BBPR versie 8: Uw bedrijf doorgelicht

BBPR maakt ook begrotingen van technische resultaten bij veranderingen in de bedrijfsvoering

Het schapenstapelmodel

Dit model berekent per jaar de opname aan ruwvoer en krachtvoer van een koppel schapen alsmede het aantal afgevoerde schapen en lammeren met de bijbehorende afvoergewichten

Nonlinear modeling of thermoacoustic systems

Thermoacoustic systems convert energy from heat to acoustic power and vice versa. These systems have commercial interest due to the high potential efficiency and low number of moving parts. To numerically predict the performance of a thermoacoustic device inherent nonlinearities in the system, such as thermoacoustic streaming and generation of harmonics need to be taken into account. We present a nonlinear frequency domain method with which these nonlinearities in thermoacoustic systems are modeled in a computationally efficient manner. Using this method, the nonlinear periodic steady state of a thermoacoustic engine can directly be computed, without computing the long initial transient of the system. In this publication, the developed method is applied to compute the periodic steady state of an experimental standing wave engine. The results obtained match well with experimental data

Rekenprogramma's voor adviseur en veehouder

Wageningen UR Livestock Research heeft rekenprogramma’s voor melkvee (Bedrijfs Begrotingsprogramma Rundvee -BBPR), pluimvee (Bedrijfswijzer Pluimvee) en varkens (Bedrijfswijzer Varkens). Deze programma’s simuleren de bedrijfsvoering van een praktijkbedrijf. Wat je daarmee als adviseur en veehouder kunt, beschrijft dit artike

Ruptured abdominal aortic aneurysms: Factors influencing postoperative mortality and long-term survival

Objective:To update mortality rates and long-term survival of patients admitted to the hospital with ruptured abdominal aortic aneurysm (AAA) and to study prognostic factors associated with mortality.Design:Retrospective follow-up.Materials:309 patients (274 men, 35 women, average age 71) admitted to the hospital between January 1980 and January 1994 who were surgically treated for ruptured AAA were studied.Methods:To identify the preoperative (9), intraoperative (23) and postoperative (49) variables associated with mortality logistic regression analysis (mortality within 48 h) and Cox regression analysis (mortality between 48 h and 30 days) were performed.Results:Hospital mortality improved from 1980 to 1994. Compared with the normal population adjusted for age and sex the long-term mortality rate was increased (standardised mortality ratio 2.1; 95% confidence interval 1.7–2.5). Increased age, peroperative hypotension and need for a bifurcated graft were associated with significantly increased mortality. Co-morbidity was not a predictive variable. Overall hospital mortality was 25%.Conclusion:Surgical repair of ruptured AAA should be considered even in patients with co-morbidity. Elderly patients with severe preoperative hypotension have a very high mortality rate and surgery may not be justified in these cases. Long-term survival is also worse in older patients

Error-enhanced augmented proprioceptive feedback in stroke rehabilitation training:a pilot study

Augmented feedback plays an essential role in stroke rehabilitation therapy. When a force is applied to the arm, an augmented sensory (proprioceptive) cue is provided. The question was to find out if stroke patients can learn reach-and retrieval movements with error-enhanced augmented sensory feedback. The movements were performed over a predefined path, and when deviating of the path a force is provided, as colliding to a wall of a tunnel. Two chronic stroke survivors (FM of 53 and 49) performed reach and retrieval movements in a virtual tunnel. When two consecutive series of 15 repetitions of the same movements were performed, there was a consistent decrease of collisions to the wall in the second series of movements. This indicates that these patients were able to learn the predefined trajectory by means of augmented proprioceptive feedback. Despite the small number of patients tested, this finding is promising for the usage of error-enhanced augmented proprioceptive feedback in rehabilitation therapy

Nieuwe versie Normen Voor de Voedervoorziening sluit beter aan op de praktijk

Bij de ontwikkeling van deze nieuwe versie is ook getracht het programma beter aan te laten sluiten op praktijksituaties. In dit artikel worden enkele belangrijke verschillen met de oude versie toegelicht

Membranes for Topological M-Theory

We formulate a theory of topological membranes on manifolds with G_2 holonomy. The BRST charges of the theories are the superspace Killing vectors (the generators of global supersymmetry) on the background with reduced holonomy G_2. In the absence of spinning formulations of supermembranes, the starting point is an N=2 target space supersymmetric membrane in seven euclidean dimensions. The reduction of the holonomy group implies a twisting of the rotations in the tangent bundle of the branes with ``R-symmetry'' rotations in the normal bundle, in contrast to the ordinary spinning formulation of topological strings, where twisting is performed with internal U(1) currents of the N=(2,2) superconformal algebra. The double dimensional reduction on a circle of the topological membrane gives the strings of the topological A-model (a by-product of this reduction is a Green-Schwarz formulation of topological strings). We conclude that the action is BRST-exact modulo topological terms and fermionic equations of motion. We discuss the role of topological membranes in topological M-theory and the relation of our work to recent work by Hitchin and by Dijkgraaf et al.Comment: 22 pp, plain tex. v2: refs. adde