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We study the problems to find a maximum packing of shortest edge-disjoint cycles in a graph of given girth g (g-ESCP) and its vertex-disjoint analogue g-VSCP. In the case g=3, Caprara and Rizzi (2001) have shown that g-ESCP can be solved in polynomial time for graphs with maximum degree 4, but is APX-hard for graphs with maximum degree 5, while g-VSCP can be solved in polynomial time for graphs with maximum degree 3, but is APX-hard for graphs with maximum degree 4. For g∈{4,5}, we show that both problems allow polynomial time algorithms for instances with maximum degree 3, but are APX-hard for instances with maximum degree 4. For each g?6, both problems are APX-hard already for graphs with maximum degree 3. 相似文献
34.
Parallel communicating grammar systems with regular control (RPCGS, for short) are introduced, which are obtained from returning regular parallel communicating grammar systems by restricting the derivations that are executed in parallel by the various components through a regular control language. For the class of languages that are generated by RPCGSs with constant communication complexity we derive a characterisation in terms of a restricted type of freely rewriting restarting automaton. From this characterisation we obtain that these languages are semi-linear, and that for RPCGSs with constant communication complexity, the centralised variant has the same generative power as the non-centralised variant. 相似文献
35.
Hoyer D Friedrich H Frank B Pompe B Baranowski R Zebrowski JJ Schmidt H 《Computer methods and programs in biomedicine》2006,81(3):246-255
Heart rate variability (HRV) represents the cardiovascular control mediated by the autonomic nervous system and other mechanisms. In the established task force HRV monitoring different cardiovascular control mechanisms can approximately be identified at typical frequencies of heart rate oscillations by power spectral analysis. HRV measures assessing complex and fractal behavior partly improved clinical risk stratification. However, their relationship to (patho-)physiology is not sufficiently explored. Objective of the present work is the introduction of complexity measures of different physiologically relevant time scales. This is achieved by a new concept of the autonomic information flow (AIF) analysis which was designed according to task force HRV. First applications show that different time scales of AIF improve the risk stratification of patients with multiple organ dysfunction syndrome and cardiac arrest patients in comparison to standard HRV. Each group's significant time scales correspond to their respective pathomechanisms. 相似文献
36.
A combinatorial characterization is given for those one-rule Thue systems of the form {(w
1,w
2)} with 0 |w
2||ov(w
1)| that are Church-Rosser. Here ov(w
1) denotes the longest proper self-overlap ofw
1. Further, it is shown that a Thue system of this form is Church-Rosser if and only if there is an equivalent Thue system that is Church-Rosser.This research was supported in part by the National Science Foundation under Grant No. MCS83-14977. It was performed while the first author was visiting the Department of Mathematics of the University of California at Santa Barbara. 相似文献
37.
PD Dr. med. Friedrich Heubel 《Ethik in der Medizin》2012,24(2):125-135
Definition of the problem
Hospitals serve the general purpose to improve the health of patients. Health care professionals are a necessary means to achieve that end but have their own more specific professional ends. What is the due relationship between those kinds of ends with respect to the organisation of hospitals?Arguments
Individual health care in hospitals is delivered by professionals who are dependent upon the hospital??s human, administrative and technical facilities. As organised social entities, hospitals use professionals as the means to an end we normally call health of patients. More precisely, the professional task consists in a specific, namely, therapeutic interaction, an asymmetric relationship between morally equals. Professionals have to explore, interpret and pursue patients?? interests according to their consent. From a moral perspective, this interaction should be kept free from distortion through external incentives which divert the professional??s intrinsic motivation. Although a professional responsibility, the individual professional would be overcharged with this organisational task.Conclusion
The profession has a responsibility to protect and foster professional behaviour of its members including participation in organising hospitals and the individual professional should engage in organising the profession as a collective agent. 相似文献38.
The design of two custom sample holders with a spherical cavity for commercial vibrating sample magnetometer systems is described. For such cavities, the magnetization M[over ->] and the internal magnetic field H(i)[over ->] of a sample are both homogeneous. Consequently, the material parameter M(H(i)) of a sample can be determined even for liquids and powders with a high magnetic susceptibility. 相似文献
39.
PIXHAWK: A micro aerial vehicle design for autonomous flight using onboard computer vision 总被引:1,自引:0,他引:1
Lorenz Meier Petri Tanskanen Lionel Heng Gim Hee Lee Friedrich Fraundorfer Marc Pollefeys 《Autonomous Robots》2012,33(1-2):21-39
We describe a novel quadrotor Micro Air Vehicle (MAV) system that is designed to use computer vision algorithms within the flight control loop. The main contribution is a MAV system that is able to run both the vision-based flight control and stereo-vision-based obstacle detection parallelly on an embedded computer onboard the MAV. The system design features the integration of a powerful onboard computer and the synchronization of IMU-Vision measurements by hardware timestamping which allows tight integration of IMU measurements into the computer vision pipeline. We evaluate the accuracy of marker-based visual pose estimation for flight control and demonstrate marker-based autonomous flight including obstacle detection using stereo vision. We also show the benefits of our IMU-Vision synchronization for egomotion estimation in additional experiments where we use the synchronized measurements for pose estimation using the 2pt+gravity formulation of the PnP problem. 相似文献
40.
Workers in physically demanding occupations require work breaks to recover from exertion. In a laboratory setting, we investigated the impact of ergometer cycling for 7 h in two conditions with an identical total break time but with two different activity-rest schedules. We hypothesised that more frequent but shorter breaks lead to less psychophysical strain and its effects than do less frequent but longer breaks, particularly for older workers. Twenty-nine participants representing three different age groups were tested in both conditions. Heart rate, perceived exertion/tension and feelings of fatigue were assessed and used as dependent variables. Results indicate no general activity-rest differences as well as no age-related differences of break effects under the condition of subjectively equal straining load. However, heart rate was found to be lower at some measurement points in the frequent-short-break condition and perceived exertion was lower in the infrequent-long-break condition. PRACTITIONER SUMMARY: Design of activity-rest schedules in physically demanding occupations is a key issue in the prevention of strain and hence of interest to ergonomists. Our study suggests that breaks during physically demanding work have the same effect if they are frequent and short or infrequent and long, regardless of age. 相似文献