30 research outputs found
Saturable elimination of piperacillin in critically ill patients : implications for continuous infusion
No full textThe study aimed to evaluate saturation of piperacillin elimination in critically ill adult patients. Seventeen critically ill adult patients received continuous and intermittent infusion of piperacillin/tazobactam. Piperacillin plasma concentrations (n = 217) were analysed using population pharmacokinetic (PopPK) modelling. Post-hoc simulations were performed to evaluate the type I error rate associated with the study. Unseen data were used to validate the final model. The mean error (ME) and root mean square error (RMSE) were calculated as a measure of bias and imprecision, respectively. A PopPK model with parallel linear and non-linear elimination best fitted the data. The median and 95% confidence interval (CI) for the model parameters drug clearance (CL), volume of central compartment (V), volume of peripheral compartment (Vp) and intercompartmental clearance (Q) were 9 (7.69-11) L/h, 6.18 (4.93-11.2) L, 11.17 (7.26-12) L and 15.61 (12.66-23.8) L/h, respectively. The Michaelis-Menten constant (Km) and the maximum elimination rate for Michaelis-Menten elimination (Vmax) were estimated without population variability in the model to avoid overfitting and inflation of the type I error rate. The population estimates for Km and Vmax were 37.09 mg/L and 353.57 mg/h, respectively. The bias (ME) was -20.8 (95% CI -26.2 to -15.4) mg/L, whilst imprecision (RMSE) was 49.2 (95% CI 41.2-56) mg/L. In conclusion, piperacillin elimination is (partially) saturable. Moreover, the population estimate for Km lies within the therapeutic window and therefore saturation of elimination should be accounted for when defining optimum dosing regimens for piperacillin in critically ill patients.No Full Tex
Error estimates for density-functional theory predictions of surface energy and work function
No full textDensity-functional theory (DFT) predictions of materials properties are becoming ever more widespread. With increased use comes the demand for estimates of the accuracy of DFT results. In view of the importance of reliable surface properties, this work calculates surface energies and work functions for a large and diverse test set of crystalline solids. They are compared to experimental values by performing a linear regression, which results in a measure of the predictable and material-specific error of the theoretical result. Two of the most prevalent functionals, the local density approximation (LDA) and the Perdew-Burke-Ernzerhof parametrization of the generalized gradient approximation (PBE-GGA), are evaluated and compared. Both LDA and GGA-PBE are found to yield accurate work functions with error bars below 0.3 eV, rivaling the experimental precision. LDA also provides satisfactory estimates for the surface energy with error bars smaller than 10%, but GGA-PBE significantly underestimates the surface energy for materials with a large correlation energy
The contribution of closed loop tracking control of motion platform on laterally induced postural instability of the drivers at SAAM dynamic simulator
No full textThis paper explains the effect of a motion platform closed loop control comparing to the static condition for driving simulators on postural instability. The postural instabilities of the participants (N=18, 15 male and 3 female subjects) were measured as lateral displacements of subject body centre of pressure (YCP ) just before and after each driving session via a balance platform. After having completed the experiments, the two-tailed Mann-Whitney U test was applied to analyze the objective data for merely the post-exposure cases. The objective data analysis revealed that the YCP for the dynamic case indicated a significant lower value than the static situation (U(18), p < 0,0001). It can be concluded that the closed loop tracking control of the hexapod platform of the driving simulator (dynamic platform condition) decreased significantly the lateral postural stability compared to the static operation condition. However the two-tailed Mann-Whitney U test showed that no significant difference was obtained between the two conditions in terms of psychophysical perception
Impactevaluatie in het sociaal werk : van praktijk naar theorie, via impactgedreven handelen
No full textAbstract: In dit artikel bespreken we enkele belangrijke principes omtrent de evaluatie van sociaalwerkpraktijken. Evalueren heeft als doel te begrijpen hoe een praktijk werkt en te verklaren waarom een praktijk werkt, voor wie en in welke context. Daarnaast willen we ook het verband begrijpen tussen onderdelen van een praktijk, het proces en de resultaten. Het uitgangspunt van deze bijdrage is het stimuleren van impactgedreven handelen. Het opbouwen van kennis over impact vraagt om een kruisbestuiving van kennis: ervaringskennis, praktijkkennis en academische kennis. Dit betekent dat de organisatie met haar professionals, in samenwerking met cli\uebnten, op frequente tijdstippen de impact en het proces naar die impact zichtbaar maakt (Jans, 2018). Deze bijdrage werd geschreven vanuit een samenwerkingsverband van onderzoekers van Universiteit Antwerpen, Karel de Grote Hogeschool, KU Leuven en SAM vzw, steunpunt Mens en Samenleving, dat in nauwe samenwerking met het werkveld een visie op impactevaluatie in sociaal werk ontwikkelt. Dit project wordt ondersteund door de Vlaamse overheid en het Vlaams Platform Sterk Sociaal Werk
A first-principles reassessment of the Fe-N phase diagram in the low-nitrogen limit
No full textNitriding of steels has been widely used for almost a century. However, insight in two important precipitating phases for low concentration through-thickness nitriding is still lacking, hindering further development of the process. Due to their metastable nature, manufacturing large homogeneous samples of Fe4N and Fe16N2 is very challenging. Consequently, measuring thermodynamic properties, such as heat capacity and free energy, has proven difficult at best. In this work, we have calculated those thermodynamic properties using density-functional theory (DFT) for Fe4N, Fe16N2 and ferrite with nitrogen in solid solution. This information is a prerequisite to improve the accuracy of larger-scale modeling approaches of iron nitrides. We used the free energies to construct the temperature/concentration phase diagram for low nitrogen concentrations from to . Both the range of metastability for Fe16N2 and the nitrogen solvus confirm the experimental data. On the other hand, it was concluded that the experimental Curie temperature for Fe16N2 is severely underestimated because of the thermodynamic instability above 400 K
Influence of Inertial Stimulus on Visuo-Vestibular Cues Conflict for Lateral Dynamics at Driving Simulators
No full textVersion éditeur de cet article : Aykent B, Merienne F, Paillot D, Kemeny A (2013) Influence of Inertial Stimulus on Visuo-Vestibular Cues Conflict for Lateral Dynamics at Driving Simulators. J Ergonomics 3: 113. doi:10.4172/2165-7556.1000113This paper explains the effect of having an inertial stimulus (motion platform) for driving simulators on proximity to the reality for the sensed lateral dynamics with respect to the measurements and the perceptual fidelity using a questionnaire technique. To assess this objectively, the vestibular and vehicle level lateral accelerations (ay,sensed=ay_ vest, ayv =ay_veh ) were saved by using a motion tracking sensor and SCANeR studio software respectively. A confidence interval of 95% was chosen to test the correlations (Pearson’s correlation) and to fit models for the distributions of the visual-vestibular lateral accelerations with the multiple linear regression between the conditions of static (N=16) and dynamic (N=21) platform cases in terms of visuo-vestibular level lateral accelerations for the group of subjects (N=37). The results showed that the dynamic platform provides a higher lateral dynamics reality (positive correlation with an incidence of 90.48% for N=21) compared to the static configuration (negative correlation with an incidence of 50% for N=16) from Pearson’s correlation and a better fitted model and a lower visuo-vestibular cues’ conflict for the dynamic (R2 =0.429, the model is positive sloped, N=21) condition comparing to the static one (R2 =0.072, the model is negative sloped, N=16) from the multiple linear regression models. A two-tailed Mann Whitney U test yielded that the Ucomputed (2139)>Uexpected (1300.5) as p<0.0001, there was a significant difference between the sensed lateral acclerations for the static and dynamic platform cases. Disorientation related perception had positive correlations with the vestibular sensed lateral accelerations for the static condition whereas they were negatively correlated in the dynamic case. As conclusion, the dynamic platform presented a reduced level of motion sickness depending on the sensory conflict theory and the perception fidelity studies approved that dizziness was found to have a significant positive correlation with the vestibular level measured lateral acceleration in the static platform (r=0.293, p=0.037<0.05)
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An interpretative phenomenological analysis of out-of-body experiences in two cases of novice meditators
No full textThe Out-of-Body Experience (OBE) is an anomalous experience that has been found to occur under a variety of circumstances. This paper will take as its focus the in-depth examination of the lived experience of having an OBE as described by two novice meditators. A qualitative approach was adopted using Interpretative Phenomenological Analysis. Two female participants who had OBEs whilst meditating took part in face-to-face, semi-structured interviews. Three interrelated themes emerged from the findings. Analysis highlighted the potential for the OBE to function as an adaptive form of behaviour in relation to how participants endeavoured to discharge existing need-related conflicts. Also emergent was the transactive nature of the out-of-body environments themselves, which were seen as meaningful places that facilitated participants’ embodied, goal-oriented behaviours. Accordingly, participants took pragmatic views about their OBEs, seeing them more as tools or skills that can be utilized as an extension of their selves. Also emphasized was the role of absorption in the production of both the participants’ meditative and out-of-body states
An Attempt of Early Detection of Poor Outcome after Whiplash
No full textThe main concern with whiplash is that a large proportion of whiplash patients experience disabling symptoms or whiplash-associated disorders (WAD) for months if not years following the accident. Therefore, identifying early prognostic factors of WAD development is important as WAD have widespread clinical and economic consequences. In order to tackle that question, our study was specifically aimed at combining several methods of investigation in the same WAD patients at the acute stage and 6 months later. Our longitudinal, open, prospective, multi-center study included 38 whiplash patients, and 13 healthy volunteers matched for age, gender, and socio-economic status with the whiplash group. Whiplash patients were evaluated 15–21 days after road accident, and 6 months later. At each appointment, patients underwent a neuropsychological evaluation, a full clinical neurological examination, neurophysiological and postural tests, oto-neurological tests, cervical spine cord magnetic resonance imaging (MRI) with tractography (DTI). At 6 months, whiplash patients were categorized into two subgroups based on the results of the Diagnostic and Statistical Manual of Mental Disorders as having either favorable or unfavorable progression [an unfavorable classification corresponding to the presence of post-concussion symptom (PCS)] and we searched retrospectively for early prognostic factors of WAD predicting the passage to chronicity. We found that patients displaying high level of catastrophizing at the acute stage and/or post-traumatic stress disorder associated with either abnormalities in head or trunk kinematics, abnormal test of the otolithic function and at the Equitest or a combination of these syndromes, turned to chronicity. This study suggests that low-grade whiplash patients should be submitted as early as possible after the trauma to neuropsychological and motor control tests in a specialized consultation. In addition, they should be evaluated by a neuro-otologist for a detailed examination of vestibular functions, which should include cervical vestibular evoked myogenic potential. Then, if diagnosed at risk of WAD, these patients should be subjected to an intensive preventive rehabilitation program, including vestibular rehabilitation if required.This study was funded by the French Fondation Sécurité Routièr
Quantify osteoarthritis gait at the doctor’s office: a simple pelvis accelerometer based method independent from footwear and aging
No full textThe gold standard to evaluate the severity of steoarthritis in the doctor’s office remains clinical scores (Bellamy 2002). The Western Ontario and McMaster Universities (WOMAC) oste- oarthritis index is the most largely used score in rheumatology for lower limb osteoarthritis. It is based on clinical observation and it assesses pain, stiffness, and physical function in patients with hip and knee osteoarthritis. It is valid, reliable, and sen- sitive to evaluate osteoarthritis and adapted to doctor’s office (Bellamy 2002). However, clinical scores are inherently subjective and they depend from the patient’s impression and from the clinician’s interpretation. Gait analysis in modern gait laboratories with force plates and photogrammetry is a good tool to have an objec- tive, quantified, and precise insight in osteoarthritis (Astephen et al. 2008). For practical reasons, skin-mounted inertial sensors are well suited for investigating gait kinematics (Auvinet et al. 2002). In accelerometer-based gait analysis, aging is also known to affect gait parameters (Oberg et al. 1993). To have a clinical measure of osteoarthritis, it is essential to find a technique that is independ- ent from aging. Footwear can also affect walking parameters (Chambon et al. 2014). Since it is too time consuming to ask the patient to take off his shoe for the measurement, it is essential to find a method independent from the shoe type. Walking ten meters go and ten meters back on a level sur- face at comfortable walking speed is a well-suited protocol for clinical situations. This study proposes to test a 3D pelvis accelerometer-based measurement method on a group of 47 patients suffering from lower limb osteoarthritis and 12 asymptomatic subjects. The aim was to see whether the ccelerometer-based method is correlated with the clinical severity of the lower limb osteoarthritis evalu- ated with the WOMAC index. In addition, this study valuates whether the accelerometer-based method is independent of aging on 75 asymptomatic subjects and whether the acceler- ometer-based method is independent from footwear on one asymptomatic subject
