Coupling between plasmonic and photonic crystal modes in suspended three-dimensional meta-films.

A complementary metal oxide semiconductor (CMOS) compatible fabrication method for creating three-dimensional (3D) meta-films is presented. In contrast to metasurfaces, meta-films possess structural variation throughout the thickness of the film and can possess a sub-wavelength scale structure in all three dimensions. Here we use this approach to create 2D arrays of cubic silicon nitride unit cells with plasmonic inclusions of elliptical metallic disks in horizontal and vertical orientations with lateral array-dimensions on the order of millimeters. Fourier transform infrared (FTIR) spectroscopy is used to measure the infrared transmission of meta-films with either horizontally or vertically oriented ellipses with varying eccentricity. Shape effects due to the ellipse eccentricity, as well as localized surface plasmon resonance (LSPR) effects due to the effective plasmonic wavelength are observed in the scattering response. The structures were modeled using rigorous coupled wave analysis (RCWA), finite difference time domain (Lumerical), and frequency domain finite element (COMSOL). The silicon nitride support structure possesses a complex in-plane photonic crystal slab band structure due to the periodicity of the unit cells. We show that adjustments to the physical dimensions of the ellipses can be used to control the coupling to this band structure. The horizontally oriented ellipses show narrow, distinct plasmonic resonances while the vertically oriented ellipses possess broader resonances, with lower overall transmission amplitude for a given ellipse geometry. We attribute this difference in resonance behavior to retardation effects. The ability to couple photonic slab modes with plasmonic inclusions enables a richer space of optical functionality for design of metamaterial-inspired optical components.

Adding an online community to an internet-mediated walking program. Part 2: strategies for encouraging community participation.

Starting a new online community with a limited number of members who have not self-selected for participation in the community is challenging. The space must appear active to lure visitors to return; when the pool of participants is small, a large fraction must be converted from lurkers to contributors, and contributors must receive responses quickly to encourage continued participation. We report on strategies for overcoming these challenges and our experience implementing them within an online community add-on to an existing Internet-mediated walking program. Concentrated study recruitment increased the effective membership size. Having few conversation spaces rather than many specialized ones, staff seeding of the forums before members were invited to visit, and staff posting of new topics when there were conversation lulls, all helped to make the forums appear active. In retrospect, using even fewer separate spaces and displaying a flat rather than nested reply structure would have made the forums appear even more active. Contests with small prizes around participation in the forums and around meeting walking goals generated a lot of discussion; a contest for first-time posters was especially effective at moving lurkers to post. Staff efforts to elicit participation by asking questions had mixed success. Staff replies to posts that had not received member replies created a feeling of responsiveness despite limited membership.

An online community improves adherence in an internet-mediated walking program. Part 1: results of a randomized controlled trial.

BACKGROUND: Approximately half of American adults do not meet recommended physical activity guidelines. Face-to-face lifestyle interventions improve health outcomes but are unlikely to yield population-level improvements because they can be difficult to disseminate, expensive to maintain, and inconvenient for the recipient. In contrast, Internet-based behavior change interventions can be disseminated widely at a lower cost. However, the impact of some Internet-mediated programs is limited by high attrition rates. Online communities that allow participants to communicate with each other by posting and reading messages may decrease participant attrition. OBJECTIVE: Our objective was to measure the impact of adding online community features to an Internet-mediated walking program on participant attrition and average daily step counts. METHODS: This randomized controlled trial included sedentary, ambulatory adults who used email regularly and had at least 1 of the following: overweight (body mass index [BMI] ≥ 25), type 2 diabetes, or coronary artery disease. All participants (n = 324) wore enhanced pedometers throughout the 16-week intervention and uploaded step-count data to the study server. Participants could log in to the study website to view graphs of their walking progress, individually-tailored motivational messages, and weekly calculated goals. Participants were randomized to 1 of 2 versions of a Web-based walking program. Those randomized to the "online community" arm could post and read messages with other participants while those randomized to the "no online community" arm could not read or post messages. The main outcome measures were participant attrition and average daily step counts over 16 weeks. Multiple regression analyses assessed the effect of the online community access controlling for age, sex, disease status, BMI, and baseline step counts. RESULTS: Both arms significantly increased their average daily steps between baseline and the end of the intervention period, but there were no significant differences in increase in step counts between arms using either intention-to-treat or completers analysis. In the intention-to-treat analysis, the average step count increase across both arms was 1888 ± 2400 steps. The percentage of completers was 13% higher in the online community arm than the no online community arm (online community arm, 79%, no online community arm, 66%, P = .02). In addition, online community arm participants remained engaged in the program longer than no online community arm participants (hazard ratio = 0.47, 95% CI = 0.25 - 0.90, P = .02). Participants with lower baseline social support posted more messages to the online community (P < .001) and viewed more posts (P < .001) than participants with higher baseline social support. CONCLUSION: Adding online community features to an Internet-mediated walking program did not increase average daily step counts but did reduce participant attrition. Participants with low baseline social support used the online community features more than those with high baseline social support. Thus, online communities may be a promising approach to reducing attrition from online health behavior change interventions, particularly in populations with low social support. TRIAL REGISTRATION: NCT00729040; http://clinicaltrials.gov/ct2/show/NCT00729040 (Archived by WebCite at http://www.webcitation.org/5v1VH3n0A).

Evaluating Active U: an Internet-mediated physical activity program.

BACKGROUND: Engaging in regular physical activity can be challenging, particularly during the winter months. To promote physical activity at the University of Michigan during the winter months, an eight-week Internet-mediated program (Active U) was developed providing participants with an online physical activity log, goal setting, motivational emails, and optional team participation and competition. METHODS: This study is a program evaluation of Active U. Approximately 47,000 faculty, staff, and graduate students were invited to participate in the online Active U intervention in the winter of 2007. Participants were assigned a physical activity goal and were asked to record each physical activity episode into the activity log for eight weeks. Statistics for program reach, effectiveness, adoption, and implementation were calculated using the Re-Aim framework. Multilevel regression analyses were used to assess the decline in rates of data entry and goal attainment during the program, to assess the likelihood of joining a team by demographic characteristics, to test the association between various predictors and the number of weeks an individual met his or her goal, and to analyze server load. RESULTS: Overall, 7,483 individuals registered with the Active U website ( approximately 16% of eligible), and 79% participated in the program by logging valid data at least once. Staff members, older participants, and those with a BMI < 25 were more likely to meet their weekly physical activity goals, and average rate of meeting goals was higher among participants who joined a competitive team compared to those who participated individually (IRR = 1.28, P < .001). CONCLUSION: Internet-mediated physical activity interventions that focus on physical activity logging and goal setting while incorporating team competition may help a significant percentage of the target population maintain their physical activity during the winter months.

Adolescents searching for health information on the Internet: an observational study.

BACKGROUND: Adolescents' access to health information on the Internet is partly a function of their ability to search for and find answers to their health-related questions. Adolescents may have unique health and computer literacy needs. Although many surveys, interviews, and focus groups have been utilized to understand the information-seeking and information-retrieval behavior of adolescents looking for health information online, we were unable to locate observations of individual adolescents that have been conducted in this context. OBJECTIVE: This study was designed to understand how adolescents search for health information using the Internet and what implications this may have on access to health information. METHODS: A convenience sample of 12 students (age 12-17 years) from 1 middle school and 2 high schools in southeast Michigan were provided with 6 health-related questions and asked to look for answers using the Internet. Researchers recorded 68 specific searches using software that captured screen images as well as synchronized audio recordings. Recordings were reviewed later and specific search techniques and strategies were coded. A qualitative review of the verbal communication was also performed. RESULTS: Out of 68 observed searches, 47 (69%) were successful in that the adolescent found a correct and useful answer to the health question. The majority of sites that students attempted to access were retrieved directly from search engine results (77%) or a search engine's recommended links (10%); only a small percentage were directly accessed (5%) or linked from another site (7%). The majority (83%) of followed links from search engine results came from the first 9 results. Incorrect spelling (30 of 132 search terms), number of pages visited within a site (ranging from 1-15), and overall search strategy (eg, using a search engine versus directly accessing a site), were each important determinants of success. Qualitative analysis revealed that participants used a trial-and-error approach to formulate search strings, scanned pages randomly instead of systematically, and did not consider the source of the content when searching for health information. CONCLUSIONS: This study provides a useful snapshot of current adolescent searching patterns. The results have implications for constructing realistic simulations of adolescent search behavior, improving distribution and usefulness of Web sites with health information relevant to adolescents, and enhancing educators' knowledge of what specific pitfalls students are likely to encounter.

Implementation and evaluation of an incentivized Internet-mediated walking program for obese adults.

In response to rising health care costs associated with obesity rates, some health care insurers are adopting incentivized technology-enhanced wellness programs. The purpose of this study is to evaluate the large-scale implementation of an incentivized Internet-mediated walking program for obese adults and to examine program acceptance, adherence, and impact. A mixed-methods evaluation was conducted to investigate program implementation, acceptance, and adherence rates, and physical activity rates among program participants. Program implementation was shaped by national and state policies, data security concerns, and challenges related to incentivizing participation. Among 15,397 eligible individuals, 6,548 (43 %) elected to participate in the walking program, achieving an average of 6,523 steps/day (SD 2,610 steps). Participants who uploaded step counts for 75 % of days for a full year (n = 2,885) achieved an average of 7,500 steps (SD 3,093). Acceptance and participation rates in this incentivized Internet-mediated walking program suggest that such interventions hold promise for engaging obese adults in physical activity.

Does pornography-blocking software block access to health information on the Internet?

CONTEXT: The Internet has become an important tool for finding health information, especially among adolescents. Many computers have software designed to block access to Internet pornography. Because pornography-blocking software cannot perfectly discriminate between pornographic and nonpornographic Web sites, such products may block access to health information sites, particularly those related to sexuality. OBJECTIVE: To quantify the extent to which pornography-blocking software used in schools and libraries limits access to health information Web sites. DESIGN AND SETTING: In a simulation of adolescent Internet searching, we compiled search results from 24 health information searches (n = 3206) and 6 pornography searches (n = 781). We then classified the content of each site as either health information (n = 2467), pornography (n = 516), or other (n = 1004). We also compiled a list of top teen health information sites (n = 586). We then tested 6 blocking products commonly used in schools and libraries and 1 blocking product used on home computers, each at 2 or 3 levels of blocking restrictiveness. MAIN OUTCOME MEASURE: Rates of health information and pornography blocking. RESULTS: At the least restrictive blocking setting, configured to block only pornography, the products blocked a mean of only 1.4% of health information sites. The differences between blocking products was small (range, 0.6%-2.3%). However, about 10% of health sites found using some search terms related to sexuality (eg, safe sex, condoms) and homosexuality (eg, gay) were blocked. The mean pornography blocking rate was 87% (range, 84%-90%). At moderate settings, the mean blocking rate was 5% for health information and 90% for pornography. At the most restrictive settings, health information blocking increased substantially (24%), but pornography blocking was only slightly higher (91%). CONCLUSIONS: Blocking settings have a greater impact than choice of blocking product on frequency of health information blocking. At their least restrictive settings, overblocking of general health information poses a relatively minor impediment. However, searches on some terms related to sexuality led to substantially more health information blocking. More restrictive blocking configurations blocked pornography only slightly more, but substantially increased blocking of health information sites.