A simple and efficient face detection algorithm for video database applications

The objective of this work is to provide a simple and yet efficient tool to detect human faces in video sequences. This information can be very useful for many applications such as video indexing and video browsing. In particular the paper focuses on the significant improvements made to our face detection algorithm presented by Albiol, Bouman and Delp (see IEEE Int. Conference on Image Processing, Kobe, Japan, 1999). Specifically, a novel approach to retrieve skin-like homogeneous regions is presented, which is later used to retrieve face images. Good results have been obtained for a large variety of video sequences.Peer ReviewedPostprint (published version

Tree-Structured Nonlinear Adaptive Signal Processing

In communication systems, nonlinear adaptive filtering has become increasingly popular in a variety of applications such as channel equalization, echo cancellation and speech coding. However, existing nonlinear adaptive filters such as polynomial (truncated Volterra series) filters and multilayer perceptrons suffer from a number of problems. First, although high Order polynomials can approximate complex nonlinearities, they also train very slowly. Second, there is no systematic and efficient way to select their structure. As for multilayer perceptrons, they have a very complicated structure and train extremely slowly Motivated by the success of classification and regression trees on difficult nonlinear and nonparametfic problems, we propose the idea of a tree-structured piecewise linear adaptive filter. In the proposed method each node in a tree is associated with a linear filter restricted to a polygonal domain, and this is done in such a way that each pruned subtree is associated with a piecewise linear filter. A training sequence is used to adaptively update the filter coefficients and domains at each node, and to select the best pruned subtree and the corresponding piecewise linear filter. The tree structured approach offers several advantages. First, it makes use of standard linear adaptive filtering techniques at each node to find the corresponding Conditional linear filter. Second, it allows for efficient selection of the subtree and the corresponding piecewise linear filter of appropriate complexity. Overall, the approach is computationally efficient and conceptually simple. The tree-structured piecewise linear adaptive filter bears some similarity to classification and regression trees. But it is actually quite different from a classification and regression tree. Here the terminal nodes are not just assigned a region and a class label or a regression value, but rather represent: a linear filter with restricted domain, It is also different in that classification and regression trees are determined in a batch mode offline, whereas the tree-structured adaptive filter is determined recursively in real-time. We first develop the specific structure of a tree-structured piecewise linear adaptive filter and derive a stochastic gradient-based training algorithm. We then carry out a rigorous convergence analysis of the proposed training algorithm for the tree-structured filter. Here we show the mean-square convergence of the adaptively trained tree-structured piecewise linear filter to the optimal tree-structured piecewise linear filter. Same new techniques are developed for analyzing stochastic gradient algorithms with fixed gains and (nonstandard) dependent data. Finally, numerical experiments are performed to show the computational and performance advantages of the tree-structured piecewise linear filter over linear and polynomial filters for equalization of high frequency channels with severe intersymbol interference, echo cancellation in telephone networks and predictive coding of speech signals

Preferred Tone of Nutrition Text Messages for Young Adults: Focus Group Testing

BACKGROUND: Young adults are a particularly hard to reach group using conventional health promotion practices as they do not see nutrition messages as personally relevant to them. Text messaging (short message service, SMS) offers an innovative approach to reaching young adults to support and promote dietary behavior change. OBJECTIVE: The aim of this study was to develop and test tonal preferences for nutrition text messages among young adults using focus groups. METHODS: A total of 39 young adults aged 18-30 years residing in Perth, Western Australia participated in four focus groups. Participants briefly discussed their perception of healthy eating and their responses to messages about increasing fruit and vegetables, and reducing "junk food" and alcohol intake. They ranked their preference for 15 nutrition messages across 3 dietary behaviors (fruit and vegetables, junk food, and alcohol) with 5 different message tones (authoritative, empathetic, generation Y, solutions, and substitutions) and identified the messages most likely to persuade young adults to change their diet. A 5-point ranking of the nutrition messages was from the most likely to least likely to persuade (1-5). The focus groups were conducted by a trained facilitator and observer and were recorded. Data driven content analysis was used to explore themes. Tonal preferences and potential motivators were collated and frequencies presented. RESULTS: Participants ranked offering substitutes (29%, 11/39) and using empathy (22%, 9/39) as the most persuasive message techniques in improving diets of young adults, with low responses for Generation Y (17%, 7/39), solutions (17%, 7/39), and authoritative (15%, 6/39) tones. Females were more likely to consider substitution messages persuasive (35%, 7/20) compared with males (22%, 4/19). A greater proportion of males compared with females considered authoritative messages persuasive: (22%, 4/19) compared with (7%, 1/20). There is a strong preference for a substitution tone for fruit and vegetable messages (52%, 20/39), and no overall message tone preference for junk food and alcohol messages. Substitutions were viewed as helpful and practical. Empathy was liked as it acknowledged previous efforts. Responses to authoritative tone were mixed with some feeling guilt while others found them informative. Acceptability of the solutions depended on the behavioral change and acceptability of the solution proposed. Generation Y tone had some support for junk food and alcohol messages, and if favored, was considered casual, humorous, catchy, and motivational. CONCLUSIONS: Substitutions and tone of empathy were favored as the most likely execution styles to motivate nutrition behavior change across all participants. There is no "one size fits all" with different tones preferred by individuals for different dietary behaviors. Although text messaging provides instant message delivery direct to the individual, these results demonstrate the complexity of developing motivational nutrition message for young adults. These findings reveal the importance of considering the tone and content and pretesting messages for health promotion text message interventions

Diffusion Inertial Poser: Human Motion Reconstruction from Arbitrary Sparse IMU Configurations

Motion capture from a limited number of inertial measurement units (IMUs) has important applications in health, human performance, and virtual reality. Real-world limitations and application-specific goals dictate different IMU configurations (i.e., number of IMUs and chosen attachment body segments), trading off accuracy and practicality. Although recent works were successful in accurately reconstructing whole-body motion from six IMUs, these systems only work with a specific IMU configuration. Here we propose a single diffusion generative model, Diffusion Inertial Poser (DiffIP), which reconstructs human motion in real-time from arbitrary IMU configurations. We show that DiffIP has the benefit of flexibility with respect to the IMU configuration while being as accurate as the state-of-the-art for the commonly used six IMU configuration. Our system enables selecting an optimal configuration for different applications without retraining the model. For example, when only four IMUs are available, DiffIP found that the configuration that minimizes errors in joint kinematics instruments the thighs and forearms. However, global translation reconstruction is better when instrumenting the feet instead of the thighs. Although our approach is agnostic to the underlying model, we built DiffIP based on physiologically realistic musculoskeletal models to enable use in biomedical research and health applications

Feasibility and use of the mobile food record for capturing eating occasions among children ages 3–10 years in Guam

Children’s readiness to use technology supports the idea of children using mobile applications for dietary assessment. Our goal was to determine if children 3–10 years could successfully use the mobile food record (mFR) to capture a usable image pair or pairs. Children in Sample 1 were tasked to use the mFR to capture an image pair of one eating occasion while attending summer camp. For Sample 2, children were tasked to record all eating occasions for two consecutive days at two time periods that were two to four weeks apart. Trained analysts evaluated images. In Sample 1, 90% (57/63) captured one usable image pair. All children (63/63) returned the mFR undamaged. Sixty-two children reported: The mFR was easy to use (89%); willingness to use the mFR again (87%); and the fiducial marker easy to manage (94%). Children in Sample 2 used the mFR at least one day at Time 1 (59/63, 94%); Time 2 (49/63, 78%); and at both times (47/63, 75%). This latter group captured 6.21 ± 4.65 and 5.65 ± 3.26 mean (±SD) image pairs for Time 1 and Time 2, respectively Results support the potential for children to independently record dietary intakes using the mFR

Simulated Space Radiation and Weightlessness: Vascular-Bone Coupling Mechanisms to Preserve Skeletal Health

Weightlessness causes a cephalad fluid shift and reduction in mechanical stimulation, adversely affecting both cortical and trabecular bone tissue in astronauts. In rodent models of weightlessness, the onset of bone loss correlates with reduced skeletal perfusion, reduced and rarified vasculature and lessened vasodilation, which resembles blood-bone symbiotic events that can occur with fracture repair and aging. These are especially serious risks for long term, exploration class missions when astronauts will face the challenge of increased exposure to space radiation and abrupt transitions between different gravity environments upon arrival and return. Previously, we found using the mouse hindlimb unloading model and exposure to heavy ion radiation, both disuse and irradiation cause an acute bone loss that was associated with a reduced capacity to produce bone-forming osteoblasts from the bone marrow. Together, these findings led us to hypothesize that exposure to space radiation exacerbates weightlessness-induced bone loss and impairs recovery upon return, and that treatment with anti-oxidants may mitigate these effects. The specific aims of this recently awarded grant are to: AIM 1 Determine the functional and structural consequences of prolonged weightlessness and space radiation (simulated spaceflight) for bone and skeletal vasculature in the context of bone cell function and oxidative stress. AIM 2 Determine the extent to which an anti-oxidant protects against weightlessness and space radiation-induced bone loss and vascular dysfunction. AIM 3 Determine how space radiation influences later skeletal and vasculature recovery from prolonged weightlessness and the potential of anti-oxidants to preserve adaptive remodeling

Characterizing early adolescent food waste using the mobile food record.

This study aimed to assess the amount of plate waste and how plate waste was disposed by early adolescent girls using a mobile food record (mFR). Participants were girls nine to thirteen years residing in O’ahu, Hawai’i (n = 93). Foods selected and leftover were estimated using a three day mFR. Each leftover food was then classified as thrown into the trash, fed to a pet, eaten later, or other (e.g., composted). Repeated measures analyses of variance (ANOVA) were conducted and Tukey’s post-hoc test were used to adjust for multiple comparisons between times (breakfast, lunch, dinner, and snack) on leftover food and leftover food thrown into the trash. The percentage of food leftover and thrown into the trash was highest at lunch. The percentage of protein, grain, vegetables, fruit, and dairy leftover at lunch were unexpectedly low compared to previous studies. The median for percentage of food thrown into the trash at lunch was <5% for all food groups, and was consistently low across the day (<10%). Average energy intake was 436 kcal (±216) at lunch, and 80% of caregivers reported total household income as ≥$70,000. Studies in real-time using technology over full days may better quantify plate waste among adolescents