Last data update: Sep 23, 2024. (Total: 47723 publications since 2009)
Records 1-30 (of 32 Records) |
Query Trace: Sears M [original query] |
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Identifying factors associated with physical therapy use versus non-use among injured workers with back pain in Washington State
Chin B , Rundell SD , Sears JM , Fulton-Kehoe D , Spector JT , Franklin GM . Am J Ind Med 2024 BACKGROUND: There is little information about predictors of physical therapy (PT) use among injured workers with back pain. The primary objective of this study is to investigate the associations between PT use and baseline factors not routinely captured in workers' compensation (WC) data. METHODS: We conducted a secondary analysis using the Washington State Workers' Compensation Disability Risk Identification Study Cohort, which combines self-reported surveys with claims data from the Washington State Department of Labor and Industries State Fund. Workers with an accepted or provisional WC claim for back injury between June 2002 and April 2004 were eligible. Baseline factors for PT use were selected from six domains (socio-demographic, pain and function, psychosocial, clinical, health behaviors, and employment-related). The outcome was a binary measure for PT use within 1 year of injury. Bivariate and multivariable logistic regression models were conducted to evaluate the associations between PT use and baseline factors. RESULTS: Among the 1370 eligible study participants, we identified 673 (49%) who received at least one PT service. Baseline factors from five of the six domains (all but health behaviors) were associated with PT use, including gender, income, pain and function measures, injury severity rating, catastrophizing, recovery expectations, fear avoidance, mental health score, body mass index, first provider seen for injury, previous injury, and several work-related factors. CONCLUSION: We identify baseline factors that are associated with PT use, which may be useful in addressing disparities in access to care for injured workers with back pain in a WC system. |
Using a severity threshold to improve occupational injury surveillance: Assessment of a severe traumatic injury-based occupational health indicator across the International Classification of Diseases lexicon transition
Sears JM , Victoroff TM , Bowman SM , Marsh SM , Borjan M , Reilly A , Fletcher A . Am J Ind Med 2023 67 (1) 18-30 BACKGROUND: Traumatic injury is a leading cause of death and disability among US workers. Severe injuries are less subject to systematic ascertainment bias related to factors such as reporting barriers, inpatient admission criteria, and workers' compensation coverage. A state-based occupational health indicator (OHI #22) was initiated in 2012 to track work-related severe traumatic injury hospitalizations. After 2015, OHI #22 was reformulated to account for the transition from the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) to ICD-10-CM. This study describes rates and trends in OHI #22, alongside corresponding metrics for all work-related hospitalizations. METHODS: Seventeen states used hospital discharge data to calculate estimates for calendar years 2012-2019. State-panel fixed-effects regression was used to model linear trends in annual work-related hospitalization rates, OHI #22 rates, and the proportion of work-related hospitalizations resulting from severe injuries. Models included calendar year and pre- to post-ICD-10-CM transition. RESULTS: Work-related hospitalization rates showed a decreasing monotonic trend, with no significant change associated with the ICD-10-CM transition. In contrast, OHI #22 rates showed a monotonic increasing trend from 2012 to 2014, then a significant 50% drop, returning to a near-monotonic increasing trend from 2016 to 2019. On average, OHI #22 accounted for 12.9% of work-related hospitalizations before the ICD-10-CM transition, versus 9.1% post-transition. CONCLUSIONS: Although hospital discharge data suggest decreasing work-related hospitalizations over time, work-related severe traumatic injury hospitalizations are apparently increasing. OHI #22 contributes meaningfully to state occupational health surveillance efforts by reducing the impact of factors that differentially obscure minor injuries; however, OHI #22 trend estimates must account for the ICD-10-CM transition-associated structural break in 2015. |
Mitigating outbreaks in congregate settings by decreasing the size of the susceptible population (preprint)
Blumberg S , Lu P , Hoover CM , Lloyd-Smith JO , Kwan AT , Sears D , Bertozzi SM , Worden L . medRxiv 2021 While many transmission models have been developed for community spread of respiratory pathogens, less attention has been given to modeling the interdependence of disease introduction and spread seen in congregate settings, such as prisons or nursing homes. As demonstrated by the explosive outbreaks of COVID-19 seen in congregate settings, the need for effective outbreak prevention and mitigation strategies for these settings is critical. Here we consider how interventions that decrease the size of the susceptible populations, such as vaccination or depopulation, impact the expected number of infections due to outbreaks. Introduction of disease into the resident population from the community is modeled as a branching process, while spread between residents is modeled via a compartmental model. Control is modeled as a proportional decrease in both the number of susceptible residents and the reproduction number. We find that vaccination or depopulation can have a greater than linear effect on anticipated infections. For example, assuming a reproduction number of 3.0 for density-dependent COVID-19 transmission, we find that reducing the size of the susceptible population by 20% reduced overall disease burden by 47%. We highlight the California state prison system as an example for how these findings provide a quantitative framework for implementing infection control in congregate settings. Additional applications of our modeling framework include optimizing the distribution of residents into independent residential units, and comparison of preemptive versus reactive vaccination strategies. |
Intensity of physical therapy services: Association with work and health outcomes in injured workers with back pain in Washington State
Chin B , Rundell SD , Sears JM , Fulton-Kehoe D , Spector JT , Franklin GM . Am J Ind Med 2022 66 (1) 94-106 BACKGROUND: Associations between the intensity of physical therapy (PT) treatments and health outcomes among individuals with back pain have been examined in the general population; however, few studies have explored these associations in injured workers. Our study objective was to examine whether intensity of PT treatments is positively associated with work and health outcomes in injured workers with back pain. METHODS: We conducted a secondary analysis of prospective data collected from the Washington State Workers' Compensation (WC) Disability Risk Identification Study Cohort (D-RISC). D-RISC combined survey results with WC data from the Washington State Department of Labor and Industries. Workers with a State Fund WC claim for back injuries between June 2002 and April 2004 and who received PT services within the first year of injury were eligible. Intensity of PT treatment was measured as the type and amount of PT services within 28 days from the first PT visit. Outcome measures included work disability and self-reported measures for working for pay, pain intensity, and functional status at 1-year follow-up. We conducted linear and logistic regression models to test associations. RESULTS: We identified 662 eligible workers. In adjusted models, although the intensity of PT treatment was not significantly associated with work disability at 1-year follow-up, it was associated with lower odds of working for pay, decreased pain intensity, and improved functional status. CONCLUSIONS: Our findings suggest that there may be small benefits from receiving active PT, manual therapy, and frequent PT treatments within 28 days of initiating PT care. |
Modeling scenarios for mitigating outbreaks in congregate settings.
Blumberg S , Lu P , Kwan AT , Hoover CM , Lloyd-Smith JO , Sears D , Bertozzi SM , Worden L . PLoS Comput Biol 2022 18 (7) e1010308 The explosive outbreaks of COVID-19 seen in congregate settings such as prisons and nursing homes, has highlighted a critical need for effective outbreak prevention and mitigation strategies for these settings. Here we consider how different types of control interventions impact the expected number of symptomatic infections due to outbreaks. Introduction of disease into the resident population from the community is modeled as a stochastic point process coupled to a branching process, while spread between residents is modeled via a deterministic compartmental model that accounts for depletion of susceptible individuals. Control is modeled as a proportional decrease in the number of susceptible residents, the reproduction number, and/or the proportion of symptomatic infections. This permits a range of assumptions about the density dependence of transmission and modes of protection by vaccination, depopulation and other types of control. We find that vaccination or depopulation can have a greater than linear effect on the expected number of cases. For example, assuming a reproduction number of 3.0 with density-dependent transmission, we find that preemptively reducing the size of the susceptible population by 20% reduced overall disease burden by 47%. In some circumstances, it may be possible to reduce the risk and burden of disease outbreaks by optimizing the way a group of residents are apportioned into distinct residential units. The optimal apportionment may be different depending on whether the goal is to reduce the probability of an outbreak occurring, or the expected number of cases from outbreak dynamics. In other circumstances there may be an opportunity to implement reactive disease control measures in which the number of susceptible individuals is rapidly reduced once an outbreak has been detected to occur. Reactive control is most effective when the reproduction number is not too high, and there is minimal delay in implementing control. We highlight the California state prison system as an example for how these findings provide a quantitative framework for understanding disease transmission in congregate settings. Our approach and accompanying interactive website (https://phoebelu.shinyapps.io/DepopulationModels/) provides a quantitative framework to evaluate the potential impact of policy decisions governing infection control in outbreak settings. |
Roof stability and support strategies associated with longwall-induced horizontal stress changes in belt entries
Zhang P , Esterhuizen G , Sears M , Trackemas J , Minoski T , Tulu B . Min Metall Explor 2022 39 (5) 1873-1885 Longwall mining is a highly productive and efficient coal mining method used in the USA. During longwall retreating, the belt entry must be maintained stable, and any roof fall in the belt entry would jeopardize mine safety and substantially interrupt the continuous production of coal in the longwall face. Past experience of longwall mining has shown that belt entry stability was the greatest challenge in longwall ground control, and the occurrence of roof falls in belt entries was largely associated with high horizontal stress. To properly support the roof in the belt entry, it is important to understand how longwall-induced horizontal stress changes affect roof stability in belt entries and to strategically install supplementary support to prevent any potential roof falls. Researchers from the National Institute for Occupational Safety and Health (NIOSH) performed horizontal stress measurements in the immediate roof of the belt entries for two Pittsburgh seam longwall panels oriented unfavorably to high horizontal stress. Hollow inclusion cells (HICells) were installed in the immediate roof at the intersection in each of the belt entries, and stress changes were monitored as the longwall face was approaching and passing the intersection. Numerical models were set up to calculate the longwall-induced horizontal stress changes in the roof at the monitoring sites. With the verified model, investigations were made of how horizontal stress is concentrated and relieved in the belt entry roof near the face under different panel orientations. Both measurements and modeling results showed that high horizontal stress is concentrated in the roof in the belt entry within about 15 m outby the face when a longwall panel is unfavorably oriented to the major horizontal stress. The study demonstrated that longwall-induced differential horizontal stress can be used as an indication of the degree of horizontal stress concentration. Roof support strategies are discussed on how to maintain the stability of belt entry under high horizontal stress concentration. © 2022, This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply. |
Detection of SARS-CoV-2 in Wastewater at Residential College, Maine, USA, August-November 2020.
Brooks YM , Gryskwicz B , Sheehan S , Piers S , Mahale P , McNeil S , Chase J , Webber D , Borys D , Hilton M , Robinson D , Sears S , Smith E , Lesher EK , Wilson R , Goodwin M , Pardales M . Emerg Infect Dis 2021 27 (12) 3111-3114 We used wastewater surveillance to identify 2 coronavirus disease outbreaks at a college in Maine, USA. Cumulative increases of >1 log(10) severe acute respiratory syndrome coronavirus 2 RNA in consecutive 24-hour composite samples preceded the outbreaks. For 76% of cases, RNA was identified in grab samples from residence halls <7 days before case discovery. |
RPAcan3990: an ultrasensitive recombinase polymerase assay to detect Angiostrongylus cantonensis DNA.
Sears WJ , Qvarnstrom Y , Nutman TB . J Clin Microbiol 2021 59 (9) Jcm0118521 Angiostrongylus cantonensis (Ac) is one of the leading causes of eosinophilic meningitis worldwide. A field deployable molecular detection method could enhance both environmental surveillance and clinical diagnosis of this emerging pathogen. Accordingly, RPAcan3990, a recombinase polymerase assay (RPA) was developed to target a region predicted to be highly repeated in the Ac genome. The assay was then adapted to produce a visually interpretable fluorescent readout using an orange camera lens filter and a blue light. Using Ac genomic DNA, the limit of detection was found to be 1fg/μl by both fluorometer measurement and visual reading. All clinical samples known to be positive for Ac from various areas of the globe were positive by RPAcan3990. Cerebrospinal fluid samples from other etiologies of eosinophilic meningitis (i.e. Toxocara sp., Gnathostoma sp.) were negative in the RPAcan3990 assay. The optimal incubation temperature range for the reaction was between 35-40°C. The assay successfully detected 1fg/μl of Ac genomic DNA after incubation at human body temperature (in a shirt pocket). In conclusion, these data suggest RPAcan3990 is potentially a point of contact molecular assay capable of sensitively detecting Ac by producing visually interpretable results with minimal instrumentation. |
Assessing Longwall Gateroad Ground Response and Support Alternatives
Esterhuizen GS , Klemetti T , Sears MM , Zhang P , van Dyke M , Dougherty H , Tulu IB . Min Metall Explor 2021 38 (4) 1739-1759 Ground falls in longwall gateroad entries remain a concern in modern longwall operations. The gateroads are subject to changing horizontal and vertical ground stress induced by longwall extraction. These stress changes can result in failure of the strata around an entry leading to large deformations of the entry roof, floor, and ribs. The gateroad support systems are required to control the failed strata while maintaining safe access to the longwall face and unimpeded ventilation. This paper presents research that was conducted to better understand the stability issues in gateroad excavations and to develop procedures for evaluating support and layout alternatives for longwall gateroads. Using the results of a field-monitoring program and numerical model analysis of case histories, a conceptual model of gateroad support needs was developed. The conceptual model formed the basis for developing a set of equations that can be used to estimate likely roof sag and support loading for given roof geology and longwall-induced loading conditions. The developed equations were used to compare predicted gateroad stability to field study results, showing satisfactory agreement. The calculation procedures are used to demonstrate their application in assessing support alternatives at a case study mine. It is concluded that the developed analysis procedures provide realistic assessments of likely ground stability and can be used to evaluate alternative gateroad support systems at operating longwall mines. © 2021, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply. |
A parametric study for the effect of dip on stone mine pillar stability using a simplified model geometry
Rashed G , Slaker B , Sears MM , Murphy MM . Min Metall Explor 2021 38 (2) 967-977 In this study, a parametric study was conducted using FLAC3D numerical models to examine the impact of oblique loading, generated from seam dip, on the strength and the failure propagation pattern of a stone pillar using two simplified geometry types. In type 1, the sidewalls of the pillars were assumed to be perpendicular to the roof and the floor, while in type 2, the sidewalls of pillars were assumed to be vertical. The complex pillar geometry in dipping mines was frequently modeled using these two geometries. To capture a complete picture of the effect of seam dip on pillar stability, the modeled width-to-height (W/H) ratio of the pillars, in situ stress field, and pillars roof/floor interfaces were systematically varied to account for the potential distribution of values for these parameters across the underground stone mines in USA. Results from the numerical modeling indicate that dipping pillars have reduced strength compared with horizontal pillars. Also, an asymmetric failure propagation pattern could be obtained depending on an interaction between the W/H ratio, seam dip, in situ stresses, and pillar geometry. |
Analysis of the impacts of mining sequence and overburden depth on stability at a dipping limestone mine
Sears MM , Slaker B , Rashed G , Miller J . Min Metall Explor 2021 38 (2) 959-965 Ground falls represent a significant hazard at underground mines in the stone, sand, and gravel (SSG) sector in the USA. Researchers from the National Institute for Occupational Safety and Health (NIOSH) are currently conducting detailed investigations into the complex loading conditions at underground stone mines operating in challenging conditions. This paper presents the application of numerical modeling to analyze pillar and roof stability at a dipping underground limestone mine. A validated numerical model was used to explore the potential behavior of the pillars and roof as loading conditions change. The validated model was used to compare changes in mining sequence, overburden depth, and the in situ stress field. This will allow mine operators and engineers to have a better idea of the conditions that could be encountered as mining progresses. Results from the numerical modeling indicate that roof displacement more than doubles as the vertical stress increases from 10 MPa (1450 psi) to 19 MPa (2750 psi) when the maximum and minimum horizontal stresses were 41 MPa (5950 psi) and 22 MPa (3190 psi), respectively. Consequently, as the pillar load increases, the safety factor of the pillars is projected to decrease by about 25%. The impact of the practical application of numerical models can result in a reduction of ground-fall accidents and injuries as well as generally safer working conditions. |
Preliminary rib support requirements for solid coal ribs using a coal pillar rib rating (CPRR)
Mohamed K , Van Dyke M , Rashed G , Sears MM , Kimutis R . Int J Min Sci Technol 2020 31 (1) 15-22 Researchers from the National Institute for Occupational Safety and Health (NIOSH) are developing a coal pillar rib rating (CPRR) technique to measure the integrity of coal ribs. The CPRR characterizes the rib composition and evaluates its impact on the inherent stability of the coal ribs. The CPRR utilizes four parameters: rib homogeneity, bedding condition, face cleat orientation with respect to entry direction, and rib height. All these parameters are measurable in the field. A rib data collecting procedure and a simple sheet to calculate the CPRR were developed. The developed CPRR can be used as a rib quality mapping tool in underground coal mines and to determine the potential of local rib instabilities and support requirements associated with overburden depth. CPRR calculations were conducted for 22 surveyed solid coal ribs, mainly composed of coal units. Based on this study, the rib performance was classified into four categories. A preliminary minimum primary rib support density (PRSD) line was obtained from these surveyed cases. Two sample cases are presented that illustrate the data collection form and CPRR calculations. |
AcanR3990 qPCR: a novel, highly sensitive, bioinformatically-informed assay to detect Angiostrongylus cantonensis infections.
Sears WJ , Qvarnstrom Y , Dahlstrom E , Snook K , Kaluna L , Baláž V , Feckova B , Šlapeta J , Modry D , Jarvi S , Nutman TB . Clin Infect Dis 2020 73 (7) e1594-e1600 BACKGROUND: Angiostrongylus cantonensis (Ac), or the rat lungworm, is a major cause of eosinophilic meningitis. Humans are infected by ingesting the 3 rd stage larvae from primary hosts, snails and slugs, or paratenic hosts. The currently used molecular test is a qPCR assay targeting the ITS1 rDNA region (ITS1) of Ac. METHODS: In silico design of a more sensitive qPCR assay was performed based on tandem repeats predicted to be the most abundant by the RepeatExplorer algorithm. Genomic DNA (gDNA) of Ac were used to determine the analytical sensitivity and specificity of the best primer/probe combination. This assay was then applied to clinical and environmental samples. RESULTS: The limit of detection of the best performing assay, AcanR3990, was 1 fg (the DNA equivalent of 1/100,000 dilution of a single 3 rd stage larvae). Out of 127 CDC archived CSF samples from varied geographic locations, the AcanR3990 qPCR detected the presence of Ac in 49/49 ITS1 confirmed angiostrongyliasis patients along with 15/73 samples previously negative by ITS1 qPCR despite strong clinical suspicion for angiostrongyliasis. Intermediate hosts (gastropods) and an accidental host, a symptomatic horse, were also tested with similar improvement in detection observed. AcanR3990 qPCR did not cross-react in five CSF from patients with proven neurocysticercosis, toxocariasis, gnathostomiasis and baylisascariasis. AcanR3990 qPCR failed to amplify genomic DNA from the other related Angiostrongylus species tested except for A. mackerrasae (Am), a neurotropic species limited to Australia that would be expected to present with a clinical syndrome indistinguishable from Ac. CONCLUSION: These results suggest AcanR3990 qPCR assay is highly sensitive and specific with potential wide applicability as a One Health detection method for Ac and Am. |
Associations of breast milk consumption with urinary phthalate and phenol exposure biomarkers in infants
Henderson NB , Sears CG , Calafat A , Chen A , Lanphear B , Romano M , Yolton K , Braun JM . Environ Sci Technol Lett 2020 7 (10) 733-739 Phthalates and phenols are readily detected in human breast milk, but the contribution of breast milk feeding to an infant's exposure to these chemicals is unknown. Among 248 mother-infant pairs in the HOME Study, we assessed breast milk consumption via maternal report and quantified concentrations of eight phthalate metabolites and three phenols (bisphenol A, triclosan, benzophenone-3) in infants' urine at age 12 months. We estimated covariate-adjusted percent differences in phthalate metabolite and phenol concentrations by breast milk consumption. Seventy infants (28%) were fed some breast milk up to age 12 months. Urinary phenol concentrations were similar in infants who were or were not fed breast milk at 12 months. In contrast, urinary concentrations of monocarboxyisooctyl phthalate (MCOP) and mono-3-carboxypropyl phthalate (MCPP) were 42% (95% CI: 3, 97) and 24% (95% CI:-8, 62) higher among infants fed breast milk at 12 months, respectively. Moreover, MCOP and MCPP concentrations were positively associated with the quantity of breast milk consumed in the prior month and 24 h. In this cohort, we found evidence suggesting that breast milk consumption may be a source of exposure to some phthalates. Future studies should examine whether plastic feeding bottles or pumped milk is a potential exposure source among infants. |
Lowering urinary phthalate metabolite concentrations among children by reducing contaminated dust in housing units: A randomized controlled trial and observational study
Sears CG , Lanphear BP , Calafat AM , Chen A , Skarha J , Xu Y , Yolton K , Braun JM . Environ Sci Technol 2020 54 (7) 4327-4335 Dust in homes can contain phthalates that may adversely affect child development, but whether residential interventions and dust removal can prevent children's exposure to phthalates is unknown. We quantified the influence of a residential lead hazard intervention and dust control on children's urinary phthalate metabolite concentrations. Between 2003 and 2006, The Health Outcomes and Measures of the Environment (HOME) Study randomized 355 pregnant women to receive an intervention to reduce either residential lead or injury hazards before delivery. We quantified eight urinary phthalate metabolites from 288 children at ages 1, 2, or 3 years (680 observations). During yearly home visits, we assessed dust accumulation in housing units. Children in the lead intervention group had 11-12% lower concentrations of the sum of di(2-ethylhexyl) phthalate metabolites, monocarboxyoctyl phthalate, and monocarboxynonyl phthalate compared to the injury intervention group. Monoethyl phthalate concentrations did not differ by group. In observational analyses, children living in housing units that appeared clean had 12-17% lower concentrations of these phthalate metabolites and monobenzyl phthalate, compared to children living in housing units with more dust accumulation. Features of this lead hazard intervention and measures to control dust may reduce children's exposure to phthalates found in building materials and household furnishings. |
Overview of current US longwall gateroad support practices
Sears MM , Esterhuizen GS , Tulu IB . Min Metall Explor 2019 36 (6) 1137-1144 In 2015, 40 longwall mines provided nearly 60% of the US coal production from underground mining methods. This represents a substantial, yet gradual increase from just under 50% over the last 5 years. As a result of this increased production share, the percentage of ground fall related fatalities in longwall mines has also increased when compared to all US underground coal mines. Additionally, about 80% of ground fall related fatalities have occurred in areas where the roof was supported. In an attempt to better understand the status quo of current US longwall support practices, a sample of 21 longwall mines were visited, representing about 40% of the currently active longwall mines in 4 of the 5 major US longwall producing regions. The resulting data was obtained from a wide variety of overburden depths, geologic conditions, mining heights, ground conditions, support practices, and gateroad configurations. The data collected is reported using both qualitative and quantitative methods. The results from the research update previous efforts in classifying mining accidents and injuries as well as current support practices. This data provides a necessary background for future research aimed at further reduction of ground fall accidents and injuries. |
Coal rib response during bench mining: A case study
Sears MM , Rusnak J , Van Dyke M , Rashed G , Mohamed K , Sloan M . Int J Min Sci Technol 2017 28 (1) 107-113 In 2016, room-and-pillar mining provided nearly 40% of underground coal production in the United States. Over the past decade, rib falls have resulted in 12 fatalities, representing 28% of the ground fall fatalities in U.S. underground coal mines. Nine of these 12 fatalities (75%) have occurred in room-and-pillar mines. The objective of this research is to study the geomechanics of bench room-and-pillar mining and the associated response of high pillar ribs at overburden depths greater than 300 m. This paper provides a definition of the bench technique, the pillar response due to loading, observational data for a case history, a calibrated numerical model of the observed rib response, and application of this calibrated model to a second site. |
Geotechnical considerations for concurrent pillar recovery in close-distance multiple seams
Zhang P , Tulu B , Sears M , Trackemas J . Int J Min Sci Technol 2017 28 (1) 21-27 Room-and-pillar mining with pillar recovery has historically been associated with more than 25% of all ground fall fatalities in underground coal mines in the United States. The risk of ground falls during pillar recovery increases in multiple-seam mining conditions. The hazards associated with pillar recovery in multiple-seam mining include roof cutters, roof falls, rib rolls, coal outbursts, and floor heave. When pillar recovery is planned in multiple seams, it is critical to properly design the mining sequence and panel layout to minimize potential seam interaction. This paper addresses geotechnical considerations for concurrent pillar recovery in two coal seams with 21 m of interburden under about 305 m of depth of cover. The study finds that, for interburden thickness of 21 m, the multiple-seam mining influence zone in the lower seam is directly under the barrier pillar within about 30 m from the gob edge of the upper seam. The peak stress in the interburden transfers down at an angle of approximately 20°away from the gob, and the entries and crosscuts in the influence zone are subjected to elevated stress during development and retreat. The study also suggests that, for full pillar recovery in close-distance multiple-seam scenarios, it is optimal to superimpose the gobs in both seams, but it is not necessary to superimpose the pillars. If the entries and/or crosscuts in the lower seam are developed outside the gob line of the upper seam, additional roof and rib support needs to be considered to account for the elevated stress in the multiple-seam influence zone. |
Design concerns of room and pillar retreat panels
Klemetti TM , Sears MM , Tulu IB . Int J Min Sci Technol 2016 27 (1) 29-35 Why do some room and pillar retreat panels encounter abnormal conditions? What factors deserve the most consideration during the planning and execution phases of mining and what can be done to mitigate those abnormal conditions when they are encountered? To help answer these questions, and to determine some of the relevant factors influencing the conditions of room and pillar (R & P) retreat mining entries, four consecutive R & P retreat panels were evaluated. This evaluation was intended to reinforce the influence of topographic changes, depth of cover, multiple-seam interactions, geological conditions, and mining geometry. This paper details observations were made in four consecutive R & P retreat panels and the data were collected from an instrumentation site during retreat mining. The primary focus was on the differences observed among the four panels and within the panels themselves. The instrumentation study was initially planned to evaluate the interactions between primary and secondary support, but produced rather interesting results relating to the loading encountered under the current mining conditions. In addition to the observation and instrumentation, numerical modeling was performed to evaluate the stress conditions. Both the LaModel 3.0 and Rocscience Phase 2 programs were used to evaluate these four panels. The results of both models indicated a drastic reduction in the vertical stresses experienced in these panels due to the full extraction mining in overlying seams when compared to the full overburden load. Both models showed a higher level of stress associated with the outside entries of the panels. These results agree quite well with the observations and instrumentation studies performed at the mine. These efforts provided two overarching conclusions concerning R & P retreat mine planning and execution. The first was that there are four areas that should not be overlooked during R & P retreat mining: topographic relief, multiple-seam stress relief, stress concentrations near the gob edge, and geologic changes in the immediate roof. The second is that in order to successfully retreat an R & P panel, a three-phased approach to the design and analysis of the panel should be conducted: the planning phase, evaluation phase, and monitoring phase. |
Vaccine effectiveness of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine during a pertussis outbreak in Maine
Terranella A , Rea V , Griffith M , Manning S , Sears S , Farmer A , Martin S , Patel M . Vaccine 2016 34 (22) 2496-500 BACKGROUND: Multiple school-associated pertussis outbreaks were reported in Maine from 2010 to 2011. These outbreaks were associated with an overall increase in pertussis cases statewide. Waning of protection in students recently vaccinated with tetanus, diphtheria, and acellular pertussis (Tdap) has been implicated in the increase in reported rates of pertussis nationally. METHODS: We conducted a retrospective cohort study to evaluate Tdap vaccine effectiveness (VE) among students aged 11-19 years in two schools reporting outbreaks in 2011. All pertussis cases reported from August through November, 2011 at the two schools were included. Vaccination history was verified using provider information, state vaccine registry data, and parental verification. Attack rates (AR) were calculated. VE and duration of protection was calculated as VE=1-(ARvaccinated/ARunvaccinated)x100% using a log binomial regression model. RESULTS: Of 416 students enrolled, 314 were included in the analyses. Twenty-nine cases collectively in Schools A and B. Tdap coverage was 65% at School A and 42% at School B before the start of the outbreak. Among students enrolled in the study, attack rates were 11.9% and 7.7% at Schools A and B, respectively. Overall VE was 68.5% (95% confidence interval (CI) 37.7-86.2). VE was 70.4% (95% CI 17.5-89.4) for School A and 65.2% (95% CI -19.2 to 89.9) for School B. VE <2 years versus ≥2 years from outbreak onset was not significantly different. CONCLUSIONS: Tdap was moderately effective in preventing disease among vaccinated students. Vaccine coverage of 65% or less was suboptimal and might contribute to outbreaks. Waning VE was not demonstrated. Increased vaccination coverage rates as well as further evaluation of the role of acellular vaccine on VE is needed. |
Institutional tuberculosis transmission. Controlled trial of upper room ultraviolet air disinfection: a basis for new dosing guidelines
Mphaphlele M , Dharmadhikari AS , Jensen PA , Rudnick SN , van Reenen TH , Pagano MA , Leuschner W , Sears TA , Milonova SP , van der Walt M , Stoltz AC , Weyer K , Nardell EA . Am J Respir Crit Care Med 2015 192 (4) 477-84 RATIONALE: Transmission is driving the global tuberculosis epidemic, especially in congregate settings. Worldwide, natural ventilation is the most common means of air disinfection, but it is inherently unreliable and of limited use in cold climates. Upper room germicidal ultraviolet (UV) air disinfection with air mixing has been shown to be highly effective, but improved evidence-based dosing guidelines are needed. OBJECTIVES: To test the efficacy of upper room germicidal air disinfection with air mixing to reduce tuberculosis transmission under real hospital conditions, and to define the application parameters responsible as a basis for proposed new dosing guidelines. METHODS: Over an exposure period of 7 months, 90 guinea pigs breathed only untreated exhaust ward air, and another 90 guinea pigs breathed only air from the same six-bed tuberculosis ward on alternate days when upper room germicidal air disinfection was turned on throughout the ward. MEASUREMENTS AND MAIN RESULTS: The tuberculin skin test conversion rates (>6 mm) of the two chambers were compared. The hazard ratio for guinea pigs in the control chamber converting their skin test to positive was 4.9 (95% confidence interval, 2.8-8.6), with an efficacy of approximately 80%. CONCLUSIONS: Upper room germicidal UV air disinfection with air mixing was highly effective in reducing tuberculosis transmission under hospital conditions. These data support using either a total fixture output (rather than electrical or UV lamp wattage) of 15-20 mW/m(3) total room volume, or an average whole-room UV irradiance (fluence rate) of 5-7 muW/cm(2), calculated by a lighting computer-assisted design program modified for UV use. |
Anti-malarial prescription practices among children admitted to six public hospitals in Uganda from 2011 to 2013
Sserwanga A , Sears D , Kapella BK , Kigozi R , Rubahika D , Staedke SG , Kamya M , Yoon SS , Chang MA , Dorsey G , Mpimbaza A . Malar J 2015 14 (1) 331 BACKGROUND: In 2011, Uganda's Ministry of Health switched policy from presumptive treatment of malaria to recommending parasitological diagnosis prior to treatment, resulting in an expansion of diagnostic services at all levels of public health facilities including hospitals. Despite this change, anti-malarial drugs are often prescribed even when test results are negative. Presented is data on anti-malarial prescription practices among hospitalized children who underwent diagnostic testing after adoption of new treatment guidelines. METHODS: Anti-malarial prescription practices were collected as part of an inpatient malaria surveillance program generating high quality data among children admitted for any reason at government hospitals in six districts. A standardized medical record form was used to collect detailed patient information including presenting symptoms and signs, laboratory test results, admission and final diagnoses, treatments administered, and final outcome upon discharge. RESULTS: Between July 2011 and December 2013, 58,095 children were admitted to the six hospitals (hospital range 3294-20,426).A total of 56,282 (96.9 %) patients were tested for malaria, of which 26,072 (46.3 %) tested positive (hospital range 5.9-57.3 %). Among those testing positive, only 84 (0.3 %) were first tested after admission and 295 of 30,389 (1.0 %) patients who tested negative at admission later tested positive. Of 30,210 children with only negative test results, 11,977 (39.6 %) were prescribed an anti-malarial (hospital range 14.5-53.6 %). The proportion of children with a negative test result who were prescribed an anti-malarial fluctuated over time and did not show a significant trend at any site with the exception of one hospital where a steady decline was observed. Among those with only negative test results, children 6-12 months of age (aOR 3.78; p < 0.001) and those greater than 12 months of age (aOR 4.89; p < 0.001) were more likely to be prescribed an anti-malarial compared to children less than 6 months of age. Children with findings suggestive of severe malaria were also more likely to be prescribed an anti-malarial after a negative test result (aOR 1.98; p < 0.001). CONCLUSIONS: Despite high testing rates for malaria at all sites, prescription of anti-malarials to patients with negative test results remained high, with the exception of one site where a steady decline occurred. |
Serogroup B meningococcal disease outbreak and carriage evaluation at a college - Rhode Island, 2015
Soeters HM , McNamara LA , Whaley M , Wang X , Alexander-Scott N , Kanadanian KV , Kelleher CM , MacNeil J , Martin SW , Raines N , Sears S , Vanner C , Vuong J , Bandy U , Sicard K , Patel M . MMWR Morb Mortal Wkly Rep 2015 64 (22) 606-7 On February 2, 2015, the Rhode Island Department of Health was notified of a case of meningococcal disease in a male undergraduate student at Providence College. Three days later, a second case was reported in a male undergraduate with no contact with the first student, indicating an attack rate of 44 cases per 100,000 students, nearly 500 times higher than the national incidence of 0.15 cases per 100,000 among persons aged 17-22 years (Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, CDC, unpublished data, 2013). Both cases were caused by a rare outbreak strain of Neisseria meningitidis serogroup B (ST-9069); neither case was fatal. In response to the outbreak, potential contacts received antibiotic chemoprophylaxis, and a mass vaccination campaign with a recently licensed serogroup B meningococcal (MenB) vaccine was implemented. In collaboration with CDC, the first phase of a meningococcal carriage evaluation was undertaken. |
Quality of inpatient pediatric case management for four leading causes of child mortality at six government-run Ugandan hospitals
Sears D , Mpimbaza A , Kigozi R , Sserwanga A , Chang MA , Kapella BK , Yoon S , Kamya MR , Dorsey G , Ruel T . PLoS One 2015 10 (5) e0127192 BACKGROUND: A better understanding of case management practices is required to improve inpatient pediatric care in resource-limited settings. Here we utilize data from a unique health facility-based surveillance system at six Ugandan hospitals to evaluate the quality of pediatric case management and the factors associated with appropriate care. METHODS: All children up to the age of 14 years admitted to six district or regional hospitals over 15 months were included in the study. Four case management categories were defined for analysis: suspected malaria, selected illnesses requiring antibiotics, suspected anemia, and diarrhea. The quality of case management for each category was determined by comparing recorded treatments with evidence-based best practices as defined in national guidelines. Associations between variables of interest and the receipt of appropriate case management were estimated using multivariable logistic regression. RESULTS: A total of 30,351 admissions were screened for inclusion in the analysis. Ninety-two percent of children met criteria for suspected malaria and 81% received appropriate case management. Thirty-two percent of children had selected illnesses requiring antibiotics and 89% received appropriate antibiotics. Thirty percent of children met criteria for suspected anemia and 38% received appropriate case management. Twelve percent of children had diarrhea and 18% received appropriate case management. Multivariable logistic regression revealed large differences in the quality of care between health facilities. There was also a strong association between a positive malaria diagnostic test result and the odds of receiving appropriate case management for comorbid non-malarial illnesses - children with a positive malaria test were more likely to receive appropriate care for anemia and less likely for illnesses requiring antibiotics and diarrhea. CONCLUSIONS: Appropriate management of suspected anemia and diarrhea occurred infrequently. Pediatric quality improvement initiatives should target deficiencies in care unique to each health facility, and interventions should focus on the simultaneous management of multiple diagnoses. |
Prevalence of eastern equine encephalitis virus antibodies among white-tailed deer populations in Maine
Mutebi JP , Godsey M , Smith RP Jr , Renell MR , Smith L , Robinson S , Sears S , Lubelczyk C . Vector Borne Zoonotic Dis 2015 15 (3) 210-4 During the fall of 2010, 332 deer serum samples were collected from 15 of the 16 (93.8%) Maine counties and screened for eastern equine encephalitis virus (EEEV) antibodies using plaque reduction neutralizing tests (PRNTs). The aim was to detect and map EEEV activity in the state of Maine. Forty-seven of the 332 (14.2%) sera were positive for EEEV antibodies, showing a much wider distribution of EEEV activity in Maine than previously known. The percentage of EEEV antibody-positive deer sera was ≥10% in six counties-Piscataquis (100%), Somerset (28.6%), Waldo (22.2%), Penobscot (21.7%), Kennebec (13.7%), and Sagadahoc (10%). Positive sera were detected in all the six counties (Somerset, Waldo, Penobscot, Kennebec, Cumberland, and York) that were positive in 2009, suggesting endemic EEEV activity in these counties. EEEV antibodies were not detected in sera collected in five counties-Franklin, Knox, Lincoln, Oxford, and Washington-which was either due to low sample size or lack of EEEV activity in these counties. Our data suggest higher EEEV activity in central Maine compared to southern Maine, whereas EEEV activity in Maine has historically been associated with the southern counties of York and Cumberland. |
Ascariasis in humans and pigs on small-scale farms, Maine, USA, 2010-2013
Miller LA , Colby K , Manning SE , Hoenig D , McEvoy E , Montgomery S , Mathison B , de Almeida M , Bishop H , Dasilva A , Sears S . Emerg Infect Dis 2015 21 (2) 332-4 Ascaris is a genus of parasitic nematodes that can cause infections in humans and pigs. During 2010-2013, we identified 14 cases of ascariasis in persons who had contact with pigs in Maine, USA. Ascaris spp. are important zoonotic pathogens, and prevention measures are needed, including health education, farming practice improvements, and personal and food hygiene. |
Severity of rhinovirus infection in hospitalized adults is unrelated to genotype.
McCulloch DJ , Sears MH , Jacob JT , Lyon GM , Burd EM , Caliendo AM , Hill CE , Nix WA , Oberste MS , Kraft CS . Am J Clin Pathol 2014 142 (2) 165-72 OBJECTIVES: To determine whether rhinovirus (RV) species is associated with more severe clinical illness in adults. METHODS: Seventy-two RV-positive viral respiratory samples from adult patients were sequenced and analyzed phylogenetically after reverse transcriptase polymerase chain reaction of the region spanning the VP4 gene and 5' terminus of the VP2 gene. The clinical features and severity of illness associated with the different RV species were compared. RESULTS: Phylogenetic analysis identified three distinct clusters as RV-A (54%), B (11%), or C (35%) species. In an unadjusted model, patients with RV-B infection were significantly more likely to have the composite outcome variable of death or intensive care unit admission (P = .03), but this effect diminished when controlling for patient sex. A logistic model of the relationship between RV species and adverse outcomes produced nonsignificant odds ratios when controlling for patient sex. CONCLUSIONS: Infection with RV-A or RV-B was associated with greater severity of illness in our adult population; however, the association disappeared after controlling for confounders. |
Entry and exit screening of airline travellers during the A(H1N1) 2009 pandemic: a retrospective evaluation
Khan K , Eckhardt R , Brownstein JS , Naqvi R , Hu W , Kossowsky D , Scales D , Arino J , Macdonald M , Wang J , Sears J , Cetron MS . Bull World Health Organ 2013 91 (5) 368-76 OBJECTIVE: To evaluate the screening measures that would have been required to assess all travellers at risk of transporting A(H1N1)pdm09 out of Mexico by air at the start of the 2009 pandemic. METHODS: Data from flight itineraries for travellers who flew from Mexico were used to estimate the number of international airports where health screening measures would have been needed, and the number of travellers who would have had to be screened, to assess all air travellers who could have transported the H1N1 influenza virus out of Mexico during the initial stages of the 2009 A(H1N1) pandemic. FINDINGS: Exit screening at 36 airports in Mexico, or entry screening of travellers arriving on direct flights from Mexico at 82 airports in 26 other countries, would have resulted in the assessment of all air travellers at risk of transporting A(H1N1)pdm09 out of Mexico at the start of the pandemic. Entry screening of 116 travellers arriving from Mexico by direct or connecting flights would have been necessary for every one traveller at risk of transporting A(H1N1)pdm09. Screening at just eight airports would have resulted in the assessment of 90% of all air travellers at risk of transporting A(H1N1)pdm09 out of Mexico in the early stages of the pandemic. CONCLUSION: During the earliest stages of the A(H1N1) pandemic, most public health benefits potentially attainable through the screening of air travellers could have been achieved by screening travellers at only eight airports. |
An epizootic of Eastern equine encephalitis virus, Maine, USA in 2009: outbreak description and entomological studies
Lubelczyk C , Mutebi JP , Robinson S , Elias SP , Smith LB , Juris SA , Foss K , Lichtenwalner A , Shively KJ , Hoenig DE , Webber L , Sears S , Smith RP Jr . Am J Trop Med Hyg 2012 88 (1) 95-102 From July to September, 2009, an outbreak of Eastern equine encephalitis virus (EEEv) occurred in five counties in Maine. The virus was isolated from 15 horses, 1 llama, and pheasants in three separate captive flocks. One wild turkey, screened before translocation, also showed exposure to the virus in January 2010. Two pools of Culiseta melanura (Coquillett) tested positive for EEEv during routine seasonal surveillance in York County in September, but none of the mosquitoes collected during rapid response surveys tested positive. There were more Cs. melanura in July, August, and September 2009 than in preceding (2006-08) and subsequent (2010-11) years. August and September Cs. melanura abundances were correlated with July rainfall, and abundance of all species combined was correlated with total rainfall for the meteorological summer. This outbreak represents a substantial expansion of the range of EEEv activity in northern New England. |
Effects of immunizing school children with 2009 influenza A (H1N1) monovalent vaccine on absenteeism among students and teachers in Maine
Graitcer SB , Dube NL , Basurto-Davila R , Smith PF , Ferdinands J , Thompson M , Uzicanin A , Gargiullo P , Chaves SS , Robinson S , Sears S , Tipton M , Monto AS , Mills D , Shay DK . Vaccine 2012 30 (32) 4835-41 The overall and indirect effects of immunizing school children with influenza A (H1N1) 2009 pandemic virus vaccine prior to and during the peak of virus circulation were evaluated on student and teacher school absenteeism. We used records collected from late 2009 through early 2010 from schools in four Maine counties. Mixed logistic regression models were used to estimate the daily association between school-level immunization coverage and absenteeism by level of influenza activity, after adjusting for the proportion of students receiving reduced-cost lunches, student minority status, absences adjacent to weekends and Thanksgiving, rural school location, and the circulation of other respiratory viruses. Increasing student immunization coverage was associated with reduced absenteeism during periods of high influenza activity. For example, as immunization coverage during the peak week of pandemic virus circulation increased from 38% to 69% (the 10th and 90th percentiles of observed coverage, respectively), relative reductions in daily absenteeism among all students, unimmunized students, and teachers were 8.2% (95% confidence interval [CI]: 6.5, 9.9), 5.7% (95% CI: 4.2, 7.3), and 8.7% (95% CI: 1.3, 16), respectively. Increased vaccination coverage among school-aged Maine children had modest overall and indirect effects on student and teacher absenteeism, despite vaccination occurring just prior and during peak pandemic virus circulation. |
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