Underwater target detection using multichannel subband adaptive filtering and high-order correlation schemes

Includes bibliographical references.In this paper, new pre- and post-processing schemes are developed to process shallow-water sonar data to improve the accuracy of target detection. A multichannel subband adaptive filtering is applied to preprocess the data in order to isolate the potential target returns from the acoustic backscattered signals and improve the signal-to-reverberation ratio. This is done by estimating the time delays associated with the reflections in different subbands. The preprocessed results are then beamformed to generate an image for each ping of the sonar. The testing results on both the simulated and real data revealed the efficiency of this scheme in time-delay estimation and its capability in removing most of the competing reverberations and noise. To improve detection rate while significantly minimizing the incident of false detections, a high-order correlation (HOC) method for postprocessing the beamformed images is then developed. This method determines the consistency in occurrence of the target returns in several consecutive pings. The application of the HOC process to the real beamformed sonar data showed the ability of this method for removing the clutter and at the same time boosting the target returns in several consecutive pings. The algorithm is simple, fast, and easy to implement.This work was supported by the Office of Naval Research (ONR 321TS) under Contract N61331-94-K-0018

Physical Activity Research in Nursing

Purpose: To present exemplars of physical activity research in nursing, illustrate the importance of physical activity research across the lifespan, and recommend directions for theory development and research. Methods: Studies of physical activity and exercise currently being conducted by nurse investigators were reported and critiqued by attendees of the Midwest Nursing Research Society 2000 Preconference session entitled “Promoting Physical Activity Among Diverse Groups Across the Health Continuum.” Physical activity and exercise literature during the past decade was reviewed. Databases searched included Medline, CINAHL, Wilson, and ERIC. Findings: Investigators have emphasized the need to evaluate the effects of theory-based physical activity interventions designed to alter key correlates of physical activity identified through descriptive research. Conclusions: Regular physical activity is necessary for health promotion and disease prevention for all populations. Continued research in this important area of health behavior is critical to identify the most effective interventions to increase physical activity among diverse populations

MIDLIFE FEMALE NURSES: WORK PATTERNS, GENERAL HEALTH AND PSYCHOLOGICAL WELL-BEING.

MIDLIFE FEMALE NURSES: WORK PATTERNS, GENERAL HEALTH AND PSYCHOLOGICAL WELL-BEING

Correlates of Physical Activity in Urban Midwestern African-American Women

Background: African-American women are at higher risk than white women of cardiovascular disease and stroke. In addition, fewer African-American women reap the cardiovascular benefits of exercise, because of low physical activity. The study goals were to identify personal, social environmental, and physical environmental correlates of physical activity of urban dwelling, Midwestern, African-American women and to obtain their recommendations for increasing exercise in their communities. Methods: A face-to-face interview (Women and Physical Activity Survey) covering personal, social environmental, and physical environmental correlates of physical activity was administered to 399 volunteer African-American women aged 20 to 50 years, living in Chicago. Physical activity was measured with questions on lifestyle and planned leisure-time activity (exercise) from the Behavioral Risk Factor Surveillance System. Results: The women were from a wide socioeconomic spectrum of education and income. Forty-two percent of the women met current recommendations for moderate or vigorous physical activity; 48% were insufficiently active; and 9% were inactive. The following groups of women were more likely to be physically active: women with at least a high school education; women with perceived good health; women who knew people who exercise; and women who viewed the neighborhood as safe. These findings were statistically significant. Conclusions: Interventions that target urban African-American women must address the safety of the physical environment and personal and social environmental correlates of physical activity, and they should focus especially on inactive women who have less than a high school education or perceive themselves to be in poor health

Isolation of resonance in acoustic backscatter from elastic targets using adaptive estimation schemes

Includes bibliographical references.The problem of underwater target detection and classification from acoustic backscatter is the central focus of this paper. It has been shown that at certain frequencies the acoustic backscatter from elastic targets exhibits certain resonance behavior which closely relates to the physical properties of the target such as dimension, thickness, and composition. Several techniques in both the time domain and frequency domain have been developed to characterize the resonance phenomena in acoustic backscatter from spherical or cylindrical thin shells. The purpose of this paper is to develop an automated approach for identifying the presence of resonance in the acoustic backscatter from an unknown target by isolating the resonance part from the specular contribution. An adaptive transversal filter structure is used to estimate the specular part of the backscatter and consequently the error signal would provide an estimate of the resonance part. An important aspect of this scheme lies in the fact that it does not require an underlying model for the elastic return. The adaptation rule is based upon fast Recursive Least Squares (RLS) learning. The approach taken in this paper is general in the sense that it can be applied to targets of unknown geometry and thickness and, further, does not require any a priori information about the target and/or the environment. Test results on acoustic data are presented which indicate the effectiveness of the proposed approach.The work of M. R. Azimi-Sadjadi was supported by the ASEE-ONR program under the High Area Rate Recon. Project. The work of J. Wilbur and G. J. Dobeck was supported by the ONR

Correlates of Physical Activity in Urban Midwestern Latinas

Background: Latinas (Latino women) are at higher risk than non-Latina white women of cardiovascular disease and stroke, primarily because of higher rates of obesity and type-2 diabetes mellitus. Increases in physical activity help control these cardiovascular risk factors, but a higher percentage of Latinas than white women are inactive. The study goals were to identify personal, social environmental, and physical environmental correlates of physical activity of urban-dwelling, Midwestern Latinas and to obtain their recommendations for increasing exercise in their communities. Methods: A face-to-face interview (Women and Physical Activity Survey) that covered personal, social environmental, and physical environmental correlates of physical activity was performed with 300 volunteer Latinas (242 in Spanish, 58 in English), aged 20 to 50 years, living in Chicago. Physical activity was measured with questions on lifestyle and planned leisure activity (exercise) from the Behavioral Risk Factor Surveillance System survey. Results: The sample consisted of urban-dwelling Latinas who were primarily from Mexico and who spoke predominantly Spanish. The breakdown was as follows: 36% met current recommendations for moderate or vigorous physical activity, 52.3% were insufficiently active, and 11.7% were inactive. Physical activity was higher among younger women, married women, and women with the following characteristics: had some confidence about becoming more active, saw people exercising in the neighborhood, attended religious services, or lived in areas with heavy traffic. Conclusions: Interventions need to focus on encouraging Latinas, especially those who are older, to reach the level of physical activity recommended to benefit health. The church may be a suitable community setting for initiating programs that provide women with the knowledge, skills, and motivation to become more active so that they can bring back to the larger Latina community.https://www.ajpmonline.org/article/S0749-3797(03)00167-3/abstrac

New time delay estimation in subbands for resolving multiple specular reflections, A

Includes bibliographical references.In this correspondence, a new time delay estimation procedure is proposed using the multiresolution analysis framework through a discrete wavelet transform (DWT). Once the signals are decomposed, the time delays are estimated iteratively in each sub-band using two different adaptation mechanisms that minimize the mean squared error (MSE) between the reference and primary signals in the corresponding sub-band and level. The localization of the minima of the MSE curves at different levels and subbands is used in order to arrive at the time delay estimates. The proposed scheme is then applied to a real-life problem of underwater target detection from the acoustic backscttered data.This work was supported by the Office of Naval Research (ONR 321TS). The Technical Agent was Coastal Systems Station, Panama City, FL

Community-based research: Barriers to recruitment of African Americans

The elimination of health disparities for African Americans requires culturally relevant, empirical knowledge, which in turn requires including African Americans in research studies. However, power-difference barriers and conceptual barriers continue to inhibit the recruitment of African Americans. The purpose of this article is to define and discuss certain barriers to the recruitment of African Americans into research studies and to present culturally and contextually sensitive strategies to overcoming these barriers. Power-difference barriers reflect unequal authority and often generate mistrust. Conceptual barriers reflect researchers’ need for better understanding about African Americans. Effective strategies include collaboration with the community through a community advisory board and conducting community-based participatory action research. Also, integrating alternative conceptual frameworks with mainstream frameworks may reduce researchers’ ideological assumptions about African Americans. To promote optimal recruitment of African Americans, researchers must be aware of power difference barriers and conceptual barriers and move toward active collaboration with African American communities.http://www.sciencedirect.com/science/article/pii/S002965540400099