Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.769
Filtrar
1.
Nat Commun ; 11(1): 205, 2020 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-31924764

RESUMO

The fossil record of the terminal Ediacaran Period is typified by the iconic index fossil Cloudina and its relatives. These tube-dwellers are presumed to be primitive metazoans, but resolving their phylogenetic identity has remained a point of contention. The root of the problem is a lack of diagnostic features; that is, phylogenetic interpretations have largely centered on the only available source of information-their external tubes. Here, using tomographic analyses of fossils from the Wood Canyon Formation (Nevada, USA), we report evidence of recognizable soft tissues within their external tubes. Although alternative interpretations are plausible, these internal cylindrical structures may be most appropriately interpreted as digestive tracts, which would be, to date, the earliest-known occurrence of such features in the fossil record. If this interpretation is correct, their nature as one-way through-guts not only provides evidence for establishing these fossils as definitive bilaterians but also has implications for the long-debated phylogenetic position of the broader cloudinomorphs.


Assuntos
Abdome/anatomia & histologia , Anelídeos/anatomia & histologia , Cnidários/anatomia & histologia , Fósseis , Animais , Anelídeos/classificação , Evolução Biológica , Cnidários/classificação , Sedimentos Geológicos , Nevada , Filogenia
2.
Sci Total Environ ; 705: 135813, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31826805

RESUMO

The study of bio-effects of Schumann resonances is a very complex issue. There is a need to identify mechanisms and pathways that explain how Extremely Low Frequency magnetic fields affect biology or human health. This particular study tries to identify statistical associations between ELF magnetic fields in the province of Granada (Spain) and cardiovascular related hospital admission in the same province for the period April, 1st 2013 to March, 31st 2014. Research is developed under an epidemiological approach based on an Event Coincidence Analysis statistical method. Clustered events, statistically significant (ECA shuffle-surrogate test p = .01 and p < .01), were found for the minimum values of the first and the third Schuman resonances frequency on east-west and north-south directions, and for the amplitude parameter of the second resonance and the total signal energy in the north-south direction. Empirical measurements of SR parameters were recorded at the Sierra Nevada Mountain in Granada province (Spain). Results show a clear coincidence of the events for the minima amplitudes of Shuman resonances and energy in the north-south orientation and the number of the cardiovascular related hospital admissions. Further research is needed with longer temporal series and a new approach based on gender seems to be also interesting for future studies.


Assuntos
Sistema Cardiovascular , Vibração , Humanos , Nevada , Espanha
3.
Zootaxa ; 4671(4): zootaxa.4671.4.11, 2019 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-31716039

RESUMO

A new species of Strengeriana Pretzmann, 1971, is described from the El Jardín Natural Reserve, Quindío Department, Colombia, on the western slope of the Central Andes. The genus is endemic to Colombia and is distributed in the Sierra Nevada de Santa Marta, and the Western and Central Andes, at elevations ranging from 700 to 2400 m. With the addition of the new species, Strengeriana now includes 17 species. Strengeriana quindiensis n. sp. is distinguished from its congeners mainly by the exopod of the third maxilliped being 0.92 times the length of the ischium and by the morphology of the first male gonopod, particularly the shapes of the mesial and lateral processes.


Assuntos
Braquiúros , Decápodes , Animais , Colômbia , Água Doce , Masculino , Nevada
4.
Zootaxa ; 4668(4): zootaxa.4668.4.8, 2019 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-31716611

RESUMO

A new species of Pimelodella is described from northern coastal drainages of the Sierra Nevada de Santa Marta (SNSM), Colombia. The new species is diagnosed from all trans-Andean congeners by the following unique combination of characters: head length 22.2-23.7% SL, bony interorbital width 17.6-21.6% HL, maxillary barbels length 53.0-68.3% SL, inner mental-barbels length 14.4-20.0% SL, body width 17.6-21.1% SL, dorsal-fin spine length 8.3-13.7% SL, dorsal-fin base 12.3-14.9% SL, pectoral-fin spine length 12.9-14.5% SL, pectoral-fin spine length without dentations on the distal posterior margin 21.6-29.8% in pectoral-fin spine length, maximum depth of dentations in posterior margin of pectoral-fin spine 1.40-1.68 times in the width of the spine at its base, adipose-fin base length 22.8-26.4% SL, caudal-peduncle depth 9.2-10.5% SL, 40 vertebrae, having a conspicuous paired dark brown stripe on the dorsal surface of body, extending from posterior margin of head to caudal-fin insertion and a wide dark brown midlateral stripe present. The isolated occurrence of this new taxon living in allopatry in coastal drainages of the SNSM could have interesting biogeographic implications for dispersal and vicariance processes of the ichthyofauna from northern South America.


Assuntos
Peixes-Gato , Animais , Colômbia , Nevada , América do Norte , América do Sul
5.
Medicine (Baltimore) ; 98(47): e17739, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31764772

RESUMO

To examine trends and contributing factors of opioid, heroin, and cannabis-associated emergency department (ED) visits in Nevada.The 2009 to 2017 Nevada State ED database (n = 7,950,554 ED visits) were used. Use of opioid, heroin, and cannabis, respectively, was identified by the International Classification of Diseases, 9th & 10th Revisions. Three multivariable models, one for each of the 3 dependent variables, were conducted. Independent variables included year, insurance status, race/ethnicity, use of other substance, and mental health conditions.The number of individuals with opioid, heroin, cannabis-associated ED visits increased 3%, 10%, and 23% annually from 2009 to 2015, particularly among 21 to 29 age group, females, and African Americans. Use of other substance (odds ratio [OR] = 3.91; 95% confidence interval [CI] = 3.84, 3.99; reference - no use of other substance), mental health conditions (OR = 2.48; 95% CI = 2.43, 2.53; reference - without mental health conditions), Medicaid (OR = 1.41; 95% CI = 1.38, 1.44; reference - non-Medicaid), Medicare (OR = 1.44; 95% CI = 1.39, 1.49; reference - non-Medicare) and uninsured patients (OR = 1.52; 95% CI = 1.49, 1.56; reference - insured) were predictors of all three substance-associated ED visits.With a steady increase in trends of opioid, heroin, and cannabis-associated ED visits in recent years, the main contributing factors include patient sociodemographic factors, mental health conditions, and use of other substances.


Assuntos
Emergências/epidemiologia , Dependência de Heroína/epidemiologia , Abuso de Maconha/epidemiologia , Transtornos Relacionados ao Uso de Opioides/epidemiologia , Adolescente , Adulto , Idoso , Criança , Estudos Transversais , Serviço Hospitalar de Emergência , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Nevada/epidemiologia , Fatores de Risco , Adulto Jovem
6.
Oecologia ; 191(4): 931-944, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31628545

RESUMO

Freshwater springs are important ecosystems. In the arid regions of North America, groundwater extraction has caused the desiccation of springs and the extinction of taxa. To better describe the biodiversity of freshwater springs in the hope of establishing a sensitive approach for monitoring the predicted change in spring systems, we used high-resolution genetic methods to estimate the alpha and beta diversity of 19 springs and two reservoirs within the Ash Meadows National Wildlife Refuge in southwestern Nevada. We discovered a large number of distinct taxa based on eukaryote ribosomal gene sequences and show water temperature, spring size, and the presence or absence of non-native predators predicts alpha diversity, and temperature predicts beta diversity. Our study highlights how DNA data support inferences of environmental factors influencing community diversity and demonstrates the method may be an important tool for monitoring ecological communities.


Assuntos
Eucariotos , Biodiversidade , Ecossistema , Pradaria , Nevada , América do Norte
7.
Environ Sci Technol ; 53(21): 12238-12246, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31589027

RESUMO

The migration of low levels of plutonium has been observed at the Nevada National Security Site (NNSS) and attributed to colloids. To better understand the mechanism(s) of colloid-facilitated transport at this site, we performed flow cell desorption experiments with mineral colloid suspensions produced by hydrothermal alteration of NNSS nuclear melt glass, residual material left behind from nuclear testing. Three different colloid suspensions were used: (1) colloidal material from hydrothermal alteration of nuclear melt glass at 140 °C; (2) at 200 °C; and (3) plutonium sorbed to SWy-1 montmorillonite at room temperature. The 140 °C sample contained only montmorillonite, while zeolite and other phases were present in the 200 °C sample. Overall, more plutonium was desorbed from the 140 °C colloids (ca. 9-16%) than from the 200 °C colloids (ca. 4-8%). Furthermore, at the end of the 4.5 day flow cell experiments, the desorption rates for the 140 °C colloids and the Pu-montmorillonite colloids were similar while the desorption rates from the 200 °C colloids were up to an order of magnitude lower. We posit that the formation of zeolites and clays hydrothermally altered at 200 °C may lead to a more stable association of plutonium with colloids, resulting in lower desorption rates. This may give rise to more extensive colloid-facilitated transport and help explain why trace levels of plutonium are found downgradient from their original source decades after a nuclear detonation. Interestingly, in the case of cesium (a co-contaminant of plutonium), no difference was observed between the 140 and 200 °C colloids. This reflects intrinsic differences between cesium and plutonium sorption/desorption behavior (charge, cation size) and suggests that the Cs sorption mechanism (cation exchange) is not similarly affected by colloid formation temperature.


Assuntos
Plutônio , Bentonita , Coloides , Nevada , Medidas de Segurança
8.
PLoS One ; 14(9): e0219981, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31536501

RESUMO

Amphibians, the most threatened group of vertebrates, are seen as indicators of the sixth mass extinction on earth. Thousands of species are threatened with extinction and many have been affected by an emerging infectious disease, chytridiomycosis, caused by the fungal pathogen, Batrachochytrium dendrobatidis (Bd). However, amphibians exhibit different responses to the pathogen, such as survival and population persistence with infection, or mortality of individuals and complete population collapse after pathogen invasion. Multiple factors can affect host pathogen dynamics, yet few studies have provided a temporal view that encompasses both the epizootic phase (i.e. pathogen invasion and host collapse), and the transition to a more stable co-existence (i.e. recovery of infected host populations). In the Sierra Nevada mountains of California, USA, conspecific populations of frogs currently exhibit dramatically different host/ Bd-pathogen dynamics. To provide a temporal context by which present day dynamics may be better understood, we use a Bd qPCR assay to test 1165 amphibian specimens collected between 1900 and 2005. Our historical analyses reveal a pattern of pathogen invasion and eventual spread across the Sierra Nevada over the last century. Although we found a small number of Bd-infections prior to 1970, these showed no sign of spread or increase in infection prevalence over multiple decades. After the late 1970s, when mass die offs were first noted, our data show Bd as much more prevalent and more spatially spread out, suggesting epizootic spread. However, across the ~400km2 area, we found no evidence of a wave-like pattern, but instead discovered multiple, nearly-simultaneous invasions within regions. We found that Bd invaded and spread in the central Sierra Nevada (Yosemite National Park area) about four decades before it invaded and spread in the southern Sierra Nevada (Sequoia and Kings Canyon National Parks area), and suggest that the temporal pattern of pathogen invasion may help explain divergent contemporary host pathogen dynamics.


Assuntos
Doenças dos Animais/epidemiologia , Doenças dos Animais/microbiologia , Quitridiomicetos , Interações Hospedeiro-Patógeno , Micoses/veterinária , Anfíbios/microbiologia , Animais , California/epidemiologia , Quitridiomicetos/fisiologia , Museus , Nevada
9.
J Environ Radioact ; 208-209: 106047, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31526956

RESUMO

As part of an underground gas migration study, two radioactive noble gases (37Ar and 127Xe) and two stable tracer gases (SF6 and PFDMCH) were injected into a historic nuclear explosion test chimney and allowed to migrate naturally. The purpose of this experiment was to provide a bounding case (natural transport) for the flow of radioactive noble gases following an underground nuclear explosion. To accomplish this, soil gas samples were collected from a series of boreholes and a range of depths from the shallow subsurface (3 m) to deeper levels (~160 m) over a period of eleven months. These samples have provided insights into the development and evolution of the subsurface plume and constrained the relative migration rates of the radioactive and stable gas species in the case when the driving pressure from the cavity is low. Analysis of the samples concluded that the stable tracer SF6 was consistently enriched in the subsurface samples relative to the radiotracer 127Xe, but the ratios of SF6 and 37Ar remained similar throughout the samples.


Assuntos
Gases Nobres/análise , Armas Nucleares , Monitoramento de Radiação , Radioatividade , Explosões , Nevada , Medidas de Segurança
10.
mSphere ; 4(4)2019 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-31462415

RESUMO

We report the first census of natural microbial communities of the Bonneville Salt Flats (BSF), a perennial salt pan at the Utah-Nevada border. Environmental DNA sequencing of archaeal and bacterial 16S rRNA genes was conducted on samples from multiple evaporite sediment layers collected from the upper 30 cm of the surface salt crust. Our results show that at the time of sampling (September 2016), BSF hosted a robust microbial community dominated by diverse halobacteria and Salinibacter species. Sequences identical to Geitlerinema sp. strain PCC 9228, an anoxygenic cyanobacterium that uses sulfide as the electron donor for photosynthesis, are also abundant in many samples. We identified taxonomic groups enriched in each layer of the salt crust sediment and revealed that the upper gypsum sediment layer found immediately under the uppermost surface halite contains a robust microbial community. In these sediments, we found an increased presence of Thermoplasmatales, Hadesarchaeota, Nanoarchaeaeota, Acetothermia, Desulfovermiculus, Halanaerobiales, Bacteroidetes, and Rhodovibrio This study provides insight into the diversity, spatial heterogeneity, and geologic context of a surprisingly complex microbial ecosystem within this macroscopically sterile landscape.IMPORTANCE Pleistocene Lake Bonneville, which covered a third of Utah, desiccated approximately 13,000 years ago, leaving behind the Bonneville Salt Flats (BSF) in the Utah West Desert. The potash salts that saturate BSF basin are extracted and sold as an additive for agricultural fertilizers. The salt crust is a well-known recreational and economic commodity, but the biological interactions with the salt crust have not been studied. This study is the first geospatial analysis of microbially diverse populations at this site using cultivation-independent environmental DNA sequencing methods. Identification of the microbes present within this unique, dynamic, and valued sedimentary evaporite environment is an important step toward understanding the potential consequences of perturbations to the microbial ecology on the surrounding landscape and ecosystem.


Assuntos
Archaea/classificação , Bactérias/classificação , Variação Genética , Microbiota , Filogenia , DNA Bacteriano/genética , Ecossistema , Lagos/química , Lagos/microbiologia , Nevada , RNA Ribossômico 16S/genética , Tolerância ao Sal , Utah
11.
PLoS One ; 14(8): e0221337, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31425558

RESUMO

Colorectal cancer (CRC) is the third greatest cancer burden in the United States. The remarkably diverse Mountain West state of Nevada has uncharacteristically high CRC mortality compared to other Western states. We aimed to study the determinants of the CRC excess burden by using data from the Nevada Central Cancer Registry from 2003-2013. Five-year cause-specific age-adjusted survival from colorectal cancer was calculated and stratified by sex, race/ethnicity and region of Nevada. Cox Proportional Hazards regression modelling was used to study the impact of demographic, social, and clinical factors on CRC survival in Nevada, assessing follow-up as accurately as possible. The extent to which differences in survival can be explained by receipt of stage-appropriate treatment was also assessed. 12,413 CRC cases from 2003-2013 in Nevada were analyzed. Five-year CRC survival was low: 56.0% (95% CI: 54.6-57.5) among males and 59.5% (95% CI: 58.0-61.1) among females; significantly lower than national 5-year survival of 65.1% and 66.5%, respectively. Low survival was driven by populous Southern Nevada; after adjustment for all covariates, Southern Nevadans were at 17% higher risk of death than their counterparts in Northwestern Nevada (HR:1.17; 95% CI:1.08-1.27). Many patients did not receive stage-appropriate treatment, although this only partly explained the poor survival, uniformly low for every race/ethnicity in Nevada. The observed disparity for this one state within a single nation merits public health attention; regardless of the state or region of residence, all Americans deserve equal opportunity for optimum health outcomes in the face of a cancer diagnosis. The current study provides baseline information critical to clinicians, public health professionals, and all relevant stakeholders as they attempt to discern why Nevada's outcomes are vastly divergent from its neighboring Western states and make plans for remediation.


Assuntos
Neoplasias Colorretais/mortalidade , Disparidades nos Níveis de Saúde , Disparidades em Assistência à Saúde , Adolescente , Adulto , Idoso , Neoplasias Colorretais/terapia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Nevada/epidemiologia , Sistema de Registros/estatística & dados numéricos , Fatores de Risco , Fatores Sexuais , Fatores Socioeconômicos , Taxa de Sobrevida , Adulto Jovem
12.
J Physician Assist Educ ; 30(3): 149-154, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31385911

RESUMO

PURPOSE: Community medicine curriculum prepares physician assistant (PA) students to provide services to vulnerable and underserved populations. This article describes a service-learning model that uses a mobile health clinic (MHC) experience as part of the community medicine rotation. It provides an overview of the clinic's operation, patient documentation and characteristics, and student learning experiences. METHODS: Students collected demographic information on patients who visited the MHC during January through December 2017. The students summarized patient demographics and reflected on their experiences in a report. RESULTS: Two main outcomes are discussed: characteristics of the MHC patients and student observations about their experiences. In 2017, 113 students rotated through the MHC and recorded 813 patient encounters. The largest proportions of patients reported living on the street or in a shelter (71%) and were older than 56 years (40%), males (74%), Caucasian (43%), single (65%), nonveterans (77%), and high school graduates (41%). The top 5 reasons for visits were preventive care, cognitive/functional impairment, cardiometabolic disorders, skin issues, and respiratory illness. The MHC experience and process of recording and analyzing demographic data contributed to students' data management and analytical skills. The students identified problems of recordkeeping and their implications for patient care, gained a greater understanding of medical needs and complexities of treating the homeless, and provided suggestions for improving quality and efficiency of care. CONCLUSIONS: The MHC service-learning model provides diverse, meaningful experiences for students. Our findings benefit PA programs aiming to expand and strengthen their community medicine curriculum.


Assuntos
Unidades Móveis de Saúde/organização & administração , Assistentes Médicos/educação , Estudantes de Ciências da Saúde , Adolescente , Adulto , Eficiência Organizacional , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Unidades Móveis de Saúde/estatística & dados numéricos , Modelos Educacionais , Nevada , Assistentes Médicos/organização & administração , Melhoria de Qualidade , Adulto Jovem
13.
Anaerobe ; 58: 1-5, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31255715

RESUMO

In June 2018, the Anaerobe Society of the America's (ASA) held their 14th Biennial Congress in Las Vegas, Nevada. The Congress was attended by over 200 individuals from many different countries. The focus of the meeting was the fast-growing area of anaerobes in human and animal infectious disease, computational tools to understand basic biology and therapeutic development, the role of anaerobes in the microbiome, and clinical trials of novel bacterial-based therapies. To strengthen the community of researchers working on anaerobes, the congress held two training workshops on clinical bacteriology and anaerobes in the microbiome, several networking events, as well as a dinner which honored the lifetime achievement award given to Ellen Jo Baron. The meeting was also attended by the grandfather of anaerobic bacteriology and the founder of (ASA), Sydney Finegold, at the age of 97. In all, there was a broad diversity of research presented that showed new ways that anaerobes play a important role in health and disease.


Assuntos
Bactérias Anaeróbias/fisiologia , Bactérias Anaeróbias/patogenicidade , Infecções Bacterianas/diagnóstico , Infecções Bacterianas/veterinária , Animais , Infecções Bacterianas/terapia , Pesquisa Biomédica/tendências , Gerenciamento Clínico , Interações Hospedeiro-Patógeno , Humanos , Nevada , Sociedades Científicas
14.
J Environ Radioact ; 208-209: 106014, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31323601

RESUMO

This work focuses on the usability of event zero time determination using xenon isotopic activity ratios. Two data sets from Nevada underground nuclear test and Fukushima accident debris were used to calculate the age of radioxenon release by considering three kinds of radioactivity release radionuclide sources: nuclear explosion scenarios, nuclear power reactor release and medical isotopes production facilities release. Typical nuclear power reactor releases were characterized and reference values are proposed for six isotopic activity ratios, which data can be considered as reference point of nuclear reactor effluents at the time of their release obtained from real observations. The same reference values of isotopic activity ratio are given for medical isotopes production facilities releases. The purpose of this study is to evaluate the use of zero-time calculation for source characterization under the assumption that a hypothesis about the event time is made. The event time information may come from a seismo-acoustic event of interest or an inverse atmospheric transport simulation or other context information. For both data sets used in this study, the age precisions are calculated and the time precision difference is evaluated and used as a parameter for the characterization of each radionuclide event. Almost all radioxenon isotopic activity ratios are found to correctly identifying the source type of the radionuclide events studied in this work. The results from this radionuclide events characterization study may be helpful for event screening activities of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO).


Assuntos
Poluentes Radioativos do Ar/análise , Monitoramento de Radiação , Radioisótopos de Xenônio/análise , Atmosfera/química , Nevada , Armas Nucleares , Valores de Referência
15.
J Safety Res ; 69: 75-83, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31235238

RESUMO

INTRODUCTION: This study presents the prediction of driver yielding compliance and pedestrian tendencies to press pushbuttons at signalized mid-block Danish offset crosswalks. METHOD: It applies Bayesian Networks (BNs) analysis, which is basically a graphical non-functional form model, on observational survey data collected from five signalized crosswalks in Las Vegas, Nevada. The BNs structures were learnt from the data by the application of several score functions. By considering prediction accuracy and the Area under the Receiver Operating Characteristic (ROC) curves, the BN learnt using the Bayesian Information Criterion (BIC) score resulted as the best network structure, compared to the ones learnt using K2 and the Akaike Information Criterion (AIC). The BIC score-based structure was then used for parameter learning and probabilistic inference. RESULTS: Results show that, when considering an individual scenario, the highest predicted yielding compliance (81%) is attained when pedestrians arrive at the crosswalk while the flashes are active, whereas the lowest predicted yielding compliance (23.4%) is observed when the pedestrians cross between the yield line and advanced pedestrian crosswalk sign. On the other hand, crossing within marked stripes, approaching the crosswalk from the near side of the pushbutton pole, inactive flashing lights, and being the first to arrive at the crosswalk result in relatively high-predicted probabilities of pedestrians pressing pushbutton. Furthermore, with a combination of scenarios, the maximum achievable predicted yielding probability is 87.5%, while that of pressing the button was 96.3%. Practical applications: Traffic engineers and planners may use these findings to improve the safety of crosswalk users.


Assuntos
Acidentes de Trânsito , Condução de Veículo , Comportamento , Pedestres , Equipamentos de Proteção , Segurança , Caminhada , Acidentes de Trânsito/prevenção & controle , Acidentes de Trânsito/estatística & dados numéricos , Área Sob a Curva , Teorema de Bayes , Dinamarca , Planejamento Ambiental , Humanos , Nevada , Pedestres/estatística & dados numéricos , Curva ROC , Registros
16.
Environ Sci Technol ; 53(13): 7363-7370, 2019 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-31192587

RESUMO

Approximately 2.8 t of plutonium (Pu) has been deposited in the Nevada National Security Site (NNSS) subsurface as a result of underground nuclear testing. Most of this Pu is sequestered in nuclear melt glass. However, Pu migration has been observed and attributed to colloid facilitated transport. To identify the mechanisms controlling Pu mobilization, long-term (∼3 year) laboratory nuclear melt glass alteration experiments were performed at 25 to 200 °C to mimic hydrothermal conditions in the vicinity of underground nuclear tests. The clay and zeolite colloids produced in these experiments are similar to those identified in NNSS groundwater. At 200 °C, maximum Pu and colloid concentrations of 30 Bq/L and 150 mg/L, respectively, were observed. However, much lower Pu and colloid concentrations were observed at 25 and 80 °C. These data suggest that Pu concentrations above the drinking water Maximum Contaminant Levels (0.56 Bq/L) may exist during early hydrothermal conditions in the vicinity of underground nuclear tests. However, formation of colloid-associated Pu will tend to decrease with time as nuclear test cavity temperatures decrease. Furthermore, median colloid concentrations in NNSS groundwater (1.8 mg/L) suggest that the high colloid and Pu concentrations observed in our 140 and 200 °C experiments are unlikely to persist in downgradient NNSS groundwater. While our experiments did not span all groundwater and nuclear melt glass conditions that may be present at the NNSS, our results are consistent with the documented low Pu concentrations in NNSS groundwater.


Assuntos
Plutônio , Poluentes Radioativos da Água , Coloides , Nevada , Medidas de Segurança
17.
PLoS One ; 14(6): e0218078, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31194788

RESUMO

In this study, we perform a full genome-wide association study (GWAS) to identify statistically significantly associated single nucleotide polymorphisms (SNPs) with three red blood cell (RBC) components and follow it with two independent PheWASs to examine associations between phenotypic data (case-control status of diagnoses or disease), significant SNPs, and RBC component levels. We first identified associations between the three RBC components: mean platelet volume (MPV), mean corpuscular volume (MCV), and platelet counts (PC), and the genotypes of approximately 500,000 SNPs on the Illumina Infimum DNA Human OmniExpress-24 BeadChip using a single cohort of 4,673 Northern Nevadans. Twenty-one SNPs in five major genomic regions were found to be statistically significantly associated with MPV, two regions with MCV, and one region with PC, with p<5x10-8. Twenty-nine SNPs and nine chromosomal regions were identified in 30 previous GWASs, with effect sizes of similar magnitude and direction as found in our cohort. The two strongest associations were SNP rs1354034 with MPV (p = 2.4x10-13) and rs855791 with MCV (p = 5.2x10-12). We then examined possible associations between these significant SNPs and incidence of 1,488 phenotype groups mapped from International Classification of Disease version 9 and 10 (ICD9 and ICD10) codes collected in the extensive electronic health record (EHR) database associated with Healthy Nevada Project consented participants. Further leveraging data collected in the EHR, we performed an additional PheWAS to identify associations between continuous red blood cell (RBC) component measures and incidence of specific diagnoses. The first PheWAS illuminated whether SNPs associated with RBC components in our cohort were linked with other hematologic phenotypic diagnoses or diagnoses of other nature. Although no SNPs from our GWAS were identified as strongly associated to other phenotypic components, a number of associations were identified with p-values ranging between 1x10-3 and 1x10-4 with traits such as respiratory failure, sleep disorders, hypoglycemia, hyperglyceridemia, GERD and IBS. The second PheWAS examined possible phenotypic predictors of abnormal RBC component measures: a number of hematologic phenotypes such as thrombocytopenia, anemias, hemoglobinopathies and pancytopenia were found to be strongly associated to RBC component measures; additional phenotypes such as (morbid) obesity, malaise and fatigue, alcoholism, and cirrhosis were also identified to be possible predictors of RBC component measures.


Assuntos
Eritrócitos/citologia , Estudo de Associação Genômica Ampla , Fenótipo , Adulto , Mapeamento Cromossômico , Estudos de Coortes , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Nevada , Polimorfismo de Nucleotídeo Único
18.
J Environ Manage ; 242: 315-326, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31054396

RESUMO

Expansion of native pinyon-juniper (Pinus monophylla-Juniperus osteosperma) woodlands can decrease shrub and herbaceous cover in the Intermountain West, U.S., affecting habitat quality and biodiversity. Removing pinyon-juniper woodlands in former sagebrush ecosystems to increase understory cover has a long management history, and short- and long-term monitoring reveal different understory plant community responses. We revisited a 500 mm average precipitation site in the sagebrush steppe of western Nevada, 32 years after three types of tree thinning treatments and seeding had occurred in a mature, closed-canopy woodland. We measured vegetation foliar cover and density within plots arranged in a 3-block randomized design. We found significantly lower cover of P. monophylla in treated plots (average of 2-8%), relative to controls (32%). However, P. monophylla seedlings (<0.5 m tall) were detected throughout all plots (average of 86-160 trees/ha in treated plots, 111 in controls). Cover of perennial graminoids and shrubs was higher in all treatments (600-870% higher grass cover and 470-570% higher shrub cover) than controls. Cover of invasive annual species, primarily Bromus tectorum, was highly variable and not significantly different among plots, but B. tectorum had the highest cover of all species in two of the three woodland removal treatment types. Control plots contained significantly larger perennial canopy gaps compared to all treatments (average of 318 cm vs. 104-133 cm), and had significantly more woody litter cover than clear cut plots (average of 14% vs. 3%). These results suggest tree thinning and removal in tree dominated woodlands can increase shrub and perennial grass cover and reduce litter and canopy gaps, especially in conjunction with seeding, but that tree recolonization over the long-term is inevitable. Perennial forbs did not respond well to treatments (<1% average foliar cover in all plots), and seeding or other treatments may be needed to improve their response. Further, if tree seedlings survive, these plots will likely return to tree dominance without additional treatments.


Assuntos
Juniperus , Ecossistema , Florestas , Nevada , Árvores
19.
J Anim Ecol ; 88(8): 1240-1249, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31077366

RESUMO

As global temperatures rise, the mechanistic links between temperature, physiology and behaviour will increasingly define predictions of ecological change. However, for many taxa, we currently lack consensus about how thermal performance traits vary within and across populations, and whether and how locally adaptive trait plasticity can buffer warming effects. The metabolic cold adaptation hypothesis posits that cold environments (e.g. high elevations and latitudes) select for high metabolic rates (MR), even after controlling for body size differences, and that this enables high activity levels when an organism is near its cold lower thermal limits. Steep MR reaction norms are further predicted at cold temperatures to enable rapid behavioural activation with rising temperatures needed to exploit brief thermal windows suitable for performing eco-evolutionary tasks. We tested these predictions by performing common garden experiments comparing thermal reaction norms of MR (from 15 to 32°C) and behaviour (from 10 to 40°C) across populations of the ant Aphaenogaster iberica sampled from a 2 km elevation gradient in the Sierra Nevada Mountains of southern Spain. As predicted, high-elevation ants had higher MR and steeper MR-temperature reaction norms. However, higher rates of energy use did not yield the predicted benefits of steeper activity-level reaction norms. The evidence for locally adaptive metabolic physiology only became apparent at intermediate temperatures, highlighting the importance of testing thermal performance hypotheses across thermal gradients, rather than focusing only on performance at thermal limits (i.e. critical thermal values). The partial support for the metabolic cold adaptation hypothesis highlights that while organisms likely show a wealth of unexplored metabolic temperature plasticity, the physiological mechanisms and eco-evolutionary trade-offs underlying such local adaptation remain obscure.


Assuntos
Formigas , Adaptação Fisiológica , Animais , Nevada , Espanha , Temperatura
20.
Sci Total Environ ; 677: 184-193, 2019 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-31055099

RESUMO

Rivers are being increasingly analyzed from a holistic scale focus, imposing the challenge to establish a clear sampling framework that integrates complex valley-to-reach hydrogeomorphic features. Here, we address this challenge by examining macroinvertebrate communities of different hydrogeomorphic patches, or Functional Process Zones (FPZs), established by the GIS-based model RESonate. We delineated FPZs across three endorheic drainages in the Great Basin, USA, using a self-emerging clustering method that classifies segments of rivers with similar hydrogeomorphic characteristics. We sampled macroinvertebrate communities across different FPZs. We examined the taxonomic and functional organizations of these communities, and we assessed the relative contributions of in-stream and watershed-scale environmental filters in structuring these communities. We found discreet macroinvertebrate communities associated with FPZs across drainages, where elevation prevailed on valley confinement in structuring these communities. Communities of upland FPZs exhibited a higher heterogeneity suggested by higher ß-diversity and nested structure of communities, while lowland FPZs showed a higher pairwise abundance agreement across communities. Eltonian trait composition, primarily describing bionomic traits, showed a higher degree of niche differentiation in upland FPZs, thereby increasing the overall ecosystem function. Differences in variance partitioning among environmental filters acting at different spatial scales show a strong spatial structure in the response of communities in different FPZs. Overall, environmental filters had a stronger control of the communities' functional organization than the taxonomic composition. Our results support the paradigm of different FPZs having distinct communities that express different ecosystem properties. Findings of this study constitute a fruitful avenue for expanding community-based research using the FPZ template as a tool for riverine ecology. However, the unique nature of rivers in endorheic basins needs to be considered when applying our conclusions to other systems, as some findings (e.g., the higher community homogenization in lowland FPZs) might be specific to this rarely examined type of river systems.


Assuntos
Monitoramento Ambiental/métodos , Invertebrados , Rios , Animais , Nevada , Qualidade da Água
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA