Branch-and-lift algorithm for deterministic global optimization in nonlinear optimal control

This paper presents a branch-and-lift algorithm for solving optimal control problems with smooth nonlinear dynamics and potentially nonconvex objective and constraint functionals to guaranteed global optimality. This algorithm features a direct sequential method and builds upon a generic, spatial branch-and-bound algorithm. A new operation, called lifting, is introduced, which refines the control parameterization via a Gram-Schmidt orthogonalization process, while simultaneously eliminating control subregions that are either infeasible or that provably cannot contain any global optima. Conditions are given under which the image of the control parameterization error in the state space contracts exponentially as the parameterization order is increased, thereby making the lifting operation efficient. A computational technique based on ellipsoidal calculus is also developed that satisfies these conditions. The practical applicability of branch-and-lift is illustrated in a numerical example. © 2013 Springer Science+Business Media New York

An integrated mid-range theory of postpartum family development: a guide for research and practice.

AIM: This paper is a report of a study to identify parents' perceptions of postpartum family experiences. BACKGROUND: There is a growing worldwide emphasis on family support. Government policy in the United Kingdom advocates a family-centred approach in which a core universal postbirth service is offered to all families with additional support for parents of children with complex needs. Health visitors provide family postpartum care without an agreed theory directing or standardizing practice. There is a need to identify parental experiences to define family-centred care. METHOD: A qualitative, exploratory approach was undertaken using a purposive sample of 17 postpartum families. Data were collected in one region of Northern Ireland in 2001-2002. Participants' experiences and views were accessed during two focus groups with a total of seven participants, and six in-depth interviews. Thematic analysis was conducted. FINDINGS: One core theme, 'thriving and surviving', and three main themes, 'baby nurture', 'life changes', 'coping and adapting resources', were identified to describe how parents developed during the first 8-week postpartum. These were influenced by the physical, the psychosocial and the environmental factors. The identified themes were mapped together to form an Integrated Mid-Range Theory of Postpartum Parent Development. CONCLUSION: As parents need to negotiate successfully both present coping and future development during the postpartum period, there is a need for professionals to offer services that are orientated to holistic short- and long-term well-being. The findings, further to additional research, may be used by health visitors and other professionals to direct universal postpartum care

Long-Term Morphological and Microarchitectural Stability of Tissue-Engineered, Patient-Specific Auricles In Vivo

Current techniques for autologous auricular reconstruction produce substandard ear morphologies with high levels of donor-site morbidity, whereas alloplastic implants demonstrate poor biocompatibility. Tissue engineering, in combination with noninvasive digital photogrammetry and computer-assisted design/computer-aided manufacturing technology, offers an alternative method of auricular reconstruction. Using this method, patient-specific ears composed of collagen scaffolds and auricular chondrocytes have generated auricular cartilage with great fidelity following 3 months of subcutaneous implantation, however, this short time frame may not portend long-term tissue stability. We hypothesized that constructs developed using this technique would undergo continued auricular cartilage maturation without degradation during long-term (6 month) implantation. Full-sized, juvenile human ear constructs were injection molded from high-density collagen hydrogels encapsulating juvenile bovine auricular chondrocytes and implanted subcutaneously on the backs of nude rats for 6 months. Upon explantation, constructs retained overall patient morphology and displayed no evidence of tissue necrosis. Limited contraction occurred in vivo, however, no significant change in size was observed beyond 1 month. Constructs at 6 months showed distinct auricular cartilage microstructure, featuring a self-assembled perichondrial layer, a proteoglycan-rich bulk, and rounded cellular lacunae. Verhoeff's staining also revealed a developing elastin network comparable to native tissue. Biochemical measurements for DNA, glycosaminoglycan, and hydroxyproline content and mechanical properties of aggregate modulus and hydraulic permeability showed engineered tissue to be similar to native cartilage at 6 months. Patient-specific auricular constructs demonstrated long-term stability and increased cartilage tissue development during extended implantation, and offer a potential tissue-engineered solution for the future of auricular reconstructions