65 research outputs found

    Resonant Optical Solitons in (3 + 1)-Dimensions Dominated by Kerr Law and Parabolic Law Nonlinearities

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    This study investigates the optical solitons of of (3+1)-dimensional resonant nonlinear Schrödinger (3D-RNLS) equation with the two laws of nonlinearity. The two forms of nonlinearity are represented by Kerr law and parabolic law. Based on complex transformation, the traveling wave reduction of the governing model is derived. The projective Riccati equations technique is applied to obtain the exact solutions of 3D-RNLS equation. Various types of waves that represent different structures of optical solitons are extracted. These structures include bright, dark, singular, dark-singular and combined singular solitons. Additionally, the obliquity effect on resonant solitons is illustrated graphically and is found to cause dramatic variations in soliton behaviors

    Changes in Self-Efficacy and Social Support after an Intervention to Increase Physical Activity Among Adults with Type 2 Diabetes in Oman:A 12-month follow-up of the MOVEdiabetes trial

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    Objectives: This study aimed to describe changes in self-efficacy (SE) and social support (SS) 12 months after the MOVEdiabetes trial, an intervention designed to increase physical activity (PA) among adults with type 2 diabetes mellitus in Oman. Methods: The original MOVEdiabetes trial was conducted between April 2016 and June 2017 in Muscat, Oman. The intervention group (IG) received personalised PA consultations, pedometers and monthly messages using a web-based application, while the comparison group received usual care. Self-reported SE and SS from family and friends were assessed using validated psychosocial scales. Results: Of the 232 original participants in the trial, a total of 174 completed the 12 months follow-up study period (response rate: 75%). However, based on intention-to-treat analysis with several imputation procedures for missing data at 3 and/or 12 months, there was a significant increase in SE scores in the IG (+10.3, 95% confidence interval [CI]: 7.1–13.5; P <0.001); however, the correlation with PA levels was weak (+4.2, 95% CI: 2.7–5.7; P <0.001). Higher SE scores were noted in those without comorbidities (+12.2, 95% CI: 6.8–17.6; P <0.001) and with high income levels (+9.7, 95% CI: 5.2–14.2; P <0.001). Additionally, SS scores increased significantly among those in the IG who received support from friends (+2.3, 95% CI: 1.1–3.7; P <0.001), but not family (+1.2, 95% CI: −0.4–2.8; P = 0.110). The reliability of the scales was acceptable for SE and SS from family, but poor for SS from friends (Cronbach’s alpha coefficients = 0.82, 0.82 and 0.40, respectively). Conclusion: The PA intervention was associated with positive changes in SE and SS from friends. However, further tools for assessing psychosocial influences on PA are needed in Arab countries.   KEYWORDS Physical Activity; Type 2 Diabetes Mellitus; Self-Management; Health Behaviors; Social Support, Self-Efficacy; Primary Healthcare; Oman

    On the Modelling of Immiscible Viscous Fingering in Two-Phase Flow in Porous Media

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    Health professionals’ perceptions about physical activity promotion in diabetes care within primary health care settings in Oman

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    Background: As part of formative work to inform an interventional design to increase physical activity (PA) in patients with type 2 diabetes in Oman, this qualitative study aimed to determine health professionals’ perception of barriers and opportunities, personnel responsibilities and plausible PA promotional approaches. Methods: Four focus group discussions were carried out with groups of health care professionals (family physicians, dieticians and health educators, managers and general practitioners). All discussions were audio recorded and transcribed. Responses were analysed using a thematic analysis. Results: Barriers to PA reported by participants (n = 29) were identified at three levels: health care system (e.g. deficient PA guidelines); individual (e.g. obstructive social norms) and community (e.g. lack of facilities). Participants felt that a multilevel approach is needed to address perceived barriers and to widen current opportunities. In the presence of various diabetes primary care providers, the potential for dieticians to include individualised PA consultations as part of their role was highlighted. Participants felt that consultations should be augmented by approaches within the community (volunteer support and/or appropriate facilities). However, despite lack of experience with technology supported approaches and motivational tools, the telephone application “WhatsApp” and use of pedometers were considered potentially suitable. The need for training in behaviour change techniques and clearly communicated intervention guidelines was emphasised. Conclusions: A multi-component approach including PA consultations, possibly led by trained dieticians, technological routes for providing support along with community mapping for resources appear to offer promising approaches for further PA intervention studies within diabetes primary health care

    Speeds of sound in binary mixtures of water and carbon dioxide at temperatures from 273 K to 313 K and at pressures up to 50 MPa

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    Knowledge of thermodynamic properties of aqueous solutions of CO2 is crucial for various applications including climate science, carbon capture, utilisation and storage (CCUS), and seawater desalination. However, there is a lack of reliable experimental data, and the equation of state (EOS) predictions are not reliable, particularly for sound speeds in low CO2 concentrations typical of water resources. For this reason, we have measured speeds of sound in three different aqueous solutions containing CO2. We report speeds of sound in the single-phase liquid region for binary mixtures of water and CO2 for mole fractions of CO2 of 0.0118, 0.0066 and 0.0015 at temperatures from 273.15 K to 313.15 K and at pressures up to 50 MPa, measured using a dual-path pulse-echo apparatus. The relative standard uncertainties of the sound speeds are 0.05 %, 0.03 % and 0.01 % at 0.0118, 0.0066 and 0.0015 CO2 mole fractions, respectively. The change in sound speeds as functions of composition, pressure and temperature are analysed in this study. We find that dissolution of CO2 in water increases its sound speeds at all conditions, with the greatest increase occurring at the highest mole fractions of CO2. Our sound speed data agree well with the limited available experimental data in the literature but deviate from the EOS-CG of Gernert and Span by up to 7 % at the lowest temperatures, highest pressures, and highest CO2 mole fraction. The new low-uncertainty sound speed data presented in this work could provide a basis for development of an improved EOS and in establishing reliable predictions of the change in thermodynamic properties of seawater-like mixtures due to absorption of CO2 gas
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