The Plant Propagation Algorithm on Timetables: First Results

One Stochastic HillClimber and two implementations of the Plant Propagation Algorithm (PPA-1 and PPA-2) are applied to an instance of the University Course Timetabling Problem from the Univer- sity of Amsterdam. After completing 10 runs of 200,000 objective function evaluations each, results show that PPA-1 outperforms the HillClimber, but PPA-2 makes the best timetables

CO80 89. Estudio multicéntrico español de la capacidad predictiva de las escalas de riesgo CHADS2 y CHA2DS2vasc en el accidente cerebrovascular tras cirugía coronaria aislada

ObjetivosValidar las escalas de riesgo CHADS2 y CHA2DS-2VASC como modelos predictivos de desarrollo de accidente cerebrovascular (ACV) en cirugía coronaria aislada (CCA).Material y métodosPacientes consecutivos sometidos a CCA en 16 hospitales españoles. Excluidos casos con igual o más de una variable/s incompleta/s. Puntuaciones CHADS2 y CHA2DS2VASC computadas para todos los pacientes, considerándose variable de resultado la aparición de ACV (ataque isquémico transitorio [AIT]/ictus) perioperatorio precoz (primer mes postoperatorio y/o alta hospitalaria). Análisis uni y multivariante. La capacidad discriminativa fue cuantificada por el cálculo del área bajo la curva ROC (AUC).ResultadosVeinte mil novecientos ochenta pacientes incluidos, 282 desarrollaron ACV postoperatorio (1,34%). La incidencia de ACV fue superior en pacientes con insuficiencia cardíaca congestiva (ICC) y/o fracción de eyección inferior al 40% (4,10 vs 0,83%), diabéticos (1,70 vs 1,11%), hipertensos (1,60 vs 0,98%), ACV previo (2,72 vs 1,26%) y a enfermedad arterial periférica (EAP) (3,04 vs 1,04%; p < 0,05). En el análisis multivariante, ICCC (odds ratio [OR]: 4,06), ACV previo (OR: 1,48), EAP (OR: 1,49) constituyeron factores de riesgo independientes para el desarrollo de ACV postoperatorio (p < 0,05). El AUC para CHADS2 fue 0,666, y para CHA2DS2VASc 0,655 (p < 0,0001). La distribución de las tasas de ACV postoperatorio según las puntuaciones de las anteriores escalas se recoge en la figura 1 (p < 0,0001). Figura 1Tasas de ACV postoperatorio en pacientes sometidos a CCA según puntuaciones de las escalas CHADS2 (gris) y CHA2DS2VASC (negro).ConclusionesLas escalas de riesgo CHADS2 y CHA2DS-2VASC pueden resultar útiles en la práctica clínica para estratificar el riesgo de desarrollo de ACV postoperatorio en pacientes sometidos a CCA

A stochastic view on surface inhomogeneity of nanoparticles

The interactions between and with nanostructures can only be fully understood when the functional group distribution on their surfaces can be quantified accurately. Here we apply a combination of direct stochastic optical reconstruction microscopy (dSTORM) imaging and probabilistic modelling to analyse molecular distributions on spherical nanoparticles. The properties of individual fluorophores are assessed and incorporated into a model for the dSTORM imaging process. Using this tailored model, overcounting artefacts are greatly reduced and the locations of dye labels can be accurately estimated, revealing their spatial distribution. We show that standard chemical protocols for dye attachment lead to inhomogeneous functionalization in the case of ubiquitous polystyrene nanoparticles. Moreover, we demonstrate that stochastic fluctuations result in large variability of the local group density between particles. These results cast doubt on the uniform surface coverage commonly assumed in the creation of amorphous functional nanoparticles and expose a striking difference between the average population and individual nanoparticle coverage

Is there an indication for computed tomography and magnetic resonance imaging in the evaluation of coronary artery bypass grafts?

This meta-analysis evaluates the diagnostic accuracy of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) for bypass graft occlusion and stenosis detection compared with coronary angiography in post-coronary artery bypass graft patients. The indication for noninvasive imaging in post-coronary artery bypass graft patients with these techniques is discussed. Overall, MRI had significantly lower sensitivity (81%) and specificity (91%) for occlusion detection than MDCT (96% and 98%, respectively). Only 2 studies assessed the accuracy of stenosis detection with MRI. Stenosis detection with MDCT had a pooled sensitivity of 89% and specificity of 97%. Multidetector computed tomography is therefore superior to MRI for the noninvasive detection of coronary bypass graft occlusion and stenosis. For stenosis detection, the accuracy of MDCT is, however, not sufficient to warrant a wide clinical use. The remaining indication for MRI-guided bypass graft assessment is in combination with myocardial evaluation such as magnetic resonance perfusion, wall motion, and stress test as a "one-stop-shop" procedur

Nonoperatively treated type A spinal fractures:mid-term versus long-term functional outcome

This study focuses on the mid-term (four years) and long-term (ten years) functional outcome of patients treated nonoperatively for a type A spinal fracture without primary neurological deficit. Functional outcome was measured using the visual analogue scale spine score (VAS) and the Roland–Morris disability questionnaire (RMDQ). The 50 patients included were on average 41.2 years old at the time of injury. Four years post injury, a mean VAS score of 74.5 and a mean RMDQ score of 4.9 were found. Ten years after the accident, the mean VAS and RMDQ scores were 72.6 and 4.7, respectively (NS). No significant relationships were found between the difference scores of the VAS and RMDQ compared with age, gender, fracture sub-classification, and time between measurements. Three (6%) patients had a poor long-term outcome. None of the patients required surgery for late onset pain or progressive neurological deficit. Functional outcome after a nonoperatively treated type A spinal fracture is good, both four and ten years post injury. For the group as a whole, four years after the fracture a steady state exists in functional outcome, which does not change for ten years at least after the fracture