Imaging the three-dimensional Fermi-surface pairing near the hidden-order transition in URu2Si2 using angle-resolved photoemission spectroscopy.

We report angle-resolved photoemission spectroscopy experiments probing deep into the hidden-order state of URu(2)Si(2), utilizing tunable photon energies with sufficient energy and momentum resolution to detect the near Fermi-surface (FS) behavior. Our results reveal (i) the full itinerancy of the 5f electrons, (ii) the crucial three-dimensional k-space nature of the FS and its critical nesting vectors, in good comparison with density-functional theory calculations, and (iii) the existence of hot-spot lines and pairing of states at the FS, leading to FS gapping in the hidden-order phase.

Integrated experimental setup for angle resolved photoemission spectroscopy of transuranic materials.

We have developed the Angle Resolved Photoemission Spectroscopy (ARPES) system for transuranic materials. The ARPES transuranic system is an endstation upgrade to the Laser Plasma Light Source (LPLS) at Los Alamos National Laboratory. The LPLS is a tunable light source for photoemission with a photon energy range covering the vacuum ultraviolet (VUV) and soft x-ray regions (27-140 eV). The LPLS was designed and developed for transuranic materials. Transuranic photoemission is currently not permitted at the public synchrotrons worldwide in the VUV energy range due to sample encapsulation requirements. With the addition of the ARPES capability to the LPLS system there is an excellent opportunity to explore new details centered on the electronic structure of actinide and transuranic materials.

The Maze Test: A significant predictor of older driver crash risk.

A study sponsored by the National Highway Traffic Safety Administration performed functional assessments on approximately 700 drivers age 70 and older who presented for license renewal in urban, suburban, and rural offices of the Maryland Motor Vehicle Administration. This volunteer sample received a small compensation for study participation, with an assurance that their license status would not be affected by the results. A comparison with all older drivers who visited the same sites on the same days indicated that the study sample was representative of Maryland older drivers with respect to age and prior driving safety indices. Relationships between drivers' scores on a computer touchscreen version of the Maze Test and prospective crash and serious moving violation experience were analyzed. Results identified specific mazes as highly significant predictors of future safety risk for older drivers, with a particular focus on non-intersection crashes. Study findings indicate that performance on Maze Tests was predictive of prospective crashes and may be useful, as a complement to other, established cognitive screening tools, in identifying at-risk older drivers.

Effect of spin-orbit coupling on the actinide dioxides AnO2 (An=Th, Pa, U, Np, Pu, and Am): a screened hybrid density functional study.

We present a systematic comparison of the lattice structures, electronic density of states, and band gaps of actinide dioxides, AnO(2) (An=Th, Pa, U, Np, Pu, and Am) predicted by the Heyd-Scuseria-Ernzerhof screened hybrid density functional (HSE) with the self-consistent inclusion of spin-orbit coupling (SOC). The computed HSE lattice constants and band gaps of AnO(2) are in consistently good agreement with the available experimental data across the series, and differ little from earlier HSE results without SOC. ThO(2) is a simple band insulator (f(0)), while PaO(2), UO(2), and NpO(2) are predicted to be Mott insulators. The remainders (PuO(2) and AmO(2)) show considerable O2p/An5f mixing and are classified as charge-transfer insulators. We also compare our results for UO(2), NpO(2), and PuO(2) with the PBE+U, self interaction correction (SIC), and dynamic mean-field theory (DMFT) many-body approximations.

Pursuit of Licensure by Senior Drivers Referred by Police to a State Licensing Agency's Medical Advisory Board.

In all fifty United States and the District of Columbia, police Requests for Re-examination (RRE) concerning fitness to driver are accepted by licensing agencies. This study assessed licensing outcomes of senior drivers, ≥75 years of age, who had RREs submitted to the Medical Advisory Board (MAB) of a Maryland Motor Vehicle Administration from March 2005 through April 2007. RRE traffic event information (including crashed, did not crash), driver demographic information, initial MAB recommendations (suspension vs no suspension), driving occupational therapists assessments, and drivers' pursuit of continued licensure were entered into a database. During the period of study, 475 RREs were referred to the MAB. The percent of referred senior drivers (n=240, 50.4%) was similar to that of younger drivers (n=235, 49.5%). A higher percentage of senior drivers retired from driving compared to younger drivers; being, 57.1% vs 23.8% (p <.01), respectively. Further analyses limited to the 240 senior drivers found: 139 (57.9%) were men, 150 (62.5%) were 75-84 years of age, 119 (49.5%) were noted to be disoriented at the traffic scene, 141 (58.8%) were involved in a crash, and 127 (52.9%) were initially suspended as the result of MAB review. The following factors were significantly related to retiring from driving, initial MAB suspension and greater age. Of the 127 drivers who were initially suspended, 82 (64.6%) retired from driving, and 45 (35.4%) pursued further licensure (p <0.01). In contrast, the percentage of non-suspended drivers who did or did not pursue further licensure was similar; being 48.7% vs 51.3%. Among drivers ≥85 years of age, 68.9% retired from driving, compared with 50% of the drivers who were 75 to 84 years of age (p <0.01) While not statisically significant, higher percentages of driving retirement were noted for the following: sex - a greater percentage of men compared to women (61.9% vs 49.5%); confusion at the traffic scene (confused, 57.1% vs non-confused, 42.9%); and crash involvement (56.7% who crashed, retired vs 43.3% of those who did not crash, retired). Overall, the most important finding of this study is that as a result of police referral, only one-fifth (20.4%) of senior drivers 75 years of age or older, continued to maintain their driving privilege. However, only 40 drivers (16.7%) retained their original driving privilege without added restrictions. The data suggest that senior drivers who are not medically fit to drive may be identified by police referrals to a licensing agency. Driving occupational therapy assessments and training, and additional driving restrictions are recommended to facilitate continuation of the driving privilege for some drivers.

Do older drivers at-risk for crashes modify their driving over time?

Five-year driving habit trajectories among older adults (n = 645) at-risk for crashes were examined. Performance measures included Useful Field of View (UFOV). Motor-Free Visual Perception Test, Rapid Walk, and Foot Tap. Self-report measures included demographics and the Driving Habits Questionnaire. Longitudinal random-effects models revealed that drivers at-risk for subsequent crashes, based upon UFOV, regulated their driving more than the lower-risk participants. Restricted driving was present at baseline for the at-risk group and was observed in longitudinal trajectories that controlled for baseline differences. Results indicate that persons at-risk for subsequent crashes increasingly limit their driving over time. Despite this self-regulation, a larger sample of such older drivers was twice as likely to incur subsequent at-fault crashes. Results suggest that self-regulation among older drivers at-risk for crashes is an insufficient compensatory approach to eliminating increased crash risk. UFOV is a registered trademark of Visual Awareness, Inc.

Police referral of drivers to the Maryland Motor Vehicle Administration's Medical Advisory Board.

In the 50 United States and the District of Columbia law enforcement medical referrals are accepted by licensing agencies. This study assessed driving actions, medical concerns, and medical conditions in 486 police referrals to the Medical Advisory Board of the Maryland Motor Vehicle Administration during a 25-month period. Driving actions, medical concerns, and medical conditions were grouped into categories and entered into a database. These elements were analyzed relative to driver age and sex. In addition, the issuance of citations for driving violations was studied relative to age and sex. A greater percentage of drivers 60 years of age or greater (senior adults) were referred compared to the general population of licensed drivers that age, being 71.4% vs 20.6% (p <0.01). Crashing, the most common driving action, was not associated with age or sex. Among driving actions frequently mentioned relative to older drivers, only confusion of pedals was associated with senior adults drivers as compared to younger drivers (6.1% vs 0.1%, p <0.01). Of the most frequently mentioned medical concerns, confusion/disorientation was associated with being a senior adult (p <0.01), while loss of consciousness was associated with younger drivers (p <0.01). The most frequently mentioned medical conditions, diabetes and seizure, were associated with being under 60 years of age. All mentions of dementia were in senior adult drivers. Compared with younger drivers, drivers 60 years of age or older, were less often summoned for driving violations, being 33.0% vs 53.5% (p <0.01), respectively. The threshold for the issuance of fewer citations was lower for men (40 to 59 years of age) compared to women (60 years of age or greater). Studies are needed to correlate specific traffic violations and/or crashes to specific medical conditions.

Medical review of fitness to drive in older drivers: the Maryland experience.

BACKGROUND: Over the next several decades, both the number and percentage of older drivers will increase dramatically. Older age is inherently associated with medical conditions, particularly those involving cognition and vision, that can affect medical fitness to drive. Over a 60-year period, the Maryland Motor Vehicle Administration (MVA) in conjunction with its medical advisory board (MAB) has matured a comprehensive system to identify at-risk older drivers and to assess their medical fitness to drive. METHODS: This paper describes the medical review process in general, and in particular for older drivers, that has evolved in the state of Maryland. The resources, philosophy and research underpinnings of its MAB review process are examined. RESULTS: Studies of functional screening measures in older drivers indicate that older drivers at risk of being at-fault for future crashes can be identified. The feasibility of using such screening measures for drivers referred to the MVA has been confirmed by practical use for a period of seven years. CONCLUSIONS: It is possible to create a medical review process with a goal of "safe mobility for life" that supports preservation of the driving privilege among many older drivers.

Dispersion in the Mott insulator UO2: A comparison of photoemission spectroscopy and screened hybrid density functional theory.

We present a comparison between the screened hybrid density functional theory of Heyd, Scuseria, and Enzerhof (HSE06) and high-resolution photoemission (PES) measurement on a single crystal of UO(2). Angle-resolved photoemission data show a slight dispersion in the f-orbital derived bands in good agreement with the HSE band structure. The effect of spin-orbit coupling on the HSE band gap has also been calculated and found to be negligible.

Persuasion and licensure: a randomized controlled intervention trial to increase licensure rates among Maryland motorcycle owners.

OBJECTIVE: This study aimed to determine whether a persuasive educational intervention could increase licensure among motorcycle owners. Unlicensed motorcycle operators appear to be disproportionately involved in police-reported motorcycle crashes in Maryland, accounting for about 27% of motorcycle operators in police-reported crashes, although unlicensed owners comprise 17% of primary motorcycle owners. METHODS: A randomized controlled trial was conducted among unlicensed owners. Linking Maryland records of registered motorcycles with license files, 8,499 unlicensed owners who had no licensed co-owners were identified. Half were randomized to receive a persuasive educational mailing in early June 2005 from Maryland Motor Vehicle Administration (MVA). Motorcycle licenses can be attained by passing an accredited motorcycle training class or passing knowledge and skills tests administered by the state driver licensing agency. Licensure rates and motorcycle class enrollment were followed for 6 months post-intervention. RESULTS: As of December 16, 2005, 280 intervention group owners had obtained Class M motorcycle licenses and 158 had obtained Class R motorcycle learner's permits. The comparison group obtained 209 M licenses and 122 R permits. The overall success rate in the intervention group, defined as obtaining Class M or R, was 10.4% compared with 7.9% in the comparison group (licensure ratio (LR) = 1.33; 95% confidence interval (CI) = 1.16-1.52). The intervention was most successful among men, whose LR for obtaining M licenses was 1.45 (95% CI = 1.21-1.75). LRs were higher among owners ages 40-48 and 49+ receiving the intervention compared with younger groups. Motorcycle training class enrollment rates were higher in the intervention group, particularly among those taking a course for riders with intermediate skills (enrollment ratio = 2.24; 95% CI = 1.41-3.55). CONCLUSION: The intervention appeared to increase licensure, yet the licensure rate remained low among the intervention group. Potential risks and benefits of increasing the percentage of motorcyclists who are licensed need to be studied.

Can high-risk older drivers be identified through performance-based measures in a Department of Motor Vehicles setting?

OBJECTIVES: To evaluate the relationship between performance-based risk factors and subsequent at-fault motor vehicle collision (MVC) involvement in a cohort of older drivers. DESIGN: Prospective cohort study. SETTING: Motor Vehicle Administration (MVA) field sites in Maryland. PARTICIPANTS: Of the 4,173 older drivers invited to participate in the study, 2,114 individuals aged 55 to 96 agreed to do so. These analyses focus on 1,910 individuals recruited through MVA field sites. MEASUREMENTS: Gross Impairment Screening Battery, which included Rapid Pace Walk, Head/Neck Rotation, Foot Tap, Arm Reach, Cued Recall, Symbol Scan, Visual Closure subtest of the Motor Free Visual Perception Test (MVPT), Delayed Recall, and Trail Making Test with an Abbreviated Part A and standard Part B; Useful Field of View (UFOV) subtest 2; a Mobility Questionnaire; and MVC occurrence. RESULTS: In drivers aged 55 and older with intact vision (20/70 far visual acuity and 140 degrees visual field), age, sex, history of falls, and poorer cognitive performance, as measured using Trails B, MVPT, and UFOV subtest 2, were predictive of future at-fault MVC involvement. After adjusting for annual mileage, participants aged 78 and older were 2.11 as more likely to be involved in an at-fault MVC, those who made four or more errors on the MVPT were 2.10 times as likely to crash, those who took 147 seconds or longer to complete Trails B were 2.01 times as likely to crash, and those who took 353 ms or longer on subtest 2 of the UFOV were 2.02 times as likely to incur an at-fault MVC. Older adults, men, and individuals with a history of falls were more likely to be involved in subsequent at-fault MVCs. CONCLUSION: Performance-based cognitive measures are predictive of future at-fault MVCs in older adults. Cognitive performance, in particular, is a salient predictor of subsequent crash involvement in older adults. High-risk older drivers can be identified through brief, performance-based measures administered in a MVA setting.