Dynamic spectrum access in heterogeneous unlicensed wireless networks

Existing wireless systems are normally regulated by a fixed spectrum assignment strategy. This policy leads to an undesirable situation that some systems may only use the allocated spectrum to a limited extent while others have very serious spectrum insufficiency situation. Dynamic Spectrum Access (DSA) is emerging as a promising technology to address this issue such that the unused licensed spectrum can be opportunistically accessed by the unlicensed users. To enable DSA, the unlicensed user shall have the capability of detecting the unoccupied spectrum, controlling its spectrum access in an adaptive manner, and coexisting with other unlicensed users automatically. In this article, we propose a radio system Transmission Opportunity-based spectrum access control protocol with the aim to improve spectrum access fairness and ensure safe coexistence of multiple heterogeneous unlicensed radio systems. In the scheme, multiple radio systems will coexist and dynamically use available free spectrum without interfering with licensed users. Simulation is carried out to evaluate the performance of the proposed scheme with respect to spectrum utilisation, fairness and scalability. Comparing with the existed studies, our strategy is able to achieve higher scalability and controllability without degrading spectrum utilisation and fairness performance.

Probabilistic synchronisation of pinning control

This paper is concerned with synchronization of complex stochastic dynamical networks in the presence of noise and functional uncertainty. A probabilistic control method for adaptive synchronization is presented. All required probabilistic models of the network are assumed to be unknown therefore estimated to be dependent on the connectivity strength, the state and control values. Robustness of the probabilistic controller is proved via the Liapunov method. Furthermore, based on the residual error of the network states we introduce the definition of stochastic pinning controllability. A coupled map lattice with spatiotemporal chaos is taken as an example to illustrate all theoretical developments. The theoretical derivation is complemented by its validation on two representative examples.

Multi-Agent Information Processing and Adaptive Control in Global Telecommunication and Computer Networks

The problems and methods for adaptive control and multi-agent processing of information in global telecommunication and computer networks (TCN) are discussed. Criteria for controllability and communication ability (routing ability) of dataflows are described. Multi-agent model for exchange of divided information resources in global TCN has been suggested. Peculiarities for adaptive and intelligent control of dataflows in uncertain conditions and network collisions are analyzed.

Teaching our children when to eat:how parental feeding practices inform the development of emotional eating-a longitudinal experimental design

Background: Emotional eating in children has been related to the consumption of energy-dense foods and obesity, but the development of emotional eating in young children is poorly understood. Objectives: We evaluated whether emotional eating can be induced in 5-7-y-old children in the laboratory and assessed whether parental use of overly controlling feeding practices at 3-5 y of age predicts a greater subsequent tendency for children to eat under conditions of mild stress at ages 5-7 y. Design: Forty-one parent-child dyads were recruited to participate in this longitudinal study, which involved parents and children being observed consuming a standard lunch, completing questionnaire measures of parental feeding practices, participating in a research procedure to induce child emotion (or a control procedure), and observing children's consumption of snack foods. Results: Children at ages 5-7 y who were exposed to a mild emotional stressor consumed significantly more calories from snack foods in the absence of hunger than did children in a control group. Parents who reported the use of more food as a reward and restriction of food for health reasons with their children at ages 3-5 y were more likely to have children who ate more under conditions of negative emotion at ages 5-7 y. Conclusions: Parents who overly control children's food intake may unintentionally teach children to rely on palatable foods to cope with negative emotions. Additional research is needed to evaluate the implications of these findings for children's food intake and weight outside of the laboratory setting. This trial was registered at clinicaltrials.gov as NCT01122290.

A Stochastic Control Approach to a Parabolic Equation, Reciprocal Processes

2000 Mathematics Subject Classi cation: 49L60, 60J60, 93E20.

Stress, burnout and coping strategies in the emergency and intensive care hospital departments

Doctors and nurses working at the accident and emergency (A&E), and intensive care departments are at risk of burnout. They often spend substantial time in intense interactions with other people, centered on patients? health problems (physical, psychological and social) that may lead to feelings of anger, anxiety and frustration, and eventually to burnout. Burnout is a syndrome of emotional exhaustion, depersonalization and reduced personal accomplishment (Maslach & Jackson, 1981) The purpose of this chapter is to assess work stressors, burnout and stress-coping mechanisms among doctors and nurses at the A&E and intensive care departments. A quantitative design using the survey approach was used to collect data from a sample of 200 participants with a response rate of 71% (n=154) Work stressors were associated with burnout in both doctors and nurses. Workload was the most salient work stressor in the sample. Nurses experienced more stress (M=1.5, SD=0.4) than doctors (M=1.2, SD=0.4) in all the work stressor variables examined. The A&E department was reported as more stressful than the intensive care department. Avoidance-oriented and task-oriented coping were the most and the least frequently reported coping strategies respectively. Additionally, only emotion-oriented coping strategy was significantly different between doctors and nurses, and this strategy was also significantly positively correlated with all the variables in the adapted nursing stress scale, and the three burnout variables. Death and dying was most strongly correlated with emotion-oriented coping. This chapter provides an assessment of stress, burnout and coping experienced by both doctors and nurses within the A&E and intensive care departments. Methods that may mitigate stress in these environments may be adequate staffing, supportive management, stress management programs, as well as improvement in communication strategies between doctors and nurses.

Well-structured teams and the buffering of hospital employees from stress

Membership in well-structured teams, which show clarity in team and individual goals, meet regularly, and recognize diverse skills of their members, is known to reduce stress. This study examined how membership of well-structured teams was associated with lower levels of strain, when testing a work stressors-to-strains relationship model across the three levels of team structure, namely well-structured, poorly structured (do not fulfill all the criteria of well-structured teams) and no team. The work stressors tested, were quantitative overload and hostile environment, whereas strains were measured through job satisfaction and intention to leave job. This investigation was carried out on a random sample of 65,142 respondents in acute/specialist National Health Service hospitals across the UK. Using multivariate analysis of variance, statistically significant differences between means across the three groups of team structure, with mostly moderate effect sizes, were found for the study variables. Those in well-structured teams have the highest levels of job satisfaction and the least intention to leave job. Multigroup structural equation modelling confirmed the model's robustness across the three groups of team structure. Work stressors explained 45%, 50% and 65% of the variance of strains for well-structured, poorly structured and no team membership, respectively. An increase of one standard deviation in work stressors, resulted in an increase in 0.67, 0.70 and 0.81 standard deviations in strains for well-structured, poorly structured and no team membership, respectively. This investigation is an eye-opener for hospitals to work towards achieving well-structured teams, as this study shows weaker stressor-to-strain relationships for members of these teams.

Rotor retaining sleeve design for a 1.12-MW high-speed PM machine

Permanent-magnet (PM) synchronous machines (PMSMs) can provide excellent performance in terms of torque density, energy efficiency, and controllability. However, PMs on the rotor are prone to centrifugal force, which may break their physical integrity, particularly at high-speed operation. Typically, PMs are bound with carbon fiber or retained by alloy sleeves on the rotor surface. This paper is concerned with the design of a rotor retaining sleeve for a 1.12-MW 18-kr/min PM machine; its electromagnetic performance is investigated by the 2-D finite-element method (FEM). Theoretical and numerical analyses of the rotor stress are carried out. For the carbon fiber protective measure, the stresses of three PM configurations and three pole filler materials are compared in terms of operating temperature, rotor speed, retaining sleeve thickness, and interference fit. Then, a new hybrid protective measure is proposed and analyzed by the 2-D FEM for operational speeds up to 22 kr/min (1.2 times the rated speed). The rotor losses and machine temperatures with the carbon fiber retaining sleeve and the hybrid retaining sleeve are compared, and the sleeve design is refined. Two rotors using both designs are prototyped and experimentally tested to validate the effectiveness of the developed techniques for PM machines. The developed retaining sleeve makes it possible to operate megawatt PM machines at high speeds of 22 kr/min. This opens doors for many high-power high-speed applications such as turbo-generator, aerospace, and submarine motor drives.

A Dynamic Input-Output Model with Renewable Resources

The paper studies a generalisation of the dynamic Leontief input-output model. The standard dynamic Leontief model will be extended with the balance equation of renewable resources. The renewable stocks will increase regenerating and decrease exploiting primary natural resources. In this study the controllability of this extended model is examined by taking the consumption as the control parameter. Assuming balanced growth for both consumption and production, we investigate the exhaustion of renewable resources in dependence on the balanced growth rate and on the rate of natural regeneration. In doing so, classic results from control theory and on eigenvalue problems in linear algebra are applied.

A Dynamic Input-Output Model with Renewable Resources

The paper studies a generalisation of the dynamic Leontief input-output model. The standard dynamic Leontief model will be extended with the balance equation of renewable resources. The renewable stocks will increase regenerating and decrease exploiting primary natural resources. In this study the controllability of this extended model is examined by taking the consumption as the control parameter. Assuming balanced growth for both consumption and production, we investigate the exhaustion of renewable resources in dependence on the balanced growth rate and on the rate of natural regeneration. In doing so, classic results from control theory and on eigenvalue problems in linear algebra are applied.

Implications of a theoretical framework on stress and burnout for the development of graduate nursing education curricula

This study had two purposes: (a) to develop a theoretical framework integrating and synthesizing findings of prior research regarding stress and burnout among critical care nurses (CCRNs), and (b) to validate the theoretical framework with an empirical study to assure a theory/research based teaching-learning process for graduate courses preparing nursing clinical specialists and administrators.^ The methods used to test the theoretical framework included: (a) adopting instruments with reported validity, (b) conducting a pilot study, (c) revising instruments using results of the pilot study and following concurrence of a panel of experts, and (d) establishing correlations within predetermined parameters. The reliability of the tool was determined through the use of Cronbach's Alpha Coefficient with a resulting range from.68 to.88 for all measures.^ The findings supported all the research hypotheses. Correlations were established at r =.23 for statistically significant alphas at the.01 level and r =.16 for alphas.05. The conclusions indicated three areas of strong correlation among the theoretical variables: (a) work environment stressor antecedents and specific stressor events were correlated significantly with subjective work stress and burnout; (b) subjective work stress (perceived work related stress) was a function of the work environment stressor antecedents and specific stressor events, and (c) emotional exhaustion, the first phase of burnout, was confirmed to be related to stressor antecedents and specific stressor events. This dimension was found to be a function of the work environment stressor antecedents, modified by the individual characteristics of work and non-work related social support, non-work daily stress, and the number of hours worked per week. The implications of the study for nursing graduate curricula, nursing practice and nursing education were discussed. Recommendations for further research were enumerated. ^

Stressors, mediators, and health care outcomes of home enteral nutrition in family caregivers and their older adult care recipients

Family caregivers manage home enteral nutrition (HEN) for over 77% of an estimated 1 of every 400 Medicare recipients. Increasing usage of HEN in older adults combined with reliance on family caregivers raises concerns for the quality, outcomes, and costs of care. These concerns are relevant in light of Medicare limitations on nursing assistance and non-reimbursement for nutrition services, despite annual costs of over $600 million. This study applied stress process theories to assess stressor, mediator, and outcome variables salient to HEN and caregiving. In-home structured interviews occurred with a multi-ethnic sample of 30 caregiving dyads at 1–3 months after discharge on HEN. Care recipients were aged ≥60 (M = 68.4 years) and did not have dementia. Caregivers were aged ≥21, unpaid, and lived within 45 minutes of care recipients. Caregivers performed an average of 19.7 tasks daily for 61.9 hours weekly. Training needs were identified for 33 functional, care management, technical, and nutritional tasks. Preparedness scores were low (M = 1.73/4.0), and positively correlated with competence, self-rated quality of care and positive feelings, and negatively with overload, role captivity, and negative feelings (Ps < .05). Caregivers had multiple changes in lifestyle and dietary behaviors. Lifestyle changes positively correlated with overload, and negatively with preparedness and positive feelings. Dietary changes positively correlated with number of tasks, overload, role captivity and negative feelings, and negatively with preparedness (Ps < .01). Fifty-seven percent of caregivers aged >50 were at nutrition risk. Care recipients fared worse. Average weight change was −4.35 pounds (P < .001). Physical complications interrupted daily enteral infusions. Water intake was half of fluid need and associated with signs of dehydration (P < .001). Physical and social function was poor, with older subjects more impaired ( P < .04). Those with better prepared or less overloaded caregivers had higher functionality and QOL (P < .002). Complications, type of feeding tube, and caregiver preparedness correlated with frequency of health care utilization (Ps < .05). Efficacy of HEN in older adults requires specialized caregiver training, attention to caregivers' needs, and frequent monitoring from a highly skilled multidisciplinary team including dietitians. ^

Causal attributions for success or failure by passing and failing students in College Algebra

Success in mathematics has been identified as a predictor of baccalaureate degree completion. Within the coursework of college mathematics, College Algebra has been identified as a high-risk course due to its low success rates. ^ Research in the field of attribution theory and academic achievement suggests a relationship between a student's attributional style and achievement. Theorists and researchers contend that attributions influence individual reactions to success and failure. They also report that individuals use attributions to explain and justify their performance. Studies in mathematics education identify attribution theory as the theoretical orientation most suited to explain academic performance in mathematics. This study focused on the relationship among a high risk course, low success rates, and attribution by examining the difference in the attributions passing and failing students gave for their performance in College Algebra. ^ The methods for the study included a pilot administration of the Causal Dimension Scale (CDSII) which was used to conduct reliability and principal component analyses. Then, students (n = 410) self-reported their performance on an in-class test and attributed their performance along the dimensions of locus of causality, stability, personal controllability, and external controllability. They also provided open-ended attribution statements to explain the cause of their performance. The quantitative data compared the passing and failing groups and their attributions for performance on a test using One-Way ANOVA and Pearson chi square procedures. The open-ended attribution statements were coded in relation to ability, effort, task difficulty, and luck and compared using a Pearson chi square procedure. ^ The results of the quantitative data comparing passing and failing groups and their attributions along the dimensions measured by the CDSII indicated statistical significance in locus of causality, stability, and personal controllability. The results comparing the open-ended attribution statements indicated statistical significance in the categories of effort and task difficulty. ^

Physiological performance measures and tolerance limits of estuarine indicator species in south Florida

Current water management practices in South Florida have negatively impacted many species inhabiting Florida Bay. Variable and high salinity has been identified as a key stressor in these estuaries. The Comprehensive Everglades Restoration Plan (CERP) includes water redistribution projects that will restore natural freshwater flows to northeastern Florida Bay. My studies focused on the following central theme and hypotheses: Biological performance measures (i.e., growth, reproduction, survival), behavior (i.e., habitat preference and locomotor behavior) and diversity of estuarine fish will be controlled by changes in salinity and water quality that will occur as a result of the restoration of freshwater flow to the bay. A series of acute and subchronic physiological toxicity studies were conducted to determine the effects of salinity changes on the life stages (embryo/larval, juvenile, adult) and fecundity of four native estuarine fish (Cyprinodon variegatus, Floridichthys carpio, Poecilia latipinna, and Gambusia holbrooki). Fish were exposed to a range of salinity concentrations (freshwater to hypersaline) based on salinity profiles in the study areas. Growth (length, weight) and survival were measured. Salinity trials included both rapid and gradual change events. Results show negative effects of acute, abrupt salinity changes on fish survival, development and reproductive success as a result of salinity stress. Other studies targeted reproduction and critical embryo-larval/neonate development as key areas for detecting long-term population effects of salinity change in Florida Bay. Adults of C. variegates and P. latipinna were also examined for behavioral responses to pulsed salinity changes. These responses include changes in swimming performance, locomotor behavior and zone preference. Finally, an ecological risk assessment was conducted for adverse salinity conditions in northeastern Florida Bay. Using the U.S. EPA's framework, the risk to estuarine fish species diversity was assessed against regional salinity profiles from a 17-year database. Based on the risk assessment, target salinity profiles for these areas are recommended for managers.^

System-on-a-Chip (SOC) based environmental monitoring platform for the detection of hazardous materials

The purpose of this research is design considerations for environmental monitoring platforms for the detection of hazardous materials using System-on-a-Chip (SoC) design. Design considerations focus on improving key areas such as: (1) sampling methodology; (2) context awareness; and (3) sensor placement. These design considerations for environmental monitoring platforms using wireless sensor networks (WSN) is applied to the detection of methylmercury (MeHg) and environmental parameters affecting its formation (methylation) and deformation (demethylation). ^ The sampling methodology investigates a proof-of-concept for the monitoring of MeHg using three primary components: (1) chemical derivatization; (2) preconcentration using the purge-and-trap (P&T) method; and (3) sensing using Quartz Crystal Microbalance (QCM) sensors. This study focuses on the measurement of inorganic mercury (Hg) (e.g., Hg2+) and applies lessons learned to organic Hg (e.g., MeHg) detection. ^ Context awareness of a WSN and sampling strategies is enhanced by using spatial analysis techniques, namely geostatistical analysis (i.e., classical variography and ordinary point kriging), to help predict the phenomena of interest in unmonitored locations (i.e., locations without sensors). This aids in making more informed decisions on control of the WSN (e.g., communications strategy, power management, resource allocation, sampling rate and strategy, etc.). This methodology improves the precision of controllability by adding potentially significant information of unmonitored locations.^ There are two types of sensors that are investigated in this study for near-optimal placement in a WSN: (1) environmental (e.g., humidity, moisture, temperature, etc.) and (2) visual (e.g., camera) sensors. The near-optimal placement of environmental sensors is found utilizing a strategy which minimizes the variance of spatial analysis based on randomly chosen points representing the sensor locations. Spatial analysis is employed using geostatistical analysis and optimization occurs with Monte Carlo analysis. Visual sensor placement is accomplished for omnidirectional cameras operating in a WSN using an optimal placement metric (OPM) which is calculated for each grid point based on line-of-site (LOS) in a defined number of directions where known obstacles are taken into consideration. Optimal areas of camera placement are determined based on areas generating the largest OPMs. Statistical analysis is examined by using Monte Carlo analysis with varying number of obstacles and cameras in a defined space. ^