Frederick, MD, United States
Frederick, MD, United States

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Calabrese C.,Volpe National Transportation Systems Center | Mejia B.,Volpe National Transportation Systems Center | McInnis C.A.,Volpe National Transportation Systems Center | France M.,Volpe National Transportation Systems Center | And 2 more authors.
Journal of Safety Research | Year: 2017

Introduction The purpose of this study is to examine how time of day affects injury risk of railroad maintenance of way employees and signalmen (roadway workers). Railroads reported 15,654 serious roadway worker injuries between 1997 and 2014. Roadway workers primarily work outdoors on or near railroad tracks and frequently encounter hazardous conditions. To avoid closing an active rail line during peak hours, railroads sometimes require roadway workers to work at night. Previous studies of roadway worker injury have not adequately accounted for exposure to time of day effects, nor have they investigated the human factors issues contributing to roadway worker injury. Method The Federal Railroad Administration (FRA) database of injury reports provided data for circadian rhythm models of the odds of fatal and nonfatal injuries. The FRA database and fatal injury investigation reports also permitted an analysis of the circumstances and the human factors issues associated with injuries that occur at different times of day. Results Odds of injury increased during nighttime work. The odds of nonfatal injury for both roadway worker crafts rose above 9:1 in the early morning hours. The relative odds of a fatal injury also increased significantly at night. A human factors analysis suggested that during all three shifts most nonfatal injuries involve workload, but workload was not identified as a factor in fatal injuries. Conclusions Nighttime work is more hazardous for roadway workers than daytime work. Several factors related to fatigue and other conditions appear to increase the risk of injury during the outdoor, nighttime work required of roadway workers. Practical application For practical reasons, nighttime roadway work is sometimes unavoidable. Therefore, new practices for nighttime work must be developed to adequately address fatigue and protect roadway workers from harm. © 2017


PubMed | U.S. National Institute on Drug Abuse, Texas Tech University, University of Oregon, University of Chicago and Institutes for Behavior Resources
Type: Journal Article | Journal: Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology | Year: 2016

Previous studies suggest dopamine (DA) D2-like receptor involvement in the reinforcing effects of food. To determine contributions of the three D2-like receptor subtypes, knockout (KO) mice completely lacking DA D2, D3, or D4 receptors (D2R, D3R, or D4R KO mice) and their wild-type (WT) littermates were exposed to a series of fixed-ratio (FR) food-reinforcement schedules in two contexts: an open economy with additional food provided outside the experimental setting and a closed economy with all food earned within the experimental setting. A behavioral economic model was used to quantify reinforcer effectiveness with food pellets obtained as a function of price (FR schedule value) plotted to assess elasticity of demand. Under both economies, as price increased, food pellets obtained decreased more rapidly (ie, food demand was more elastic) in DA D2R KO mice compared with WT littermates. Extinction of responding was studied in two contexts: by eliminating food deliveries and by delivering food independently of responding. A hyperbolic model quantified rates of extinction. Extinction in DA D2R KO mice occurred less rapidly compared with WT mice in both contexts. Elasticity of food demand was higher in DA D4R KO than WT mice in the open, but not closed, economy. Extinction of responding in DA D4R KO mice was not different from that in WT littermates in either context. No differences in elasticity of food demand or extinction rate were obtained in D3R KO mice and WT littermates. These results indicate that the D2R is the primary DA D2-like receptor subtype mediating the reinforcing effectiveness of food.


Mitchell S.G.,Friends Research Institute Inc. | Gryczynski J.,Friends Research Institute Inc. | Kelly S.M.,Friends Research Institute Inc. | O'Grady K.E.,University of Maryland University College | And 4 more authors.
Journal of Drug Issues | Year: 2014

This secondary analysis compared outcomes in African American adults newly admitted to buprenorphine treatment and who were on parole and probation with outcomes in patients who were not under criminal justice (CJ) supervision. Buprenorphine patients (N = 300) were randomly assigned to receive either intensive outpatient (IOP) treatment or standard outpatient (OP) treatment and were assessed at baseline, and 3 and 6 months. There were no differences between groups in treatment retention. Among probationers/parolees, IOP treatment was associated with lower 3-month treatment retention compared with OP treatment, but among participants not on probation/parole, the relationship was reversed (p = .004). Both conditions showed significant declines in heroin and cocaine use, illegal activity, and in meeting Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) criteria for opioid and cocaine dependence. Probationers/parolees reported a lower frequency of illegal activities at 3 months compared with nonprobationers/nonparolees (p = .007). Buprenorphine treatment should be made more widely available to individuals on parole/probation as they respond as well to treatment as patients not supervised by the CJ system. © The Author(s) 2013.


Goswami N.,Medical University of Graz | Batzel J.J.,Medical University of Graz | Batzel J.J.,University of Graz | Clement G.,University of Strasbourg | And 7 more authors.
European Journal of Applied Physiology | Year: 2013

Regulatory systems are affected in space by exposure to weightlessness, high-energy radiation or other spaceflight-induced changes. The impact of spaceflight occurs across multiple scales and systems. Exploring such interactions and interdependencies via an integrative approach provides new opportunities for elucidating these complex responses. This paper argues the case for increased emphasis on integration, systematically archiving, and the coordination of past, present and future space and ground-based analogue experiments. We also discuss possible mechanisms for such integration across disciplines and missions. This article then introduces several discipline-specific reviews that show how such integration can be implemented. Areas explored include: adaptation of the central nervous system to space; cerebral autoregulation and weightlessness; modelling of the cardiovascular system in space exploration; human metabolic response to spaceflight; and exercise, artificial gravity, and physiologic countermeasures for spaceflight. In summary, spaceflight physiology research needs a conceptual framework that extends problem solving beyond disciplinary barriers. Administrative commitment and a high degree of cooperation among investigators are needed to further such a process. Well-designed interdisciplinary research can expand opportunities for broad interpretation of results across multiple physiological systems, which may have applications on Earth. © 2012 Springer-Verlag Berlin Heidelberg.


Freeman K.B.,University of Mississippi Medical Center | McMaster B.C.,University of Mississippi Medical Center | Roma P.G.,Institutes for Behavior Resources | Roma P.G.,Johns Hopkins University | Woolverton W.L.,University of Mississippi Medical Center
Psychopharmacology | Year: 2014

Rationale: Recent research has demonstrated that the drug, histamine, can function as a punisher of cocaine self-administration. However, little is known about how drug punishers affect the maximum reinforcing effectiveness of drugs as reinforcers. Objective: The goal of the present study was to determine if histamine, when self-administered as a mixture with cocaine, could reduce cocaine's maximum reinforcing effectiveness using two procedures designed for measuring reinforcing effectiveness. Methods: In the first experiment, rhesus monkeys were allowed to self-administer cocaine (0.1 mg/kg/inj) alone or as a mixture with histamine (0.012-0.05 mg/kg/inj) in a behavioral economic design. In the second experiment, monkeys were allowed to self-administer cocaine alone (0.006-0.56 mg/kg/inj) or as a mixture with histamine (0.025-0.1 mg/kg/inj) under a progressive-ratio schedule of reinforcement. Results: In Experiment 1, histamine decreased the reinforcing effectiveness of cocaine in a dose-dependent manner as evidenced by increases in cocaine's demand elasticity with increases in histamine dose. In Experiment 2, histamine decreased cocaine's potency and effectiveness as a reinforcer in a dose-dependent manner as indicated by rightward and downward shifts, respectively, in the dose-response functions. Conclusion: The reinforcing effectiveness of cocaine can be reduced by contingent self-administration of histamine. These results indicate that combining drug punishers with drug reinforcers reduces the maximum reinforcing effect of the drug reinforcer, which suggests a use for drug punishers as a deterrent to drug abuse (e.g., as mixtures with prescription medications with abuse potential). © 2014 Springer-Verlag Berlin Heidelberg.


Soto P.L.,Texas Tech University | Hiranita T.,U.S. National Institute on Drug Abuse | Xu M.,University of Chicago | Hursh S.R.,Institutes for Behavior Resources | And 2 more authors.
Neuropsychopharmacology | Year: 2016

Previous studies suggest dopamine (DA) D2-like receptor involvement in the reinforcing effects of food. To determine contributions of the three D2-like receptor subtypes, knockout (KO) mice completely lacking DA D2, D3, or D4 receptors (D2R, D3R, or D4R KO mice) and their wild-type (WT) littermates were exposed to a series of fixed-ratio (FR) food-reinforcement schedules in two contexts: an open economy with additional food provided outside the experimental setting and a closed economy with all food earned within the experimental setting. A behavioral economic model was used to quantify reinforcer effectiveness with food pellets obtained as a function of price (FR schedule value) plotted to assess elasticity of demand. Under both economies, as price increased, food pellets obtained decreased more rapidly (ie, food demand was more elastic) in DA D2R KO mice compared with WT littermates. Extinction of responding was studied in two contexts: by eliminating food deliveries and by delivering food independently of responding. A hyperbolic model quantified rates of extinction. Extinction in DA D2R KO mice occurred less rapidly compared with WT mice in both contexts. Elasticity of food demand was higher in DA D4R KO than WT mice in the open, but not closed, economy. Extinction of responding in DA D4R KO mice was not different from that in WT littermates in either context. No differences in elasticity of food demand or extinction rate were obtained in D3R KO mice and WT littermates. These results indicate that the D2R is the primary DA D2-like receptor subtype mediating the reinforcing effectiveness of food. © 2016 American College of Neuropsychopharmacology. All rights reserved.


Gryczynski J.,Friends Research Institute | Jaffe J.H.,Friends Research Institute | Jaffe J.H.,University of Maryland Baltimore County | Schwartz R.P.,Friends Research Institute | And 6 more authors.
American Journal on Addictions | Year: 2013

Background Recent policy initiatives in Baltimore City, MD significantly reduced access disparities between methadone and buprenorphine in the publicly funded treatment sector. Objectives This study examines reasons for choosing buprenorphine over methadone among patients with access to both medications. Method This study was embedded within a larger clinical trial conducted at two outpatient substance abuse treatment programs offering buprenorphine. Qualitative and quantitative data on treatment choice were collected for new patients starting buprenorphine treatment (n = 80). The sample consisted of predominantly urban African American (94%) heroin users who had prior experience with non-prescribed street buprenorphine (85%), and opioid agonist treatment (68%). Qualitative data were transcribed and coded for themes, while quantitative data were analyzed using descriptive and bivariate statistics. Results Participants typically conveyed their choice of buprenorphine treatment as a decision against methadone. Buprenorphine was perceived as a helpful medication while methadone was perceived as a harmful narcotic with multiple unwanted physical effects. Positive experiences with non-prescribed "street buprenorphine" were a central factor in participants' decisions to seek buprenorphine treatment. Conclusions Differences in service structure between methadone and buprenorphine did not strongly influence treatment-seeking decisions in this sample. Personal experiences with medications and the street narrative surrounding them play an important role in treatment selection decisions. Scientific Significance This study characterizes important decision factors that underlie patients' selection of buprenorphine over methadone treatment. © American Academy of Addiction Psychiatry.


Davis C.M.,Johns Hopkins University | Decicco-Skinner K.L.,American University of Washington | Roma P.G.,Johns Hopkins University | Roma P.G.,Institutes for Behavior Resources | Hienz R.D.,Johns Hopkins University
Radiation Research | Year: 2014

To assess the possible neurobehavioral performance risks to astronauts from living in a space radiation environment during long-duration exploration missions, the effects of head-only proton irradiation (150 MeV/n) at low levels (25-50 cGy, approximating an astronaut's exposure during a 2-year planetary mission) were examined in adult male Long-Evans rats performing an analog of the human psychomotor vigilance test (PVT). The rodent version of PVT or rPVT tracks performance variables analogous to the human PVT, including selective attention/inattention, inhibitory control ("impulsivity") and psychomotor speed. Exposure to head-only proton radiation (25, 50, 100 or 200 cGy) disrupted rPVT performance (i.e., decreased accuracy, increased premature responding, elevated lapses in attention and slowed reaction times) over the 250 day testing period. However, the performance decrements only occurred in a subgroup of animals at each exposure level, that is, the severity of the rPVT performance deficit was unrelated to proton exposure level. Analysis of brain tissue from irradiated and control rats indicated that only rats with rPVT performance deficits displayed changes in the levels of the dopamine transporter and, to a lesser extent, the D2 receptor. Additional animals trained to perform a line discrimination task measuring basic and reversal learning showed no behavioral effects over the same exposure levels, suggesting a specificity of the proton exposure effects to attentional deficits and supporting the rPVT as a sensitive neurobehavioral assay.


PubMed | Institutes for Behavior Resources
Type: Journal Article | Journal: Journal of the experimental analysis of behavior | Year: 2013

The application of economics principles to the analysis of behavior has yielded novel insights on value and choice across contexts ranging from laboratory animal research to clinical populations to national trends of global impact. Recent innovations in demand curve methods provide a credible means of quantitatively comparing qualitatively different reinforcers as well as quantifying the choice relations between concurrently available reinforcers. The potential of the behavioral economic approach to inform public policy is illustrated with examples from basic research, pre-clinical behavioral pharmacology, and clinical drug abuse research as well as emerging applications to public transportation and social behavior. Behavioral Economics can serve as a broadly applicable conceptual, methodological, and analytical framework for the development and evaluation of empirical public policy.


PubMed | Johns Hopkins University and Institutes for Behavior Resources
Type: | Journal: Journal of visualized experiments : JoVE | Year: 2017

The human Psychomotor Vigilance Test (PVT) is a widely used procedure for measuring changes in fatigue and sustained attention. The present article describes a rodent version of the PVT-termed the rPVT-that measures similar aspects of attention (i.e., performance accuracy, motor speed, premature responding, and lapses in attention). Data are presented that demonstrate both the short- and long-term usefulness of the rPVT when employed with laboratory rats. Rats easily learn the rPVT, and learning to perform the basic procedure takes less than two weeks of training. Once acquired, rat performances in the rPVT show a high degree of similarity to these same performance measures in the human PVT, including similarities in, lapses in attention, reaction times, vigilance decrements across session time (i.e., the human time-on-task effects), and the response-stimulus interval (RSI) effect described for humans. Thus the rPVT can be an extremely valuable tool for assessing the effects of a wide range of variables on sustained attention quite similar to human PVT performances, and thus can be useful for developing novel treatments for neurobehavioral dysfunctions.

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