268 research outputs found
On certain problems of arithmetic arising in the realization of linear systems with symmetries
Developing an alcohol policy assessment toolkit: application in the western pacific
Objective: To demonstrate the development and feasibility of a tool to assess the adequacy of national policies aimed at reducing alcohol consumption and related problems. Methods: We developed a quantitative tool – the Toolkit for Evaluating Alcohol policy Stringency and Enforcement (TEASE-16) – to assess the level of stringency and enforcement of 16 alcohol control policies. TEASE-16 was applied to policy data from nine study areas in the western Pacific: Australia, China excluding Hong Kong Special Administrative Region (SAR), Hong Kong SAR, Japan, Malaysia, New Zealand, the Philippines, Singapore and Viet Nam. Correlation and regression analyses were then used to examine the relationship between alcohol policy scores and income-adjusted levels of alcohol consumption per capita. Findings: Vast differences exist in how alcohol control policies are implemented in the western Pacific. Out of a possible 100 points, the nine study areas achieved TEASE-16 scores that ranged from 24.1 points for the Philippines to 67.5 points for Australia. Study areas with high policy scores – indicating relatively strong alcohol policy frameworks – had lower alcohol consumption per capita. Sensitivity analyses indicated scores and rankings for each study area remained relatively stable across different weighting schemes, indicating that TEASE-16 was robust. Conclusion: TEASE-16 could be used by international and national regulatory bodies and policy-makers to guide the design, implementation, evaluation and refinement of effective policies to reduce alcohol consumption and related problems
Brief report: Using global positioning system (GPS) enabled cell phones to examine adolescent travel patterns and time in proximity to alcohol outlets
As adolescents gain freedom to explore new environments unsupervised, more time in proximity to alcohol outlets may increase risks for alcohol and marijuana use. This pilot study: 1) Describes variations in adolescents' proximity to outlets by time of day and day of the week, 2) Examines variations in outlet proximity by drinking and marijuana use status, and 3) Tests feasibility of obtaining real-time data to study adolescent proximity to outlets. U.S. adolescents (N = 18) aged 16–17 (50% female) carried GPS-enabled smartphones for one week with their locations tracked. The geographic areas where adolescents spend time, activity spaces, were created by connecting GPS points sequentially and adding spatial buffers around routes. Proximity to outlets was greater during after school and evening hours. Drinkers and marijuana users were in proximity to outlets 1½ to 2 times more than non-users. Findings provide information about where adolescents spend time and times of greatest risk, informing prevention efforts
Probability of the most massive cluster under non-Gaussian initial conditions
Very massive high redshift clusters can be used to constrain and test the
Lambda CDM model. Taking into account the observational constraints of Jee et
al. (2009) we have calculated the probability for the most massive cluster to
be found in the range (5.2-7.6)e14 M_sun, between redshifts 1.4-2.2, with a sky
area of 11 sqdeg and under non-Gaussian initial conditions. Clusters constrain
the non-Gaussianity on smaller scales than current cosmic microwave background
or halo bias data and so can be used to test for running of the non-Gaussianity
parameter f_NL.Comment: Matches MNRAS accepted versio
Photonic-chip-based tunable slow and fast light via stimulated Brillouin scattering
We report the first (to our knowledge) demonstration of photonic chip based tunable slow and fast light via stimulated Brillouin scattering. Slow, fast, and negative group velocities were observed in a 7 cm long chalcogenide (As2S3) rib waveguide with a group index change ranging from ∼−44 to +130, which results in a maximum delay of ∼23 ns at a relatively low gain of ∼23 dB. Demonstration of large tunable delays in a chip scale device opens up applications such as frequency sensing and true-time delay for a phased array antenna, where integration and delays ∼10 ns are highly desirable
Photonic chip based tunable and reconfigurable narrowband microwave photonic filter using stimulated Brillouin scattering
We report the first demonstration of a photonic chip based dynamically reconfigurable, widely tunable, narrow pass-band, high Q microwave photonic filter (MPF). We exploit stimulated Brillouin scattering (SBS) in a 6.5 cm long chalcogenide (As2S3) photonic chip to demonstrate a MPF that exhibited a high quality factor of ~520 and narrow bandwidth and was dynamically reconfigurable and widely tunable. It maintained a stable 3 dB bandwidth of 23 ± 2MHz and amplitude of 20 ± 2 dB over a large frequency tuning range of 2-12 GHz. By tailoring the pump spectrum, we reconfigured the 3 dB bandwidth of the MPF from ~20 MHz to ~40 MHz and tuned the shape factor from 3.5 to 2 resulting in a nearly flat-topped filter profile. This demonstration represents a significant advance in integrated microwave photonics with potential applications in on-chip microwave signal processing for RADAR and analogue communications
Elwha River restoration: evolution of habitats and nearshore ecosystems during large-scale dam removal project
Located on the North Olympic Peninsula, the Elwha River nearshore is a critical component of the Salish Sea. It is depended on by no fewer than six federally listed salmon species including chum, and numerous forage fish such as surf smelt and sand lance. The Elwha nearshore is impaired ecologically due to extensive shoreline armoring and in-river channelization and dams. The Elwha nearshore is undergoing an unprecedented restoration event with the removal of two large in river dams from September 2011 to 2014, exposing 21 million cubic meters of sediment. According to Foley et al. 2016, as of December 2016, approximately 70% has been eroded of which 90% transported to the Strait of Juan de Fuca equating 13.23 million cubic meters of sediment that has been delivered to the sediment starved Elwha nearshore. The Coastal Watershed Institute and partners lead long-term studies of the Elwha nearshore ecological function. In this presentation, we provide an overview of fish use of the Elwha and comparative nearshore areas, and observations of nearshore ecological function response of the juvenile fish migration and forage fish spawning to dam removal. Despite the sediment delivery from the dam removal, nearshore restoration is incomplete due to remaining shoreline armoring and lower river alterations. These are the focus of ongoing community collaboration and large-scale restoration projects presented by Michel et al. Finally, we provide an overview of linkages of the nearshore restoration event for the larger Elwha and Salish Sea ecosystem
Exposure to alcohol outlets, alcohol access, and alcohol consumption among adolescents
Background: Adolescents who live near more alcohol outlets tend to consume more alcohol, despite laws prohibiting alcohol purchases for people aged <21 years. We examined relationships between adolescents' exposure to alcohol outlets, the sources through which they access alcohol, and their alcohol consumption.
Methods: Participants for this longitudinal study (n = 168) were aged 15-18 years and were from 10 cities in the San Francisco Bay Area. We collected survey data to measure participant characteristics, followed by 1 month of GPS tracking to measure exposure to alcohol outlets (separated into exposures near home and away from home for bars, restaurants, and off-premise outlets). A follow-up survey approximately 1 year later measured alcohol access (through outlets, family members, peers aged <21 years, peers aged ≥21 years) and alcohol consumption (e.g. count of drinking days in last 30). Generalized structural equation models related exposure to alcohol outlets, alcohol access, and alcohol consumption.
Results: Exposure to bars and off-premise outlets near home was positively associated with accessing alcohol from peers aged <21, and in turn, accessing alcohol from peers aged <21 was positively associated with alcohol consumption. There was no direct association between exposure to alcohol outlets near home or away from home and alcohol consumption.
Conclusions: Interventions that reduce adolescents' access through peers aged <21 may reduce adolescents' alcohol consumption
Assessing Individuals’ Exposure to Environmental Conditions Using Residence-Based Measures, Activity Location-Based Measures, and Activity Path-Based Measures
Background: Many approaches are available to researchers who wish to measure individuals' exposure to environmental conditions. Different approaches may yield different estimates of associations with health outcomes. Taking adolescents' exposure to alcohol outlets as an example, we aimed to (1) compare exposure measures and (2) assess whether exposure measures were differentially associated with alcohol consumption.
Methods: We tracked 231 adolescents 14-16 years of age from the San Francisco Bay Area for 4 weeks in 2015/2016 using global positioning systems (GPS). Participants were texted ecologic momentary assessment surveys six times per week, including assessment of alcohol consumption. We used GPS data to calculate exposure to alcohol outlets using three approach types: residence-based (e.g., within the home census tract), activity location-based (e.g., within buffer distances of frequently attended places), and activity path-based (e.g., average outlets per hour within buffer distances of GPS route lines). Spearman correlations compared exposure measures, and separate Tobit models assessed associations with the proportion of ecologic momentary assessment responses positive for alcohol consumption.
Results: Measures were mostly strongly correlated within approach types (ρ ≥ 0.7), but weakly (ρ < 0.3) to moderately (0.3 ≤ ρ < 0.7) correlated between approach types. Associations with alcohol consumption were mostly inconsistent within and between approach types. Some of the residence-based measures (e.g., census tract: β = 8.3, 95% CI = 2.8, 13.8), none of the activity location-based approaches, and most of the activity path-based approaches (e.g., outlet-hours per hour, 100 m buffer: β = 8.3, 95% CI = 3.3, 13.3) were associated with alcohol consumption.
Conclusions: Methodologic decisions regarding measurement of exposure to environmental conditions may affect study results
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