Helicopter tail rotor orthogonal blade vortex interaction

The aerodynamic operating environment of the helicopter is particularly complex and, to some extent, dominated by the vortices trailed from the main and tail rotors. These vortices not only determine the form of the induced flow field but also interact with each other and with elements of the physical structure of the flight vehicle. Such interactions can have implications in terms of structural vibration, noise generation and flight performance. In this paper, the interaction of main rotor vortices with the helicopter tail rotor is considered and, in particular, the limiting case of the orthogonal interaction. The significance of the topic is introduced by highlighting the operational issues for helicopters arising from tail rotor interactions. The basic phenomenon is then described before experimental studies of the interaction are presented. Progress in numerical modelling is then considered and, finally, the prospects for future research in the area are discussed

Evaluation of a Medicaid Lock-in Program

Background: "Lock-in" programs (LIPs) identify beneficiaries demonstrating potential overutilization of opioids, and other controlled substances, and restrict their access to these medications. LIPs are expanding to address the opioid crisis and could be an effective tool for connecting people to opioid use disorder treatment. We examined the immediate and sustained effects of a Medicaid LIP on overdose risk and use of medication-assisted treatment (MAT) for opioid use disorder. Methods: We analyzed North Carolina Medicaid claims from July 2009 through June 2013. We estimated daily risk differences and ratios of MAT use and overdose during lock-in and following release from the program, compared with periods before program enrollment. Results: The daily probability of MAT use during lock-in and following release was greater, when compared with a period just before LIP enrollment [daily risk ratios: 1.50, 95% confidence interval (CI): 1.18-1.91; 2.27, 95% CI: 1.07-4.80; respectively]. Beneficiaries' average overdose risk while enrolled in the program and following release was similar to their risk just before enrollment (daily risk ratios: 1.01, 95% CI: 0.79-1.28; 1.12, 95% CI: 0.82-1.54; respectively). Discussion: North Carolina's Medicaid LIP was associated with increased use of MAT during enrollment, and this increase was sustained in the year following release from the program. However, we did not observe parallel reductions in overdose risk during lock-in and following release. Identifying facilitators of MAT access and use among this population, as well as potential barriers to overdose reduction are important next steps to ensuring effective LIP design

The Health Belief Model Applied to Understanding Diabetes Regimen Compliance

Inadequate adherence to prescribed treatment plans is perhaps the most serious obstacle to achieving success ful therapeutic outcomes, and non compliance by diabetic patients is no exception. This is partly based on pa tients' realization that compliance does not necessarily result in lack of illness. A psychosocial framework for under standing patient compliance is the Health Belief Model, which is based upon the value an individual places on the identified goal and the likelihood that compliance will achieve that goal. This Model has been useful to explain noncompliance, to make an "educa tional diagnosis," and for designing compliance-enhancing interventions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68410/2/10.1177_014572178501100108.pd

Connections Between Opioids and Road Injury: Linkage of Prescription Monitoring and Crash Databases

Road traffic injuries and drug overdoses are the two leading causes of injury death in the U.S. In 2017, these two mechanisms were responsible for more than 100,000 deaths. Perhaps more importantly, these two leading causes of injury are closely interconnected. Opioids and other drugs affect driving abilities (e.g., reaction time, alertness, concentration) and crash-related injuries often result in opioid prescribing, creating a potential feedback loop from crash to injury to pain to opioid use and back to crash. At any given time, about 20% of drivers have a potentially impairing drug in their system

Methodologic limitations of prescription opioid safety research and recommendations for improving the evidence base

Purpose: The ongoing opioid epidemic has claimed more than a quarter million Americans' lives over the past 15 years. The epidemic began with an escalation of prescription opioid deaths and has now evolved to include secondary waves of illicit heroin and fentanyl deaths, while the deaths due to prescription opioid overdoses are still increasing. In response, the Centers for Disease Control and Prevention (CDC) moved to limit opioid prescribing with the release of opioid prescribing guidelines for chronic noncancer pain in March 2016. The guidelines represent a logical and timely federal response to this growing crisis. However, CDC acknowledged that the evidence base linking opioid prescribing to opioid use disorders and overdose was grades 3 and 4. Methods: Motivated by the need to strengthen the evidence base, this review details limitations of the opioid safety studies cited in the CDC guidelines with a focus on methodological limitations related to internal and external validity. Results: Internal validity concerns were related to poor confounding control, variable misclassification, selection bias, competing risks, and potential competing interventions. External validity concerns arose from the use of limited source populations, historical data (in a fast-changing epidemic), and issues with handling of cancer and acute pain patients' data. We provide a nonexhaustive list of 7 recommendations to address these limitations in future opioid safety studies. Conclusion: Strengthening the opioid safety evidence base will aid any future revisions of the CDC guidelines and enhance their prevention impact

Spin-charge separation in the single hole doped Mott antiferromagnet

The motion of a single hole in a Mott antiferromagnet is investigated based on the t-J model. An exact expression of the energy spectrum is obtained, in which the irreparable phase string effect [Phys. Rev. Lett. 77, 5102 (1996)] is explicitly present. By identifying the phase string effect with spin backflow, we point out that spin-charge separation must exist in such a system: the doped hole has to decay into a neutral spinon and a spinless holon, together with the phase string. We show that while the spinon remains coherent, the holon motion is deterred by the phase string, resulting in its localization in space. We calculate the electron spectral function which explains the line shape of the spectral function as well as the ``quasiparticle'' spectrum observed in angle-resolved photoemission experiments. Other analytic and numerical approaches are discussed based on the present framework.Comment: 16 pages, 9 figures; references updated; to appear in Phys. Rev.

Potential injuries and costs averted by increased use of evidence-based behavioral road safety policies in North Carolina

Objective: The purpose of this study was to estimate the potential injuries and costs that could be averted by implementing evidence-based road safety policies and interventions not currently utilized in one U.S. state, North Carolina (NC). NC consistently has annual motor vehicle-related death rates above the national average. Methods: We used the Centers for Disease Control and Prevention’s Motor Vehicle Prioritizing Interventions and Cost Calculator for States (MV PICCS) tool as a foundation for examining the potential injuries and costs that could be averted from underutilized evidence-based policies, assuming a $1.5 million implementation budget and that income generated from policy-related fines and fees would help offset costs. We further examined costs by payer source. Results: Model results indicated that seven interventions should be prioritized for implementation in NC: increased alcohol ignition interlock use, increased seat belt fines, in-person license renewal for ages 70 and older, license plate impoundment, seat belt enforcement campaigns, saturation patrols, and speed cameras. Increasing the seat belt fine had the potential to avert the greatest number of fatal (n = 70) and non-fatal (n = 6,597) injuries annually, along with being the most cost-effective of the recommended interventions. Collectively, the seven recommended evidence-based policies/interventions have the potential to avert 302 fatal injuries, 16,607 non-fatal injuries, and$839 million annually in NC with the greatest costs averted for insurers. Conclusions: This study demonstrates the utility of the MV PICCS tool as a foundation for exploring state-specific impacts that could be realized through increased evidence-based road safety policy and intervention implementation. For NC, we found that increasing the seat belt fine would avert the most injuries, and had the greatest financial benefits for the state, and the lowest implementation costs. Incorporating fines and fees into policy implementation can create important financial feedbacks that allow for implementation of additional evidence-based and cost-effective policies/interventions. Given the recent uptick in U.S. motor vehicle-related deaths, analyses informed by the MV PICCS tool can help researchers and policy makers initiate discussions about successful state-specific strategies for reducing the burden of crashes

Z-Score Burden Metric: A Method for Assessing Burden of Injury and Disease

Introduction: Traditional methods of summarizing burden of disease have limitations in terms of identifying communities within a population that are in need of prevention and intervention resources. This paper proposes a new method of burden assessment for use in guiding these decisions. Methods: This new method for assessing burden utilizes the sum of population-weighted age-specific z-scores. This new Z-Score Burden Metric was applied to firearm-related deaths in North Carolina counties using 2010‒2017 North Carolina Violent Death Reporting System data. The Z-Score Burden Metric consists of 4 measures describing various aspects of burden. The Z-Score Burden Metric Overall Burden Measure was compared with 2 traditional measures (unadjusted and age-adjusted death rates) for each county to assess similarities and differences in the relative burden of firearm-related death. Results: Of all 100 North Carolina counties, 73 met inclusion criteria (≥5 actual and expected deaths during the study period in each age strata). Ranking by the Overall Burden Measure produced an ordering of counties different from that of ranking by traditional measures. A total of 8 counties (11.0%) differed in burden rank by at least 10% when comparing the Overall Burden Measure with age-adjusted and unadjusted rates. All the counties with large differences between the measures were substantially burdened by firearm-related death. Conclusions: The use of the Z-Score Burden Metric provides an alternative way of measuring realized community burden of injury while still facilitating comparisons between communities with different age distributions. This method can be used for any injury or disease outcome and may help to prioritize the allocation of resources to communities suffering high burdens of injury and disease

Health Care Utilization and Comorbidity History of North Carolina Medicaid Beneficiaries in a Controlled Substance "Lock-in" Program

BACKGROUND Medicaid "lock-in" programs (MLIPs) are a widely used strategy for addressing potential misuse of prescription drugs among beneficiary populations. However, little is known about the health care needs and attributes of beneficiaries selected into these programs. Our goal was to understand the characteristics of those eligible, enrolled, and retained in a state MLIP. METHODS Demographics, comorbidities, and health care utilization were extracted from Medicaid claims from June 2009 through June 2013. Beneficiaries enrolled in North Carolina's MLIP were compared to those who were MLIP-eligible, but not enrolled. Among enrolled beneficiaries, those completing the 12-month MLIP were compared to those who exited prior to 12 months. RESULTS Compared to beneficiaries who were eligible for, but not enrolled in the MLIP (N = 11,983), enrolled beneficiaries (N = 5,424) were more likely to have: 1) substance use (23% versus 14%) and mental health disorders, 2) obtained controlled substances from multiple pharmacies, and 3) visited more emergency departments (mean: 8.3 versus 4.2 in the year prior to enrollment). One-third (N = 1,776) of those enrolled in the MLIP exited the program prior to completion. LIMITATIONS Accurate information on unique prescribers visited by beneficiaries was unavailable. Time enrolled in Medicaid differed for beneficiaries, which may have led to underestimation of covariate prevalence. CONCLUSIONS North Carolina's MLIP appears to be successful in identifying subpopulations that may benefit from provision and coordination of services, such as substance abuse and mental health services. However, there are challenges in retaining this population for the entire MLIP duration

Trends in unintentional polysubstance overdose deaths and individual and community correlates of polysubstance overdose, North Carolina, 2009-2018

Background: Polysubstance involvement is increasing among fatal drug overdoses. However, little is known about the epidemiology of polysubstance drug overdoses. This paper describes emerging trends in unintentional polysubstance overdose deaths in North Carolina (NC) and examines associations with individual and community factors. Methods: Using 2009–2018 NC death certificate data, we identified unintentional drug overdose deaths and commonly involved substances (opioids, stimulants, benzodiazepines, alcohol, and antiepileptics). We examined polysubstance combinations, comparing opioid and non-opioid involved deaths. We examined individual level correlates from death certificate data and community level correlates from the American Community Survey and Robert Wood Johnson Foundation County Health Rankings to quantify associations. Results: From 2009–2018, 53 % of opioid and 19 % of non-opioid overdose deaths involved multiple substances. During this period, polysubstance overdose death increased dramatically, from 2.9 to 12.1 per 100,000 persons, with the greatest increases among drug combinations involving stimulants. The most common polysubstance combinations were: opioids and stimulants (12.1 % of overdose deaths); opioids and benzodiazepines (9.0 %); opioids and alcohol (5.1 %); opioids, stimulants, and benzodiazepines (3.1 %); and opioids, benzodiazepines, and antiepileptics (2.2 %). Compared to overdoses involving opioids alone, overdoses involving combinations of opioids, stimulants, and benzodiazepines involved younger individuals (53.7 % in 15−34 years of age vs. 40.7 %). Men comprised two-thirds of overdoses involving opioids alone, however, overdoses involving opioids, benzodiazepines, and antiepileptics were predominantly among women (60.6 %). Conclusions: Polysubstance involvement has increased among overdose deaths in NC. These findings can be used to inform public health interventions addressing polysubstance deaths and associated individual and community level factors