16 resultados para Cross-layer design

em Digital Commons at Florida International University


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With the developments in computing and communication technologies, wireless sensor networks have become popular in wide range of application areas such as health, military, environment and habitant monitoring. Moreover, wireless acoustic sensor networks have been widely used for target tracking applications due to their passive nature, reliability and low cost. Traditionally, acoustic sensor arrays built in linear, circular or other regular shapes are used for tracking acoustic sources. The maintaining of relative geometry of the acoustic sensors in the array is vital for accurate target tracking, which greatly reduces the flexibility of the sensor network. To overcome this limitation, we propose using only a single acoustic sensor at each sensor node. This design greatly improves the flexibility of the sensor network and makes it possible to deploy the sensor network in remote or hostile regions through air-drop or other stealth approaches. Acoustic arrays are capable of performing the target localization or generating the bearing estimations on their own. However, with only a single acoustic sensor, the sensor nodes will not be able to generate such measurements. Thus, self-organization of sensor nodes into virtual arrays to perform the target localization is essential. We developed an energy-efficient and distributed self-organization algorithm for target tracking using wireless acoustic sensor networks. The major error sources of the localization process were studied, and an energy-aware node selection criterion was developed to minimize the target localization errors. Using this node selection criterion, the self-organization algorithm selects a near-optimal localization sensor group to minimize the target tracking errors. In addition, a message passing protocol was developed to implement the self-organization algorithm in a distributed manner. In order to achieve extended sensor network lifetime, energy conservation was incorporated into the self-organization algorithm by incorporating a sleep-wakeup management mechanism with a novel cross layer adaptive wakeup probability adjustment scheme. The simulation results confirm that the developed self-organization algorithm provides satisfactory target tracking performance. Moreover, the energy saving analysis confirms the effectiveness of the cross layer power management scheme in achieving extended sensor network lifetime without degrading the target tracking performance.

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With the developments in computing and communication technologies, wireless sensor networks have become popular in wide range of application areas such as health, military, environment and habitant monitoring. Moreover, wireless acoustic sensor networks have been widely used for target tracking applications due to their passive nature, reliability and low cost. Traditionally, acoustic sensor arrays built in linear, circular or other regular shapes are used for tracking acoustic sources. The maintaining of relative geometry of the acoustic sensors in the array is vital for accurate target tracking, which greatly reduces the flexibility of the sensor network. To overcome this limitation, we propose using only a single acoustic sensor at each sensor node. This design greatly improves the flexibility of the sensor network and makes it possible to deploy the sensor network in remote or hostile regions through air-drop or other stealth approaches. Acoustic arrays are capable of performing the target localization or generating the bearing estimations on their own. However, with only a single acoustic sensor, the sensor nodes will not be able to generate such measurements. Thus, self-organization of sensor nodes into virtual arrays to perform the target localization is essential. We developed an energy-efficient and distributed self-organization algorithm for target tracking using wireless acoustic sensor networks. The major error sources of the localization process were studied, and an energy-aware node selection criterion was developed to minimize the target localization errors. Using this node selection criterion, the self-organization algorithm selects a near-optimal localization sensor group to minimize the target tracking errors. In addition, a message passing protocol was developed to implement the self-organization algorithm in a distributed manner. In order to achieve extended sensor network lifetime, energy conservation was incorporated into the self-organization algorithm by incorporating a sleep-wakeup management mechanism with a novel cross layer adaptive wakeup probability adjustment scheme. The simulation results confirm that the developed self-organization algorithm provides satisfactory target tracking performance. Moreover, the energy saving analysis confirms the effectiveness of the cross layer power management scheme in achieving extended sensor network lifetime without degrading the target tracking performance.

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This research sought to understand the role that differentially assessed lands (lands in the United States given tax breaks in return for their guarantee to remain in agriculture) play in influencing urban growth. Our method was to calibrate the SLEUTH urban growth model under two different conditions. The first used an excluded layer that ignored such lands, effectively rendering them available for development. The second treated those lands as totally excluded from development. Our hypothesis was that excluding those lands would yield better metrics of fit with past data. Our results validate our hypothesis since two different metrics that evaluate goodness of fit both yielded higher values when differentially assessed lands are treated as excluded. This suggests that, at least in our study area, differential assessment, which protects farm and ranch lands for tenuous periods of time, has indeed allowed farmland to resist urban development. Including differentially assessed lands also yielded very different calibrated coefficients of growth as the model tried to account for the same growth patterns over two very different excluded areas. Excluded layer design can greatly affect model behavior. Since differentially assessed lands are quite common through the United States and are often ignored in urban growth modeling, the findings of this research can assist other urban growth modelers in designing excluded layers that result in more accurate model calibration and thus forecasting.

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Context: While research suggests whole body vibration (WBV) positively affects measures of neuromuscular performance in athletes, researchers have yet to address appropriate and effective vibration protocols. Objective: To identify the acute effects of continuous and intermittent WBV on muscular power and agility in recreationally active females. Design: We used a randomized 3-period cross-over design to observe the effects of 3 vibration protocols on muscular power and agility. Setting: Sports Science and Medicine Research Laboratory at Florida International University. Patients or Other Participants: Eleven recreationally active female volunteers (age=24.4±5.7y; ht=166.0±10.3cm; mass=59.7±14.3kg). Interventions: Each session, subjects stood on the Galileo WBV platform (Orthometrix, White Plains, NY) and received one of three randomly assigned vibration protocols. Our independent variable was vibration length (continuous, intermittent, or no vibration). Main Outcome Measures: An investigator blinded to the vibration protocol measured muscular power and agility. We measured muscular power with heights of squat and countermovement jumps. We measured agility with the Illinois Agility Test. Results: Continuous WBV significantly increased SJ height from 97.9±7.6cm to 98.5±7.5cm (P=0.019, β=0.71, η2 =0.07) but not CMJ height [99.1±7.4cm pretest and 99.4±7.4cm posttest (P=0.167, β=0.27)] or agility [19.2±2.1s pretest and 19.0±2.1s posttest (P=0.232, β=0.21)]. Intermittent WBV significantly enhanced SJ height from 97.6±7.7cm to 98.5±7.7cm (P=0.017, β=0.71, η2 =0.11) and agility 19.4±2.2s to 19.0±2.1s (P=0.001, β=0.98, η2=0.16), but did not effect CMJ height [98.7±7.7cm pretest and 99.3±7.3cm posttest (P=0.058, β=0.49)]. Conclusion: Continuous WBV increased squat jump height, while intermittent vibration enhanced agility and squat jump height. Future research should continue investigating the effect of various vibration protocols on athletic performance.

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Adoption of special needs children is now seen as a life long event whereby the adoptive child and family have unique needs. The need for postplacement resources throughout the life cycle of the adoption process is evident. This exploratory-descriptive research employed a random stratified cross-sectional design. The purpose of the study was to describe, identify, examine, and assess the relative influence of identified empirically and conceptually relevant variables of self-report experiences of adoptive parents of special needs children. Primary areas of exploration included: (1) adoptive children and families' characteristics, (2) postplacement service needs, utilization and satisfaction, and (3) adoptive parents' perceptions of their adoption experiences. A proportionate stratified random mail survey was used to obtain 474 families who had adopted special needs children from the 15 geographic districts which make up the state adoption social service agency in Florida. A 144-item survey questionnaire was used to collect basic information on demographic data, service provision, and adoption experiences. Four research questions were analyzed to test the effect the predictor variables had on willingness to adopt another special needs child, successful adoption, satisfying experience, and realism about problems. All four research questions revealed that the full model and the child's antecedent and the adoptive parents' intervening variable blocks were significant in explaining the variance in the dependent variables. The child's intervening variables alone were only significant in explaining the variance for one of the dependent variables. The results of the statistical analysis on the fifth research question and the three hypotheses determined that (1) only one postplacement service, crisis intervention, had a statistically significant impact on the adoptive parents' perceived level of satisfaction with the adoption experience; (2) adoptive parents who rate their adoption as successful are more likely to express a desire to adopt another special needs child; (3) the more adequate information on the child the adoptive parents perceived that they had prior to placement, the more they perceived they were realistic about the problems they would encounter; and (4) six specific postplacement services were found to be significant in predicting successful adoptions--crisis intervention, outpatient drug/alcohol treatment, maintenance subsidy, physical therapy, special medical equipment, and family counseling. Implications for the social work field and future research are discussed. ^

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This study used a cross-sectional design and descriptive research methodology to assess the characteristics and practices of employers participating in Florida school-to-work (STW) initiatives, the factors influencing their participation, and their STW partnerships with schools. The study also examined the relationships between employer characteristics and participation. ^ A sampling frame of 15,202 employers from the 28 Florida STW regions was constructed. Data were collected via a mail survey with a random sample of employers, using a researcher-designed questionnaire. Data were analyzed using descriptive statistics, correlational analysis, and analysis of variance. ^ At the 95% confidence level, it was estimated that the mean establishment size in the population is between 25 and 51 employees and that employers have been involved in STW partnerships between five and seven years. ^ The study revealed broad-based employer participation in three of four areas: Working with Students, Working with Educators, and Internal Company Practices Supporting STW. A fourth area, Building a System, showed generally low participation. Data indicate that workforce needs are important incentives to employer STW participation beyond their desire to contribute to education or the community. Data also indicate that lack of information on STW is the greatest barrier to employer participation. ^ Sample employers have more positive perceptions of the value of their partnerships with schools than of the quality of the partnerships. Ninety-four percent agreed that students are better prepared for work and careers as a result of the partnership's activities. More than half agreed that a sense of trust and good communication exist between educators and employer partners. ^ Employer variables found to have a significant, positive relationship with participation include size (coefficient of determination r2 = .116), years in STW partnerships (r2 = .128), and perceptions of partnership quality (r2 = .092) and value (r2 = .112). ^ A major conclusion based on the findings of this study is that employer participation is optimized in initiatives that achieve important STW outcomes for students and build long-term relationships between employers and schools. Another that in Florida, the STW Opportunities Act of 1994 has not resulted in substantially greater employer involvement in building a STW system. ^

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The Dahlgren and Whitehead ecological theory provides the framework for a cross-sectional design to compare socio-demographic characteristics, living and working conditions, and lifestyle daily habits as well as cultural and ecological factors among six diabetic multiethnic Black groups in Miami and Abidjan. Approximately 180 Black Americans (African-, Caribbean-, and Haitian-) and 180 Black Africans (Akan, Malinke, and Krou) aged 20 years and older were surveyed. During the preliminary of this study participants' attitudes and behaviors were qualitatively assessed (N=60) and a tool was developed to describe, in the main study (N=360), differences in participants' strength of commitment to diabetes lifestyle self-management. Despite similarities found in terms of age and gender, statistically significant differences were also found within and among groups in terms of living and working conditions, education level, and religion. African American groups were more likely to participate in more diabetes classes than Haitian Americans and Caribbean Americans. However, African Americans were less likely to adhere to daily dietary and weight control regimens. Although, Black African groups reported limited access to equipment, facilities, and financial support they were more likely to follow dietary and weight control recommendations than Black American groups. Overall, African American participants showed the poorest attitudes towards recommended foods, Caribbean American respondents reported the best attitudes and behaviors towards weight control regimens, and the Malinke group had significantly more strength of commitment to successful weight control. Furthermore, Black African groups had significantly more strength of commitment to successful dietary adherence and significantly less support for weight control than Black American groups. ^ Significant differences found within Black groups suggest that understanding each patient's conditions may help healthcare professionals in initiating individualized appropriate counseling before goal setting, and in developing culturally relevant type 2 diabetes management programs. Moreover, significant differences exist in strength of commitment to lifestyle adherence among Black groups in Miami and Abidjan. Cultural, socio-demographic factors and self-management habits may explain differences in participants' outcomes. At the policy level, Black groups should not be approached as a homogenous group and assessment of the vulnerability of each ethnic group may be necessary in the decision-making process.^

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This study examined differences in cultural competency levels between undergraduate and graduate nursing students (age, ethnicity, gender, language at home, education level, program standing, program track, diversity encounters, and previous diversity training). Participants were 83% women, aged 20 to 62; 50% Hispanic/Latino; with a Bachelor of Science in Nursing (n = 82) and a Master of Science in Nursing (n = 62). Degrees included high school diplomas, associate/diplomas, bachelors' degrees in or out of nursing, and medical doctorate degrees from outside the United States. Students spoke English (n = 82) or Spanish ( n = 54). The study used a cross-sectional design guided by the three-dimensional cultural competency model. The Cultural Competency Assessment (CCA) tool is composed of two subscales: Cultural Awareness and Sensitivity (CAS) and Culturally Competent Behaviors (CCB). Multiple regressions, Pearson's correlations, and ANOVAs determined relationships and differences among undergraduate and graduate students. Findings showed significant differences between undergraduate and graduate nursing students in CAS, p <.016. Students of Hispanic/White/European ethnicity scored higher on the CAS, while White/non-Hispanic students scored lower on the CAS, p < .05. One-way ANOVAs revealed cultural competency differences by program standing (grade-point averages), and by program tracks, between Master of Science in Nursing Advanced Registered Nurse Practitioners and both Traditional Bachelor of Science in Nursing and Registered Nurse-Bachelor of Science in Nursing. Univariate analysis revealed that higher cultural competency was associated with having previous diversity training and participation in diversity training as continuing education. After controlling for all predictors, multiple regression analysis found program level, program standing, and diversity training explained a significant amount of variance in overall cultural competency (p = .027; R2 = .18). Continuing education is crucial in achieving students' cultural competency. Previous diversity training, graduate education, and higher grade-point average were correlated with higher cultural competency levels. However, increased diversity encounters were not associated with higher cultural competency levels.^

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Virtual machines (VMs) are powerful platforms for building agile datacenters and emerging cloud systems. However, resource management for a VM-based system is still a challenging task. First, the complexity of application workloads as well as the interference among competing workloads makes it difficult to understand their VMs’ resource demands for meeting their Quality of Service (QoS) targets; Second, the dynamics in the applications and system makes it also difficult to maintain the desired QoS target while the environment changes; Third, the transparency of virtualization presents a hurdle for guest-layer application and host-layer VM scheduler to cooperate and improve application QoS and system efficiency. This dissertation proposes to address the above challenges through fuzzy modeling and control theory based VM resource management. First, a fuzzy-logic-based nonlinear modeling approach is proposed to accurately capture a VM’s complex demands of multiple types of resources automatically online based on the observed workload and resource usages. Second, to enable fast adaption for resource management, the fuzzy modeling approach is integrated with a predictive-control-based controller to form a new Fuzzy Modeling Predictive Control (FMPC) approach which can quickly track the applications’ QoS targets and optimize the resource allocations under dynamic changes in the system. Finally, to address the limitations of black-box-based resource management solutions, a cross-layer optimization approach is proposed to enable cooperation between a VM’s host and guest layers and further improve the application QoS and resource usage efficiency. The above proposed approaches are prototyped and evaluated on a Xen-based virtualized system and evaluated with representative benchmarks including TPC-H, RUBiS, and TerraFly. The results demonstrate that the fuzzy-modeling-based approach improves the accuracy in resource prediction by up to 31.4% compared to conventional regression approaches. The FMPC approach substantially outperforms the traditional linear-model-based predictive control approach in meeting application QoS targets for an oversubscribed system. It is able to manage dynamic VM resource allocations and migrations for over 100 concurrent VMs across multiple hosts with good efficiency. Finally, the cross-layer optimization approach further improves the performance of a virtualized application by up to 40% when the resources are contended by dynamic workloads.

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This study examined the predictors of independent living outcomes among community–living older women who received informal care. The central hypothesis was that older women’s level of functioning is influenced by their relationship with their informal caregiver. The study attempted to understand the independence of older women through the perspective of both informal caregivers and the older women themselves. The following eight variables were measured: 1) the older women’s independence (dependent variable); 2) the relationship between older women and their informal caregivers (independent variable); 3) roles of both the informal caregiver and older women (independent variable); 4) the older women’s attitudes toward aging (independent variable); 5) the older women’s age identity (independent variable); 6) the older women’s health (control variable); 7) the older women’s level of social support (control variable); and 8) the older women’s level of depression (control variable). The variables were measured from the perspective of the older woman herself and her informal caregiver. This study used an ecological and developmental framework along with role theory to understand the interaction among the aforementioned variables through a cross-sectional design. The recruited older women participants of this study were receiving ongoing care and personal assistance from two large home care agencies located in Miami, FL. An analysis was conducted through a mixed-methods incorporated into the study design. The present study aimed to contribute to the understanding of how the relationship between older women and their informal caregivers influences older women’s ability to maintain independent outcomes. The primary finding of this study was that there were both positive and negative experiences within the relationship dynamic of older women and their informal caregivers and that this relationship was either unidirectional or bi-directional.

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This study examined differences in cultural competency levels between undergraduate and graduate nursing students (age, ethnicity, gender, language at home, education level, program standing, program track, diversity encounters, and previous diversity training). Participants were 83% women, aged 20 to 62; 50% Hispanic/Latino; with a Bachelor of Science in Nursing (n = 82) and a Master of Science in Nursing (n = 62). Degrees included high school diplomas, associate/diplomas, bachelors’ degrees in or out of nursing, and medical doctorate degrees from outside the United States. Students spoke English (n = 82) or Spanish (n = 54). The study used a cross-sectional design guided by the three-dimensional cultural competency model. The Cultural Competency Assessment (CCA) tool is composed of two subscales: Cultural Awareness and Sensitivity (CAS) and Culturally Competent Behaviors (CCB). Multiple regressions, Pearson’s correlations, and ANOVAs determined relationships and differences among undergraduate and graduate students. Findings showed significant differences between undergraduate and graduate nursing students in CAS, p <.016. Students of Hispanic/White/European ethnicity scored higher on the CAS, while White/non-Hispanic students scored lower on the CAS, p < .05. One-way ANOVAs revealed cultural competency differences by program standing (grade-point averages), and by program tracks, between Master of Science in Nursing Advanced Registered Nurse Practitioners and both Traditional Bachelor of Science in Nursing and Registered Nurse-Bachelor of Science in Nursing. Univariate analysis revealed that higher cultural competency was associated with having previous diversity training and participation in diversity training as continuing education. After controlling for all predictors, multiple regression analysis found program level, program standing, and diversity training explained a significant amount of variance in overall cultural competency (p = .027; R2 = .18). Continuing education is crucial in achieving students’ cultural competency. Previous diversity training, graduate education, and higher grade-point average were correlated with higher cultural competency levels. However, increased diversity encounters were not associated with higher cultural competency levels.

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Series Micro-Electro-Mechanical System (MEMS) switches based on superconductor are utilized to switch between two bandpass hairpin filters with bandwidths of 365 MHz and nominal center frequencies of 2.1 GHz and 2.6 GHz. This was accomplished with 4 switches actuated in pairs, one pair at a time. When one pair was actuated the first bandpass filter was coupled to the input and output ports. When the other pair was actuated the second bandpass filter was coupled to the input and output ports. The device is made of a YBa2Cu 3O7 thin film deposited on a 20 mm x 20 mm LaAlO3 substrate by pulsed laser deposition. BaTiO3 deposited by RF magnetron sputtering in utilized as the insulation layer at the switching points of contact. These results obtained assured great performance showing a switchable device at 68 V with temperature of 40 K for the 2.1 GHz filter and 75 V with temperature of 30 K for the 2.6 GHz hairpin filter. ^

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Today, the development of domain-specific communication applications is both time-consuming and error-prone because the low-level communication services provided by the existing systems and networks are primitive and often heterogeneous. Multimedia communication applications are typically built on top of low-level network abstractions such as TCP/UDP socket, SIP (Session Initiation Protocol) and RTP (Real-time Transport Protocol) APIs. The User-centric Communication Middleware (UCM) is proposed to encapsulate the networking complexity and heterogeneity of basic multimedia and multi-party communication for upper-layer communication applications. And UCM provides a unified user-centric communication service to diverse communication applications ranging from a simple phone call and video conferencing to specialized communication applications like disaster management and telemedicine. It makes it easier to the development of domain-specific communication applications. The UCM abstraction and API is proposed to achieve these goals. The dissertation also tries to integrate the formal method into UCM development process. The formal model is created for UCM using SAM methodology. Some design errors are found during model creation because the formal method forces to give the precise description of UCM. By using the SAM tool, formal UCM model is translated to Promela formula model. In the dissertation, some system properties are defined as temporal logic formulas. These temporal logic formulas are manually translated to promela formulas which are individually integrated with promela formula model of UCM and verified using SPIN tool. Formal analysis used here helps verify the system properties (for example multiparty multimedia protocol) and dig out the bugs of systems.

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Hurricane is one of the most destructive and costly natural hazard to the built environment and its impact on low-rise buildings, particularity, is beyond acceptable. The major objective of this research was to perform a parametric evaluation of internal pressure (IP) for wind-resistant design of low-rise buildings and wind-driven natural ventilation applications. For this purpose, a multi-scale experimental, i.e. full-scale at Wall of Wind (WoW) and small-scale at Boundary Layer Wind Tunnel (BLWT), and a Computational Fluid Dynamics (CFD) approach was adopted. This provided new capability to assess wind pressures realistically on internal volumes ranging from small spaces formed between roof tiles and its deck to attic to room partitions. Effects of sudden breaching, existing dominant openings on building envelopes as well as compartmentalization of building interior on the IP were systematically investigated. Results of this research indicated: (i) for sudden breaching of dominant openings, the transient overshooting response was lower than the subsequent steady state peak IP and internal volume correction for low-wind-speed testing facilities was necessary. For example a building without volume correction experienced a response four times faster and exhibited 30–40% lower mean and peak IP; (ii) for existing openings, vent openings uniformly distributed along the roof alleviated, whereas one sided openings aggravated the IP; (iii) larger dominant openings exhibited a higher IP on the building envelope, and an off-center opening on the wall exhibited (30–40%) higher IP than center located openings; (iv) compartmentalization amplified the intensity of IP and; (v) significant underneath pressure was measured for field tiles, warranting its consideration during net pressure evaluations. The study aimed at wind driven natural ventilation indicated: (i) the IP due to cross ventilation was 1.5 to 2.5 times higher for Ainlet/Aoutlet>1 compared to cases where Ainlet/Aoutlet<1, this in effect reduced the mixing of air inside the building and hence the ventilation effectiveness; (ii) the presence of multi-room partitioning increased the pressure differential and consequently the air exchange rate. Overall good agreement was found between the observed large-scale, small-scale and CFD based IP responses. Comparisons with ASCE 7-10 consistently demonstrated that the code underestimated peak positive and suction IP.

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Aim: to determine cut off points for The Homeostatic Model Assessment Index 1 and 2 (HOMA-1 and HOMA-2) for identifying insulin resistance and metabolic syndrome among a Cuban-American population. Study Design: Cross sectional. Place and Duration of Study: Florida International University, Robert Stempel School of Public Health and Social Work, Department of Dietetics and Nutrition, Miami, FL from July 2010 to December 2011. Methodology: Subjects without diabetes residing in South Florida were enrolled (N=146, aged 37 to 83 years). The HOMA1-IR and HOMA2-IR 90th percentile in the healthy group (n=75) was used as the cut-off point for insulin resistance. A ROC curve was constructed to determine the cut-off point for metabolic syndrome. Results: HOMA1-IR was associated with BMI, central obesity, and triglycerides (P3.95 and >2.20 and for metabolic syndrome were >2.98 (63.4% sensitivity and 73.3% specificity) and >1.55 (60.6% sensitivity and 66.7% specificity), respectively. Conclusion: HOMA cut-off points may be used as a screening tool to identify insulin resistance and metabolic syndrome among Cuban-Americans living in South Florida.