Last data update: Jun 03, 2024. (Total: 46935 publications since 2009)
Records 1-14 (of 14 Records) |
Query Trace: Gearhart D [original query] |
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Demographic and travel characteristics and self-reported predeparture SARS-CoV-2 testing behavior in air passengers entering the United States from foreign destinations from July to September 2021
Panasci A , Gearhart S , Shaum A , Simental AJ , Mitchell C , Mitcham D , Williams G , Shake N , Brown C , Gertz AM . Immun Inflamm Dis 2023 11 (12) e1019 INTRODUCTION: From January 2021 to June 2022, the United States Centers for Disease Control and Prevention required predeparture SARS-CoV-2 testing for all air passengers arriving into the United States from a foreign country. METHODS: Using data collected during a surveillance project, we described predeparture testing behavior among a convenience sample of international air passengers entering the United States from July to September 2021 at six US ports of entry. We analyzed pairwise relationships between self-reported test type, test timing, demographic and travel characteristics, and COVID-19 vaccination status using chi-square and Fisher's exact tests. RESULTS: Participants were more likely to get a NAAT versus antigen test if they identified as non-Hispanic Asian or Pacific Islander (68.2%, n = 173), non-Hispanic Black (62.6%, n = 147), or if they preferred not to report race and ethnicity (60.8%, n = 209) when compared to those who identified as non-Hispanic White (47.1%, n = 1086, all p < 0.05). Those who identified as Hispanic or Latino (n = 671) were less likely to get a NAAT than the non-Hispanic White group (39.5% vs. 47.1%, p < 0.05). Participants arriving in the US from the Americas were less likely to get a NAAT (38.5%, n = 871) compared to those arriving from Europe (45.5%, n = 1165, p < 0.05). Participants who reported receiving their predeparture test 2 days or 3 or more days before departure were more likely to report receiving a NAAT (52.2%, n = 879, and 60.2%, n = 410, respectively) than those who reported testing within 1 day (41.4%, n = 1040, all p < 0.001) of departure. DISCUSSION: Test type was significantly associated with race and ethnicity, departure region, and test timing. Differences likely reflected regional disparities in the availability of tests at the time of the activity. Discrepancies in predeparture test timing and type worldwide may have consequences for the effectiveness and equity of travel requirements in future pandemics. |
Measles virus transmission patterns and public health responses during Operation Allies Welcome: a descriptive epidemiological study
Masters NB , Beck AS , Mathis AD , Leung J , Raines K , Paul P , Stanley SE , Weg AL , Pieracci EG , Gearhart S , Jumabaeva M , Bankamp B , Rota PA , Sugerman DE , Gastañaduy PA . Lancet Public Health 2023 8 (8) e618-e628 BACKGROUND: On Aug 29, 2021, Operation Allies Welcome (OAW) was established to support the resettlement of more than 80 000 Afghan evacuees in the USA. After identification of measles among evacuees, incoming evacuee flights were temporarily paused, and mass measles vaccination of evacuees aged 6 months or older was introduced domestically and overseas, with a 21-day quarantine period after vaccination. We aimed to evaluate patterns of measles virus transmission during this outbreak and the impact of control measures. METHODS: We conducted a measles outbreak investigation among Afghan evacuees who were resettled in the USA as part of OAW. Patients with measles were defined as individuals with an acute febrile rash illness between Aug 29, 2021, and Nov 26, 2021, and either laboratory confirmation of infection or epidemiological link to a patient with measles with laboratory confirmation. We analysed the demographics and clinical characteristics of patients with measles and used epidemiological information and whole-genome sequencing to track transmission pathways. A transmission model was used to evaluate the effects of vaccination and other interventions. FINDINGS: 47 people with measles (attack rate: 0·65 per 1000 evacuees) were reported in six US locations housing evacuees in four states. The median age of patients was 1 year (range 0-26); 33 (70%) were younger than 5 years. The age distribution shifted during the outbreak towards infants younger than 12 months. 20 (43%) patients with wild-type measles virus had rash onset after vaccination. No fatalities or community spread were identified, nor further importations after flight resumption. In a non-intervention scenario, transmission models estimated that a median of 5506 cases (IQR 10-5626) could have occurred. Infection clusters based on epidemiological criteria could be delineated into smaller clusters using phylogenetic analyses; however, sequences with few substitution count differences did not always indicate single lines of transmission. INTERPRETATION: Implementation of control measures limited measles transmission during OAW. Our findings highlight the importance of integration between epidemiological and genetic information in discerning between individual lines of transmission in an elimination setting. FUNDING: US Centers for Disease Control and Prevention. |
Estimating the incubation period of monkeypox virus during the 2022 multi-national outbreak (preprint)
Charniga K , Masters NB , Slayton RB , Gosdin L , Minhaj FS , Philpott D , Smith D , Gearhart S , Alvarado-Ramy F , Brown C , Waltenburg MA , Hughes CM , Nakazawa Y . medRxiv 2022 23 Monkeypox is a zoonotic disease endemic in Central and West Africa. In May 2022, an outbreak of monkeypox characterized by human-to-human transmission was detected in multiple non-endemic countries. We estimated the incubation period for monkeypox using information from 22 probable (N = 1) and confirmed (N = 21) monkeypox cases in patients reported in the United States through June 6, 2022. We pooled U.S. patient data with the data from 18 confirmed cases in patients reported from the Netherlands through May 31, 2022. The mean incubation period from exposure to first symptom onset was 7.6 days (95% credible interval: 6.2 - 9.7), and the 95th percentile was 17.1 days (95% CrI: 12.7-24.3). These findings align with current CDC recommendations for monitoring close contacts of people with monkeypox for 21 days after their last exposure. Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available for use under a CC0 license. |
IVIVE: Facilitating the use of in vitro toxicity data in risk assessment and decision making
Chang X , Tan YM , Allen DG , Bell S , Brown PC , Browning L , Ceger P , Gearhart J , Hakkinen PJ , Kabadi SV , Kleinstreuer NC , Lumen A , Matheson J , Paini A , Pangburn HA , Petersen EJ , Reinke EN , Ribeiro AJS , Sipes N , Sweeney LM , Wambaugh JF , Wange R , Wetmore BA , Mumtaz M . Toxics 2022 10 (5) During the past few decades, the science of toxicology has been undergoing a transformation from observational to predictive science. New approach methodologies (NAMs), including in vitro assays, in silico models, read-across, and in vitro to in vivo extrapolation (IVIVE), are being developed to reduce, refine, or replace whole animal testing, encouraging the judicious use of time and resources. Some of these methods have advanced past the exploratory research stage and are beginning to gain acceptance for the risk assessment of chemicals. A review of the recent literature reveals a burst of IVIVE publications over the past decade. In this review, we propose operational definitions for IVIVE, present literature examples for several common toxicity endpoints, and highlight their implications in decision-making processes across various federal agencies, as well as international organizations, including those in the European Union (EU). The current challenges and future needs are also summarized for IVIVE. In addition to refining and reducing the number of animals in traditional toxicity testing protocols and being used for prioritizing chemical testing, the goal to use IVIVE to facilitate the replacement of animal models can be achieved through their continued evolution and development, including a strategic plan to qualify IVIVE methods for regulatory acceptance. |
Public health actions to control measles among Afghan evacuees during Operation Allies Welcome - United States, September-November 2021
Masters NB , Mathis AD , Leung J , Raines K , Clemmons NS , Miele K , Balajee SA , Lanzieri TM , Marin M , Christensen DL , Clarke KR , Cruz MA , Gallagher K , Gearhart S , Gertz AM , Grady-Erickson O , Habrun CA , Kim G , Kinzer MH , Miko S , Oberste MS , Petras JK , Pieracci EG , Pray IW , Rosenblum HG , Ross JM , Rothney EE , Segaloff HE , Shepersky LV , Skrobarcek KA , Stadelman AM , Sumner KM , Waltenburg MA , Weinberg M , Worrell MC , Bessette NE , Peake LR , Vogt MP , Robinson M , Westergaard RP , Griesser RH , Icenogle JP , Crooke SN , Bankamp B , Stanley SE , Friedrichs PA , Fletcher LD , Zapata IA , Wolfe HO , Gandhi PH , Charles JY , Brown CM , Cetron MS , Pesik N , Knight NW , Alvarado-Ramy F , Bell M , Talley LE , Rotz LD , Rota PA , Sugerman DE , Gastañaduy PA . MMWR Morb Mortal Wkly Rep 2022 71 (17) 592-596 On August 29, 2021, the United States government oversaw the emergent establishment of Operation Allies Welcome (OAW), led by the U.S. Department of Homeland Security (DHS) and implemented by the U.S. Department of Defense (DoD) and U.S. Department of State (DoS), to safely resettle U.S. citizens and Afghan nationals from Afghanistan to the United States. Evacuees were temporarily housed at several overseas locations in Europe and Asia* before being transported via military and charter flights through two U.S. international airports, and onward to eight U.S. military bases,(†) with hotel A used for isolation and quarantine of persons with or exposed to certain infectious diseases.(§) On August 30, CDC issued an Epi-X notice encouraging public health officials to maintain vigilance for measles among Afghan evacuees because of an ongoing measles outbreak in Afghanistan (25,988 clinical cases reported nationwide during January-November 2021) (1) and low routine measles vaccination coverage (66% and 43% for the first and second doses, respectively, in 2020) (2). |
Current status and future directions for a neurotoxicity hazard assessment framework that integrates in silico approaches
Crofton KM , Bassan A , Behl M , Chushak YG , Fritsche E , Gearhart JM , Marty MS , Mumtaz M , Pavan M , Ruiz P , Sachana M , Selvam R , Shafer TJ , Stavitskaya L , Szabo DT , Szabo ST , Tice RR , Wilson D , Woolley D , Myatt GJ . Comput Toxicol 2022 22 Neurotoxicology is the study of adverse effects on the structure or function of the developing or mature adult nervous system following exposure to chemical, biological, or physical agents. The development of more informative alternative methods to assess developmental (DNT) and adult (NT) neurotoxicity induced by xenobiotics is critically needed. The use of such alternative methods including in silico approaches that predict DNT or NT from chemical structure (e.g., statistical-based and expert rule-based systems) is ideally based on a comprehensive understanding of the relevant biological mechanisms. This paper discusses known mechanisms alongside the current state of the art in DNT/NT testing. In silico approaches available today that support the assessment of neurotoxicity based on knowledge of chemical structure are reviewed, and a conceptual framework for the integration of in silico methods with experimental information is presented. Establishing this framework is essential for the development of protocols, namely standardized approaches, to ensure that assessments of NT and DNT based on chemical structures are generated in a transparent, consistent, and defendable manner. 2022 Elsevier B.V. |
CATMoS: Collaborative Acute Toxicity Modeling Suite.
Mansouri K , Karmaus AL , Fitzpatrick J , Patlewicz G , Pradeep P , Alberga D , Alepee N , Allen TEH , Allen D , Alves VM , Andrade CH , Auernhammer TR , Ballabio D , Bell S , Benfenati E , Bhattacharya S , Bastos JV , Boyd S , Brown JB , Capuzzi SJ , Chushak Y , Ciallella H , Clark AM , Consonni V , Daga PR , Ekins S , Farag S , Fedorov M , Fourches D , Gadaleta D , Gao F , Gearhart JM , Goh G , Goodman JM , Grisoni F , Grulke CM , Hartung T , Hirn M , Karpov P , Korotcov A , Lavado GJ , Lawless M , Li X , Luechtefeld T , Lunghini F , Mangiatordi GF , Marcou G , Marsh D , Martin T , Mauri A , Muratov EN , Myatt GJ , Nguyen DT , Nicolotti O , Note R , Pande P , Parks AK , Peryea T , Polash AH , Rallo R , Roncaglioni A , Rowlands C , Ruiz P , Russo DP , Sayed A , Sayre R , Sheils T , Siegel C , Silva AC , Simeonov A , Sosnin S , Southall N , Strickland J , Tang Y , Teppen B , Tetko IV , Thomas D , Tkachenko V , Todeschini R , Toma C , Tripodi I , Trisciuzzi D , Tropsha A , Varnek A , Vukovic K , Wang Z , Wang L , Waters KM , Wedlake AJ , Wijeyesakere SJ , Wilson D , Xiao Z , Yang H , Zahoranszky-Kohalmi G , Zakharov AV , Zhang FF , Zhang Z , Zhao T , Zhu H , Zorn KM , Casey W , Kleinstreuer NC . Environ Health Perspect 2021 129 (4) 47013 BACKGROUND: Humans are exposed to tens of thousands of chemical substances that need to be assessed for their potential toxicity. Acute systemic toxicity testing serves as the basis for regulatory hazard classification, labeling, and risk management. However, it is cost- and time-prohibitive to evaluate all new and existing chemicals using traditional rodent acute toxicity tests. In silico models built using existing data facilitate rapid acute toxicity predictions without using animals. OBJECTIVES: The U.S. Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) Acute Toxicity Workgroup organized an international collaboration to develop in silico models for predicting acute oral toxicity based on five different end points: Lethal Dose 50 (LD50 value, U.S. Environmental Protection Agency hazard (four) categories, Globally Harmonized System for Classification and Labeling hazard (five) categories, very toxic chemicals [LD50 (LD50 ≤ 50 mg/kg)], and nontoxic chemicals (LD50 > 2,000 mg/kg). METHODS: An acute oral toxicity data inventory for 11,992 chemicals was compiled, split into training and evaluation sets, and made available to 35 participating international research groups that submitted a total of 139 predictive models. Predictions that fell within the applicability domains of the submitted models were evaluated using external validation sets. These were then combined into consensus models to leverage strengths of individual approaches. RESULTS: The resulting consensus predictions, which leverage the collective strengths of each individual model, form the Collaborative Acute Toxicity Modeling Suite (CATMoS). CATMoS demonstrated high performance in terms of accuracy and robustness when compared with in vivo results. DISCUSSION: CATMoS is being evaluated by regulatory agencies for its utility and applicability as a potential replacement for in vivo rat acute oral toxicity studies. CATMoS predictions for more than 800,000 chemicals have been made available via the National Toxicology Program's Integrated Chemical Environment tools and data sets (ice.ntp.niehs.nih.gov). The models are also implemented in a free, standalone, open-source tool, OPERA, which allows predictions of new and untested chemicals to be made. https://doi.org/10.1289/EHP8495. |
Assessing support alternatives for longwall gateroads subject to changing stress
Esterhuizen GS , Tulu IB , Gearhart DF , Dougherty H , van Dyke M . Int J Min Sci Technol 2020 31 (1) 103-110 Longwall gateroad entries are subject to changing horizontal and vertical stress induced by redistribution of loads around the extracted panel. The stress changes can result in significant deformation of the entries that may include roof sag, rib dilation, and floor heave. Mine operators install different types of supports to control the ground response and maintain safe access and ventilation of the longwall face. This paper describes recent research aimed at quantifying the effect of longwall-induced stress changes on ground stability and using the information to assess support alternatives. The research included monitoring of ground and support interaction at several operating longwall mines in the U.S., analysis and calibration of numerical models that adequately represent the bedded rock mass, and observation of the support systems and their response to changes in stress. The models were then used to investigate the impact of geology and stress conditions on ground deformation and support response for various depths of cover and geologic scenarios. The research results were summarized in two regression equations that can be used to estimate the likely roof deformation and height of roof yield due to longwall-induced stress changes. This information is then used to assess the ability of support systems to maintain the stability of the roof. The application of the method is demonstrated with a retrospective analysis of the support performance at an operating longwall mine that experienced a headgate roof fall. The method is shown to produce realistic estimates of gateroad entry stability and support performance, allowing alternative support systems to be assessed during the design and planning stage of longwall operations. |
Analysis of gateroad stability at two longwall mines based on field monitoring results and numerical model analysis
Esterhuizen GS , Gearhart DF , Klemetti T , Dougherty H , van Dyke M . Int J Min Sci Technol 2018 29 (1) 35-43 Coal mine longwall gateroads are subject to changing loading conditions induced by the advancing longwall face. The ground response and support requirements are closely related to the magnitude and orientation of the stress changes, as well as the local geology. This paper presents the monitoring results of gateroad response and support performance at two longwall mines at a 180-m and 600-m depth of cover. At the first mine, a three-entry gateroad layout was used. The second mine used a four-entry, yield-abutment-yield gateroad pillar system. Local ground deformation and support response were monitored at both sites. The monitoring period started during the development stage and continued during first panel retreat and up to second panel retreat. The two data sets were used to compare the response of the entries in two very different geotechnical settings and different gateroad layouts. The monitoring results were used to validate numerical models that simulate the loading conditions and entry response for these widely differing conditions. The validated models were used to compare the load path and ground response at the two mines. This paper demonstrates the potential for numerical models to assist mine engineers in optimizing longwall layouts and gateroad support systems. |
Ground response to high horizontal stresses during longwall retreat and its implications for longwall headgate support
Zhang P , Gearhart D , Dyke MV , Su D , Esterhuizen E , Tulu B . Int J Min Sci Technol 2018 26 (1) 27-33 Roof falls in longwall headgate can occur when weak roof and high horizontal stress are present. To prevent roof falls in the headgate under high horizontal stress, it is important to understand the ground response to high horizontal stress in the longwall headgate and the requirements for supplemental roof support. In this study, a longwall headgate under high horizontal stress was instrumented to monitor stress change in the pillars, deformations in the roof, and load in the cable bolts. The conditions in the headgate were monitored for about six months as the longwall face passed by the instrumented site. The roof behavior in the headgate near the face was carefully observed during longwall retreat. Numerical modeling was performed to correlate the modeling results with underground observation and instrumentation data and to quantify the effect of high horizontal stress on roof stability in the long-wall headgate. This paper discusses roof support requirements in the longwall headgate under high horizontal stress in regard to the pattern of supplemental cable bolts and the critical locations where additional supplemental support is necessary. |
Analysis of monitored ground support and rock mass response in a longwall tailgate entry
Esterhuizen GS , Gearhart DF , Tulu IB . Int J Min Sci Technol 2017 28 (1) 43-51 A comprehensive monitoring program was conducted to measure the rock mass displacements, support response, and stress changes at a longwall tailgate entry in West Virginia. Monitoring was initiated a few days after development of the gateroad entries and continued during passage of the longwall panels on both sides of the entry. Monitoring included overcore stress measurements of the initial stress within the rock mass, changes in cable bolt loading, standing support pressure, roof deformation, rib deformation, stress changes in the coal pillar, and changes in the full three-dimensional stress tensor within the rock mass at six locations around the monitoring site. During the passage of the first longwall, stress measurements in the rock and coal detected minor changes in loading while minor changes were detected in roof deformation. As a result of the relatively favorable stress and geological conditions, the support systems did not experience severe loading or rock deformation until the second panel approached within 10-15 m of the instrumented locations. After reaching the peak loading at about 50-75 mm of roof sag, the cable bolts started to unload, and load was transferred to the standing supports. The standing support system was able to maintain an adequate opening inby the shields to provide ventilation to the first crosscut inby the face, as designed. The results were used to calibrate modeled cable bolt response to field data, and to validate numerical modeling procedures that have been developed to evaluate entry support systems. It is concluded that the support system was more than adequate to control the roof of the tailgate up to the longwall face location. The monitoring results have provided valuable data for the development and validation of support design strategies for longwall tailgate entries. |
Analysis of global and local stress changes in a longwall gateroad
Tulu IB , Esterhuizen GS , Gearhart D , Klemetti TM , Mohamed KM , Su DWH . Int J Min Sci Technol 2017 28 (1) 127-135 A numerical-model-based approach was recently developed for estimating the changes in both the horizontal and vertical loading conditions induced by an approaching longwall face. In this approach, a systematic procedure is used to estimate the model's inputs. Shearing along the bedding planes is modeled with ubiquitous joint elements and interface elements. Coal is modeled with a newly developed coal mass model. The response of the gob is calibrated with back analysis of subsidence data and the results of previously published laboratory tests on rock fragments. The model results were verified with the subsidence and stress data recently collected from a longwall mine in the eastern United States. |
Vertical load capacities of roof truss cross members
Gearhart DF , Morsy MK . Int J Min Sci Technol 2016 26 (3) 517-520 Trusses used for roof support in coal mines are constructed of two grouted bolts installed at opposing forty-five degree angles into the roof and a cross member that ties the angled bolts together. The load on the cross member is vertical, which is transverse to the longitudinal axis, and therefore the cross member is loaded in the weakest direction. Laboratory tests were conducted to determine the vertical load capacity and deflection of three different types of cross members. Single-point load tests, with the load applied in the center of the specimen and double-point load tests, with a span of 2.4 m, were conducted. For the single-point load configuration, the yield of the 25 mm solid bar cross member was nominally 98 kN of vertical load, achieved at 42 cm of deflection. For cable cross members, yield was not achieved even after 45 cm of deflection. Peak vertical loads were about 89 kN for 17 mm cables and 67 kN for the 15 mm cables. For the double-point load configurations, the 25 mm solid bar cross members yielded at 150 kN of vertical load and 25 cm of deflection. At 25 cm of deflection individual cable strands started breaking at 133 and 111 kN of vertical load for the 17 and 15 mm cable cross members respectively. |
Dietary iodine sufficiency and moderate insufficiency in the lactating mother and nursing infant: A computational perspective
Fisher W , Wang J , George NI , Gearhart JM , McLanahan ED . PLoS One 2016 11 (3) e0149300 The Institute of Medicine recommends that lactating women ingest 290 mug iodide/d and a nursing infant, less than two years of age, 110 mug/d. The World Health Organization, United Nations Children's Fund, and International Council for the Control of Iodine Deficiency Disorders recommend population maternal and infant urinary iodide concentrations ≥ 100 mug/L to ensure iodide sufficiency. For breast milk, researchers have proposed an iodide concentration range of 150-180 mug/L indicates iodide sufficiency for the mother and infant, however no national or international guidelines exist for breast milk iodine concentration. For the first time, a lactating woman and nursing infant biologically based model, from delivery to 90 days postpartum, was constructed to predict maternal and infant urinary iodide concentration, breast milk iodide concentration, the amount of iodide transferred in breast milk to the nursing infant each day and maternal and infant serum thyroid hormone kinetics. The maternal and infant models each consisted of three sub-models, iodide, thyroxine (T4), and triiodothyronine (T3). Using our model to simulate a maternal intake of 290 mug iodide/d, the average daily amount of iodide ingested by the nursing infant, after 4 days of life, gradually increased from 50 to 101 mug/day over 90 days postpartum. The predicted average lactating mother and infant urinary iodide concentrations were both in excess of 100 mug/L and the predicted average breast milk iodide concentration, 157 mug/L. The predicted serum thyroid hormones (T4, free T4 (fT4), and T3) in both the nursing infant and lactating mother were indicative of euthyroidism. The model was calibrated using serum thyroid hormone concentrations for lactating women from the United States and was successful in predicting serum T4 and fT4 levels (within a factor of two) for lactating women in other countries. T3 levels were adequately predicted. Infant serum thyroid hormone levels were adequately predicted for most data. For moderate iodide deficient conditions, where dietary iodide intake may range from 50 to 150 mug/d for the lactating mother, the model satisfactorily described the iodide measurements, although with some variation, in urine and breast milk. Predictions of serum thyroid hormones in moderately iodide deficient lactating women (50 mug/d) and nursing infants did not closely agree with mean reported serum thyroid hormone levels, however, predictions were usually within a factor of two. Excellent agreement between prediction and observation was obtained for a recent moderate iodide deficiency study in lactating women. Measurements included iodide levels in urine of infant and mother, iodide in breast milk, and serum thyroid hormone levels in infant and mother. A maternal iodide intake of 50 mug/d resulted in a predicted 29-32% reduction in serum T4 and fT4 in nursing infants, however the reduced serum levels of T4 and fT4 were within most of the published reference intervals for infant. This biologically based model is an important first step at integrating the rapid changes that occur in the thyroid system of the nursing newborn in order to predict adverse outcomes from exposure to thyroid acting chemicals, drugs, radioactive materials or iodine deficiency. |
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