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A discrete time optimal control for linear time-delay systems is developed to ensure that all closed-loop eigenvalues will lie inside a circular region centred at (β;, 0) with radius α. It is shown that by suitable manipulations the problem can be reduced to a standard discrete time quadratic regulator problem. An illustrative example is included to demonstrate the applicability of the proposed method. 相似文献
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Anterior Cruciate Ligament Reconstruction:
State of the Art 总被引:2,自引:0,他引:2
Abstract The rupture of the Anterior cruciate ligament (ACL)
belongs to the most common ligament injuries of the
human knee joint. ACL rupture results in an increased
anterior translation and internal rotation of the tibia.
Untreated knee instability causes a disintegration of
the roll and sliding movement and a high incidence of
secondary meniscus and chondral damages with consecutive
or advanced arthritic changes.
For deciding on a conservative or operative therapy, it is
necessary to develop a high-risk profile. Elderly, inactive
patients without instability symptoms can be treated
conservatively; younger, active people and complex
ligament injuries should receive an ACL replacement.
The goal is to eliminate instability by maintaining the
physiological kinematics of the knee.
Anterior cruciate ligament may be reconstructed
arthroscopically assisted by autologous tendons. Predominantly,
hamstring- and bone-patellar-tendon
grafts are used. No significant differences in knee laxity,
clinically and functionally, were observed between
both grafts. Various reconstruction techniques, single-
or double-bundle techniques, were described. Successful
replacement depends on a correct tunnel placement
and reconstruction of the physiological band
tension, a sufficient mechanical stability of fixation, an
impingement-free range of motion and an adequate
rehabilitation.
A high degree of patient satisfaction in clinical and
functional outcome could be evaluated. 相似文献
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Predictors, costs and characteristics of out of area placement for people with intellectual disability and challenging behaviour 总被引:1,自引:0,他引:1
D. G. Allen K. Lowe K. Moore & S. Brophy 《Journal of intellectual disability research : JIDR》2007,51(6):409-416
Background Out of area placements for people with challenging behaviour represent an expensive and often ineffective strategy for meeting the needs of this service user group. Methods More than 800 agencies and service settings in a large area of South Wales were screened to identify children and adults with challenging behaviour against a number of defined operational criteria. Detailed data on identified individuals and the services they received were collected by interviewing key informants. Univariate and multivariate statistics were employed to identify predictors of out of area placement. Results In total, 1458 people were identified. Full data were available for 901 participants, 97 of whom were placed out of area. Predictors of out of area placement included behaviours resulting in physical injury and exclusion from service settings, a history of formal detention under the mental health act, the presence of mental health problems, a diagnosis of autism and higher total score on the Adaptive Behaviour Scale. Out of area placements were typically of high cost, and associated with only limited evidence of improved service quality. Conclusions Identifying predictors for out of area placement can be used to highlight deficiencies in local services and individuals at increased risk of exclusion from local services. 相似文献
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Benoit J. M. Pirotte Alphonse Lubansu Michael Bruneau Chakir Loqa Nathalie Van Cutsem Jacques Brotchi 《Child's nervous system》2007,23(11):1251-1261
Objective The objective of this study was to evaluate whether the rigid application of a sterile protocol for shunt placement was applicable
on a routine basis and allowed the reduction of shunt infections (SI) in children.
Materials and methods Since 2001, a rigid sterile protocol for shunt placement in children using neither antibiotic-impregnated catheters nor laminar
airflow was prospectively applied at Erasme Hospital, Brussels, Belgium. For assessing the protocol efficacy before continuation,
we preliminarily analyzed the results of the first 100 operated children (43 females, 57 males, 49 aged <12 months; 115 consecutive
shunt placement/revision procedures). All procedures were performed by the same senior surgeon, one assistant, one circulating
nurse, one anesthesiologist. The sterile protocol was rigidly imposed to these four staff members: uniformed surgical technique;
limited implant and skin edge manipulation; minimized human circulation in the room; scheduling surgery as first morning operation;
avoiding postoperative cerebrospinal fluid (CSF) leak; double gloving; procedures of less than 30-min duration; systemic antibiotics
prophylaxis. We analyzed separately: (1) children carrying an increased risk of SI (n = 38) due to preoperative external ventricular drainage, CSF leak, meningitis, glucocorticoids, chemotherapy; (2) children
aged <12 months; (3) procedures for shunt revision.
Results Errors in protocol application were recorded in 71/115 procedures. They were mainly done by non-surgical staff, decreased
with time and were medically justified in some young children. Surprisingly, no SI occurred (follow-up, 4 to 70 months). One
child developed an appendicitis with peritonitis (Streptococcus faecalis) after 6 months. No SI was found. After peritonitis was cured, shunt reinsertion was uneventful.
Conclusion These preliminary results suggest that a uniform and drastic sterile surgical technique for shunt placement: (1) can be rigidly
applied on a routine basis; (2) can lower the early SI rate below 1%; (3) might have a stronger impact to reduce SI than using
antibiotic-impregnated catheters and optimizing the operative environment such as using laminar airflow and reducing the non-surgical
staff. This last issue will be evaluated further in the present ongoing protocol. 相似文献
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目的探讨采用带蒂大网膜在胆管引流管周围做成人工窦道的方法及效果。方法建立实验兔胆管引流动物模型。100只新西兰大白兔随机分为2组,即实验组及对照组。每组再随机分成5个亚组,每亚组10只,在手术后3、6、9、12、15d分别剖腹了解5亚组中一亚组胆管引流管窦道形成情况,并取部分窦道壁送病理检查。结果实验组在不同时间点,窦道完全形成动物数分别为:3d8只,6d10只,9d10只,12d10只,15d10只;对照组分别为:3d1只,6d1只,9d2只,12d3只,15d4只。两组比较差异有统计学意义(P<0.01)。结论采用带蒂大网膜在胆管引流管周围形成人工窦道的方法简单、实用,不仅可缩短留置T管的时间,而且可有效防止拔T管后胆漏的发生,值得临床推广使用。 相似文献
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Riyanto T. Bambang Etsujiro Shimemura Kenko Uchida 《Optimal control applications & methods.》1994,15(3):151-173
The problem of mixed H2/H∞ control with pole placement is considered for linear time-invariant systems. This is the problem of determining a controller for linear time-invariant systems which minimizes the H2-norm of a certain closed-loop transfor function subject to an H∞-norm constraint on another closed-loop transfer function and an additional constraint on the location of the closed-loop poles in the complex plane. An optimization problem is posed for the pole-constrained H2/H∞, problem in such a way that the objective function is expressed as a weighted sum of the actual H2 cost and its upper bound. A necessary condition for the optimization problem is derived via the Lagrange multiplier technique. The condition involves a set of highly coupled equations. By sacrificing the H2 performance, an alternative optimization problem is posed in order to simplify the necessary condition. An iterative algorithm for solving the coupled equations arising in the necessary conditions is proposed and numerical examples are presented. 相似文献
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