The inert polymer polyethylene glycol (PEG) induces a "bundling" phenomenon in F actin solutions when its concentration exceeds a critical onset value C(o). Over a limited range of PEG molecular weight and ionic strength, C(o) can be expressed as a function of these two variables. The process is reversible, but hysteresis is also observed in the dissolution of the bundles, with ionic strength having a large influence. Additional actin filaments are able to join the previously formed bundles. PEG polymers are not incorporated into the actin bundles. Estimates of the Asakura-Oosawa depletion force, Coulomb repulsion, and van der Waals potential are combined in order to explain the bundling effect and hysteresis. Conjectures are presented concerning the apparent limit in bundle size.

The Delayed Resonator (DR) and Dual Frequency Fixed Delayed Resonator (DFFDR) are newly introduced control techniques for active vibration absorption. Both methods propose a delayed position feedback within the absorber section of the structure to impart ideal resonance features to the absorber. When installed on an oscillating primary body, they form “notch filters” at their resonance frequencies attenuating the response of the primary structure. The DR absorber is shown to be real-time tunable to time varying disturbance frequencies. In this article, a number of new issues are considered. First, the basic theory is modified for acceleration feedback instead of position, which was originally proposed for the DR methodology. Second, the new absorption methods are implemented on distributed parameter structures which are under high frequency excitation (around 1 KHz). Stability of the combined structure is studied on a reduced order multi-degree-of-freedom primary structure together with the DR absorber. Experimental tests are conducted on a steel beam to verify the analytical findings. Piezoelectric actuators are used both to generate harmonic disturbances and to implement the control. The correspondence observed between the theoretical and experimental results is encouraging. The efficiency of the DR and DFFDR absorption techniques is demonstrated.

The main objectives of this qualitative study were to describe the perceptions and needs of pediatric health care professionals (HCPs) taking care of children with palliative care needs and to develop a concept for the first Center of Competence for Pediatric Palliative Care (PPC) in Switzerland. Within two parts of the study, 76 HCPs were interviewed. The main interview topics were: (1) definition of and attitude toward PPC; (2) current provision of PPC; (3) the support needs of HCPs in the provision of PPC; and (4) the role of specialized PPC teams. HCPs expressed openness to PPC and reported distinctive needs for support in the care of these patients. The main tasks of specialized PPC teams in Switzerland would encompass the coaching of attending teams, coordination of care, symptom control, and direct support of affected families during and beyond the illness of their child. Conclusion: This study indicates the need for specialized PPC in Switzerland both inside and outside of centers providing top quality medical care (Spitzenmedizin). Specialized PPC teams could have a significant impact on the care of children and families with PPC needs. Whether hospices are an option in Switzerland remains unanswered; however, a place to meet other families with similar destinies was emphasized. Conclusion This study indicates the need for specialized PPC in Switzerland both inside and outside of centers providing top quality medical care (Spitzenmedizin). Specialized PPC teams could have a significant impact on the care of children and families with PPC needs. Whether hospices are an option in Switzerland remains unanswered; however, a place to meet other families with similar destinies was emphasized.

A novel active vibration absorption technique, the Delayed Resonator, has been introduced recently as a unique way of suppressing undesired oscillations. It suggests a control force on a mass-spring-damper absorber in the form of a proportional position feedback with a time delay. Its strengths consist of extremely simple implementation of the control algorithm, total vibration suppression of the primary structure against a harmonic force excitation and full effectiveness of the absorber in a semi-infinite range of disturbance frequency, achieved by real-time tuning. All this development work was done using the absolute displacements of the absorber in the feedback. These measurements, however, may be difficult to obtain and for some applications impossible. This paper deals with the operating and design repercussions caused by the substituting of an easier measurement: the relative motion of the absorber with respect to the primary structure. Although the proposition sounds like a trivial extension to the prior work it gives rise to important concerns such as system stability. Theoretical foundations for the Delayed Resonator (DR) are briefly recapitulated and its implementation on a single-degree-of-freedom primary structure disturbed by a harmonic force is discussed utilizing both absolute and relative position measurement of absorber mass. Methods for stability range analysis and transient behavior are presented as design tools. Properties observed for the same system with these two different feedbacks are compared. Another important advantage of the relative position feature is is to decouple the operation of the absorber from the primary structure entirely.

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