Last data update: Sep 23, 2024. (Total: 47723 publications since 2009)
Records 1-24 (of 24 Records) |
Query Trace: Shearer E [original query] |
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On alert for Ebola: public health risk assessment of travellers from Uganda to the U.S. during the 2022 outbreak
Fowler JJ , Preston LE , Gearhart SL , Figueroa A , LChristensen D , Mitchell C , Hernandez E , Grills AW , Morrison SM , Wilkinson M , Talib T , Marie Lavilla K , Watson T , Mitcham D , Nash R , Veguilla MAC , Hansen S , Cohen NJ , Nu Clarke SA , Smithson A , Shearer E , Pella DG , Morris JD , Meehan S , Aboukheir M , Adams K , Sunavala Z , Conley J , Abouattier M , Palo M , Pimentel LC , Berro A , Mainzer H , Byrkit R , Kim D , Katebi V , Alvarado-Ramy F , Roohi S , Wojno AE , Brown CM , Gertz AM . J Travel Med 2024 31 (5) BACKGROUND: On 20 September 2022, the Ugandan Ministry of Health declared an outbreak of Ebola disease caused by Sudan ebolavirus. METHODS: From 6 October 2022 to 10 January 2023, Centers for Disease Control and Prevention (CDC) staff conducted public health assessments at five US ports of entry for travellers identified as having been in Uganda in the past 21 days. CDC also recommended that state, local and territorial health departments ('health departments') conduct post-arrival monitoring of these travellers. CDC provided traveller contact information, daily to 58 health departments, and collected health department data regarding monitoring outcomes. RESULTS: Among 11 583 travellers screened, 132 (1%) required additional assessment due to potential exposures or symptoms of concern. Fifty-three (91%) health departments reported receiving traveller data from CDC for 10 114 (87%) travellers, of whom 8499 (84%) were contacted for monitoring, 1547 (15%) could not be contacted and 68 (1%) had no reported outcomes. No travellers with high-risk exposures or Ebola disease were identified. CONCLUSION: Entry risk assessment and post-arrival monitoring of travellers are resource-intensive activities that had low demonstrated yield during this and previous outbreaks. The efficiency of future responses could be improved by incorporating an assessment of risk of importation of disease, accounting for individual travellers' potential for exposure, and expanded use of methods that reduce burden to federal agencies, health departments, and travellers. |
Serum concentrations of per- and polyfluoroalkyl substances and risk of renal cell carcinoma in the Multiethnic Cohort Study
Rhee J , Chang VC , Cheng I , Calafat AM , Botelho JC , Shearer JJ , Sampson JN , Setiawan VW , Wilkens LR , Silverman DT , Purdue MP , Hofmann JN . Environ Int 2023 180 108197 Per- and polyfluoroalkyl substances (PFAS) are environmentally persistent organic pollutants detectable in the serum of most U.S. adults. We previously reported a positive association between serum perfluorooctanoate (PFOA) concentrations and risk of renal cell carcinoma (RCC) within the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, comprising predominantly White individuals enrolled in 1993-2001. To extend our investigations to a larger and more racially and ethnically diverse population, we conducted a nested case-control study of serum PFAS concentrations and RCC within the Multiethnic Cohort Study. We measured pre-diagnostic serum concentrations of nine PFAS among 428 RCC cases and 428 individually matched controls. We estimated odds ratios (ORs) and 95 % confidence intervals (CIs) for risk of RCC in relation to each PFAS using conditional logistic regression, adjusting for RCC risk factors and other PFAS. PFOA was not associated with RCC risk overall [doubling in serum concentration, OR(continuous) = 0.89 (95 %CI = 0.67, 1.18)]. However, we observed suggestive positive associations among White participants [2.12 (0.87, 5.18)] and among participants who had blood drawn before 2002 [1.49 (0.77, 2.87)]. Furthermore, higher perfluorononanoate (PFNA) concentration was associated with increased risk of RCC overall [fourth vs. first quartile, OR = 1.84 (0.97, 3.50), P(trend) = 0.04; OR(continuous) = 1.29 (0.97, 1.71)], with the strongest association observed among African American participants [OR(continuous) = 3.69 (1.33, 10.25)], followed by Native Hawaiian [2.24 (0.70, 7.19)] and White [1.98 (0.92, 4.25)] participants. Most other PFAS were not associated with RCC. While PFOA was not associated with RCC risk overall in this racially and ethnically diverse population, the positive associations observed among White participants and those with sera collected before 2002 are consistent with previous PLCO findings. Our study also provided new evidence of a positive association between PFNA and RCC risk that was strongest in African American participants. These findings highlight the need for additional epidemiologic research investigating PFAS exposures and RCC in large racially and ethnically diverse populations. |
Glyphosate Exposure and Urinary Oxidative Stress Biomarkers in the Agricultural Health Study.
Chang VC , Andreotti G , Ospina M , Parks CG , Liu D , Shearer JJ , Rothman N , Silverman DT , Sandler DP , Calafat AM , Beane Freeman LE , Hofmann JN . J Natl Cancer Inst 2023 115 (4) 394-404 BACKGROUND: Glyphosate is the most widely applied herbicide worldwide, and its use has been associated with increased risks of certain hematopoietic cancers in epidemiologic studies. Animal and in vitro experiments suggest that glyphosate may induce oxidative stress, a key characteristic of carcinogens; however, evidence in human populations remains scarce. We investigated associations between glyphosate exposure and urinary oxidative stress biomarkers in the Biomarkers of Exposure and Effect in Agriculture study, a molecular epidemiologic subcohort in the Agricultural Health Study. METHODS: This analysis included 268 male farmers selected based on self-reported recent and lifetime occupational glyphosate use and 100 age- and geography-matched male non-farmers. Concentrations of glyphosate and oxidative stress biomarkers (8-hydroxy-2'-deoxyguanosine [8-OHdG], 8-iso-prostaglandin-F2α [8-isoprostane], and malondialdehyde [MDA]) were quantified in first-morning-void urine. We performed multivariable linear regression to evaluate associations of urinary glyphosate and self-reported glyphosate use with each oxidative stress biomarker. RESULTS: Urinary glyphosate concentrations were positively associated with levels of 8-OHdG (highest vs. lowest glyphosate quartile; geometric mean ratio [GMR]=1.15, 95% confidence interval [CI]=1.03-1.28, Ptrend=.02) and MDA (GMR = 1.20, 95% CI = 1.03-1.40, Ptrend=.06) overall. Among farmers reporting recent glyphosate use (last 7 days), use in the previous day was also associated with significantly increased 8-OHdG and MDA levels. Compared with non-farmers, we observed elevated 8-isoprostane levels among farmers with recent, high past 12-month, or high lifetime glyphosate use. CONCLUSIONS: Our findings contribute to the weight of evidence supporting an association between glyphosate exposure and oxidative stress in humans and may inform evaluations of the carcinogenic potential of this herbicide. |
Effectiveness of the CPDM in reducing overexposures to coal mine dust
Colinet JF , Mischler SE . Min Metall Explor 2022 39 (2) 283-290 The Mine Safety and Health Administration (MSHA) promulgated a rule in 2014 that required numerous changes in compliance dust sampling requirements for coal mine operators. Two key parts of this rule were the lowering of the respirable coal mine dust standard from 2.0 mg/m3 to 1.5 mg/m3 and requiring operators of underground coal mines to use a continuous personal dust monitor (CPDM) for compliance sampling. The CPDM currently approved for compliance sampling is equipped with a display that provides miners with in-shift information on their respirable dust exposure. The goal is to provide an indication of a potential overexposure and empower the miner and mine operator to implement changes in controls and/or operating practices to prevent an overexposure from occurring. Compliance sampling data for four occupations that have historically had elevated dust exposures were downloaded from the MSHA website and analyzed to assess the impact of the CPDM on overexposures. These occupations include continuous miner operator, roof bolter operator, tailgate-side shearer operator, and jacksetter. MSHA inspector and mine operator sampling data from five years before the rule became effective was compared to sampling results for five years after the dust standard was lowered and CPDM use was required. The analysis indicates that use of the CPDM has resulted in substantially lower percentages of samples exceeding the applicable respirable dust standard for these four occupations. A discussion of key dust rule changes, the CPDM, and compliance sampling results are provided. © 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 results of foam application testing for longwall shield dust control in a simulated environment
Reed WR , Shahan MR , Zheng Y , Mazzella A . Int J Coal Sci Technol 2021 8 (2) 217-227 There were 37 longwall faces operating in mines in the United States in 2019. The average panel width for these longwalls was approximately 368.5 m (1209 ft). This translates to a range of approximately 170–240 shields per longwall, depending upon the width of shield. The movement of longwall shields is a significant contributor to respirable dust overexposures to longwall operators. Foam is expected to have the potential to reduce this shield dust generation. The foam is applied to the area on the roof between the coal face and the shield tip after the shearer passes. In this study, the longwall shield dust simulator was used to test three foam agents for their ability to control dust from longwall shield movements. Results showed that at low-velocity ventilation (≈ 3.0 m/s (600 fpm)) all foam agents were able to produce dust reduction levels of at least 45%. At high-velocity ventilation (≈ 5.1 m/s (1000 fpm)), the reductions were lower and more variable, ranging from being undeterminable for one foam agent to having 46%–63% reductions for the other two foam agents, with one instance of an increase in dust concentration. Overall, the use of foam agents can provide longwall shield dust control. Important factors are roof coverage and the ability of foam to remain on the roof for extended time periods. |
Serum concentrations of per- and polyfluoroalkyl substances and risk of renal cell carcinoma
Shearer JJ , Callahan CL , Calafat AM , Huang WY , Jones RR , Sabbisetti VS , Freedman ND , Sampson JN , Silverman DT , Purdue MP , Hofmann JN . J Natl Cancer Inst 2020 113 (5) 580-587 BACKGROUND: Per- and polyfluoroalkyl substances (PFAS) are highly persistent chemicals that have been detected in the serum of > 98% of the U.S. population. Studies among highly exposed individuals suggest an association with perfluorooctanoic acid (PFOA) exposure and kidney cancer. It remains unclear whether PFOA or other PFAS are renal carcinogens, or if they influence risk of renal cell carcinoma (RCC) at concentrations observed in the general population. METHODS: We measured pre-diagnostic serum concentrations of PFOA and seven additional PFAS in 324 RCC cases and 324 individually matched controls within the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Multivariable conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CIs) relating serum PFAS concentrations and RCC risk. Individual PFAS were modeled continuously (log2-transformed) and categorically, with adjustment for kidney function and additional potential confounders. All statistical tests were two-sided. RESULTS: We observed a positive association with RCC risk for PFOA (doubling in serum concentration, ORcontinuous = 1.71, 95% CI = 1.23 to 2.37; P = .002), and a greater than two-fold increased risk among those in the highest quartile vs. the lowest (OR = 2.63, 95% CI = 1.33 to 5.20; Ptrend = .007). The association with PFOA was similar after adjustment for other PFAS (ORcontinuous = 1.68, 95% CI = 1.07 to 2.63; P = .02), and remained apparent in analyses restricted to individuals without evidence of diminished kidney function and in cases diagnosed ≥8 years after phlebotomy. CONCLUSIONS: Our findings add substantially to the weight of evidence that PFOA is a renal carcinogen and may have important public health implications for the many individuals exposed to this ubiquitous and highly persistent chemical. |
Progress toward hepatitis B and hepatitis C elimination using a catalytic funding model - Tashkent, Uzbekistan, December 6, 2019-March 15, 2020
Dunn R , Musabaev E , Razavi H , Sadirova S , Bakieva S , Razavi-Shearer K , Brigida K , Kamili S , Averhoff F , Nasrullah M . MMWR Morb Mortal Wkly Rep 2020 69 (34) 1161-1165 In 2016, the World Health Organization (WHO) set hepatitis elimination targets of 90% reduction in incidence and 65% reduction in mortality worldwide by 2030 (1). Hepatitis B virus (HBV) and hepatitis C virus (HCV) infection prevalences are high in Uzbekistan, which lacks funding for meeting WHO's targets. In the absence of large financial donor programs for eliminating HBV and HCV infections, insufficient funding is an important barrier to achieving those targets in Uzbekistan and other low- and middle-income countries. A pilot program using a catalytic funding model, including simplified test-and-treat strategies, was launched in Tashkent, Uzbekistan, in December 2019. Catalytic funding is a mechanism by which the total cost of a program is paid for by multiple funding sources but is begun with upfront capital that is considerably less than the total program cost. Ongoing costs, including those for testing and treatment, are covered by payments from 80% of the enrolled patients, who purchase medications at a small premium that subsidizes the 20% who cannot afford treatment and therefore receive free medication. The 1-year pilot program set a target of testing 250,000 adults for HBV and HCV infection and treating all patients who have active infection, including those who had a positive test result for hepatitis B surface antigen (HBsAg) and those who had a positive test result for HCV core antigen. During the first 3 months of the program, 24,821 persons were tested for HBV and HCV infections. Among those tested, 1,084 (4.4%) had positive test results for HBsAg, and 1,075 (4.3%) had positive test results for HCV antibody (anti-HCV). Among those infected, 275 (25.4%) initiated treatment for HBV, and 163 (15.2%) initiated treatment for HCV, of whom 86.5% paid for medications and 13.5% received medications at no cost. Early results demonstrate willingness of patients to pay for treatment if costs are low, which can offset elimination costs. However, improvements across the continuum of care are needed to recover the upfront investment. Lessons learned from this program, including the effectiveness of using simplified test-and-treat guidelines, general practitioners in lieu of specialist physicians, and innovative financing to reduce costs, can guide similar initiatives in other countries and help curb the global epidemic of viral hepatitis, especially among low- and middle-income countries. |
Notes from the Field: Measles Outbreak Associated with International Air Travel - California, March-April 2017.
Lu L , Roland E , Shearer E , Zahn M , Djuric M , McDonald E , Redd S , Tardivel K . MMWR Morb Mortal Wkly Rep 2020 69 (25) 803-804 On March 14, 2017, the County of San Diego Health and Human Services Agency (COSD HHSA) notified CDC of a measles case in an adult airline passenger (patient A), with recent travel to Indonesia. The patient had developed rash and swollen eyes during a flight from Hong Kong to Los Angeles on March 8, followed by conjunctivitis and cough after arrival; the patient proceeded to an urgent care clinic, but a measles diagnosis was not considered. On March 9, patient A visited the clinic again, at which time measles was confirmed by polymerase chain reaction (PCR) testing on March 14. Patient A reported having received 1 dose of measles, mumps, and rubella (MMR) vaccine. CDC identified 22 contacts from the flight, involving seven U.S. states and two countries; potentially exposed flight crew were notified on March 15. COSD HHSA identified 483 community contacts, 81 of whom received self-quarantine recommendations because they lacked presumptive evidence of immunity.* |
Public health implementation considerations for state-level Ebola monitoring and movement restrictions
Sell TK , Shearer MP , Meyer D , Leinhos M , Thomas E , Carbone EG . Disaster Med Public Health Prep 2020 15 (5) 1-6 OBJECTIVE: This article describes implementation considerations for Ebola-related monitoring and movement restriction policies in the United States during the 2013-2016 West Africa Ebola epidemic. METHODS: Semi-structured interviews were conducted between January and May 2017 with 30 individuals with direct knowledge of state-level Ebola policy development and implementation processes. Individuals represented 17 jurisdictions with variation in adherence to US Centers for Disease Control and Prevention (CDC) guidelines, census region, predominant state political affiliation, and public health governance structures, as well as the CDC. RESULTS: Interviewees reported substantial resource commitments required to implement Ebola monitoring and movement restriction policies. Movement restriction policies, including for quarantine, varied from voluntary to mandatory programs, and, occasionally, quarantine enforcement procedures lacked clarity. CONCLUSIONS: Efforts to improve future monitoring and movement restriction policies may include addressing surge capacity to implement these programs, protocols for providing support to affected individuals, coordination with law enforcement, and guidance on varying approaches to movement restrictions. |
Influencing factors in the development of state-level movement restriction and monitoring policies in response to Ebola, United States, 2014-15
Sell TK , Shearer MP , Meyer D , Leinhos M , Carbone EG , Thomas E . Health Secur 2019 17 (5) 364-371 During the 2014-15 domestic Ebola response, US states developed monitoring and movement restriction policies for potentially exposed individuals. We describe decision-making processes and factors in the development of these policies. Results may help health officials anticipate potential concerns and policy influencers in future infectious disease responses. Thirty individuals with knowledge of state-level Ebola policy development participated in semi-structured interviews conducted from January to May 2017. Interviewees represented 18 jurisdictions from diverse census regions, state political affiliations, and public health governance structures as well as the US Centers for Disease Control and Prevention (CDC). Limited and/or changing guidance and unique state-level public health, legal, and operational environments resulted in variation in policy responses. Federal guidance developed by the CDC was an important information source influencing state-level policy responses, as was available scientific evidence; however, other external factors, such as local events, contributing experts, political environment, public concern, news media, and the influence of neighboring states, contributed to additional variation. Improvements in timing, consistency, and communication of federal guidance for monitoring and movement restrictions at the state level-along with balanced approaches to addressing ethical concerns, scientific evidence, and public concern at the state level-are considerations for policy development for future disease responses. |
Design and experimental evaluation of a flooded-bed dust scrubber integrated into a longwall shearer
Arya S , Sottile J , Rider JP , Colinet JF , Novak T , Wedding C . Powder Technol 2018 339 487-496 Continuous mining machines operating in U.S. underground coal mines have, for decades, utilized flooded-bed dust scrubbers for capturing and removing respirable dust generated at the production face. However, the application of dust scrubbers to longwall mining systems has not yet been successful. Considering that nearly 60% of U.S. underground coal production is from longwall mines, the successful application of dust scrubbers to longwall mining systems could have a significant impact on miner health. A full-scale mock-up of a longwall shearer was constructed and equipped with a flooded-bed dust scrubber designed to capture dust produced by the headgate cutting drum. The mockup was installed at the National Institute for Occupational Safety and Health (NIOSH) Longwall Dust Gallery and a series of 40 experiments was conducted to evaluate the scrubber's performance. Results show that the scrubber achieved a 56% reduction of respirable dust in the return airway and a 74% reduction of respirable dust in the walkway area near the shearer. Although these tests were conducted under a controlled environment, the results suggest that a similar scrubber design could be very effective at achieving a significant reduction in respirable dust in longwall mining systems. |
Public health resilience checklist for high-consequence infectious diseases-informed by the domestic Ebola response in the United States
Sell TK , Shearer MP , Meyer D , Chandler H , Schoch-Spana M , Thomas E , Rose DA , Carbone EG , Toner E . J Public Health Manag Pract 2018 24 (6) 510-518 CONTEXT: The experiences of communities that responded to confirmed cases of Ebola virus disease in the United States provide a rare opportunity for collective learning to improve resilience to future high-consequence infectious disease events. DESIGN: Key informant interviews (n = 73) were conducted between February and November 2016 with individuals who participated in Ebola virus disease planning or response in Atlanta, Georgia; Dallas, Texas; New York, New York; or Omaha, Nebraska; or had direct knowledge of response activities. Participants represented health care; local, state, and federal public health; law; local and state emergency management; academia; local and national media; individuals affected by the response; and local and state governments. Two focus groups were then conducted in New York and Dallas, and study results were vetted with an expert advisory group. RESULTS: Participants focused on a number of important areas to improve public health resilience to high-consequence infectious disease events, including governance and leadership, communication and public trust, quarantine and the law, monitoring programs, environmental decontamination, and waste management. CONCLUSIONS: Findings provided the basis for an evidence-informed checklist outlining specific actions for public health authorities to take to strengthen public health resilience to future high-consequence infectious disease events. |
Lessons from the domestic Ebola response: Improving health care system resilience to high consequence infectious diseases
Meyer D , Kirk Sell T , Schoch-Spana M , Shearer MP , Chandler H , Thomas E , Rose DA , Carbone EG , Toner E . Am J Infect Control 2017 46 (5) 533-537 BACKGROUND: The domestic response to the West Africa Ebola virus disease (EVD) epidemic from 2014-2016 provides a unique opportunity to distill lessons learned about health sector planning and operations from those individuals directly involved. This research project aimed to identify and integrate these lessons into an actionable checklist that can improve health sector resilience to future high-consequence infectious disease (HCID) events. METHODS: Interviews (N = 73) were completed with individuals involved in the domestic EVD response in 4 cities (Atlanta, Dallas, New York, and Omaha), and included individuals who worked in academia, emergency management, government, health care, law, media, and public health during the response. Interviews were transcribed and analyzed qualitatively. Two focus groups were then conducted to expand on themes identified in the interviews. Using these themes, an evidence-informed checklist was developed and vetted for completeness and feasibility by an expert advisory group. RESULTS: Salient themes identified included health care facility issues-specifically identifying assessment and treatment hospitals, isolation and treatment unit layout, waste management, community relations, patient identification, patient isolation, limitations on treatment, laboratories, and research considerations-and health care workforce issues-specifically psychosocial impact, unit staffing, staff training, and proper personal protective equipment. CONCLUSIONS: The experiences of those involved in the domestic Ebola response provide critical lessons that can help strengthen resilience of health care systems and improve future responses to HCID events. |
Methane emissions and airflow patterns on a longwall face: Potential influences from longwall gob permeability distributions on a bleederless longwall panel
Schatzel SJ , Krog RB , Dougherty H . Trans Soc Min Metall Explor Inc 2017 342 (1) 51-61 Longwall face ventilation is an important component of the overall coal mine ventilation system. Increased production rates due to higher-capacity mining equipment tend to also increase methane emission rates from the coal face, which must be diluted by the face ventilation. Increases in panel length, with some mines exceeding 6,100 m (20,000 ft), and panel width provide additional challenges to face ventilation designs. To assess the effectiveness of current face ventilation practices at a study site, a face monitoring study with continuous monitoring of methane concentrations and automated recording of longwall shearer activity was combined with a tracer gas test on a longwall face. The study was conducted at a U.S. longwall mine operating in a thick, bituminous coal seam and using a U-type, bleederless ventilation system. Multiple gob gas ventholes were located near the longwall face. These boreholes had some unusual design concepts, including a system of manifolds to modify borehole vacuum and flow and completion depths close to the horizon of the mined coalbed that enabled direct communication with the mine atmosphere. The mine operator also had the capacity to inject nitrogen into the longwall gob, which occurred during the monitoring study. The results show that emission rates on the longwall face showed a very limited increase in methane concentrations from headgate to tailgate despite the occurrence of methane delays during monitoring. Average face air velocities were 3.03 m/s (596 fpm) at shield 57 and 2.20 m/s (433 fpm) at shield 165. The time required for the sulfur hexafluoride (SF(6)) peak to occur at each monitoring location has been interpreted as being representative of the movement of the tracer slug. The rate of movement of the slug was much slower in reaching the first monitoring location at shield 57 compared with the other face locations. This lower rate of movement, compared with the main face ventilation, is thought to be the product of a flow path within and behind the shields that is moving in the general direction of the headgate to the tailgate. Barometric pressure variations were pronounced over the course of the study and varied on a diurnal basis. |
Characterization of airborne float coal dust emitted during continuous mining, longwall mining and belt transport
Shahan MR , Seaman CE , Beck TW , Colinet JF , Mischler SE . Min Eng 2017 69 (9) 61-66 Float coal dust is produced by various mining methods, carried by ventilating air and deposited on the floor, roof and ribs of mine airways. It deposited, float dust is re-entrained during a methane explosion. Without sufficient inert rock dust quantities, this float coal dust can propagate an explosion throughout mining entries. Consequently, controlling float coaf dust is of critical interest to mining operations. Rock dusting, which is the adding of inert material to airway surfaces, is the main control technique currently used by the coal mining industry to reduce the float coal dust explosion hazard. To assist the industry in reducing this hazard, the Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health initiated a project to investigate methods and technologies to reduce float ooal dust in underground coal mines through prevention, capture and suppression prior to deposition. Field characterization studies were performed to determine quantitatively the sources, types and amounts of dust produced during various coal mining processes. The operations chosen for study were a continuous miner section, a longwall section and a coal-handling facility. For each of these operations, the primary dust sources were confirmed to be the continuous mining machine, longwall shearer and conveyor belt transfer points, respectively. Respirable and total airborne float dust samples were collected and analyzed for each operation, and the ratio of total airborne float coal dust to respirable dust was calculated. During the continuous mining process, the ratio of total airborne float ooal dust to respirable dust ranged from 10.3 to 13.6. The ratios measured on the longwall face were between 1B.5 and 21.5. The total airborne float coal dust to respirable dust ratio observed during belt transport ranged between 7.5 and 21.8. |
Challenges in the evaluation of interventions to improve engagement along the HIV care continuum in the United States: A systematic review
Risher KA , Kapoor S , Daramola AM , Paz-Bailey G , Skarbinski J , Doyle K , Shearer K , Dowdy D , Rosenberg E , Sullivan P , Shah M . AIDS Behav 2017 21 (7) 2101-2123 In the United States (US), there are high levels of disengagement along the HIV care continuum. We sought to characterize the heterogeneity in research studies and interventions to improve care engagement among people living with diagnosed HIV infection. We performed a systematic literature search for interventions to improve HIV linkage to care, retention in care, reengagement in care and adherence to antiretroviral therapy (ART) in the US published from 2007-mid 2015. Study designs and outcomes were allowed to vary in included studies. We grouped interventions into categories, target populations, and whether results were significantly improved. We identified 152 studies, 7 (5%) linkage studies, 33 (22%) retention studies, 4 (3%) reengagement studies, and 117 (77%) adherence studies. 'Linkage' studies utilized 11 different outcome definitions, while 'retention' studies utilized 39, with very little consistency in effect measurements. The majority (59%) of studies reported significantly improved outcomes, but this proportion and corresponding effect sizes varied substantially across study categories. This review highlights a paucity of assessments of linkage and reengagement interventions; limited generalizability of results; and substantial heterogeneity in intervention types, outcome definitions, and effect measures. In order to make strides against the HIV epidemic in the US, care continuum research must be improved and benchmarked against an integrated, comprehensive framework. |
Spread of yellow fever virus outbreak in Angola and the Democratic Republic of the Congo 2015-16: a modelling study
Kraemer MU , Faria NR , Reiner RC Jr , Golding N , Nikolay B , Stasse S , Johansson MA , Salje H , Faye O , Wint GRW , Niedrig M , Shearer FM , Hill SC , Thompson RN , Bisanzio D , Taveira N , Nax HH , Pradelski BSR , Nsoesie EO , Murphy NR , Bogoch II , Khan K , Brownstein JS , Tatem AJ , de Oliveira T , Smith DL , Sall AA , Pybus OG , Hay SI , Cauchemez S . Lancet Infect Dis 2016 17 (3) 330-338 BACKGROUND: Since late 2015, an epidemic of yellow fever has caused more than 7334 suspected cases in Angola and the Democratic Republic of the Congo, including 393 deaths. We sought to understand the spatial spread of this outbreak to optimise the use of the limited available vaccine stock. METHODS: We jointly analysed datasets describing the epidemic of yellow fever, vector suitability, human demography, and mobility in central Africa to understand and predict the spread of yellow fever virus. We used a standard logistic model to infer the district-specific yellow fever virus infection risk during the course of the epidemic in the region. FINDINGS: The early spread of yellow fever virus was characterised by fast exponential growth (doubling time of 5-7 days) and fast spatial expansion (49 districts reported cases after only 3 months) from Luanda, the capital of Angola. Early invasion was positively correlated with high population density (Pearson's r 0.52, 95% CI 0.34-0.66). The further away locations were from Luanda, the later the date of invasion (Pearson's r 0.60, 95% CI 0.52-0.66). In a Cox model, we noted that districts with higher population densities also had higher risks of sustained transmission (the hazard ratio for cases ceasing was 0.74, 95% CI 0.13-0.92 per log-unit increase in the population size of a district). A model that captured human mobility and vector suitability successfully discriminated districts with high risk of invasion from others with a lower risk (area under the curve 0.94, 95% CI 0.92-0.97). If at the start of the epidemic, sufficient vaccines had been available to target 50 out of 313 districts in the area, our model would have correctly identified 27 (84%) of the 32 districts that were eventually affected. INTERPRETATION: Our findings show the contributions of ecological and demographic factors to the ongoing spread of the yellow fever outbreak and provide estimates of the areas that could be prioritised for vaccination, although other constraints such as vaccine supply and delivery need to be accounted for before such insights can be translated into policy. FUNDING: Wellcome Trust. |
Development of noise controls for longwall shearer cutting drums
Camargo HE , Azman AS , Alcorn L . Noise Control Eng J 2016 64 (5) 573-585 Noise-induced hearing loss is the second most pervasive disease in the mining industry. The exposure of miners to noise levels above the permissible exposure level results in hearing loss of approximately 80% of coal miners by retirement age. In addition, between 2002 and 2011, approximately 48% of longwall shearer operators were overexposed in coal mines in the United States. Previous research identified the two rotating cutting drums used by the longwall shearer to extract coal as the most significant sound-radiating components. In this context, the National Institute for Occupational Safety and Health conducted research to develop noise controls for longwall mining systems. To this end, structural and acoustic numerical models of a single cutting drum were developed to assess its dynamic and acoustic response, respectively. Once validated, these models were used to explore various noise control concepts including force isolation, varying structural damping and varying component stiffness. Upon multiple simulations, it was determined that structural modifications to increase the stiffness of the outer vane plates were the most practical and durable approach to reduce the sound radiated by the cutting drums. Furthermore, these modifications did not adversely affect the cutting performance, nor the loading ability of the drums. As a result, these structural modifications were implemented into an actual set of drums for evaluation purposes. Results from the underground evaluation, when the modified cutting drums were used under normal operation conditions, showed noise reduction across the entire frequency spectrum with an overall noise reduction of 3 dB in the sound pressure level at the operator location, confirming the validity of the developed noise controls. |
Outbreak of serogroup C meningococcal disease primarily affecting men who have sex with men - Southern California, 2016
Nanduri S , Foo C , Ngo V , Jarashow C , Civen R , Schwartz B , Holguin J , Shearer E , Zahn M , Harriman K , Winter K , Kretz C , Chang HY , Meyer S , MacNeil J . MMWR Morb Mortal Wkly Rep 2016 65 (35) 939-940 During March 4-August 11, 2016, 25 outbreak-associated cases of meningococcal disease, including two deaths (8% case-fatality ratio), were reported in Southern California. Twenty-four of the cases were caused by serogroup C Neisseria meningitidis (NmC) and one by N. meningitidis with an undetermined serogroup (Figure). On June 24, 2016, in response to this increase in NmC cases, primarily among men who have sex with men (MSM) in Los Angeles County, the city of Long Beach, and Orange County, the California Department of Public Health (CDPH) issued a press release and health advisory, declaring an outbreak of NmC in Southern California. |
New vaccine introductions: assessing the impact and the opportunities for immunization and health systems strengthening
Wang SA , Hyde TB , Mounier-Jack S , Brenzel L , Favin M , Gordon WS , Shearer JC , Mantel CF , Arora N , Durrheim D . Vaccine 2013 31 Suppl 2 B122-8 In 2010, global immunization partners posed the question, "Do new vaccine introductions (NVIs) have positive or negative impacts on immunization and health systems of countries?" An Ad-hoc Working Group was formed for WHO's Strategic Advisory Group of Experts on immunization (SAGE) to examine this question through five approaches: a published literature review, a grey literature review, in-depth interviews with regional and country immunization staff, in-depth studies of recent NVIs in 3 countries, and a statistical analysis of the impact of NVI on DTP3 coverage in 176 countries. The WHO Health System Framework of building blocks was used to organize the analysis of these data to assess potential areas of impact of NVI on health systems. In April 2012, the Ad-hoc Working Group presented its findings to SAGE. While reductions in disease burden and improvements in disease and adverse events surveillance, training, cold chain and logistics capacity and injection safety were commonly documented as beneficial impacts, opportunities for strengthening the broader health system were consistently missed during NVI. Weaknesses in planning for human and financial resource needs were highlighted as a concern. Where positive impacts on health systems following NVI occurred, these were often in areas where detailed technical guidance or tools and adequate financing were available. SAGE supported the Ad-hoc Working Group's conclusion that future NVI should explicitly plan to optimize and document the impact of NVI on broader health systems. Furthermore, opportunities for improving integration of delivery of immunization services, commodities, and messages with other parts of the health system should be actively sought with the recognition that integration is a bidirectional process. To avoid the gaps in planning for NVI that can compromise existing immunization and health systems, donors and partners should provide sufficient and timely support to facilitate country planning. Areas for future research were also identified. Finally, to support countries in using NVI as an opportunity to strengthen immunization and health systems, the WHO guidance for countries on new vaccine introduction is being updated to reflect ways this might be accomplished. |
Emergence of resistance among USA300 methicillin-resistant Staphylococcus aureus isolates causing invasive disease in the United States
McDougal LK , Fosheim GE , Nicholson A , Bulens SN , Limbago BM , Shearer JE , Summers AO , Patel JB . Antimicrob Agents Chemother 2010 54 (9) 3804-11 USA300 methicillin-resistant Staphylococcus aureus (MRSA) isolates are usually resistant only to oxacillin, erythromycin, and, increasingly, levofloxacin. Of these, oxacillin and levofloxacin resistances are chromosomally encoded. Plasmid-mediated clindamycin, mupirocin, and/or tetracycline resistance has been observed among USA300 isolates, but these descriptions were limited to specific patient populations or isolated occurrences. We examined the antimicrobial susceptibilities of invasive MRSA isolates from a national surveillance population in order to identify USA300 isolates with unusual, possibly emerging, plasmid-mediated antimicrobial resistance. DNA from these isolates was assayed for the presence of resistance determinants and the presence of a pSK41-like conjugative plasmid. Of 823 USA300 isolates, 72 (9%) were tetracycline resistant; 69 of these were doxycycline susceptible and tetK positive, and 3 were doxycycline resistant and tetM positive. Fifty-one (6.2%) isolates were clindamycin resistant and ermC positive; 22 (2.7%) isolates were high-level mupirocin resistant (mupA positive); 5 (0.6%) isolates were trimethoprim-sulfamethoxazole (TMP-SMZ) resistant, of which 4 were dfrA positive; and 7 (0.9%) isolates were gentamicin resistant and aac6'-aph2'' positive. Isolates with pSK41-like plasmids (n = 24) were positive for mupA (n = 19), dfrA (n = 6), aac6'-aph2'' (n = 6), tetM (n = 2), and ermC (n = 8); 20 pSK41-positive isolates were positive for two or more resistance genes. Conjugative transfer of resistance was demonstrated between four gentamicin- and mupirocin-resistant and three gentamicin- and TMP-SMZ-resistant USA300 isolates; transconjugants harbored a single pSK41-like plasmid, which was PCR positive for aac6'-aph2'' and either mupA and/or dfrA. USA300 and USA100 isolates from the same state with identical resistance profiles contained pSK41-like plasmids with indistinguishable restriction and Southern blot profiles, suggesting horizontal plasmid transfer between USA100 and USA300 isolates. |
Controlling dust exposures in longwall mining utilizing a simple barrier
Sweeney DD , Slagley JM , Smith DA , Rider JP . Min Eng 2009 61 (12) 58-61 The United States coal mining industry has traditionally experienced difficulty in controlling dust levels below the occupational exposure limit. While improvements in face ventilation and water spray nozzles have decreased dust exposures, approximately eight percent of experienced coal miners are still developing Coal Worker's Pneumoconiosis. This investigation tested the feasibility of enhancing existing engineering dust controls by mounting a simple barrier on a longwall shearer that separated the operators from the cutting drums. The barrier was constructed and tested above ground at the National Institute for Occupational Safety and Health Pittsburgh Research Laboratory longwall gallery test facility. A 96-percent reduction of respirable dust occurred at the headgate sampling position when tested at 2.4 m/sec (480 ft/min). The average dust level decreased from 39 mg/m3 to 1.5 mg/m3 by utilizing the barrier. |
Reconciling longwall gob gas reservoirs and venthole production performances using multiple rate drawdown well test analysis
Karacan C . Int J Coal Geol 2009 80 181-195 Longwall mining is an underground mining method during which a mechanical shearer progressively mines a large block of coal, called a panel, in an extensive area. During this operation the roof of the coal seam is supported only temporarily with hydraulic supports that protect the workers and the equipment on the coal face. As the coal is extracted, the supports automatically advance and the roof strata cave behind the supports. Caving results in fracturing and relaxation of the overlying strata, which is called "gob." Due its highly fractured nature, gob contains many flow paths for gas migration. Thus, if the overlying strata contain gassy sandstones or sandstone channels, gas shales or thinner coal seams which are not suitable for mining, then the mining-induced changes can cause unexpected or uncontrolled gas migration into the underground workplace. Vertical gob gas ventholes (GGV) are drilled into each longwall panel to capture the methane within the overlying fractured strata before it enters the work environment. Thus, it is important, first to understand the properties of the gas reservoir created by mining disturbances and, second, to optimize the well parameters and placement accordingly. In this paper, the production rate-pressure behaviors of six GGVs drilled over three adjacent panels were analyzed by using conventional multi-rate drawdown analysis techniques. The analyses were performed for infinite acting and pseudo-steady state flow models, which may be applicable during panel mining (DM) and after mining (AM) production periods of GGVs. These phases were analyzed separately since the reservoir properties, due to dynamic subsidence, boundary conditions and gas capacity of the gob reservoir may change between these two stages. The results suggest that conventional well test analysis techniques can be applicable to highly complex gob reservoirs and GGVs to determine parameters such as skin, permeability, radius of investigation, flow efficiency and damage ratio. The insights obtained from well test analyses can be used for a better understanding of the gob and for designing more effective gob gas venthole systems. |
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