77 research outputs found
Are we ready for a person-centered care model for patient- physician consultation? A survey from family physicians and their patients of East Mediterranean Region
Background: Person-centered care has long been identified as a key component of health systems and one of the six domains of quality. This study aimed to identify the perceptions of patients and physicians regarding person-centered care in the Eastern Mediterranean Region (EMR). Methods: A multicountry, cross-sectional study was conducted in 6 countries of EMR during July 2012 to September 2012. From each country, an expert Family Physician (FP) was identified and invited for the study. During the first phase, 190 FPs practising for at least 6 months were recruited. In the second phase, the recruited FPs approached 300 patients aged > 18 years with 1 or more recurring problems. Data analysis was conducted using SPSS version 19. Results: Of a total of 360 patients, 53% were between 25-40 years of age and the majority 55.7% were females. Among physicians, 66.8% were females and 72.1% had undergone specialization in Family Medicine from EMR. About 36% of the patients, while 62.6% of the physicians, preferred a person-centered care model of care. Among physicians, field of specialization (AOR= 0.7; 95% C.I: 0.3-0.9) and regularity in continuing medical education sessions (AOR= 0.3; 95% C.I: 0.1-0.5) were significant factors for preferring a person-centered care model. Educational status (AOR= 3.0; 95% C.I: 1.1- 7.9) was associated with a preference for person-centered care among patients. Conclusion: The results of the study highlight that a majority of physicians prefer person-centered care, while patients prefer a mix of both patient- and physician-centered care. Strategies should be developed that will help physicians and patients to embrace person-centered care practices
Steering proton migration in hydrocarbons using intense few-cycle laser fields
Proton migration is a ubiquitous process in chemical reactions related to
biology, combustion, and catalysis. Thus, the ability to control the movement
of nuclei with tailored light, within a hydrocarbon molecule holds promise for
far-reaching applications. Here, we demonstrate the steering of hydrogen
migration in simple hydrocarbons, namely acetylene and allene, using
waveform-controlled, few-cycle laser pulses. The rearrangement dynamics are
monitored using coincident 3D momentum imaging spectroscopy, and described with
a quantum-dynamical model. Our observations reveal that the underlying control
mechanism is due to the manipulation of the phases in a vibrational wavepacket
by the intense off-resonant laser field.Comment: 5 pages, 4 figure
A Closer Look at Precision Hard Turning of AISI4340: Multi-Objective Optimization for Simultaneous Low Surface Roughness and High Productivity
This article reports an extended investigation into the precision hard turning of AISI 4340 alloy steel when machined by two different types of inserts: wiper nose and conventional round nose. It provides a closer look at previously published work and aims at determining the optimal process parameters for simultaneously minimizing surface roughness and maximizing productivity. In the mathematical models developed by the authors, surface roughness at different cutting speeds, depths of cut and feed rates is treated as the objective function. Three robust multi-objective techniques, (1) multi-objective genetic algorithm (MOGA), (2) multi-objective Pareto search algorithm (MOPSA) and (3) multi-objective emperor penguin colony algorithm (MOEPCA), were used to determine the optimal turning parameters when either the wiper or the conventional insert is used, and the results were experimentally validated. To investigate the practicality of the optimization algorithms, two turning scenarios were used. These were the machining of the combustion chamber of a gun barrel, first with an average roughness (Ra) of 0.4 µm and then with 0.8 µm, under conditions of high productivity. In terms of the simultaneous achievement of both high surface quality and productivity in precision hard turning of AISI 4340 alloy steel, this work illustrates that MOPSA provides the best optimal solution for the wiper insert case, and MOEPCA results are the best for the conventional insert. Furthermore, the results extracted from Pareto front plots show that the wiper insert is capable of successfully meeting both the requirements of Ra values of 0.4 µm and 0.8 µm and high productivity. However, the conventional insert could not meet the 0.4 µm Ra requirement; the recorded global minimum was Ra = 0.454 µm, which reveals the superiority of the wiper compared to the conventional insert
Advanced coordination method for overcurrent protection relays using new hybrid and dynamic tripping characteristics for microgrid
Nowadays, the Overcurrent (OC) and Earth Fault (EF) relays coordination problem is one of the most complex and challenging concerns of power protection and network operators due to the high and volatile generation capacity of renewable energy sources in the grid. In this article, a new and dynamic optimal coordination scheme based on a novel hybrid tripping characteristic has been designed and developed for Over Current Relays (OCRs). Considering the impact of renewable energy sources such as the photovoltaic (PV) system on fault characteristic, this work presents and verifies a novel dynamic and hybrid tripping to achieve minimum tripping time and improve the OCR and EF relays coordination performance in terms of security, sensitivity, and selectivity. The proposed dynamic and hybrid scheme will help the OCRs to cover the EF events, and it has been tested under different fault scenarios compared to the literature. The IEEE-9 and IEEE-33 bus systems are implemented in the ETAP package to validate the effectiveness of the proposed hybrid characteristics against traditionally well-established IEC characteristics. Furthermore, the performance of the proposed advance and dynamic protection approach which doesn’t require a communication infrastructure is investigated for a power network with PV plants under different grid operation modes and topology to provide more robustness protection system. The results, as presented using Industrial software (ETAP), showed that the novel dynamic and hybrid tripping scheme improved the speed of the total time tripping different fault scenarios and location by more than 50% and covers all EF events compared to traditional OCR schemes from the literature. The proposed novel dynamic approach has superior performance in detecting high-impedance faults and significantly reducing the tripping time on the IEEE 33 bus network by 47%
Capture into Rydberg states and momentum distributions of ionized electrons
The yield of neutral excited atoms and low-energy photoelectrons generated by
the electron dynamics in the combined Coulomb and laser field after tunneling
is investigated. We present results of Monte-Carlo simulations built on the
two-step semiclassical model, as well as analytic estimates and scaling
relations for the population trapping into the Rydberg states. It is shown that
mainly those electrons are captured into bound states of the neutral atom that
due to their initial conditions (i) have moderate drift momentum imparted by
the laser field and (ii) avoid strong interaction ("hard" collision) with the
ion. In addition, it is demonstrated that the channel of capture, when
accounted for in semiclassical calculations, has a pronounced effect on the
momentum distribution of electrons with small positive energy. For the
parameters that we investigated its presence leads to a dip at zero momentum in
the longitudinal momentum distribution of the ionized electrons.Comment: 9 pages, 8 figures in one zip-archiv
Strong-field control of the dissociative ionization of N2O with near-single-cycle pulses
The dissociative ionization of N2O by near-single-cycle laser pulses is studied using phase-tagged ion-ion coincidence momentum imaging. Carrier-envelope phase (CEP) dependences are observed in the absolute ion yields and the emission direction of nearly all ionization and dissociation pathways of the triatomic molecule. We find that laser-field-driven electron recollision has a significant impact on the dissociative ionization dynamics and results in pronounced CEP modulations in the dication yields, which are observed in the product ion yields after dissociation. The results indicate that the directional emission of coincident N+ and NO+ ions in the denitrogenation of the dication can be explained by selective ionization of oriented molecules. The deoxygenation of the dication with the formation of coincident N-2(+) + O+ ions exhibits an additional shift in its CEP dependence, suggesting that this channel is further influenced by laser interaction with the dissociating dication. The experimental results demonstrate how few-femtosecond dynamics can drive and steer molecular reactions taking place on (much) longer time scales
Carrier - envelope phase-tagged imaging of the controlled electron acceleration from SiO2 nanospheres in intense few-cycle laser fields
Waveform-controlled light fields offer the possibility of manipulating
ultrafast electronic processes on sub-cycle timescales. The optical lightwave
control of the collective electron motion in nanostructured materials is key
to the design of electronic devices operating at up to petahertz frequencies.
We have studied the directional control of the electron emission from 95 nm
diameter SiO2 nanoparticles in few-cycle laser fields with a well-defined
waveform. Projections of the three-dimensional (3D) electron momentum
distributions were obtained via single-shot velocity-map imaging (VMI), where
phase tagging allowed retrieving the laser waveform for each laser shot. The
application of this technique allowed us to efficiently suppress background
contributions in the data and to obtain very accurate information on the
amplitude and phase of the waveform-dependent electron emission. The
experimental data that are obtained for 4 fs pulses centered at 720 nm at
different intensities in the range (1–4) × 1013 W cm−2 are compared to quasi-
classical mean-field Monte-Carlo simulations. The model calculations identify
electron backscattering from the nanoparticle surface in highly dynamical
localized fields as the main process responsible for the energetic electron
emission from the nanoparticles. The local field sensitivity of the electron
emission observed in our studies can serve as a foundation for future research
on propagation effects for larger particles and field-induced material changes
at higher intensities
Subfemtosecond steering of hydrocarbon deprotonation through superposition of vibrational modes
Subfemtosecond control of the breaking and making of chemical bonds in polyatomic molecules is poised to open new pathways for the laser-driven synthesis of chemical products. The break-up of the C-H bond in hydrocarbons is an ubiquitous process during laser-induced dissociation. While the yield of the deprotonation of hydrocarbons has been successfully manipulated in recent studies, full control of the reaction would also require a directional control (that is, which C-H bond is broken). Here, we demonstrate steering of deprotonation from symmetric acetylene molecules on subfemtosecond timescales before the break-up of the molecular dication. On the basis of quantum mechanical calculations, the experimental results are interpreted in terms of a novel subfemtosecond control mechanism involving non-resonant excitation and superposition of vibrational degrees of freedom. This mechanism permits control over the directionality of chemical reactions via vibrational excitation on timescales defined by the subcycle evolution of the laser waveform
Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles
Nanoparticles offer unique properties as photocatalysts with large surface areas. Under irradiation with light, the associated near-fields can induce, enhance, and control molecular adsorbate reactions on the nanoscale. So far, however, there is no simple method available to spatially resolve the near-field induced reaction yield on the surface of nanoparticles. Here we close this gap by introducing reaction nanoscopy based on three-dimensional momentum-resolved photoionization. The technique is demonstrated for the spatially selective proton generation in few-cycle laser-induced dissociative ionization of ethanol and water on SiO2 nanoparticles, resolving a pronounced variation across the particle surface. The results are modeled and reproduced qualitatively by electrostatic and quasi-classical mean-field Mie Monte-Carlo ((MC)-C-3) calculations. Reaction nanoscopy is suited for a wide range of isolated nanosystems and can provide spatially resolved ultrafast reaction dynamics on nanoparticles, clusters, and droplets
Recommended from our members
Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles
Nanoparticles offer unique properties as photocatalysts with large surface areas. Under irradiation with light, the associated near-fields can induce, enhance, and control molecular adsorbate reactions on the nanoscale. So far, however, there is no simple method available to spatially resolve the near-field induced reaction yield on the surface of nanoparticles. Here we close this gap by introducing reaction nanoscopy based on three-dimensional momentum-resolved photoionization. The technique is demonstrated for the spatially selective proton generation in few-cycle laser-induced dissociative ionization of ethanol and water on SiO2 nanoparticles, resolving a pronounced variation across the particle surface. The results are modeled and reproduced qualitatively by electrostatic and quasi-classical mean-field Mie Monte-Carlo (M3C) calculations. Reaction nanoscopy is suited for a wide range of isolated nanosystems and can provide spatially resolved ultrafast reaction dynamics on nanoparticles, clusters, and droplets
- …