive fallout from nuclear tests. Model-based estimates of fallout can be valuable for use in the reconstruction of past exposures from nuclear testing, particularly where little historical fallout monitoring data are available. The ability to make reliable predictions about fallout deposition could also have significant importance for nuclear events in the future. We evaluated the accuracy of the HYSPLIT-predicted geographic patterns of deposition by comparing those predictions against known deposition patterns following specific nuclear tests with an emphasis on nuclear weapons tests conducted in the Marshall Islands. We evaluated the ability of the computer code to quantitatively predict the proportion of fallout particles of specific sizes deposited at specific locations as well as their time of transport. In our simulations of fallout from past nuclear tests, historical meteorological data were used from a reanalysis conducted jointly by the National Centers for Environmental Prediction (NCEP) and the National Center for Atmospheric Research (NCAR). We used a systematic approach in testing the HYSPLIT model by simulating the release of a range of particle sizes from a range of altitudes and evaluating the number and location of particles deposited. Our findings suggest that the quantity and quality of meteorological data are the most important factors for accurate fallout predictions and that, when satisfactory meteorological input data are used, HYSPLIT can produce relatively accurate deposition patterns and fallout arrival times. Furthermore, when no other measurement data are available, HYSPLIT can be used to indicate whether or not fallout might have occurred at a given location and provide, at minimum, crude quantitative estimates of the magnitude of the deposited activity. A variety of simulations of the deposition of fallout from atmospheric nuclear tests conducted in the Marshall Islands (mid-Pacific), at the Nevada Test Site (U.S.), and at the Semipalatinsk Nuclear Test Site (Kazakhstan) were performed. The results of the Marshall Islands simulations were used in a limited fashion to support the dose reconstruction described in companion papers within this volume.

Currently there is no standard method for measurement of atmospheric mercury dry deposition. While all operationally defined forms of atmospheric mercury (elemental, oxidized, and particulate) can be dry deposited, oxidized forms are of concern due to high deposition velocities, water solubility, and reactivity. This paper describes the development of a surrogate surface for characterizing potential dry deposition of gaseous oxidized mercury (GOM). Laboratory tests showed that the surface collected HgCl2, HgBr2, and HgO with equal efficiency, and deposition was not significantly influenced by temperature, humidity, or ozone concentrations. Deposition of mercury to surfaces in field deployments was correlated with GOM concentrations (r2 = 0.84, p < 0.01, n = 326. Weekly mean GOM deposition velocities from surface deployments (1.1 +/- 0.6 cm s(-1)) were higher than modeled values (0.4 +/- 0.2 cm s(-1)) at four field sites, but were within the range reported for direct measurements. Although the surfaces do not simulate the heterogeneity of natural surfaces and need to be validated by direct measurements, they do provide a physical means for estimating temporal trends and spatial variability of dry deposition of GOM.

Governments and industries have introduced regulatory measures requiring safety controls to limit asbestos exposure of the general public and asbestos workers. Although erionite is a more potent health hazard mineral than asbestos, it has received far less attention. Precise definition of erionite, types of these fibrous minerals, and most importantly, characterization requirements still raise questions and often lead to arguments and even legal disputes. Many bulk erionite samples used in animal and cell experiments for carcinogenicity are not mineralogically pure. To test this hypothesis, we characterized two erionite standards from Rome, Oregon, and Pine Valley, Nevada, USA. These standards were characterized quantitatively using modern analytical techniques, and one of them, the erionite standard from Rome, Oregon, passed the required tests for positive identification, but the other, the erionite standard from Pine Valley, Nevada, did not. Furthermore, we observed ambiguous definitions, incorrect identifications, and inaccurate reporting of clinical investigations. To address this problem, we established characterization guidelines for positive identification of erionite using a modified balance error formula, and we re-evaluated and re-classified published erionite data from the literature as erionite-Ca, erionite-Na, and erionite-K. If data did not pass either the E% or Mg-content test, then we propose that reference to them in the literature be disregarded. Erionite requires special attention from the mineralogical community to help establish its true carcinogenetic properties. We believe that the characterization guidelines established in this paper will contribute to setting up rules and regulations for evaluation of erionite by regulatory agencies.

Desert springs, often the sole sources of water for wildlife and cattle, support wetland and wetland/upland transition ecosystems including rare and endemic species. In the basin and range province in Nevada, USA, springs in the Great Basin and Mojave deserts are sustained by interconnected deep carbonate and shallow basin-fill aquifers which are threatened by proposed groundwater withdrawal to sustain rapidly expanding urban areas, a common problem in arid regions worldwide. This paper draws on historic groundwater data, groundwater modeling, and studies of environmental controls of spring ecosystems to speculate on the potential effects of groundwater withdrawal and water table decline on spring-supported vegetation. The focus is on springs in the Great Basin and Mojave deserts representative of those that may be affected by future, planned groundwater withdrawal. Groundwater withdrawal is expected to reduce spring discharge directly through reduced flows from the shallow basin-fill aquifer or through reduction of the hydraulic head of the deep carbonate aquifer. This flow reduction will truncate the outflow stream, reducing the areal cover of wetland and wetland/upland transition vegetation. Lowering the local water table may also reduce the amount of upland phreatophytic vegetation by causing water levels to drop below plant rooting depths. Percolation of salts to surface soils may be reduced, eventually altering desert shrub cover from halophytes to nonhalophytes. The extent of these effects will vary among springs, based on their distance from extraction sites and location relative to regional groundwater flow paths. On-site monitoring of biotic variables (including cover of selected hygrophytes and phreatophytes) should be a necessary complement to the planned monitoring of local hydrologic conditions.

Background: Reference ranges for electrocardiogram (ECG) intervals, heart rate, and QRS axis in general use by medical personnel and ECG readers are unrepresentative of true age- and sex-related values in large populations and are not based on modern electrocardiographic and ECG reading technology., Methods and Results: The results of ECG interpretation by cardiologists using digital technology for viewing and interpreting ECGs were compiled from single, baseline ECGs of 79,743 individuals included in pharmaceutical company-sponsored clinical trials. Women comprised 48% of the total population. Ages ranged from 3 months to 99 years, and the bulk of the population (56%) was aged 40 to 70 years. Striking differences in numerical ECG values based on age and sex were observed. A subgroup of 46,129 individuals with a very low probability of cardiovascular disease was identified. The following were the reference ranges for this subgroup, determined using the 2nd and 98th percentiles: heart rate, 48 to 98 beats/min; PR interval, 113 to 212 milliseconds; QRS interval, 69 to 109 milliseconds; frontal plane QRS axis, -40 degrees to 91 degrees ; QT interval, 325 to 452 milliseconds; QTc-Bazett, 361 to 457 milliseconds; and QTc-Fridericia, 359 to 445 milliseconds. There were marked age- and sex-related variations in the reference ranges of this subgroup, and they differ substantially from previously reported norms. Small differences were observed in ECG values obtained using our digital methods as compared with readings done using paper tracings and values computed by 2 commercial computer algorithms., Conclusions: We observed large differences in electrocardiographic heart rate, interval, and axis reference ranges in this study compared with those reported previously and with reference ranges in general use. We also observed a large influence of age and sex upon normal values. Very large cohorts are required to fully assess age- and sex-related variation of reference ranges. Electrocardiographic reference ranges should be modernized.

This paper describes the use of lichen chemistry to assess airborne tungsten and cobalt in Fallon, Nevada, where a cluster of childhood leukemia has been on going since 1997. Lichens and their rock substrates were collected from Rattlesnake Hill within Fallon as well as from four different rock outcrops located north, east, south, and west of Fallon and at least 20 km away from the town center. In the lichens themselves, W and Co are significantly higher within Fallon than in the combined control site outside of Fallon. In the rock substrates of the lichens, no differences exist in W and Co. The W and Co differences in lichens cannot be attributed to substrate geochemistry. Fallon is distinctive in west central Nevada for high airborne W and Co, and given its cluster of childhood leukemia, it stands to reason that additional biomedical research is in order to test directly the leukogenicity of combined airborne W and Co.

Evaluation descriptions in the research literature tend to ignore the full context of the community change efforts from which they emerged. In this paper, we describe a range of evaluation studies and data collection activities conducted over the course of one state's effort to reform its child welfare system on behalf of families with children experiencing serious mental health problems. Initial activities included studies of the prevalence of unmet mental health need in children and youth in the state. As these needs were addressed, evaluation activities examined the impact of a pilot wraparound program that became a major part of systems reform. Later efforts included implementation analysis of wraparound programs and assessment of priorities for continued systems reform. As we describe this set of evaluation activities, we discuss how data collection evolved to meet the needs of stakeholders over time and consider lessons learned about the roles of research and information sharing in shaping community change efforts.

In the latter half of 2005, the U.S. Environmental Protection Agency (U.S. EPA) published a Proposed Rule (40 CFR Part 197) for establishing a dose rate standard for limiting radionuclide releases from the proposed Yucca Mountain high-level radioactive waste repository during the time period from 10 to 10 years after closure. The proposed standard was based on the difference in the estimated dose rate from natural background in the Amargosa Valley and the "average annual background radiation" for the State of Colorado. As defined by the U.S. EPA, "natural background radiation consists of external exposures from cosmic and terrestrial sources, and internal exposures from indoor exposures to naturally-occurring radon." On the basis of its assessments, the U.S. EPA estimated that the difference in the dose rate in the two identified areas was 3.5 mSv y. The purpose of this paper is to provide an independent evaluation and review of this estimate. One of the first observations was that, because site-specific dose rate measurements for the Amargosa Valley "were not available," the dose rates for various sources of natural background in that area, used by the U.S. EPA in its assessment, were based on modifications of the average values for the State of Nevada. A second observation was that the conversion coefficient applied in estimating the dose rates due to exposures to indoor radon and its decay products was a factor of >2 higher than the currently internationally accepted value. Further review revealed that site-specific data for many natural background sources in the Amargosa Valley were available. One particularly important observation was that about 91% of the residents of that area live in mobile homes which, due to their construction and design, have indoor radon concentrations comparable to, or less than, those outdoors. For that reason, alone, the U.S. EPA estimate of the average dose rate for residents of the Amargosa Valley, due to exposures to indoor radon, was not valid. For purposes of the comparisons in this paper, site-specific dose rates were estimated for all major natural background sources of exposure to residents of the Amargosa Valley, and those in Leadville, CO. The latter community was selected for comparison because of its altitude (3,200 m) and accompanying relatively high cosmic radiation dose rate, and the fact the size of its population is comparable to that of the Amargosa Valley. Another reason for this selection was that a comparison of the average natural background dose rate in the Amargosa Valley to that for the State of Colorado is not suitable because it fails to consider those locations within the State that have dose rates that are higher than the average. Nonetheless, for completeness, and to provide a number that could be compared to the U.S. EPA estimated difference, similar comparisons of the estimated dose rate in the Amargosa Valley to those for average residents of the States of Colorado and Nevada were included in the assessments that follow. The outcome showed that the estimated dose rates in Leadville, the State of Colorado, and the State of Nevada, were higher than those in the Amargosa Valley by 3.94 +/- 1.09, 2.54 +/- 2.18, and 0.95 +/- 0.82 mSv y, respectively. Associated uncertainties were highest for the estimated dose rates due to exposures to radon and its decay products. Had the systematic errors in the radon dose conversion coefficient and the random distribution in radon concentrations been included, the overall uncertainty in the total dose rate estimates could have been as high as 150%.

Methods to assess radiation doses from nuclear weapons test fallout have been used to estimate doses to populations and individuals in a number of studies. However, only a few epidemiology studies have relied on fallout dose estimates. Though the methods for assessing doses from local and regional compared to global fallout are similar, there are significant differences in predicted doses and contributing radionuclides depending on the source of the fallout, e.g. whether the nuclear debris originated in Nevada at the U.S. nuclear test site or whether it originated at other locations worldwide. The sparse historical measurement data available are generally sufficient to estimate external exposure doses reasonably well. However, reconstruction of doses to body organs from ingestion and inhalation of radionuclides is significantly more complex and is almost always more uncertain than are external dose estimates. Internal dose estimates are generally based on estimates of the ground deposition per unit area of specific radionuclides and subsequent transport of radionuclides through the food chain. A number of technical challenges to correctly modeling deposition of fallout under wet and dry atmospheric conditions still remain, particularly at close-in locations where sizes of deposited particles vary significantly over modest changes in distance. This paper summarizes the various methods of dose estimation from weapons test fallout and the most important dose assessment and epidemiology studies that have relied on those methods.