First Movers in Marijuana: Tourism Boom or Bust?

In 2014, Colorado and Washington legalized the cultivation, sale, and consumption of recreational marijuana for anyone over the age of 21. In doing so, the two states presented the first opportunities for marijuana-specific tourism in the United States. Direct benefits of legalization to these first movers, namely tax revenues generated through the sale of marijuana, have been quantified, but the indirect benefits in the tourism sector are as of yet unquantified. Although there is a large body of informal literature and popular media on marijuana tourism, academic study of the subject is scant. Working with a panel composed of 47 of the contiguous United States over the years 2005-2016, this study utilizes a synthetic control methodology to construct hypothetical time series for various tourism indicators for the cases of non-legalization in Colorado and Washington. Comparison of these hypothetical time series to the actual time series reveals the effects of legalization. A similar methodology is applied to all states to find the “placebo effects” and to establish significance. In traveler expenditures, traveler-generated taxes, tourism industry employment, and tourism industry payroll, Washington shows effects of legalization of greater magnitude and significance than those in Colorado. Only 8% of other states show an effect on tourism revenues as large as that of Washington. Additionally this study finds that each state can be approximated with a weighted average of a small group of peers and that weather, price, and an interacted migration and political orientation variable have low predictive power on tourism indicators. Lastly, this study suggests possible causes and policy implications of the discrepancy between the states

The influence of soft contact lens wear and two weeks cessation of lens wear on corneal curvature.

INTRODUCTION: Accurate corneal measurements are crucial in corneal refractive surgery (CRS) to ensure successful outcomes. Soft contact lens (SCL) wear may result in changes to corneal curvature and structure. United States Food and Drug Administration (FDA) pre-operative guidelines recommend that prior to CRS, SCL wearers cease SCL wear for "at least two weeks before examination and treatment" [1]. Corneal curvature changes induced by SCL wear may take longer than two weeks to resolve. PURPOSE: To examine the effect of SCL wear on corneal curvature before and following two weeks SCL wear cessation. To explore the possible impact of different SCL materials and years of SCL wear. METHODS: Retrospective data analysis, between a group of SCL wearers (SCL: n=45); and a non-contact lens control group (NCL: n=45). Corneal curvature parameters were measured using the Pentacam (Oculus, Germany), before and following two weeks cessation of SCL wear. RESULTS: No significant differences in keratometry or Sagittal radius of curvature between SCL and NCL groups prior to or following SCL cessation. Tangential radius of curvature showed significant inferior steepening for the SCL group prior to SCL cessation (SCL vs. NCL; 7.77±0.30mm vs. 7.90±0.30mm; p=0.04). Following two weeks cessation of SCL wear this appeared to have resolved. CONCLUSIONS: Two weeks cessation of SCL wear appears sufficient for resolution of corneal curvature changes with modern SCL materials and years of SCL wear. However, further studies with longer lens deprivation periods are required to ensure stability for all SCL wearing patients

Caregiver Characteristics of Adults with Acute Traumatic Brain Injury in the United States and Latin America

Objectives: To compare characteristics of caregivers of adults with acute traumatic brain injury (TBI) in the U.S. and Latin America (Mexico and Colombia). Design: Secondary data analysis of two cohorts. Cohort 1: English-speaking caregivers of adults with TBI in the U.S. (n = 80). Cohort 2: Spanish-speaking caregivers of adults with TBI in Mexico or Colombia (n = 109). Results: Similarities between the U.S. and Latin American caregiver groups, respectively, were: predominantly women (81.3%, 81.7%, respectively); spouses/domestic partners (45%, 31.2%); and motor vehicle accident (41.5%, 48.6%) followed by fall etiologies (40%, 21.1%). Differences between U.S. and Latin American caregivers were: age (49.5 years, 41.5 years, p < 0.001); employment status ((X-5(2) = 59.63, p < 0.001), full-time employment (63.7%, 25.7%), homemaker (2.5%, 31.2%), and retired (17.5%, 1.8%)); violence-related etiology (2.5%, 15.6%); and severity of depressive symptoms (M = 7.9, SD = 5.8; M = 5.8, SD = 5.7; p = 0.014). Conclusions: TBI caregivers in the U.S. were older and employed full-time or retired more often than those in Latin America. Violence-related etiology was nearly five times more common in Latin America, raising concerns for potential implications of post-traumatic stress and family adjustment after injury. Although both groups likely could use mental health support, this was particularly true of the U.S. cohort, maybe due to differential demographics, mechanisms of injury, or family and community support.Data collection was supported by NIDILRR (grant numbers: Kessler 90DPTB0003; NTX-TBIMS 90DPTB0013; JFK 90DPTB0014) and Grant #R21TW009746 from the Fogarty International Center of the National Institutes of Health and in part by the Department of Veterans Affairs. Additional support for coauthors was provided by NIDILRR (grant numbers: Spaulding/Harvard TBIMS: 90DPTB0011; TIRR 90DPTB0016)

The effect of videokeratoscope faceplate design on radius of curvature maps

A computer model using finite ray tracing methods was developed to simulate a videokeratoscope analysing an average cornea. Different faceplate designs were tested using five points in the faceplate subtending angles between 15 and 75 in 15 intervals at the corneal vertex. Image quality was assessed by adding the geometrical blurs of the 5 image points. Differences (error) between accurate sagittal radius of curvature and sagittal radius of curvature calculated by the van Saarloos algorithm were calculated for selected surfaces at the same corneal points. The calculations were repeated for the tangential radius of curvature. Differences equal or bigger than 0.02 mm were regarded as clinically significant. The surface that provided the sharpest image for an average cornea was a cylinder with the base 120 mm away from the corneal vertex and a diameter of 26 mm. Changing the faceplate design results in clinically significant differences for an average cornea

Analysis of the application of the generalized monod kinetics model to describe the human corneal oxygen-consumption rate during soft contact lens wear

This work is an analysis of the application of the generalized Monod kinetics model describing human corneal oxygen consumption during soft contact lens wear to models previously used by Chhabra et al. (J Biomed Mater Res B Appl Biomater, 2009a;90:202-209, Optom Vis Sci 2009b; 86:454-466) and Larrea and Buchler (Invest Ophthalmol Vis € Sci 2009;50:1076-1080). We use oxygen tension from in vivo estimations provided by Bonanno [Bonanno et al., Invest Ophthalmol Vis Sci 2002;43:371-376, and Bonanno et al 2009]. We consider four hydrogel and six silicone hydrogel lenses. The cornea is considered a single homogeneous layer, with constant oxygen permeability regardless of the type of lens worn. Our calculations yield different values for the maximum oxygen consumption rate Qc,max, whith differents oxygen tensions (high and low pc) at the cornea-tears interface. Surprisingly, for both models, we observe an increase in oxygen consumption near an oxygen tension of 105 mmHg until a maximum is reached, then decreasing for higher levels of oxygen pressure. That is, when lowering the pressure of oxygen, the parameter Qc,max initially increases depending on the intensity of the change in pressure. Which, it could be related with the variation of the pH. Furthermore, it is also noted that to greater reductions in pressure, this parameter decreases, possibly due to changes in the concentration of glucose related to the anaerobic respiration. The averaged in vivo human corneal oxygen consumption rate of 1.47 3 1024 cm3 of O2/cm3 tissue s, with Monod kinetics model, considering all the lenses studied, is smaller than the average oxygen consumption rate value obtained using the Larrea and Buchler model. The impact that these calculations € have on the oxygen partial pressure available at different depths in the corneal tissue is presented and discussed, taking into consideration previous models used in this studySIH is grateful to projects CONACYT SEP-2004-C01-47070, UNAM-DGAPA-PAPIIT IN113415, DGTIC-UNAM SC16-1-IR- 113, to the Red Tematica de la Materia Condensada BlandaCONACYT for a postdoctoral fellowship, and to CONACYT for a retention fellowship No. 207109. We thank Dr. Barry A. Weissman from the Southern California College of Optometry at Marshall B Ketchum University, Fullerton CA, USA for helpful comments and discussion

The speed of corneal epithelial wound healing

We propose a reaction-diffusion model of the mechanisms involved in the healing of corneal surface wounds. The model focuses on the stimulus for increased mitotic and migratory activity, specifically the role of epidermal growth factor. We determine an analytic approximation for the speed of travelling wave solutions of the model and verify the result numerically. The predicted speed compares very well with experimentally measured healing rates