Polychlorinated biphenyl (PCBs) congeners were measured in (unwashed) whole-body field (deer) mice (Peromyscus maniculaltus) collected directly upgradient from a sediment retention structure (weir) within Los Alamos C...Polychlorinated biphenyl (PCBs) congeners were measured in (unwashed) whole-body field (deer) mice (Peromyscus maniculaltus) collected directly upgradient from a sediment retention structure (weir) within Los Alamos Canyon (LAC), Los Alamos National Laboratory (LANL), New Mexico, USA, from 2007 through 2013. Samples were also collected approximately 8 km downgradient of the retention structure in 2009 and 2013. LAC, a major drainage that crosses LANL lands, contains legacy waste, including PCBs, and occasionally discharges storm water and snowmelt flows to the Rio Grande approximately 8.8 km away from the weir. The Rio Grande is the major waterway that flows southward across the state. The weir was constructed across the channel on the northeastern boundary of LANL in late 2000 to help contain sediments mobilized by floodwaters as a result of a large wildfire in early 2000 that burned forest lands west and adjacent to LANL. Total PCBs in field mice directly upgradient of the sediment retention structure from 2007 through 2012 were significantly greater (p 0.05) than in field mice collected from background locations but decreased in concentration over time;by 2013 the levels were statistically similar (p > 0.05) to background. The highest mean total PCB concentration in field mice was below the levels that may negatively impact field mice population attributes. Total PCBs in field mice collected 8 km below the sediment retention structure in 2009 were lower than field mice collected from behind the weir and decreased over time;also by 2013, the amount of PCBs in field mice 8 km below the sediment retention structure were not significantly different (p > 0.05) from background. The rank order of concentrations of ICES 7 PCB congeners in upgradient and downgradient field mice were: No. 153 > 180 > 138 > 118 > 28 > 101 > 52 and No. 153 > 180 > 138 > 52 > 101 > 118 > 28, respectively. Based on the PCB homolog distribution, the major formulation detected in field mice was Aroclor-1260. Overall, the reduction of PCBs in whole-body field mice from both sites over time was attributed, in part, to sediment control practices.展开更多
Breeding bird abundance, species richness, evenness, diversity, composition, productivity, and survivorship were determined near a high-explosive detonation site at Los Alamos National Laboratory, New Mexico, USA, dur...Breeding bird abundance, species richness, evenness, diversity, composition, productivity, and survivorship were determined near a high-explosive detonation site at Los Alamos National Laboratory, New Mexico, USA, during pre-operation (1997-1999) and operation (2000-2014) periods. The operation periods consisted of detonations ( 0.05) in mean avian abundance and species evenness in any of the operation periods as compared with the pre-operation period. Species richness and diversity were significantly higher (p < 0.05) during the vessel containment period (2007-2014) than the pre-operation period. The time period of this study coincided with a wildfire (2000), a bark beetle infestation (2002), and two periods of drought (Nov 1999-Mar 2004 and Dec 2005-Dec 2014) that affected the study area. Analysis of aerial photos determined that the average percent canopy cover of mature ponderosa pines (Pinus ponderosa) within 100 feet of mist net sites declined from 12% to 3% between 1991 and 2014 and the percent cover of shrubs slightly increased. The percent similarity in presence/abundance between the pre-operation avian community and avian community during the open air, foam containment, and vessel containment periods were 59%, 63% and 68% respectively. Two bird species associated with large trees became less common over the study period (capture rate dropped below 2.0 adults per 600 net-hours relative to the pre-operations period), and four bird species associated with edge and scrub habitats became more common over the study period (capture rate increased to more than 2.0 adults per 600 net-hours relative to the pre-operations period). Bird demographics (productivity and survival) were not negatively affected by the initiation of firing site operations. The increase in diversity and the change in bird species composition over time were probably related to the change in vegetation from a woodland to a more open woodland/shrub environment.展开更多
Benthic macroinvertebrates (aquatic insects) were collected from the Rio Grande upstream and downstream of Los Alamos Canyon (LAC), a major drainage that crosses Los Alamos National Laboratory (LANL) lands in northern...Benthic macroinvertebrates (aquatic insects) were collected from the Rio Grande upstream and downstream of Los Alamos Canyon (LAC), a major drainage that crosses Los Alamos National Laboratory (LANL) lands in northern New Mexico, USA. LAC contains legacy waste, including radionuclides and polychlorinated biphenyls, and occasionally discharges storm water and snowmelt flows to the Rio Grande. The Rio Grande is the major waterway that flows southward across the state. In 2009, rock baskets were placed in waters 61- to 76-cm-deep within each reach (five per reach), and, after approximately 6 weeks of colonization, the rock baskets were retrieved. All samples were sorted completely and organisms were identified to the lowest possible taxonomic level. Both reaches in 2009 were dominated by the collector filtering net-spinning caddisfly, Hydropsyche occidentalis. In 2011, benthic macroinvertebrates were collected using D kick nets from shallow riffle locations (15- to 31-cm depth) from each reach (six per reach). These samples were collected after post- (Las Conchas) fire flooding events moved sediment and ash through the two study areas—the downstream reach, however, was affected by higher flows and greater number of flooding events than those affecting the upstream reach. Each kick net sample consisted of ten 1-m (kick) samples. The 10 subsamples were composited and organisms were picked from randomly selected cells in a sorting pan until 500 organisms had been identified to the lowest possible taxonomic level. Both reaches in 2011 were dominated by the collector-gathering mayfly, Baetis tricaudatus. A bioassessment of the downstream reach compared with the upstream (reference) reach was conducted by scoring 10 metrics related to the structure and function of the benthic macroinvertebrate community. While 2009 ranked at the highest level (nonimpaired), 2011 ranked a level lower (slightly impaired). The slightly lower bioassessment score of the downstream reach in 2011 may be a result of flooding impacts following the Las Conchas fire rather than of LANL operations. Overall, based on the similarity of benthic macroinvertebrate metrics between reaches and the composition of benthic macroinvertebrates favoring pollution intolerant taxa, LANL influences, if any, via the LAC system to the Rio Grande are not significantly impacting water quality of the Rio Grande.展开更多
Los Alamos National Laboratory (LANL) was established in 1943 as part of the Manhattan Project to build nuclear weapons, and currently operates as a national research laboratory. As part of an ongoing assessment of si...Los Alamos National Laboratory (LANL) was established in 1943 as part of the Manhattan Project to build nuclear weapons, and currently operates as a national research laboratory. As part of an ongoing assessment of site-related ecological risk at LANL, western bluebird (Sialia mexicana) and ash-throated flycatcher (Myiarchus cinerascens) eggs were collected from 1997 to 2012 and analyzed for 18 inorganic elements. Concentrations of many inorganic elements in eggs were below reporting limits. Between species comparisons revealed that western bluebird eggs had higher levels of barium while ash-throated flycatcher eggs had higher levels of mercury. No statistically significant differences were observed in concentrations of inorganic elements in western bluebird eggs collected from the study area (which consists of areas within the current and historic LANL boundary) and from a non-industrial reference site;nor were any statistically significant differences observed between two canyons of interest, known to have received effluents and storm water runoff from LANL facilities, and the non-industrial reference site. Inorganic element levels detected in western bluebirds were typically within the range measured in eggs of other passerine in the published literature. These data suggest that concentrations of inorganic elements in passerine eggs collected from the study area appear to be at levels causing negligible risks to local bird populations.展开更多
Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and ...Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and sometimes random microcracking near coalesced fracture formation alters the mechanical properties of the nearby virgin material. Individual microcrack characterization is also significant in quantifying the material changes near the fracture faces （i.e. damage）. Acoustic emission （AE） monitoring and analysis provide unique information regarding the microcracking process temporally, and infor- mation concerning the source characterization of individual microcracks can be extracted. In this context, laboratory hydraulic fracture tests were carried out while monitoring the AEs from several piezoelectric transducers. In-depth post-processing of the AE event data was performed for the purpose of under- standing the individual source mechanisms. Several source characterization techniques including moment tensor inversion, event parametric analysis, and volumetric deformation analysis were adopted. Post-test fracture characterization through coring, slicing and micro-computed tomographic imaging was performed to determine the coalesced fracture location and structure. Distinct differences in fracture characteristics were found spatially in relation to the openhole injection interval. Individual microcrack AE analysis showed substantial energy reduction emanating spatially from the injection interval. It was quantitatively observed that the recorded AE signals provided sufficient information to generalize the damage radiating spatially away from the injection wellbore.展开更多
Hydrodynamic instabilities such as the Rayleigh–Taylor(RT)and Richtmyer–Meshkov instabilities disrupt inertial confinement fusion(ICF)implosions through the growth of 3D perturbations.Growth of these 3D imperfection...Hydrodynamic instabilities such as the Rayleigh–Taylor(RT)and Richtmyer–Meshkov instabilities disrupt inertial confinement fusion(ICF)implosions through the growth of 3D perturbations.Growth of these 3D imperfections at the interfaces of an ICF capsule during implosion lead to mixing between materials that is detrimental to performance.These instabilities have been studied extensively in planar geometry,but such experiments lack the effects of convergence in spherical implosions.While several studies have been performed in spherical geometry,these often lack a direct means to measure perturbation growth.Experiments in cylindrical geometry include convergence effects while maintaining direct diagnostic access.Although cylinders have less compression than spheres,they do provide an excellent platform to validate modeling for convergent geometries.The problem with previous cylindrical implosion experiments was that the convergence ratios were limited to∼4.With the National Ignition Facility(NIF),larger cylindrical targets can be driven to convergences of 10–15 while maintaining a large enough final diameter to measure perturbation growth.This paper reviews the design process used to both benchmark radiation hydrodynamics codes and enable 1D post-processed simulations to explore design space to separate compression effects from acceleration/deceleration RT instability.Results from 1D simulations suggest that cylindrical implosions on the NIF can produce high-convergence experiments to validate RT instability growth for ICF implosions.展开更多
Given the challenge of definitively discriminating between chemical and nuclear explosions using seismic methods alone,surface detection of signature noble gas radioisotopes is considered a positive identification of ...Given the challenge of definitively discriminating between chemical and nuclear explosions using seismic methods alone,surface detection of signature noble gas radioisotopes is considered a positive identification of underground nuclear explosions(UNEs).However,the migration of signature radionuclide gases between the nuclear cavity and surface is not well understood because complex processes are involved,including the generation of complex fracture networks,reactivation of natural fractures and faults,and thermo-hydro-mechanical-chemical(THMC)coupling of radionuclide gas transport in the subsurface.In this study,we provide an experimental investigation of hydro-mechanical(HM)coupling among gas flow,stress states,rock deformation,and rock damage using a unique multi-physics triaxial direct shear rock testing system.The testing system also features redundant gas pressure and flow rate measurements,well suited for parameter uncertainty quantification.Using porous tuff and tight granite samples that are relevant to historic UNE tests,we measured the Biot effective stress coefficient,rock matrix gas permeability,and fracture gas permeability at a range of pore pressure and stress conditions.The Biot effective stress coefficient varies from 0.69 to 1 for the tuff,whose porosity averages 35.3%±0.7%,while this coefficient varies from 0.51 to 0.78 for the tight granite(porosity<1%,perhaps an underestimate).Matrix gas permeability is strongly correlated to effective stress for the granite,but not for the porous tuff.Our experiments reveal the following key engineering implications on transport of radionuclide gases post a UNE event:(1)The porous tuff shows apparent fracture dilation or compression upon stress changes,which does not necessarily change the gas permeability;(2)The granite fracture permeability shows strong stress sensitivity and is positively related to shear displacement;and(3)Hydromechanical coupling among stress states,rock damage,and gas flow appears to be stronger in tight granite than in porous tuff.展开更多
The impact of fuel-ion diffusion in inertial confinement fusion implosions is assessed using nuclear reaction yield ratios and reaction histories.In T3He-gas-filled(with trace D)shock-driven implosions,the observed TT...The impact of fuel-ion diffusion in inertial confinement fusion implosions is assessed using nuclear reaction yield ratios and reaction histories.In T3He-gas-filled(with trace D)shock-driven implosions,the observed TT/T3He yield ratio is∼23lower than expected from temperature scaling.InD3He-gas-filled(with trace T)shock-driven implosions,the timing of theD3He reaction history is∼50 ps earlier than those of the DT reaction histories,and average-ion hydrodynamic simulations cannot reconcile this timing difference.Both experimental observations are consistent with reduced T ions in the burn region as predicted by multi-ion diffusion theory and particle-in-cell simulations.展开更多
TO THE EDITOR We read the study by Medeiros-Filho et al with much interest. The study shed light on early HCV RNA kinetics in conjunction with liver cirrhosis, different genotypes （gen-1 vs gen-3） of HCV and sustain...TO THE EDITOR We read the study by Medeiros-Filho et al with much interest. The study shed light on early HCV RNA kinetics in conjunction with liver cirrhosis, different genotypes （gen-1 vs gen-3） of HCV and sustained viral response （SVR） rates. In particular, Medeiros-Filho et al showed that the HCV RNA first phase decline, under interferon-or （IFN） and ribavirin therapy,展开更多
Diabetes mellitus, together with its complications, has been increasing in prevalence worldwide. Its complications include cardiovascular disease(e.g., myocardial infarction, stroke), neuropathy, nephropathy, and eye ...Diabetes mellitus, together with its complications, has been increasing in prevalence worldwide. Its complications include cardiovascular disease(e.g., myocardial infarction, stroke), neuropathy, nephropathy, and eye complications(e.g., glaucoma, cataracts, retinopathy, and macular edema). In patients with either type 1 or type 2 diabetes mellitus, diabetic retinopathy is the leading cause of visual impairment or blindness. It is characterized by progressive changes in the retinal microvasculature. The progression from nonproliferative diabetic retinopathy to a more advanced stage of moderate to severe nonproliferative diabetic retinopathy and proliferative diabetic retinopathy occurs very quickly after diagnosis of mild nonproliferative diabetic retinopathy. The etiology of diabetic retinopathy is unclear, and present treatments have limited effectiveness. Currently diabetic retinopathy can only be diagnosed by a trained specialist, which reduces the population that can be examined. A screening biomarker of diabetic retinopathy with high sensitivity and specificity would aid considerably in identifying those individuals in need of clinical assessment and treatment. The majority of the studies reviewed identified specific microRNAs in blood serum/plasma able to distinguish diabetic patients with retinopathy from those without retinopathy and for the progresion of the disease from nonproliferative diabetic retinopathy to proliferative diabetic retinopathy. In addition,certain microRNAs in vitreous humor were dysregulated in proliferative diabetic retinopathy compared to controls. A very high percentage of patients with diabetic retinopathy develop Alzheimer’s disease. Thus, identifying diabetic retinopathy by measurement of suitable biomarkers would also enable better screening and treatment of those individuals at risk of Alzheimer’s disease.展开更多
Alzheimer's disease(AD) is the most common age-related, progressive neurodegenerative disease. It is characterized by memory loss and cognitive decline and responsible for most cases of dementia in the elderly. La...Alzheimer's disease(AD) is the most common age-related, progressive neurodegenerative disease. It is characterized by memory loss and cognitive decline and responsible for most cases of dementia in the elderly. Late-onset or sporadic AD accounts for > 95% of cases, with age at onset > 65 years. Currently there are no drugs or other therapeutic agents available to prevent or delay the progression of AD. The cellular and molecular changes occurring in the brains of individuals with AD include accumulation of β-amyloid peptide and hyperphosphorylated tau protein, decrease of acetylcholine neurotransmitter, inflammation, and oxidative stress. Aggregation of β-amyloid peptide in extracellular plaques and the hyperphosphorylated tau protein in intracellular neurofibrillary tangles are characteristic of AD. A major challenge is identifying molecular biomarkers of the early-stage AD in patients as most studies have been performed with blood or brain tissue samples(postmortem) at late-stage AD. Subjects with mild cognitive impairment almost always have the neuropathologic features of AD with about 50% of mild cognitive impairment patients progressing to AD. They could provide important information about AD pathomechanism and potentially also highlight minimally or noninvasive, easy-to-access biomarkers. MicroRNAs are dysregulated in AD, and may facilitate the early detection of the disease and potentially the continual monitoring of disease progression and allow therapeutic interventions to be evaluated. Four recent reviews have been published of microRNAs in AD, each of which identified areas of weakness or limitations in the reported studies. Importantly, studies in the last three years have shown considerable progress in overcoming some of these limitations and identifying specific microRNAs as biomarkers for AD and mild cognitive impairment. Further large-scale human studies are warranted with less disparity in the study populations, and using an appropriate method to validate the findings.展开更多
Multiple sclerosis is an autoimmune neurodegenerative disease of the central nervous system characterized by pronounced inflammatory infiltrates entering the brain,spinal cord and optic nerve leading to demyelination....Multiple sclerosis is an autoimmune neurodegenerative disease of the central nervous system characterized by pronounced inflammatory infiltrates entering the brain,spinal cord and optic nerve leading to demyelination.Focal demyelination is associated with relapsing-remitting multiple sclerosis,while progressive forms of the disease show axonal degeneration and neuronal loss.The tests currently used in the clinical diagnosis and management of multiple sclerosis have limitations due to specificity and sensitivity.MicroRNAs(miRNAs)are dysregulated in many diseases and disorders including demyelinating and neuroinflammatory diseases.A review of recent studies with the experimental autoimmune encephalomyelitis animal model(mostly female mice 6–12 weeks of age)has confirmed miRNAs as biomarkers of experimental autoimmune encephalomyelitis disease and importantly at the pre-onset(asymptomatic)stage when assessed in blood plasma and urine exosomes,and spinal cord tissue.The expression of certain miRNAs was also dysregulated at the onset and peak of disease in blood plasma and urine exosomes,brain and spinal cord tissue,and at the post-peak(chronic)stage of experimental autoimmune encephalomyelitis disease in spinal cord tissue.Therapies using miRNA mimics or inhibitors were found to delay the induction and alleviate the severity of experimental autoimmune encephalomyelitis disease.Interestingly,experimental autoimmune encephalomyelitis disease severity was reduced by overexpression of miR-146a,miR-23b,miR-497,miR-26a,and miR-20b,or by suppression of miR-182,miR-181c,miR-223,miR-155,and miR-873.Further studies are warranted on determining more fully miRNA profiles in blood plasma and urine exosomes of experimental autoimmune encephalomyelitis animals since they could serve as biomarkers of asymptomatic multiple sclerosis and disease course.Additionally,studies should be performed with male mice of a similar age,and with aged male and female mice.展开更多
Multiple sclerosis is a chronic autoimmune disease of the central nervous system.It is the main cause of non-traumatic neurological disability in young adults.Multiple sclerosis mostly affects people aged 20–50 years...Multiple sclerosis is a chronic autoimmune disease of the central nervous system.It is the main cause of non-traumatic neurological disability in young adults.Multiple sclerosis mostly affects people aged 20–50 years;however,it can occur in young children and much older adults.Factors identified in the distribution of MS include age,gender,genetics,environment,and ethnic background.Multiple sclerosis is usually associated with progressive degrees of disability.The disease involves demyelination of axons of the central nervous system and causes brain and spinal cord neuronal loss and atrophy.Diagnosing multiple sclerosis is based on a patient’s medical history including symptoms,physical examination,and various tests such as magnetic resonance imaging,cerebrospinal fluid and blood tests,and electrophysiology.The disease course of multiple sclerosis is not well correlated with the biomarkers presently used in clinical practice.Blood-derived biomarkers that can detect and distinguish the different phenotypes in multiple sclerosis may be advantageous in personalized treatment with disease-modifying drugs and to predict response to treatment.The studies reviewed have shown that the expression levels of a large number of miRNAs in peripheral blood,serum,exosomes isolated from serum,and cerebrospinal fluid are altered in multiple sclerosis and can distinguish the disease phenotypes from each other.Further studies are warranted to independently validate these findings so that individual or pairs of miRNAs in serum or cerebrospinal fluid can be used as potential diagnostic markers for adult and pediatric multiple sclerosis and for monitoring disease progression and response to therapy.展开更多
The most common age-related neurodegenerative disease is Alzheimer's disease(AD) characterized by aggregated amyloid-β(Aβ) peptides in extracellular plaques and aggregated hyperphosphorylated tau protein in intr...The most common age-related neurodegenerative disease is Alzheimer's disease(AD) characterized by aggregated amyloid-β(Aβ) peptides in extracellular plaques and aggregated hyperphosphorylated tau protein in intraneuronal neurofibrillary tangles,together with loss of cholinergic neurons,synaptic alterations,and chronic inflammation within the brain.These lead to progressive impairment of cognitive function.There is evidence of innate immune activation in AD with microgliosis.Classically-activated microglia(M1 state) secrete inflammatory and neurotoxic mediators,and peripheral immune cells are recruited to inflammation sites in the brain.The few drugs approved by the US FDA for the treatment of AD improve symptoms but do not change the course of disease progression and may cause some undesirable effects.Translation of active and passive immunotherapy targeting Aβ in AD animal model trials had limited success in clinical trials.Treatment with immunomodulatory/anti-inflammatory agents early in the disease process,while not preventive,is able to inhibit the inflammatory consequences of both Aβ and tau aggregation.The studies described in this review have identified several agents with immunomodulatory properties that alleviated AD pathology and cognitive impairment in animal models of AD.The majority of the animal studies reviewed had used transgenic models of early-onset AD.More effort needs to be given to creat models of late-onset AD.The effects of a combinational therapy involving two or more of the tested pharmaceutical agents,or one of these agents given in conjunction with one of the cell-based therapies,in an aged animal model of AD would warrant investigation.展开更多
文摘Polychlorinated biphenyl (PCBs) congeners were measured in (unwashed) whole-body field (deer) mice (Peromyscus maniculaltus) collected directly upgradient from a sediment retention structure (weir) within Los Alamos Canyon (LAC), Los Alamos National Laboratory (LANL), New Mexico, USA, from 2007 through 2013. Samples were also collected approximately 8 km downgradient of the retention structure in 2009 and 2013. LAC, a major drainage that crosses LANL lands, contains legacy waste, including PCBs, and occasionally discharges storm water and snowmelt flows to the Rio Grande approximately 8.8 km away from the weir. The Rio Grande is the major waterway that flows southward across the state. The weir was constructed across the channel on the northeastern boundary of LANL in late 2000 to help contain sediments mobilized by floodwaters as a result of a large wildfire in early 2000 that burned forest lands west and adjacent to LANL. Total PCBs in field mice directly upgradient of the sediment retention structure from 2007 through 2012 were significantly greater (p 0.05) than in field mice collected from background locations but decreased in concentration over time;by 2013 the levels were statistically similar (p > 0.05) to background. The highest mean total PCB concentration in field mice was below the levels that may negatively impact field mice population attributes. Total PCBs in field mice collected 8 km below the sediment retention structure in 2009 were lower than field mice collected from behind the weir and decreased over time;also by 2013, the amount of PCBs in field mice 8 km below the sediment retention structure were not significantly different (p > 0.05) from background. The rank order of concentrations of ICES 7 PCB congeners in upgradient and downgradient field mice were: No. 153 > 180 > 138 > 118 > 28 > 101 > 52 and No. 153 > 180 > 138 > 52 > 101 > 118 > 28, respectively. Based on the PCB homolog distribution, the major formulation detected in field mice was Aroclor-1260. Overall, the reduction of PCBs in whole-body field mice from both sites over time was attributed, in part, to sediment control practices.
文摘Breeding bird abundance, species richness, evenness, diversity, composition, productivity, and survivorship were determined near a high-explosive detonation site at Los Alamos National Laboratory, New Mexico, USA, during pre-operation (1997-1999) and operation (2000-2014) periods. The operation periods consisted of detonations ( 0.05) in mean avian abundance and species evenness in any of the operation periods as compared with the pre-operation period. Species richness and diversity were significantly higher (p < 0.05) during the vessel containment period (2007-2014) than the pre-operation period. The time period of this study coincided with a wildfire (2000), a bark beetle infestation (2002), and two periods of drought (Nov 1999-Mar 2004 and Dec 2005-Dec 2014) that affected the study area. Analysis of aerial photos determined that the average percent canopy cover of mature ponderosa pines (Pinus ponderosa) within 100 feet of mist net sites declined from 12% to 3% between 1991 and 2014 and the percent cover of shrubs slightly increased. The percent similarity in presence/abundance between the pre-operation avian community and avian community during the open air, foam containment, and vessel containment periods were 59%, 63% and 68% respectively. Two bird species associated with large trees became less common over the study period (capture rate dropped below 2.0 adults per 600 net-hours relative to the pre-operations period), and four bird species associated with edge and scrub habitats became more common over the study period (capture rate increased to more than 2.0 adults per 600 net-hours relative to the pre-operations period). Bird demographics (productivity and survival) were not negatively affected by the initiation of firing site operations. The increase in diversity and the change in bird species composition over time were probably related to the change in vegetation from a woodland to a more open woodland/shrub environment.
文摘Benthic macroinvertebrates (aquatic insects) were collected from the Rio Grande upstream and downstream of Los Alamos Canyon (LAC), a major drainage that crosses Los Alamos National Laboratory (LANL) lands in northern New Mexico, USA. LAC contains legacy waste, including radionuclides and polychlorinated biphenyls, and occasionally discharges storm water and snowmelt flows to the Rio Grande. The Rio Grande is the major waterway that flows southward across the state. In 2009, rock baskets were placed in waters 61- to 76-cm-deep within each reach (five per reach), and, after approximately 6 weeks of colonization, the rock baskets were retrieved. All samples were sorted completely and organisms were identified to the lowest possible taxonomic level. Both reaches in 2009 were dominated by the collector filtering net-spinning caddisfly, Hydropsyche occidentalis. In 2011, benthic macroinvertebrates were collected using D kick nets from shallow riffle locations (15- to 31-cm depth) from each reach (six per reach). These samples were collected after post- (Las Conchas) fire flooding events moved sediment and ash through the two study areas—the downstream reach, however, was affected by higher flows and greater number of flooding events than those affecting the upstream reach. Each kick net sample consisted of ten 1-m (kick) samples. The 10 subsamples were composited and organisms were picked from randomly selected cells in a sorting pan until 500 organisms had been identified to the lowest possible taxonomic level. Both reaches in 2011 were dominated by the collector-gathering mayfly, Baetis tricaudatus. A bioassessment of the downstream reach compared with the upstream (reference) reach was conducted by scoring 10 metrics related to the structure and function of the benthic macroinvertebrate community. While 2009 ranked at the highest level (nonimpaired), 2011 ranked a level lower (slightly impaired). The slightly lower bioassessment score of the downstream reach in 2011 may be a result of flooding impacts following the Las Conchas fire rather than of LANL operations. Overall, based on the similarity of benthic macroinvertebrate metrics between reaches and the composition of benthic macroinvertebrates favoring pollution intolerant taxa, LANL influences, if any, via the LAC system to the Rio Grande are not significantly impacting water quality of the Rio Grande.
文摘Los Alamos National Laboratory (LANL) was established in 1943 as part of the Manhattan Project to build nuclear weapons, and currently operates as a national research laboratory. As part of an ongoing assessment of site-related ecological risk at LANL, western bluebird (Sialia mexicana) and ash-throated flycatcher (Myiarchus cinerascens) eggs were collected from 1997 to 2012 and analyzed for 18 inorganic elements. Concentrations of many inorganic elements in eggs were below reporting limits. Between species comparisons revealed that western bluebird eggs had higher levels of barium while ash-throated flycatcher eggs had higher levels of mercury. No statistically significant differences were observed in concentrations of inorganic elements in western bluebird eggs collected from the study area (which consists of areas within the current and historic LANL boundary) and from a non-industrial reference site;nor were any statistically significant differences observed between two canyons of interest, known to have received effluents and storm water runoff from LANL facilities, and the non-industrial reference site. Inorganic element levels detected in western bluebirds were typically within the range measured in eggs of other passerine in the published literature. These data suggest that concentrations of inorganic elements in passerine eggs collected from the study area appear to be at levels causing negligible risks to local bird populations.
基金financial support for much of the early development of the AE analysis methods was provided by the U.S. Department of Energy (DOE) (Grant No. DE-FE0002760)
文摘Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and sometimes random microcracking near coalesced fracture formation alters the mechanical properties of the nearby virgin material. Individual microcrack characterization is also significant in quantifying the material changes near the fracture faces （i.e. damage）. Acoustic emission （AE） monitoring and analysis provide unique information regarding the microcracking process temporally, and infor- mation concerning the source characterization of individual microcracks can be extracted. In this context, laboratory hydraulic fracture tests were carried out while monitoring the AEs from several piezoelectric transducers. In-depth post-processing of the AE event data was performed for the purpose of under- standing the individual source mechanisms. Several source characterization techniques including moment tensor inversion, event parametric analysis, and volumetric deformation analysis were adopted. Post-test fracture characterization through coring, slicing and micro-computed tomographic imaging was performed to determine the coalesced fracture location and structure. Distinct differences in fracture characteristics were found spatially in relation to the openhole injection interval. Individual microcrack AE analysis showed substantial energy reduction emanating spatially from the injection interval. It was quantitatively observed that the recorded AE signals provided sufficient information to generalize the damage radiating spatially away from the injection wellbore.
基金This work used resources provided by Los Alamos National Laboratory,supported by the U.S Department of Energy National Nuclear Security Administration,operated by Los Alamos National Security,LLC(Contract No.DE-AC52-06NA25396)until November 2018and currently operated by Triad National Security,LLC(Contract No.89233218CNA000001).
文摘Hydrodynamic instabilities such as the Rayleigh–Taylor(RT)and Richtmyer–Meshkov instabilities disrupt inertial confinement fusion(ICF)implosions through the growth of 3D perturbations.Growth of these 3D imperfections at the interfaces of an ICF capsule during implosion lead to mixing between materials that is detrimental to performance.These instabilities have been studied extensively in planar geometry,but such experiments lack the effects of convergence in spherical implosions.While several studies have been performed in spherical geometry,these often lack a direct means to measure perturbation growth.Experiments in cylindrical geometry include convergence effects while maintaining direct diagnostic access.Although cylinders have less compression than spheres,they do provide an excellent platform to validate modeling for convergent geometries.The problem with previous cylindrical implosion experiments was that the convergence ratios were limited to∼4.With the National Ignition Facility(NIF),larger cylindrical targets can be driven to convergences of 10–15 while maintaining a large enough final diameter to measure perturbation growth.This paper reviews the design process used to both benchmark radiation hydrodynamics codes and enable 1D post-processed simulations to explore design space to separate compression effects from acceleration/deceleration RT instability.Results from 1D simulations suggest that cylindrical implosions on the NIF can produce high-convergence experiments to validate RT instability growth for ICF implosions.
基金supported by the Laboratory Directed Research&Development(LDRD)program at the Los Alamos National Laboratory(LANL)(Grant No.20220019DR).
文摘Given the challenge of definitively discriminating between chemical and nuclear explosions using seismic methods alone,surface detection of signature noble gas radioisotopes is considered a positive identification of underground nuclear explosions(UNEs).However,the migration of signature radionuclide gases between the nuclear cavity and surface is not well understood because complex processes are involved,including the generation of complex fracture networks,reactivation of natural fractures and faults,and thermo-hydro-mechanical-chemical(THMC)coupling of radionuclide gas transport in the subsurface.In this study,we provide an experimental investigation of hydro-mechanical(HM)coupling among gas flow,stress states,rock deformation,and rock damage using a unique multi-physics triaxial direct shear rock testing system.The testing system also features redundant gas pressure and flow rate measurements,well suited for parameter uncertainty quantification.Using porous tuff and tight granite samples that are relevant to historic UNE tests,we measured the Biot effective stress coefficient,rock matrix gas permeability,and fracture gas permeability at a range of pore pressure and stress conditions.The Biot effective stress coefficient varies from 0.69 to 1 for the tuff,whose porosity averages 35.3%±0.7%,while this coefficient varies from 0.51 to 0.78 for the tight granite(porosity<1%,perhaps an underestimate).Matrix gas permeability is strongly correlated to effective stress for the granite,but not for the porous tuff.Our experiments reveal the following key engineering implications on transport of radionuclide gases post a UNE event:(1)The porous tuff shows apparent fracture dilation or compression upon stress changes,which does not necessarily change the gas permeability;(2)The granite fracture permeability shows strong stress sensitivity and is positively related to shear displacement;and(3)Hydromechanical coupling among stress states,rock damage,and gas flow appears to be stronger in tight granite than in porous tuff.
基金This material is based upon work supported by the Department of Energy,National Nuclear Security Administration under Award Nos.DE-NA0001857,DE-NA0002949,and DENA0002905.The work was also supported in part by NLUF(DE-NA0002035).H.S.was supported by a DOE NNSA SSGF Fellowship(DE-FC52-08NA28752)during this work.S.A.acknowledges Sapienza Project 2016 No.RM11615502006B04,as well as EUROfusion Project Nos.AWP17-ENR-IFE-CEA-01 and ENR-IFE19.CEA-01.A.L.acknowledges the LANL LDRD program.
文摘The impact of fuel-ion diffusion in inertial confinement fusion implosions is assessed using nuclear reaction yield ratios and reaction histories.In T3He-gas-filled(with trace D)shock-driven implosions,the observed TT/T3He yield ratio is∼23lower than expected from temperature scaling.InD3He-gas-filled(with trace T)shock-driven implosions,the timing of theD3He reaction history is∼50 ps earlier than those of the DT reaction histories,and average-ion hydrodynamic simulations cannot reconcile this timing difference.Both experimental observations are consistent with reduced T ions in the burn region as predicted by multi-ion diffusion theory and particle-in-cell simulations.
基金NIH grants RR06555 and P20-RR18754the U.S.Department of Energy under contract DE-AC52-06NA25396
文摘TO THE EDITOR We read the study by Medeiros-Filho et al with much interest. The study shed light on early HCV RNA kinetics in conjunction with liver cirrhosis, different genotypes （gen-1 vs gen-3） of HCV and sustained viral response （SVR） rates. In particular, Medeiros-Filho et al showed that the HCV RNA first phase decline, under interferon-or （IFN） and ribavirin therapy,
文摘Diabetes mellitus, together with its complications, has been increasing in prevalence worldwide. Its complications include cardiovascular disease(e.g., myocardial infarction, stroke), neuropathy, nephropathy, and eye complications(e.g., glaucoma, cataracts, retinopathy, and macular edema). In patients with either type 1 or type 2 diabetes mellitus, diabetic retinopathy is the leading cause of visual impairment or blindness. It is characterized by progressive changes in the retinal microvasculature. The progression from nonproliferative diabetic retinopathy to a more advanced stage of moderate to severe nonproliferative diabetic retinopathy and proliferative diabetic retinopathy occurs very quickly after diagnosis of mild nonproliferative diabetic retinopathy. The etiology of diabetic retinopathy is unclear, and present treatments have limited effectiveness. Currently diabetic retinopathy can only be diagnosed by a trained specialist, which reduces the population that can be examined. A screening biomarker of diabetic retinopathy with high sensitivity and specificity would aid considerably in identifying those individuals in need of clinical assessment and treatment. The majority of the studies reviewed identified specific microRNAs in blood serum/plasma able to distinguish diabetic patients with retinopathy from those without retinopathy and for the progresion of the disease from nonproliferative diabetic retinopathy to proliferative diabetic retinopathy. In addition,certain microRNAs in vitreous humor were dysregulated in proliferative diabetic retinopathy compared to controls. A very high percentage of patients with diabetic retinopathy develop Alzheimer’s disease. Thus, identifying diabetic retinopathy by measurement of suitable biomarkers would also enable better screening and treatment of those individuals at risk of Alzheimer’s disease.
文摘Alzheimer's disease(AD) is the most common age-related, progressive neurodegenerative disease. It is characterized by memory loss and cognitive decline and responsible for most cases of dementia in the elderly. Late-onset or sporadic AD accounts for > 95% of cases, with age at onset > 65 years. Currently there are no drugs or other therapeutic agents available to prevent or delay the progression of AD. The cellular and molecular changes occurring in the brains of individuals with AD include accumulation of β-amyloid peptide and hyperphosphorylated tau protein, decrease of acetylcholine neurotransmitter, inflammation, and oxidative stress. Aggregation of β-amyloid peptide in extracellular plaques and the hyperphosphorylated tau protein in intracellular neurofibrillary tangles are characteristic of AD. A major challenge is identifying molecular biomarkers of the early-stage AD in patients as most studies have been performed with blood or brain tissue samples(postmortem) at late-stage AD. Subjects with mild cognitive impairment almost always have the neuropathologic features of AD with about 50% of mild cognitive impairment patients progressing to AD. They could provide important information about AD pathomechanism and potentially also highlight minimally or noninvasive, easy-to-access biomarkers. MicroRNAs are dysregulated in AD, and may facilitate the early detection of the disease and potentially the continual monitoring of disease progression and allow therapeutic interventions to be evaluated. Four recent reviews have been published of microRNAs in AD, each of which identified areas of weakness or limitations in the reported studies. Importantly, studies in the last three years have shown considerable progress in overcoming some of these limitations and identifying specific microRNAs as biomarkers for AD and mild cognitive impairment. Further large-scale human studies are warranted with less disparity in the study populations, and using an appropriate method to validate the findings.
文摘Multiple sclerosis is an autoimmune neurodegenerative disease of the central nervous system characterized by pronounced inflammatory infiltrates entering the brain,spinal cord and optic nerve leading to demyelination.Focal demyelination is associated with relapsing-remitting multiple sclerosis,while progressive forms of the disease show axonal degeneration and neuronal loss.The tests currently used in the clinical diagnosis and management of multiple sclerosis have limitations due to specificity and sensitivity.MicroRNAs(miRNAs)are dysregulated in many diseases and disorders including demyelinating and neuroinflammatory diseases.A review of recent studies with the experimental autoimmune encephalomyelitis animal model(mostly female mice 6–12 weeks of age)has confirmed miRNAs as biomarkers of experimental autoimmune encephalomyelitis disease and importantly at the pre-onset(asymptomatic)stage when assessed in blood plasma and urine exosomes,and spinal cord tissue.The expression of certain miRNAs was also dysregulated at the onset and peak of disease in blood plasma and urine exosomes,brain and spinal cord tissue,and at the post-peak(chronic)stage of experimental autoimmune encephalomyelitis disease in spinal cord tissue.Therapies using miRNA mimics or inhibitors were found to delay the induction and alleviate the severity of experimental autoimmune encephalomyelitis disease.Interestingly,experimental autoimmune encephalomyelitis disease severity was reduced by overexpression of miR-146a,miR-23b,miR-497,miR-26a,and miR-20b,or by suppression of miR-182,miR-181c,miR-223,miR-155,and miR-873.Further studies are warranted on determining more fully miRNA profiles in blood plasma and urine exosomes of experimental autoimmune encephalomyelitis animals since they could serve as biomarkers of asymptomatic multiple sclerosis and disease course.Additionally,studies should be performed with male mice of a similar age,and with aged male and female mice.
文摘Multiple sclerosis is a chronic autoimmune disease of the central nervous system.It is the main cause of non-traumatic neurological disability in young adults.Multiple sclerosis mostly affects people aged 20–50 years;however,it can occur in young children and much older adults.Factors identified in the distribution of MS include age,gender,genetics,environment,and ethnic background.Multiple sclerosis is usually associated with progressive degrees of disability.The disease involves demyelination of axons of the central nervous system and causes brain and spinal cord neuronal loss and atrophy.Diagnosing multiple sclerosis is based on a patient’s medical history including symptoms,physical examination,and various tests such as magnetic resonance imaging,cerebrospinal fluid and blood tests,and electrophysiology.The disease course of multiple sclerosis is not well correlated with the biomarkers presently used in clinical practice.Blood-derived biomarkers that can detect and distinguish the different phenotypes in multiple sclerosis may be advantageous in personalized treatment with disease-modifying drugs and to predict response to treatment.The studies reviewed have shown that the expression levels of a large number of miRNAs in peripheral blood,serum,exosomes isolated from serum,and cerebrospinal fluid are altered in multiple sclerosis and can distinguish the disease phenotypes from each other.Further studies are warranted to independently validate these findings so that individual or pairs of miRNAs in serum or cerebrospinal fluid can be used as potential diagnostic markers for adult and pediatric multiple sclerosis and for monitoring disease progression and response to therapy.
文摘The most common age-related neurodegenerative disease is Alzheimer's disease(AD) characterized by aggregated amyloid-β(Aβ) peptides in extracellular plaques and aggregated hyperphosphorylated tau protein in intraneuronal neurofibrillary tangles,together with loss of cholinergic neurons,synaptic alterations,and chronic inflammation within the brain.These lead to progressive impairment of cognitive function.There is evidence of innate immune activation in AD with microgliosis.Classically-activated microglia(M1 state) secrete inflammatory and neurotoxic mediators,and peripheral immune cells are recruited to inflammation sites in the brain.The few drugs approved by the US FDA for the treatment of AD improve symptoms but do not change the course of disease progression and may cause some undesirable effects.Translation of active and passive immunotherapy targeting Aβ in AD animal model trials had limited success in clinical trials.Treatment with immunomodulatory/anti-inflammatory agents early in the disease process,while not preventive,is able to inhibit the inflammatory consequences of both Aβ and tau aggregation.The studies described in this review have identified several agents with immunomodulatory properties that alleviated AD pathology and cognitive impairment in animal models of AD.The majority of the animal studies reviewed had used transgenic models of early-onset AD.More effort needs to be given to creat models of late-onset AD.The effects of a combinational therapy involving two or more of the tested pharmaceutical agents,or one of these agents given in conjunction with one of the cell-based therapies,in an aged animal model of AD would warrant investigation.
