Direct Optical Coupling to an Unoccupied Dirac Surface State in the Topological Insulator Bi2_2Se3_3

We characterize the occupied and unoccupied electronic structure of the topological insulator Bi$_2$Se$_3$ by one-photon and two-photon angle-resolved photoemission spectroscopy and slab band structure calculations. We reveal a second, unoccupied Dirac surface state with similar electronic structure and physical origin to the well-known topological surface state. This state is energetically located 1.5 eV above the conduction band, which permits it to be directly excited by the output of a Ti:Sapphire laser. This discovery demonstrates the feasibility of direct ultrafast optical coupling to a topologically protected, spin-textured surface state.Comment: Accepted to Physical Review Letter

Rossby-gravity waves in tropical total ozone data

Evidence for Rossby-gravity waves in tropical data fields produced by the European Center for Medium Range Weather Forecasts (ECMWF) was recently reported. Similar features are observable in fields of total column ozone from the Total Ozone Mapping Spectrometer (TOMS) satellite instrument. The observed features are episodic, have zonal (east-west) wavelengths of 6,000-10,000 km, and oscillate with periods of 5-10 days. In accord with simple linear theory, the modes exhibit westward phase progression and eastward group velocity. The significance of finding Rossby-gravity waves in total ozone fields is that (1) the report of similar features in ECMWF tropical fields is corroborated with an independent data set and (2) the TOMS data set is demonstrated to possess surprising versatility and sensitivity to relatively smaller scale tropical phenomena

Low frequency oscillations in total ozone measurements

Low frequency oscillations with periods of approximately one to two months are found in eight years of global grids of total ozone data from the Total Ozone Mapping Spectrometer (TOMS) satellite instrument. The low frequency oscillations corroborate earlier analyses based on four years of data. In addition, both annual and seasonal one-point correlation maps based on the 8-year TOMS data are presented. The results clearly show a standing dipole in ozone perturbations, oscillating with 35 to 50 day periods over the equatorial Indian Ocean-west Pacific region. This contrasts with the eastward moving dipole reported in other data sets. The standing ozone dipole appears to be a dynamical feature associated with vertical atmospheric motions. Consistent with prior analyses based on lower stratospheric temperature fields, large-scale standing patterns are also found in the extratropics of both hemispheres, correlated with ozone fluctuations over the equatorial west Pacific. In the Northern Hemisphere, a standing pattern is observed extending from the tropical Indian Ocean to the north Pacific, across North America, and down to the equatorial Atlantic Ocean region. This feature is most pronounced in the NH summer

Oscillations in D-region absorption at periods of one to two months

One to two month oscillations in D-region absorption are found in seven years of daily f-min data from low latitude stations at Singapore (1N, 104E) and Rarotonga (21S, 160W). Coherency (cross-spectral) analyses reveal that solar flux variations account for much of the f-min variance at these periods. Over the range of periods from 10 to 200 days, statistically significant linear correlation is found between the f-min time series and contemporaneous 10.7 cm solar flux mearurements at periods of 16 to 19 days, the 26 to 29 day solar rotation band, and a broad band covering 43 to 80 day periods

Kelvin waves in total column ozone

Tropical Kelvin waves have been observed previously in ozone mixing ratio data from the SBUV (Solar Backscatter Ultraviolet) and LIMS (Limb Infrared Monitor of the Stratosphere) instruments on board the Nimbus-7 satellite. Kelvin wave features in total column ozone, using version 6 data from the Total Ozone Mapping Spectrometer (TOMS) instrument (also on board Nimbus-7) are investigated. Results show eastward-propagating zonal waves 1-2 with periods approximately 5-15 days, amplitudes approximately 3-5 DU, and latitudinal symmetry typical of Kelvin waves. A simplified model calculation suggests that the primary source for the perturbations is slow Kelvin waves in the lower-to-middle stratosphere. Maximum Kelvin wave signatures occur in conjunction with westward lower-to-middle stratospheric equatorial zonal winds (a quasi-biennial oscillation (QBO) wind modulation effect)

The 1979 Tornado Outbreak and Manson Storm: An Example of Tornadoes Approaching from the Northwest

It is widely believed that tornadoes move from the southwest. However, 30 percent of all Iowa tornadoes move instead from the northwest quadrant, and the majority of summer tornadoes come from this direction in the upper midwest. The greatest recorded outbreak of northwest-type tornadoes occurred on June 28, 1979, when 27 such twisters touched down in North Dakota, Minnesota, and Iowa. Ten of these were in Iowa, including the destructive Algona and Manson tornadoes. Meteorological information, satellite cloud imagery, and eyewitness accounts of the 1979 outbreak and especially the Manson storm are used here to illustrate this less-well-known class of tornadoes

Depression, antidepressants and driving safety.

BackgroundThe purpose of this study was to review to review the reported associations of depression and antidepressants with motor vehicle crashes.PurposeA literature search for material published in the English language between January, 1995, and October, 2015, in bibliographic databases was combined with a search for other relevant material referenced in the retrieved articles.MethodsRetrieved articles were systematically reviewed for inclusion criteria: 19 epidemiological studies (17 case-control and 2 cohort studies) fulfilled the inclusion criteria by estimating the crash risk associated with depression and/or psychotropic medications in naturalistic settings.ResultsThe estimates of the odds ratio (OR) of crash involvement associated with depression ranged from 1.78 to 3.99. All classes of antidepressants were reported to have side effects with the potential to affect driving safety. The majority of studies of antidepressant effects on driving reported an elevated crash risk, and ORs ranged from 1.19 to 2.03 for all crashes, and 3.19 for fatal crashes. In meta-analysis, depression was associated with approximately 2-fold increased crash risk (summary OR = 1.90; 95% CI, 1.06 to 3.39), and antidepressants were associated with approximately 40% increased crash risk (summary OR = 1.40; 95%CI, 1.18 to 1.66).ConclusionBased on the findings of the studies reviewed, depression, antidepressants or the combination of depression and antidepressants may pose a potential hazard to driving safety. More research is needed to understand the individual contributions of depression and the medications used to treat depression

Developing the Stress Strain Curves for an Epoxy Undergoing High Speed Impact

The Hopkinson Split Bar test can be used to accurately develop the relationship between the stress and strain a material undergoes during a high speed impact (rates of 1000/s). This information has many industrial uses, for example the auto industry can use this technology to analyze how materials will behave under crash-like circumstances. In this experiment the stress-strain curves were developed for the PC-Plumbing epoxy. One of the variables that can be adjusted in the Split Hopkinson Bar test is the ration between the height of the sample and the width of the sample (Hs/Ds). This experiment investigated how three different sample sizes (0.25, 0.33, \u3e1) affected the results. The stress strain curves were found, as well as the maximum strain rates, yield strengths, yield strain and modulus’s of elasticity. The effect of the Hs/Ds also was that each sample size resulted within a distinct range of maximum strain rates

The Role of Occupational Therapy in Adult Critical Care in Ohio

Abstract Objective: The purpose of this study was to explore the barriers and supports in the delivery of OT services, identify current OT-specific protocols, and explore opinions on critical care certification and OT-specific ICU best practice guidelines. Methods: A non-experimental descriptive data collection study with the use of an online survey. The secure survey link was embedded via email and sent to 10,000 Ohio occupational therapy practitioners. Inclusion criteria were licensed therapists (OTR and COTA) with past or current experience in adult critical care. The primary researcher developed survey questions focused on practitioners’ perspectives and personal experiences with critical care onboarding training, delirium management, and protocols followed in a critical care setting. Results: This study garnered 204 responses from Ohio OT practitioners with an active license. The majority of OT practitioners either “agree” (56.86%) or “strongly agree” (35.78%) that the ICU is considered a specialty setting. The majority of respondents either “strongly agreed” (65.20%) or “agreed” (31.86%) that OT-specific ICU best practice guidelines would be beneficial for new and existing OT practitioners. This study has helped identify key factors that influence the scope and proficiency development of practitioners working in an adult critical care setting. Conclusion: Developing OT-specific best practice guidelines would benefit practitioners working in an adult critical care environment. Future research into critical care experience, onboarding training, understanding of delirium management, and OT-specific protocols would be beneficial to guide the development of best practice guidelines. Keywords: Intensive care unit, critical care, occupational therapy, delirium, post-intensive care syndrome, ICU survivor, delirium managemen

Data Validation for Earth Probe-Total Ozone Mapping Spectrometer

This presentation represents the final report for the NASA grant project. The goal of this project was to provide scientific analysis to aid in validation fo data sets used in detection of long term global trends of total ozone. Ozone data from the Earth Probe Total Ozone Mapping Spectrometer instrument was compared for validation purposes with features in previous TOMS data. Atmospheric dynamic concepts were used in the analysis. The publications sponsored by the grant are listed along with abstracts