3,144 research outputs found

    An Adaptive Modular Redundancy Technique to Self-regulate Availability, Area, and Energy Consumption in Mission-critical Applications

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    As reconfigurable devices\u27 capacities and the complexity of applications that use them increase, the need for self-reliance of deployed systems becomes increasingly prominent. A Sustainable Modular Adaptive Redundancy Technique (SMART) composed of a dual-layered organic system is proposed, analyzed, implemented, and experimentally evaluated. SMART relies upon a variety of self-regulating properties to control availability, energy consumption, and area used, in dynamically-changing environments that require high degree of adaptation. The hardware layer is implemented on a Xilinx Virtex-4 Field Programmable Gate Array (FPGA) to provide self-repair using a novel approach called a Reconfigurable Adaptive Redundancy System (RARS). The software layer supervises the organic activities within the FPGA and extends the self-healing capabilities through application-independent, intrinsic, evolutionary repair techniques to leverage the benefits of dynamic Partial Reconfiguration (PR). A SMART prototype is evaluated using a Sobel edge detection application. This prototype is shown to provide sustainability for stressful occurrences of transient and permanent fault injection procedures while still reducing energy consumption and area requirements. An Organic Genetic Algorithm (OGA) technique is shown capable of consistently repairing hard faults while maintaining correct edge detector outputs, by exploiting spatial redundancy in the reconfigurable hardware. A Monte Carlo driven Continuous Markov Time Chains (CTMC) simulation is conducted to compare SMART\u27s availability to industry-standard Triple Modular Technique (TMR) techniques. Based on nine use cases, parameterized with realistic fault and repair rates acquired from publically available sources, the results indicate that availability is significantly enhanced by the adoption of fast repair techniques targeting aging-related hard-faults. Under harsh environments, SMART is shown to improve system availability from 36.02% with lengthy repair techniques to 98.84% with fast ones. This value increases to five nines (99.9998%) under relatively more favorable conditions. Lastly, SMART is compared to twenty eight standard TMR benchmarks that are generated by the widely-accepted BL-TMR tools. Results show that in seven out of nine use cases, SMART is the recommended technique, with power savings ranging from 22% to 29%, and area savings ranging from 17% to 24%, while still maintaining the same level of availability

    The Effect of Creativity on Entrepreneurial Behavior: The Moderating Role of Demographics

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    This study aims to determine the effect of creativity on entrepreneurial behavior with demographics as a moderating variable. Creativity is critical for improving entrepreneurial behavior (EB). However, few studies exist in the literature about this topic in developing countries. Building on the literature, the study proposed a positive effect between creativity and entrepreneurial behavior. The study also proposed the demographic variables as moderating variables. The population of the study consists of all the entrepreneurs and workers at entrepreneurial enterprises in Jordan. The sample of study was composed of 155 respondents; the responses were gathered using the convenience sampling method. Simple linear regression and hierarchical regression were employed to examine the data. Results show a significant effect of creativity on entrepreneurial behavior. The results also demonstrate that none of the demographic characteristics produce a significant statistical change in the influence of creativity on EB. More studies on creativity and its impact on the EB of firms and employees at entrepreneurial firms are needed

    Eruption and propagation of twisted flux ropes from the base of the solar corona to 1 au

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    Interplanetary Coronal Mass Ejections (ICMEs) originate from the eruption of complex magnetic structures occurring in our star's atmosphere. Determining the general properties of ICMEs and the physical processes at the heart of their interactions with the solar wind is a hard task, in particular using only unidimensional in situ profiles. Thus, these phenomena are still not well understood. In this study we simulate the propagation of a set of flux ropes in order to understand some of the physical processes occurring during the propagation of an ICME such as their growth or their rotation. We present simulations of the propagation of a set of flux ropes in a simplified solar wind. We consider different magnetic field strengths and sizes at the initiation of the eruption, and characterize their influence on the properties of the flux ropes during their propagation. We use the 3D MHD module of the PLUTO code on an Adaptive Mesh Refinement grid. The evolution of the magnetic field of the flux rope during the propagation matches evolution law deduced from in situ observations. We also simulate in situ profiles that spacecraft would have measured at the Earth, and we compare with the results of statistical studies. We find a good match between simulated in situ profiles and typical profiles obtained in these studies. During their propagation, flux ropes interact with the magnetic field of the wind but still show realistic signatures of ICMEs when analyzed with synthetic satellite crossings. We also show that flux ropes with different shapes and orientations can lead to similar unidimensional crossings. This warrants some care when extracting magnetic topology of ICMEs using unidimensional crossings.Comment: Accepted for publication A&A. 14 pages, 9 figures, 3 table

    Coping With The Risk Of Interest Rate Fluctuations: The Case Of Kuwait Banks

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    This study analyzed immunization behavior of a sample of eight Kuwait banks during the 1994 through 2000 period.  The financial market in Kuwait experienced relative stability of interest rates during the analysis period.  The sample banks seemed to adjust their portfolio of assets and liabilities by equating Macaulay duration of assets and Macaulay duration of liabilities.  We could not reject the null hypothesis that there is no difference between average Macaulay duration of assets and that of liabilities.  Our findings indicate that banks in Kuwait are able to match the durations of their assets and liabilities

    Maternal Gestational Diabetes Associated with Higher Child BMI Z-Score at Preschool and Lower Likelihood of Breastfeeding Initiation

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    Objectives: To examine the association of maternal GDM with 1) child BMI z-score at preschool; 2) breastfeeding initiation and duration, while adjusting for child birthweight in addition to potential confounders. Method: Sample included 53 children (3 - 5 years old) recruited from two preschools in Jeddah, Saudi Arabia. Mothers completed a self-administered questionnaire. Child anthropometry was completed using standardized procedures. BMI z-scores were calculated using the WHO standards/reference data. Linear regression models were tested to examine the association between maternal GDM and child BMI z-score, as well as breastfeeding duration. Logistic regression models were tested to examine the association between maternal GDM and breastfeeding initiation. Models were adjusted for child birthweight, maternal BMI, and maternal age at pregnancy. Results: Mean child BMI z-score was 1.10 (SD= 1.22). About one quarter (24.5%) of mothers reported being diagnosed with GDM. Mean birthweight of children whose mothers were diagnosed with GDM was 3.10 kg (SD= 0.74). Adjusting for covariates, we found that maternal GDM was associated with increased child BMI z-score (B= 1.04, 95% CI= 0.14 - 1.94, P-value= 0.02), and lower odds of breastfeeding initiation (OR= 0.10, 95% CI= 0.02 – 0.49, P-value= 0.005). Maternal GDM was not associated with breastfeeding duration (B= -4.75, 95% CI: -11.79 – 2.29, P-value= 0.18). Conclusion: Findings suggest that maternal GDM is associated with higher child BMI z-score at preschool and lower likelihood of breastfeeding initiation. Studies are needed in order to identify the underlying mechanisms of associations. Obesity prevention programs may target children whose mothers were diagnosed with GDM; prenatal breastfeeding counseling may be offered

    Prevalence of Chlamydia trachomatis infection in the general population of women in Qatar

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    Objectives The Arabian Gulf region has limited epidemiological data related to sexually transmitted infections. The objective of this study was to estimate the prevalence of Chlamydia trachomatis infection among general population women in Doha, Qatar. Methods Endocervical swabs were collected from healthy women attending primary healthcare centres in Doha, June–December 2008. The specimens were tested for C trachomatis by a commercially available PCR-based assay. Data on basic socio-demographic characteristics, medical history and sexual behaviour were obtained using self-administered questionnaires. The prevalence of C trachomatis and of background variables were stratified by nationality, Qatari nationals versus non-Qatari residents. Results A total of 377 women were enrolled in the study, out of whom 351 (37.9% Qataris, 62.1% non- Qataris) were tested for the presence of C trachomatis in their specimens. The mean age of participants was 41.2 years, and the vast majority (93%, 95% CI 90.3 to 95.7) were married. The mean age at sexual debut was significantly lower among Qatari women compared with non-Qatari women (19.2 vs 22.2 years, respectively p<0.001), but the mean number of reported lifetime sexual partners (1.1 partner) was nearly the same in both groups (p=0.110). The prevalence of C trachomatis infection was 5.3% among Qatari women and 5.5% among non-Qatari women, with no statistically significant difference between both groups ( p=0.923). Conclusions The prevalence of C trachomatis among women was higher than expected, with no significant difference between Qatari nationals and expatriate residents. The higher prevalence may reflect, in part, the limited access to and use of chlamydia screening and management.Research Committee of the College of Arts and Sciences, Qatar University (QUUG-CAS-DHS-10/11-6); Qatar National Research Fund (NPRP 4-924-3-251); The Biostatistics, Epidemiology, and Biomathematics Research Core at the Weill Cornell Medical Colleg
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