Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-30 (of 143 Records) |
Query Trace: Rock V[original query] |
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Notes from the field: Undiagnosed tuberculosis during pregnancy resulting in a neonatal death - United States, 2021
Miele K , Rock RB , LaCourse SM , Ashkin D , Armitige LY , Pomputius W , Goswami ND . MMWR Morb Mortal Wkly Rep 2023 72 (49) 1331-1332 In 2022, the World Health Organization reported 10.6 million new cases of tuberculosis (TB) globally. One third of these new cases were reported in women; however, pregnancy status was not included in these data.* CDC recently added pregnancy status to national TB reporting in the United States; however, because the number of U.S. TB cases during pregnancy is presumed to be low, adverse effects of TB on pregnancy and postpartum outcomes are likely not well characterized.† A 2017 meta-analysis of 13 studies that included approximately 123,000 pregnancies from several countries found that TB disease during pregnancy was associated with increased odds of maternal morbidity and mortality, including hospital admission, anemia of pregnancy, cesarean birth, miscarriage, preterm birth, low birthweight, and neonatal TB (1). TB diagnosis during pregnancy might be delayed because of overlap in symptoms of TB with those of pregnancy, as well as clinician reluctance to use chest radiography during pregnancy.§ Perinatal TB is a life-threatening illness, with a congenital and neonatal TB mortality rate of approximately 50% (2), highlighting the importance of diagnosing and treating TB before and during pregnancy. This report describes a case of fatal neonatal TB after successful in vitro fertilization in 2021. |
Seismoacoustic monitoring of a longwall face using distributed acoustic sensing
Chambers D , Shragge J . Bull Seismol Soc Am 2023 113 (4) 1652-1663 Violent, dynamic failures of rockmasses in underground mines pose significant hazards to workers and operations. Over the past several decades, hardrock mines have widely adopted seismic monitoring to help address such risks. However, coal mines, particularly those employing the longwall mining method, have struggled to implement similar monitoring strategies. This is because typical longwall mines are much larger and mine more rapidly than hardrock mines. Moreover, regulations place significant restrictions on the subsurface use of electronics in coal mines due to potentially explosive atmospheres. We present a new monitoring concept that uses distributed acoustic sensing (DAS) to turn an entire longwall face into a seismoacoustic array. After exploring the acoustic response of our sensors in the laboratory, we deployed the array at an active underground longwall mine for several days. We examine 33 events recorded by both the in-mine DAS array and a surface seismic network. We observed that the array records both seismic vibrations trav-eling through rock and mining equipment as well as sound waves propagating in the workings. We show that waveform moveouts are clearly visible, and that the standard deviation of the audio recordings is a straightforward yet promising metric that could help quantify burst damage. Although improvements are needed before mines can routinely use this monitoring strategy, DAS-based seismoacoustic arrays may assist in understanding coal-burst mechanisms and managing associated risks in underground longwall mines as well as enable better understanding of damage associated with dynamic failures in other underground environments. © Seismological Society of America. |
Utilization of statistical analysis to identify influential slope parameters associated with rockfall at open pit mines
Bourgeois J , Warren S , Armstrong J . Min Metall Explor 2023 The application of statistical analysis software programs has proven useful for the investigation of rockfall runout distance along a designed slope. Rockfall modeling programs are continually being upgraded with more sophisticated analysis tools, such as the use of the rigid body versus lump mass models. Engineers at mine sites utilizing the software may have varied experience related to these models, their associated input parameters, and how to interpret the generated results. To address this concern, researchers at the Spokane Mining Research Division (SMRD) of the US National Institute for Occupational Safety and Health (NIOSH) investigated the influence of slope height, slope angle, slope material, and rock size for both rigid body and lump mass models in a 2-D statistical analysis program. Based on a literature search and industry input, specific ranges common to that of an open pit mining environment were chosen for each of the input parameters to determine 90% rock runout distance as well as their sensitivity to change. Data collected from this numerical analysis and simulation will be compared to empirical rockfall data gathered through the duration of the Highwall Safety project conducted by NIOSH from 2022–2026. © 2023, This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply. |
Report of the Science Community Workshop on the proposed first sample depot for the Mars sample return campaign
Czaja AD , Zorzano MP , Kminek G , Meyer MA , Beaty DW , Sefton-Nash E , Carrier BL , Thiessen F , Haltigin T , Bouvier A , Dauphas N , French KL , Hallis LJ , Harris RL , Hauber E , Rodriguez LE , Schwenzer SP , Steele A , Tait KT , Thorpe MT , Usui T , Vanhomwegen J , Velbel MA , Edwin S , Farley KA , Glavin DP , Harrington AD , Hays LE , Hutzler A , Wadhwa M . Meteorit Planet Sci 2023 The Mars 2020/Mars Sample Return (MSR) Sample Depot Science Community Workshop was held on September 28 and 30, 2022, to assess the Scientifically-Return Worthy (SRW) value of the full collection of samples acquired by the rover Perseverance at Jezero Crater, and of a proposed subset of samples to be left as a First Depot at a location within Jezero Crater called Three Forks. The primary outcome of the workshop was that the community is in consensus on the following statement: The proposed set of ten sample tubes that includes seven rock samples, one regolith sample, one atmospheric sample, and one witness tube constitutes a SRW collection that: (1) represents the diversity of the explored region around the landing site, (2) covers partially or fully, in a balanced way, all of the International MSR Objectives and Samples Team scientific objectives that are applicable to Jezero Crater, and (3) the analyses of samples in this First Depot on Earth would be of fundamental importance, providing a substantial improvement in our understanding of Mars. At the conclusion of the meeting, there was overall community support for forming the First Depot as described at the workshop and placing it at the Three Forks site. The community also recognized that the diversity of the Rover Cache (the sample collection that remains on the rover after placing the First Depot) will significantly improve with the samples that are planned to be obtained in the future by the Perseverance rover and that the Rover Cache is the primary target for MSR to return to Earth. © 2023 His Majesty the King in Right of Canada, Royal Ontario Museum, Jet Propulsion Laboratory, California Institute of Technology and The Authors. Government sponsorship acknowledged. Meteoritics & Planetary Science published by Wiley Periodicals LLC on behalf of The Meteoritical Society. Reproduced with the permission of the Minister of Canadian Space Agency. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA. |
Numerical investigation of powder aerosolization in a mining rock dust dispersion chamber
Chen H , Turkevich LA , Jog MA , Ghia U . J Loss Prev Process Ind 2023 83 We have conducted numerical simulations of dust dispersion within the NIOSH Rock Dust Dispersion Chamber. The apparatus consists of a low-speed background ventilation flow down a long box in which is placed a tray containing a rock dust powder. A nozzle upstream of the tray introduces a short pulse of a turbulent horizontal jet flow just above the powder surface. We have utilized an incompressible Reynolds-Averaged Navier-Stokes k-ω model for the turbulent flow; particles are incorporated within a one-way Euler-Lagrangian formalism. The Rock Dust Dispersion Chamber ventilation flow exhibits a recirculation zone just above the powder-containing tray. Aerosolization proceeds via the interplay of the jet pulse flow with the background recirculation flow. The air flow is not well-mixed. The aerosolized dust is convected as a concentration cloud downstream towards the detection zone. For larger particles, gravitational settling depletes the convected cloud, so the instrument behaves as a horizontal elutriator. The instrument is robust with respect to misalignment of the jet nozzle. However, reduced streamwise drift velocity allows mixing to disperse the optically detected dust cloud concentration pulse. Our large particle simulation results compare favorably with published experimental results for large, polydisperse calcium carbonate rock dust. © 2023 |
Natural reservoir Rousettus aegyptiacus bat host model of orthonairovirus infection identifies potential zoonotic spillover mechanisms
Schuh AJ , Amman BR , Guito JC , Graziano JC , Sealy TK , Kirejczyk SGM , Towner JS . Sci Rep 2022 12 (1) 20936 The human-pathogenic Kasokero virus (KASV; genus Orthonairovirus) has been isolated from the sera of Egyptian rousette bats (ERBs; Rousettus aegyptiacus) captured in Uganda and unengorged Ornithodoros (Reticulinasus) faini ticks collected from the rock crevices of ERB colonies in South Africa and Uganda. Although evidence suggests that KASV is maintained in an enzootic transmission cycle between O. (R.) faini ticks and ERBs with potential for incidental virus spillover to humans through the bite of an infected tick, the vertebrate reservoir status of ERBs for KASV has never been experimentally evaluated. Furthermore, the potential for bat-to-bat and bat-to-human transmission of KASV is unknown. Herein, we inoculate two groups of ERBs with KASV; one group of bats is serially sampled to assess viremia, oral, fecal, and urinary shedding and the second group of bats is serially euthanized to assess virus-tissue tropism. Throughout the study, none of the bats exhibit overt signs of clinical disease. Following the detection of high KASV loads of long duration in blood, oral, fecal, and urine specimens collected from ERBs in the serial sampling group, all bats seroconvert to KASV. ERBs from the serial euthanasia group exhibit high KASV loads indicative of virus replication in the skin at the inoculation site, spleen, and inguinal lymph node tissue, and histopathology and in situ hybridization reveal virus replication in the liver and self-limiting, KASV-induced lymphohistiocytic hepatitis. The results of this study suggest that ERBs are competent, natural vertebrate reservoir hosts for KASV that can sustain viremias of appropriate magnitude and duration to support virus maintenance through bat-tick-bat transmission cycles. Viral shedding data suggests that KASV might also be transmitted bat-to-bat and highlights the potential for KASV spillover to humans through contact with infectious oral secretions, feces, or urine. |
Evaluating size effects for a porous, weak, homogeneous limestone
Sinha S , Walton G , Chaurasia A , Diederichs M , Batchler T . Rock Mech Rock Eng 2022 [Epub ahead of print] In rock engineering, size effects have been a topic of extensive research since the early 1960s, and despite many advances over the years, our understanding of size effect remains incomplete, especially for weak, porous, homogeneous rocks. Indeed, the vast majority of studies related to size effect have specifically considered low porosity rocks (generally crystalline). To bridge this gap in knowledge, we conducted unconfined compression tests on cubic limestone blocks ranging in size from 0.1 to 0.9 m. Texas Cream Limestone, which is a porous, homogeneous, weak rock, was chosen for this study. As this rock has not previously been studied in the literature, conventional compression tests and indirect tensile strength tests on cylindrical specimens were completed prior to testing the cube specimens. For the largest specimens, 3D digital image correlation (3D-DIC) was employed to track the surficial displacements as a function of the applied load. The tests revealed a lack of size effect for the entire range of block sizes considered. To evaluate size effects more broadly, data from prior studies on sedimentary rocks were compiled, and a tendency for the magnitude of the size effect on strength to decline with increasing porosity was noted. Some hypotheses regarding this trend are presented and evaluated based on strain-field heterogeneity metrics obtained from the 3D-DIC analysis. |
Review of current coal rib control practices
Guner D , Nowak S , Sherizadeh T , Sunkpal M , Mohamed K , Xue Y . Underground Space 2023 9 53-75 The instability of coal ribs in underground mines continues to result in the injuries and fatalities of mine workers. The proper estimation and evaluation of primary and secondary support for coal ribs is still a challenging problem in the field of ground control science and requires further research and study. Although mining operations have various support design criteria and support methodologies for strata control, most rib support designs are still based on experience and local practices. This review study is intended to summarize the currently applied practices for rib support and control in various countries and mining conditions. Firstly, critical parameters that control the amount and type of required rib support are considered and evaluated. The study revealed that among these parameters that control the stability of coal ribs, mining depth, rib height, cleat orientation/condition, and coal strength are the most significant parameters. Secondly, current rib support application methods were also summarized. Similar to rock mass classification systems, some studies proposed a rib control rating system for practical estimation of the current rib condition and to estimate primary support requirements. These studies are classified and summarized into two groups (categorical and empirical) based on the required inputs and methodologies. Empirically based coal rib rating systems were closely examined, and the usefulness and intuitive aspects of each rating system were compared. This comprehensive literature review demonstrates that the Australian rating system, Analysis and Design of Rib Support (ADRS), and the new U.S. rating system, Coal Pillar Rib Rating (CPRR), are highly applicable for their regions. © 2022 |
Analysis of steel prop supports subjected to vertical and lateral loading
Mohamed K , Batchler T . Min Metall Explor 2022 39 (5) 2001-2010 Standing supports have been used in coal mines for decades to enhance roof support capability. Sometimes standing supports are used as a tool to resist the lateral movement of spalled ribs. Researchers from the National Institute for Occupational Safety and Health (NIOSH) are conducting a testing program for different types of standing supports (steel and timber) to investigate the effect of lateral loading on their vertical loading capacities and the factors affecting their lateral loading capacities. In this paper, the mine roof simulator (MRS), at the NIOSH Pittsburgh research facility, was used to determine the response of steel props to vertical and horizontal loadings. Finite element models (FEMs) were developed and verified using the tested steel props. To justify the testing program for testing standing supports with end-conditions of rock-like materials, the verified prop models were used to study the effect of a wide range of roof and floor materials (gray shale, shale, and claystone) on the critical buckling loads of the steel props. Also, several lateral loading scenarios were evaluated in which the steel props were laterally loaded at different heights. The critical buckling load for steel props setting up against a claystone roof and floor was found to be one-half of that shown by the MRS test where roof and floor platens are made of steel. Minimum prop performance was observed when the lateral load was applied at the mid-height of the steel prop, especially at small lateral displacement (less than 2 in). 2022, This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply. |
Nonmalignant respiratory disease mortality in male Colorado Plateau uranium miners, 1960-2016
Kelly-Reif K , Bertke S , Daniels RD , Richardson DB , Schubauer-Berigan MK . Am J Ind Med 2022 65 (10) 773-782 BACKGROUND: To evaluate trends of nonmalignant respiratory disease (NMRD) mortality among US underground uranium miners on the Colorado Plateau, and to estimate the exposure-response association between cumulative radon progeny exposure and NMRD subtype mortality. METHODS: Standardized mortality ratios (SMRs) and excess relative rates per 100 working level months (excess relative rate [ERR]/100 WLM) were estimated in a cohort of 4021 male underground uranium miners who were followed from 1960 through 2016. RESULTS: We observed elevated SMRs for all NMRD subtypes. Silicosis had the largest SMR (n = 52, SMR = 41.4; 95% confidence interval [CI]: 30.9, 54.3), followed by other pneumoconiosis (n = 49, SMR = 39.6; 95% CI: 29.6, 52.3) and idiopathic pulmonary fibrosis (IPF) (n = 64, SMR = 4.77; 95% CI 3.67, 6.09). SMRs for silicosis increased with duration of employment; SMRs for IPF increased with duration of employment and calendar period. There was a positive association between cumulative radon exposure and silicosis with evidence of modification by smoking (ERR/100 WLM(≥10 pack-years) = 0.78; 95% CI: 0.05, 24.6 and ERR/100 WLM(<10 pack-years) = 0.01; 95% CI: -0.03, 0.52), as well as a small positive association between radon and IPF (ERR/100 WLM = 0.06, 95% CI: 0.00, 0.24); these associations were driven by workers with prior employment in hard rock mining. CONCLUSIONS: Uranium mining workers had excess NMRD mortality compared with the general population; this excess persisted throughout follow-up. Exposure-response analyses indicated a positive association between radon exposure and IPF and silicosis, but these analyses have limitations due to outcome misclassification and missing information on occupational co-exposures such as silica dust. |
Assessment of floor heave associated with bumps in a longwall mine using the discrete element method
Kim BH , Larson MK . Min Metall Explor 2022 39 (5) 1853-1861 This study was developed as part of an effort by the National Institute for Occupational Safety and Health (NIOSH) to better understand rock-mass behavior in longwall coal mines in highly stressed, bump-prone ground. The floor-heave and no-floor-heave phenomena at a western US coal mine could not be properly simulated in numerical models using conventional shear-dominant failure criteria (i.e., MohrCoulomb or HoekBrown failure criterion). The previous numerical study demonstrated these phenomena using a user-defined model of the s-shaped brittle failure criterion in conjunction with a spalling process in the FLAC3D numerical modeling software. The results of the FLAC3D modeling agreed with the observations of the relative amounts of heave from each gate-road system. However, the FLAC3D model adopted many assumptions and simplifications that were not very realistic from a physical or mechanical perspective. To overcome the limitations of the FLAC3D model, 3DEC modeling in conjunction with the discrete fracture network (DFN) technique was performed to better understand the true behavior of floor heave associated with underground mining in an anisotropic stress field. The effect of stress rotation in the mining-induced stress field was considered by using a different geometry of rock fractures in the coal seam. The heterogeneity of the engineering properties (i.e., cohesion and tensile strength) were also considered by using Monte Carlo simulations. Consequently, the 3DEC models using the DFN technique resulted in predictions of floor heave that agreed with observations of the relative amounts of heave from each gate-road system, but the cause of heave was mainly related to the degree of anisotropy instead of the size of the pillar. 2022, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply. |
A comprehensive roof bolter drilling control algorithm for enhancing energy efficiency and reducing respirable dust
Jiang H , Luo Y . Min Metall Explor 2022 39 (2) 241-249 In underground coal mines, the drilling process in roof bolting operation could generate excessive amount of respirable coal and quartz dusts. Improper drilling control might also pose safety hazard and interrupt production. Therefore, an automated, high-efficiency drilling control system with safety features can be beneficial to the bolter personnel. In this research, a comprehensive drilling control algorithm has been developed to reduce the generation of respirable dust and to increase the drilling energy efficiency based on laboratory drilling test results and safety considerations. Specific energy is used to evaluate the energy efficiency. In addition, the ratio between specific energy and rock uniaxial compressive strength can be used as a basis for determining the rational drilling bite depthtypically a determined high one permissible by the driller power and drill steel. The test results show that to achieve and maintain a desired drilling bite depth for good drilling performance, a combination of relatively low rotational rate and a rationally high penetration is preferred. By monitoring the drilling rate, the system is able to evaluate the bit wear condition and improve drilling safety. In this paper, the developed drilling control algorithm for achieving a rational drilling bite depth is demonstrated. By adapting this drilling control algorithm, the drilling efficiency and bit condition can be monitored in real time, so the system can maintain a relatively high energy efficiency, generate less respirable dust, and avoid drilling failure. 2022, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply. |
Coal and Rock Classification with Rib Images and Machine Learning Techniques
Xue Y . Min Metall Explor 2022 39 (2) 453-465 Classification of rock and coal is one preliminary problem for fully automated or intelligent mining. It assists for the automated rib stability analysis and enables the shearer to adjust the drums without human intervention. In this paper, the classification of rock from coal on rib images has been studied with machine learning techniques. A database of rock and coal image has been created by filtering photographs taken by NIOSH researchers in gateroad during site visits and only the images with fresh areas of rock and coal on the rib were selected. Machine learning was conducted on patches with a determined size, which are smaller images randomly extracted from each rock or coal image. After training, the classifier was validated with the testing dataset and an accuracy score of 0.9 was obtained. The influence of patch size and classifier was also investigated. The trained classifier was then applied to classify rock and coal on a new rib image with three rock layers of different thicknesses and good agreement was achieved. 2021, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply. |
Laboratory and field evaluations of a commercially available real-time loop-mediated isothermal amplification assay for the detection of West Nile virus in mosquito pools
Burkhalter KL , O'Keefe M , Holbert-Watson Z , Green T , Savage HM , Markowski DM . J Am Mosq Control Assoc 2021 37 (4) 256-262 Although the specific cDNA amplification mechanisms of reverse-transcriptase polymerase chain reaction (RT-PCR) and RT loop-mediated isothermal amplification (RT-LAMP) are very different, both molecular assays serve as options to detect arboviral RNA in mosquito pools. Like RT-PCR, RT-LAMP uses a reverse transcription step to synthesize complementary DNA (cDNA) from an RNA template and then uses target-specific primers to amplify cDNA to detectable levels in a single-tube reaction. Using laboratory-generated West Nile virus (WNV) samples and field-collected mosquito pools, we evaluated the sensitivity and specificity of a commercially available WNV real-time RT-LAMP assay (Pro-AmpRT™ WNV; Pro-Lab Diagnostics, Inc., Round Rock, Texas) and compared the results to a validated real-time RT-PCR assay. Laboratory generated virus stock samples containing ≥ 2.3 log10 plaque-forming units (PFU)/ml and intrathoracically inoculated mosquitoes containing ≥ 2.4 log10 PFU/ml produced positive results in the Pro-AmpRT WNV assay. Of field-collected pools that were WNV positive by real-time RT-PCR, 74.5% (70 of 94) were also positive by the Pro-AmpRT WNV assay, resulting in an overall Cohen's kappa agreement of 79.4% between the 2 tests. The Pro-AmpRT WNV assay shows promise as a suitable virus screening tool for vector surveillance programs provided agencies are aware of its characteristics and limitations. |
Impact of Statewide Prevention and Reduction of Clostridioides difficile (SPARC), a Maryland public health-academic collaborative: an evaluation of a quality improvement intervention
Rock C , Perlmutter R , Blythe D , Bork J , Claeys K , Cosgrove SE , Dzintars K , Fabre V , Harris AD , Heil E , Hsu YJ , Keller S , Maragakis LL , Milstone AM , Morgan DJ , Dullabh P , Ubri PS , Rotondo C , Brooks R , Leekha S . BMJ Qual Saf 2021 31 (2) 153-162 To evaluate changes in Clostridioides difficile incidence rates for Maryland hospitals that participated in the Statewide Prevention and Reduction of C. difficile (SPARC) collaborative. Pre-post, difference-in-difference analysis of non-randomised intervention using four quarters of preintervention and six quarters of postintervention National Healthcare Safety Network data for SPARC hospitals (April 2017 to March 2020) and 10 quarters for control hospitals (October 2017 to March 2020). Mixed-effects negative binomial models were used to assess changes over time. Process evaluation using hospital intervention implementation plans, assessments and interviews with staff at eight SPARC hospitals. Maryland, USA. All Maryland acute care hospitals; 12 intervention and 36 control hospitals. Participation in SPARC, a public health-academic collaborative made available to Maryland hospitals, with staggered enrolment between June 2018 and August 2019. Hospitals with higher C. difficile rates were recruited via email and phone. SPARC included assessments, feedback reports and ongoing technical assistance. Primary outcomes were C. difficile incidence rate measured as the quarterly number of C. difficile infections per 10 000 patient-days (outcome measure) and SPARC intervention hospitals' experiences participating in the collaborative (process measures). SPARC invited 13 hospitals to participate in the intervention, with 92% (n=12) participating. The 36 hospitals that did not participate served as control hospitals. SPARC hospitals were associated with 45% greater C. difficile reduction as compared with control hospitals (incidence rate ratio=0.55, 95% CI 0.35 to 0.88, p=0.012). Key SPARC activities, including access to trusted external experts, technical assistance, multidisciplinary collaboration, an accountability structure, peer-to-peer learning opportunities and educational resources, were associated with hospitals reporting positive experiences with SPARC. SPARC intervention hospitals experienced 45% greater reduction in C. difficile rates than control hospitals. A public health-academic collaborative might help reduce C. difficile and other hospital-acquired infections in individual hospitals and at state or regional levels. |
Laboratory development and pilot-scale deployment of a two-part foamed rock dust
Brown CB , Perera IE , Harris ML , Chasko LL , Addis JD , Klima S . J Loss Prev Process Ind 2022 74 U.S. Code of Federal Regulations 30 CFR 75.402 and 75.403 require 80% total incombustible content to be maintained within 40 feet of the coal mine face via the liberal application of rock dust. Unfortunately, this application of rock dust limits miners' visibility downwind and can increase the miners' exposures to a respirable nuisance dust. Wet rock dust applied as a slurry is, at times, used to negate these negative effects. Although this aids in meeting the total incombustible limits, the slurry forms a hard cake when dried and no longer effectively disperses as needed to suppress a coal dust explosion. As a result, a dry rock dust must be reapplied to maintain a dispersible layer. Therefore, researchers from the National Institute for Occupational Safety and Health (NIOSH) have been working towards finding and testing a foamed rock dust formulation that can be applied wet on mine surfaces and remain dispersible once dried which minimizes the likelihood of mine disasters, including mine explosions. The initial tests were aimed at discerning dispersion characteristics of three different foamed rock dusts via the NIOSH-developed dispersion chamber and led to identification of a two-part foam with adequate dispersion characteristics. The current study was conducted to assess the robustness of the two-part foamed rock dust. Through a series of laboratory-scale experiments using the dispersibility chamber, the effects of testing conditions and product formulations on the foam's dispersibility was determined. Some of the tested variables include: exposing the foam to high humidity, varying the component levels of the foamed rock dust, altering the rock dust size distribution, and varying the rock dust types. Further pilot-scale tests examined the atmospheric concentrations of dust via personal dust monitors downwind of foamed rock dust production and application. Additionally, product consistency was recorded during pilot-scale testing at key points in the formulation and application. The results of these experiments will be discussed in this paper. © 2021 |
Advancing diagnostic stewardship for healthcare associated infections, antibiotic resistance, and sepsis
Curren EJ , Lutgring JD , Kabbani S , Diekema DJ , Gitterman S , Lautenbach E , Morgan DJ , Rock C , Salerno RM , McDonald LC . Clin Infect Dis 2021 74 (4) 723-728 Diagnostic stewardship means ordering the right tests, for the right patient at the right time to inform optimal clinical care. Diagnostic stewardship is an integral part of antibiotic stewardship efforts to optimize antibiotic use and improve patient outcomes, including reductions in antibiotic resistance, and treatment of sepsis. CDC's Division of Healthcare Quality Promotion (DHQP) hosted a meeting on improving patient safety through diagnostic stewardship with a focus on the use of the laboratory. The meeting identified emerging issues in the field of diagnostic stewardship, raised awareness of these issues among stakeholders, and discussed strategies and interventions to address the issues-all with an emphasis on improved outcomes and patient safety. This white paper summarizes the key takeaways of the meeting including needs for diagnostic stewardship implementation, promising future avenues for diagnostic stewardship implementation, and areas of needed research. |
Analysis and Characterization of Anti-Caking Additives Used in Rock Dust to Mitigate Mine Explosions
Perera IE , Harris ML , Sapko MJ . Min Metall Explor 2021 38 (3) 1411-1419 Experiments conducted with limestone dusts and dolomitic marble dusts have indicated that when rock dust is wetted and subsequently dried, it becomes a solid, non-dispersible cake. However, in order to be effectively inert a coal dust explosion, rock dust must be able to disperse as individual particles to air. To counteract this, rock dust manufacturers created treated rock dusts that will resist caking after moisture exposure. National Institute for Occupational Safety and Health (NIOSH) researchers conducted a series of laboratory-scale experiments on four base rock dusts and their treated counterparts to assess the effectiveness of various anti-caking additives after being exposed to moisture and then dried. The dusts were exposed to moisture using humidity cabinets having a high relative humidity (99% RH) and by also exposing the rock dust bed to water through bottom wicking. The dusts were then evaluated for dispersibility after drying using the NIOSH-designed dust dispersion chamber. The anti-caking additives were different concentrations of stearic acid, oleic acid, and xylene-based surfactants. All results were compared to a reference rock dust used to conduct large-scale experiments in the Lake Lynn Experimental Mine (LLEM), Fairchance, PA. When the untreated dusts were dried after exposure to moisture for 1 day, no dispersion was measured. However, rock dusts treated with anti-caking agents were readily dispersible even after exposure to moisture for 6 months. This report details the analysis and characterization of anti-caking additives using the NIOSH-designed dispersion chamber and the 20-L explosion test chamber. © 2019, This is a U.S. government work and its text is not subject to copyright protection in the United States; however, its text may be subject to foreign copyright protection. |
SARS-COV-2 ANTIBODY PREVALENCE AMONG HEALTHCARE WORKERS AND FIRST RESPONDERS, FLORIDA, MAY-JUNE 2020.
Matthias J , Spencer EC , Michniewicz M , Bendle TM , Wilson C , Scheppke KA , Blackmore C , Otis A , Rivkees SA . Fla Public Health Rev 2021 18 (1) 1-10 BACKGROUND: The SARS-CoV-2 virus responsible for severe respiratory infection associated with coronavirus disease 2019 (COVID-19) was first confirmed in Florida on March 1, 2020. Responding to the pandemic, multi-agency collaborative partnerships put in place actions integrating point-of-care antibody testing at established large-scale COVID-19 testing sites where the baseline seropositivity of COVID-19 in health care workers and first responders in Florida at the start of the pandemic was established. PURPOSE: Determine the seropositivity of healthcare workers and first responders at five drive thru testing sites using a rapid SARS-CoV-2 antibody test in Florida from May 6 through June 3, 2020. METHODS: The first drive-thru SARS-CoV-2 antibody test site was opened at Miami Hard Rock Stadium, May 6, 2020. Testing expanded to three additional sites on May 9, 2020: Jacksonville, Orlando, and Palm Beach. The fifth and final site, Miami Beach, began testing on May 21, 2020. Healthcare workers and first responder's self-seeking SARS-CoV-2 testing were designated for antibody testing and completed a laboratory collection form onsite for the point-of-care test. All testing was performed on whole blood specimens (obtained by venipuncture) using the Cellex Inc. qSARS-CoV-2 IgG/IgM Rapid Test. Seropositivity was assessed by univariate analysis and by logistic regression including the covariates age, sex, race/ethnicity, and testing location. RESULTS AND DISCUSSION: As of June 3, 2020, of 5,779 healthcare workers and first responders tested, 4.1% were seropositive (range 2.6-8.2%). SARS-COV-2 antibody tests had higher odds of being positive for persons testing at the Miami Hard Rock Stadium (aOR 2.24 [95% C.I. 1.48-3.39]), persons of Haitian/Creole ethnicity (aOR 3.28 [95% C.I. 1.23-8.72]), Hispanic/Latino(a) ethnicity (aOR 2.17 [95% C.I. 1.50-3.13], and Black non-Hispanic persons (aOR 1.63 [95% C.I. 1.08-2.46]). SARS-COV-2 antibody prevalence among first responders and healthcare workers in five sites in Florida varied by race and ethnicity and by testing location. |
Risk Factors Associated With SARS-CoV-2 Seropositivity Among US Health Care Personnel.
Jacob JT , Baker JM , Fridkin SK , Lopman BA , Steinberg JP , Christenson RH , King B , Leekha S , O'Hara LM , Rock P , Schrank GM , Hayden MK , Hota B , Lin MY , Stein BD , Caturegli P , Milstone AM , Rock C , Voskertchian A , Reddy SC , Harris AD . JAMA Netw Open 2021 4 (3) e211283 IMPORTANCE: Risks for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among health care personnel (HCP) are unclear. OBJECTIVE: To evaluate the risk factors associated with SARS-CoV-2 seropositivity among HCP with the a priori hypothesis that community exposure but not health care exposure was associated with seropositivity. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study was conducted among volunteer HCP at 4 large health care systems in 3 US states. Sites shared deidentified data sets, including previously collected serology results, questionnaire results on community and workplace exposures at the time of serology, and 3-digit residential zip code prefix of HCP. Site-specific responses were mapped to a common metadata set. Residential weekly coronavirus disease 2019 (COVID-19) cumulative incidence was calculated from state-based COVID-19 case and census data. EXPOSURES: Model variables included demographic (age, race, sex, ethnicity), community (known COVID-19 contact, COVID-19 cumulative incidence by 3-digit zip code prefix), and health care (workplace, job role, COVID-19 patient contact) factors. MAIN OUTCOME AND MEASURES: The main outcome was SARS-CoV-2 seropositivity. Risk factors for seropositivity were estimated using a mixed-effects logistic regression model with a random intercept to account for clustering by site. RESULTS: Among 2 749 HCP, most were younger than 50 years (17 233 [69.6%]), were women (19 361 [78.2%]), were White individuals (15 157 [61.2%]), and reported workplace contact with patients with COVID-19 (12 413 [50.2%]). Many HCP worked in the inpatient setting (8893 [35.9%]) and were nurses (7830 [31.6%]). Cumulative incidence of COVID-19 per 10 000 in the community up to 1 week prior to serology testing ranged from 8.2 to 275.6; 20 072 HCP (81.1%) reported no COVID-19 contact in the community. Seropositivity was 4.4% (95% CI, 4.1%-4.6%; 1080 HCP) overall. In multivariable analysis, community COVID-19 contact and community COVID-19 cumulative incidence were associated with seropositivity (community contact: adjusted odds ratio [aOR], 3.5; 95% CI, 2.9-4.1; community cumulative incidence: aOR, 1.8; 95% CI, 1.3-2.6). No assessed workplace factors were associated with seropositivity, including nurse job role (aOR, 1.1; 95% CI, 0.9-1.3), working in the emergency department (aOR, 1.0; 95% CI, 0.8-1.3), or workplace contact with patients with COVID-19 (aOR, 1.1; 95% CI, 0.9-1.3). CONCLUSIONS AND RELEVANCE: In this cross-sectional study of US HCP in 3 states, community exposures were associated with seropositivity to SARS-CoV-2, but workplace factors, including workplace role, environment, or contact with patients with known COVID-19, were not. These findings provide reassurance that current infection prevention practices in diverse health care settings are effective in preventing transmission of SARS-CoV-2 from patients to HCP. |
Development of a roof bolter drilling control process to reduce the generation of respirable dust
Jiang H , Luo Y . Int J Coal Sci Technol 2021 8 (2) 199-204 The drilling operation in the roof bolting process, especially in hard rock, generates excessive respirable coal and quartz dusts, which could expose the roof bolting operator to continued health risks. Previous research has shown that the amount of respirable dust produced is dependent on the main drilling parameters, specifically the drilling rotational and penetration rate. In this paper, a roof bolter drilling control process was proposed to reduce the generation of respirable dust. Based on the analysis of laboratory drilling test results, a rational drilling control process (adjusting rotational and penetration rates) to achieve the optimal drilling parameter for different rock types was proposed. In this process, the ratio between specific energy and rock uniaxial compressive strength was used as the index to determine the optimal operation point. The recommended drilling operation range for the rock type used in the experiment was provided, and the reduction in respirable dust generation was demonstrated. By following this control process, the drilling efficiency can be monitored in real time, so the system can stay in a relatively high-energy efficiency with less respirable dust production from the drilling source. This algorithm is targeted to be incorporated into the current roof bolter drilling control system for drilling automation so that a safe and productive drilling operation can be conducted in a healthy working environment. |
Descriptive exploration of overdose codes in hospital and emergency department discharge data to inform development of drug overdose morbidity surveillance indicator definitions in ICD-10-CM
Tyndall Snow LM , Hall KE , Custis C , Rosenthal AL , Pasalic E , Nechuta S , Davis JW , Jacquemin BJ , Jagroep SR , Rock P , Contreras E , Gabella BA , James KA . Inj Prev 2021 27 i27-i34 BACKGROUND: In October 2015, discharge data coding in the USA shifted to the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM), necessitating new indicator definitions for drug overdose morbidity. Amid the drug overdose crisis, characterising discharge records that have ICD-10-CM drug overdose codes can inform the development of standardised drug overdose morbidity indicator definitions for epidemiological surveillance. METHODS: Eight states submitted aggregated data involving hospital and emergency department (ED) discharge records with ICD-10-CM codes starting with T36-T50, for visits occurring from October 2015 to December 2016. Frequencies were calculated for (1) the position within the diagnosis billing fields where the drug overdose code occurred; (2) primary diagnosis code grouped by ICD-10-CM chapter; (3) encounter types; and (4) intents, underdosing and adverse effects. RESULTS: Among all records with a drug overdose code, the primary diagnosis field captured 70.6% of hospitalisations (median=69.5%, range=66.2%-76.8%) and 79.9% of ED visits (median=80.7%; range=69.8%-88.0%) on average across participating states. The most frequent primary diagnosis chapters included injury and mental disorder chapters. Among visits with codes for drug overdose initial encounters, subsequent encounters and sequelae, on average 94.6% of hospitalisation records (median=98.3%; range=68.8%-98.8%) and 95.5% of ED records (median=99.5%; range=79.2%-99.8%), represented initial encounters. Among records with drug overdose of any intent, adverse effect and underdosing codes, adverse effects comprised an average of 74.9% of hospitalisation records (median=76.3%; range=57.6%-81.1%) and 50.8% of ED records (median=48.9%; range=42.3%-66.8%), while unintentional intent comprised an average of 11.1% of hospitalisation records (median=11.0%; range=8.3%-14.5%) and 28.2% of ED records (median=25.6%; range=20.8%-40.7%). CONCLUSION: Results highlight considerations for adapting and standardising drug overdose indicator definitions in ICD-10-CM. |
Interrupted time series analysis to evaluate the performance of drug overdose morbidity indicators shows discontinuities across the ICD-9-CM to ICD-10-CM transition
Yang H , Pasalic E , Rock P , Davis JW , Nechuta S , Zhang Y . Inj Prev 2021 27 i35-i41 INTRODUCTION: On 1 October 2015, the USA transitioned from the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) to the International Classification of Diseases, 10th Revision (ICD-10-CM). Considering the major changes to drug overdose coding, we examined how using different approaches to define all-drug overdose and opioid overdose morbidity indicators in ICD-9-CM impacts longitudinal analyses that span the transition, using emergency department (ED) and hospitalisation data from six states' hospital discharge data systems. METHODS: We calculated monthly all-drug and opioid overdose ED visit rates and hospitalisation rates (per 100 000 population) by state, starting in January 2010. We applied three ICD-9-CM indicator definitions that included identical all-drug or opioid-related codes but restricted the number of fields searched to varying degrees. Under ICD-10-CM, all fields were searched for relevant codes. Adjusting for seasonality and autocorrelation, we used interrupted time series models with level and slope change parameters in October 2015 to compare trend continuity when employing different ICD-9-CM definitions. RESULTS: Most states observed consistent or increased capture of all-drug and opioid overdose cases in ICD-10-CM coded hospital discharge data compared with ICD-9-CM. More inclusive ICD-9-CM indicator definitions reduced the magnitude of significant level changes, but the effect of the transition was not eliminated. DISCUSSION: The coding change appears to have introduced systematic differences in measurement of drug overdoses before and after 1 October 2015. When using hospital discharge data for drug overdose surveillance, researchers and decision makers should be aware that trends spanning the transition may not reflect actual changes in drug overdose rates. |
Large-scale explosion propagation testing of treated and non-treated rock dust when overlain by a thin layer of coal dust
Perera IE , Harris ML , Sapko MJ , Dyduch Z , Cybulski K , Hildebrandt R , Goodman GVR . Min Metall Explor 2021 38 (2) 1009-1017 To prevent coal dust explosion propagations, rock dust needs to be lifted and suspended in the air with the coal dust during an explosion. The addition of anti-caking agents prevents caking of rock dust in the presence of water. Mining and rock dusting processes can frequently create alternating layers of rock dust and float coal dust on mine surfaces. For this test series, a thin layer of coal dust was distributed on top of a layer of either treated or non-treated rock dust in the Experimental Mine Barbara, Poland. The experimental results compare the effectiveness of treated and non-treated rock dusts to attenuate a propagating coal dust explosion initiated with either strong or weak methane explosions. Experimental results indicate that the treated rock dust performs better than non-treated rock dust in arresting a propagating explosion, especially in the presence of moisture. |
Controlling crosscut damage in response to excessive levels of horizontal stress: Case study at the Subtropolis mine, Petersburg, OH
Evanek N , Iannacchione A , Miller T . Min Metall Explor 2021 38 (1) 645-653 The Subtropolis Mine is a room-and-pillar mine extracting the Vanport limestone near Petersburg, Ohio, at a depth of approximately 59.4 m (190 ft). In February of 2018, mine management began implementing a new layout to better control the negative effects of excessive levels of horizontal stress. Almost immediately, the conditions in the headings improved. Conversely, and as expected, stress-related damage concentrated within crosscuts. Over the last 18 months, the mine operator has diligently experimented with different techniques/methods to lessen the impact of the instabilities in the outby crosscuts. The range of controls used by the mine operator include angled crosscuts, crosscut offsets, increase distance between crosscuts, arched crosscuts, cable bolted crosscuts, altered blasting pattern, and windows. A window is used to resist roof deformation by leaving a strong brow of roof rock within the crosscuts. A window reduces the crosscut dimensions vertically and, in some applications, horizontally. With each application of engineering controls, conditions were monitored and analyzed using observational and measurement techniques. In every case, the advantages in ground conditions were weighed against its impacts to haulage, ventilation, and other mining considerations. This paper examines how each engineering control was implemented and assessed. All these controls are based on well-established geomechanics principles, but experience has shown that local modifications are needed to deal with the unique local conditions such as geology, mining method, mine equipment, and in situ stress conditions. |
Re-analysis of abutment angle method for moderate and deep cover retreat room and pillar mines and investigation of loading mechanics using finite volume modeling
Tuncay D , Tulu IB , Klemetti T . Rock Mech Rock Eng 2021 54 (7) 3447-3468 Mining-induced stresses in underground coal mines play a significant role in pillar and ground support design, hence in the safety of mining operations. In the US, Analysis of Longwall Pillar Stability (ALPS) and in Australia, Analysis of Longwall Tailgate Serviceability (ALTS) software are used for designing Longwall coal mine layouts; and in the US, Analysis of Retreat Mining Pillar Stability (ARMPS) software is used to design retreat room-and-pillar mine layouts. All these software determine the adequacy of the design by comparing the estimated loads to the load-bearing capacity of the pillars and they use the “abutment angle” concept and a square decay stress distribution function to calculate the magnitude and distribution of the mining-induced loads. The abutment angle concept has been successfully applied to US longwall coal mines with the use of ALPS and ALTS in Australia. ARMPS uses the same concept for retreat room and pillar coal mine design in the US. The suggested abutment angle for coal mines in the US was derived as 21° by the back analysis of underground stress measurements from the 1990s and implemented in ALPS and ARMPS. The ALPS methodology was re-examined and calibrated for Australian conditions with additional Australian stress measurements and resulted in the original ALTS methodology which has been continually improved and expanded with additional cases. In this paper, some recent stress measurements are back-analyzed, and the abutment angles are investigated to verify the applicability of using 21° in retreat room and pillar mines with different depths and mining dimensions. For shallow mines, the derivation of the 21° abutment angle is supported by the new case histories. However, at depths greater than 200 m, the abutment angle was found to be decreasing with increasing depth. In this study, a new equation for the calculation of abutment angle for moderate and deep cover cases was constructed and tested for its applicability in retreat room and pillar mines. The differences in the mechanism of complete side abutment loads in shallow and deep cover mines are further analyzed by applying the finite volume modeling (FVM) approach to two case study mines, one shallow, and one deep cover. A 2D model of each mine is created and one-side and two-side abutment loads of consecutive panels are analyzed. Analysis of the deep cover mine indicated that the prior panel gobs provide a considerable amount of support to the overburden strata. These higher gob loads prevent a higher percentage of overburden loads from being transferred to the active panel workings, and this is in agreement with the lower abutment angles observed for deep cover mines. The findings of this study should only be used for retreat room-and-pillar mines’ production pillar loads since these are calculated geometrically using the abutment angle concept. |
Application of the coal mine floor rating (CMFR) to assess the floor stability in a Central Appalachian Coal Mine
Cicek S , Tulu IB , Van Dyke M , Klemetti T , Wickline J . Int J Min Sci Technol 2020 31 (1) 83-89 Estimating the overall floor stability in a coal mine using deterministic methods which require complex engineering properties of floor strata is desirable, but generally it is impractical due to the difficulty of gathering essential input data. However, applying a quantitative methodology to describe floor quality with a single number provides a practical estimate for preliminary assessment of floor stability. The coal mine floor rating (CMFR) system, developed by the University of New South Wales (UNSW), is a rock- mass classification system that provides an indicator for the competence of floor strata. The most significant components of the CMFR are uniaxial compressive strength and discontinuity intensity of floor strata. In addition to the competence of the floor, depth of cover and stress notch angle are input parameters used to assess the preliminary floor stability. In this study, CMFR methodology was applied to a Central Appalachian Coal Mine that intermittently experienced floor heave. Exploratory drill core data, overburden maps, and mine plans were utilized for the study. Additionally, qualitative data (failure/non-failure) on floor conditions of the mine entries near the core holes was collected and analyzed so that the floor quality and its relation to entry stability could be estimated by statistical methods. It was found that the current CMFR classification system is not directly applicable in assessing the floor stability of the Central Appalachian Coal Mine. In order to extend the applicability of the CMFR classification system, the methodology was modified. A calculation procedure of one of the CMFR classification system's components, the horizontal stress rating (HSR), was changed and new parameters were added to the HSR. |
Assessing support alternatives for longwall gateroads subject to changing stress
Esterhuizen GS , Tulu IB , Gearhart DF , Dougherty H , van Dyke M . Int J Min Sci Technol 2020 31 (1) 103-110 Longwall gateroad entries are subject to changing horizontal and vertical stress induced by redistribution of loads around the extracted panel. The stress changes can result in significant deformation of the entries that may include roof sag, rib dilation, and floor heave. Mine operators install different types of supports to control the ground response and maintain safe access and ventilation of the longwall face. This paper describes recent research aimed at quantifying the effect of longwall-induced stress changes on ground stability and using the information to assess support alternatives. The research included monitoring of ground and support interaction at several operating longwall mines in the U.S., analysis and calibration of numerical models that adequately represent the bedded rock mass, and observation of the support systems and their response to changes in stress. The models were then used to investigate the impact of geology and stress conditions on ground deformation and support response for various depths of cover and geologic scenarios. The research results were summarized in two regression equations that can be used to estimate the likely roof deformation and height of roof yield due to longwall-induced stress changes. This information is then used to assess the ability of support systems to maintain the stability of the roof. The application of the method is demonstrated with a retrospective analysis of the support performance at an operating longwall mine that experienced a headgate roof fall. The method is shown to produce realistic estimates of gateroad entry stability and support performance, allowing alternative support systems to be assessed during the design and planning stage of longwall operations. |
Guest editorial special issue on ground control in mining in 2020
Murphy MM , Klemetti T , Lawson H , Mishra B , Perry K . Int J Min Sci Technol 2020 31 (1) 1-2 Ground control is the science of studying and controlling the behavior of rock strata in response to mining operations. Ground-control-related research has seen significant advancements over the last 40 years, and these accomplishments are well documented in the proceedings of the annual International Conference on Ground Control in Mining (ICGCM) [1]. The ICGCM is a forum to promote closer communication among researchers, consultants, regulators, manufacturers, and mine operators to expedite solutions to ground control problems in mining [2], [3], [4], [5], [6], [7]. Fundamental research and advancements in ground control science define the central core of the conference mission. Providing information to mine operators is a priority, as the conference goal is to offer solutions-oriented information. In addition, the conference has included innovative technologies and ideas in mining-related fields such as exploration, geology, and surface and underground mining in all commodities. Many new ground control technologies and design standards adopted by the mining industry were first discussed at ICGCM. This conference is recognized as the leading international forum for introducing new ground-control-related research and products. |
Investigating different methods used for approximating pillar loads in longwall coal mines
Tuncay D , Tulu IB , Klemetti T . Int J Min Sci Technol 2020 31 (1) 23-32 Accurately estimating load distributions and ground responses around underground openings play a significant role in the safety of the operations in underground mines. Adequately designing pillars and other support measures relies highly on the accurate assessment of the loads that will be carried by them, as well as the load-bearing capacities of the supports. There are various methods that can be used to approximate mining-induced loads in stratified rock masses to be used in pillar design. The empirical methods are based on equations derived from large databases of various case studies. They are implemented in government approved design tools and are widely used. There are also analytical and numerical techniques used for more detailed analysis of the induced loads. In this study, two different longwall mines with different panel width-to-depth ratios are analyzed using different methods. The empirical method used in the analysis is the square-decay stress function that uses the abutment angle concept, implemented in pillar design software developed by the National Institute for Occupational Safety and Health (NIOSH). The first numerical method used in the analysis is a displacement-discontinuity (DD) variation of the boundary element method, LaModel, which utilizes the laminated overburden model. The second numerical method used in the analysis is Fast Lagrangian Analysis of Continua (FLAC) with the numerical modeling approach recently developed at West Virginia University which is based on the approach developed by NIOSH. The model includes the 2D slice of a cross-section along the width of the panel with the chain pillar system that also includes the different stratigraphic layers of the overburden. All three methods gave similar results for the shallow mine, both in terms of load percentages and distribution where the variation was more obvious for the deep cover mine. The FLAC3D model was observed to better capture the stress changes observed during the field measurements for both the shallow and deep cover cases. This study allowed us to see the shortcomings of each of these different methods. It was concluded that a numerical model which incorporates the site-specific geology would provide the most precise estimate for complex loading conditions. |
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