Discrete mechanics and optimal control for constrained systems

The equations of motion of a controlled mechanical system subject to holonomic constraints may be formulated in terms of the states and controls by applying a constrained version of the Lagrange-d’Alembert principle. This paper derives a structure-preserving scheme for the optimal control of such systems using, as one of the key ingredients, a discrete analogue of that principle. This property is inherited when the system is reduced to its minimal dimension by the discrete null space method. Together with initial and final conditions on the configuration and conjugate momentum, the reduced discrete equations serve as nonlinear equality constraints for the minimization of a given objective functional. The algorithm yields a sequence of discrete configurations together with a sequence of actuating forces, optimally guiding the system from the initial to the desired final state. In particular, for the optimal control of multibody systems, a force formulation consistent with the joint constraints is introduced. This enables one to prove the consistency of the evolution of momentum maps. Using a two-link pendulum, the method is compared with existing methods. Further, it is applied to a satellite reorientation maneuver and a biomotion problem

Kinematic Flexibility Analysis: Hydrogen Bonding Patterns Impart a Spatial Hierarchy of Protein Motion

Elastic network models (ENM) and constraint-based, topological rigidity analysis are two distinct, coarse-grained approaches to study conformational flexibility of macromolecules. In the two decades since their introduction, both have contributed significantly to insights into protein molecular mechanisms and function. However, despite a shared purpose of these approaches, the topological nature of rigidity analysis, and thereby the absence of motion modes, has impeded a direct comparison. Here, we present an alternative, kinematic approach to rigidity analysis, which circumvents these drawbacks. We introduce a novel protein hydrogen bond network spectral decomposition, which provides an orthonormal basis for collective motions modulated by non-covalent interactions, analogous to the eigenspectrum of normal modes, and decomposes proteins into rigid clusters identical to those from topological rigidity. Our kinematic flexibility analysis bridges topological rigidity theory and ENM, and enables a detailed analysis of motion modes obtained from both approaches. Our analysis reveals that collectivity of protein motions, reported by the Shannon entropy, is significantly lower for rigidity theory versus normal mode approaches. Strikingly, kinematic flexibility analysis suggests that the hydrogen bonding network encodes a protein-fold specific, spatial hierarchy of motions, which goes nearly undetected in ENM. This hierarchy reveals distinct motion regimes that rationalize protein stiffness changes observed from experiment and molecular dynamics simulations. A formal expression for changes in free energy derived from the spectral decomposition indicates that motions across nearly 40% of modes obey enthalpy-entropy compensation. Taken together, our analysis suggests that hydrogen bond networks have evolved to modulate protein structure and dynamics

Review of \u3ci\u3e Trials and Triumphs: A Colorado Portrait of the Great Depression with FSA Photographs\u3c/i\u3e by Stephen J. Leonard

Stephen J. Leonard has written a book about Colorado during the depression. He portrays an economically and politically conservative state whose failed attempts at local relief forced its officers to seek solutions offered by Franklin Roosevelt\u27s New Deal. Both Colorado officials and residents resented federal assistance believing that it threatened their state\u27s independence. Leonard sets the scene by summarizing the final years of the 1920s in Colorado before describing how the crash affected the state and its dwellers. After commenting on its devastation in urban areas, he turns to rural sections particularly the agricultural Plains, the San Luis Valley and the Western Slope

"Mobility patterns and urban structure" [Book Review]

Authors: Paulo Pinho & Cecília Silva (Ashgate Publishing

Call to action: towards a practice of inclusive road safety

Road safety in the UK is of a checkered history. Originating from an age of free motoring and wide-open roads of adventure, its practices and processes have often been preventative to walking and cycling. UK road safety resorts to uttering warning words rather than a combination approach of engineering, education and enforcement, and so regularly blames and restricts the active travel modes. This is to active travel's exclusion and reduction in participation when walking and cycling should be promoted and prioritised in environmentally, socially and economically ailing UK cities. A new approach to road safety will be discussed in this article, using principles of engineering risk assessment and sustainability. Countries like the Netherlands have road safety systems that are more holistic, take into account road design as well as promotion campaigns. By example of three case studies this article seeks to describe current practices of UK road safety, then continues to outline how a system of “Sustainable Safety” can be applied in the UK. A revised road-safety approach would include engineers and planners becoming more interactive on the political plane and employing wider assessment boundaries to road-safety analyses

Review of \u3ci\u3e Trials and Triumphs: A Colorado Portrait of the Great Depression with FSA Photographs\u3c/i\u3e by Stephen J. Leonard

Stephen J. Leonard has written a book about Colorado during the depression. He portrays an economically and politically conservative state whose failed attempts at local relief forced its officers to seek solutions offered by Franklin Roosevelt\u27s New Deal. Both Colorado officials and residents resented federal assistance believing that it threatened their state\u27s independence. Leonard sets the scene by summarizing the final years of the 1920s in Colorado before describing how the crash affected the state and its dwellers. After commenting on its devastation in urban areas, he turns to rural sections particularly the agricultural Plains, the San Luis Valley and the Western Slope

Spiritual Quality of Life Among Geriatric Cancer Patients: A Descriptive Correlational Study

A solid understanding of spiritual quality of life (SQOL) is critical for healthcare providers as they strive to achieve optimum care of geriatric cancer patient. However, there is a gap in the current literature regarding SQOL in geriatric cancer patients. Therefore, the purpose of this descriptive correlational study was to describe the spiritual quality of life (SQOL) among geriatric cancer patients as it relates to their demographic characteristics and self described wellness. A convenience sample of 32 participants from a cancer center in Midwest Ohio were recruited for this study. The participants completed the World Health Organization Quality of Life-Spiritual, Religious, Personal Beliefs (WHO QOL-SRPB) survey. The WHO QOL-SRPB survey is a paper-and-pencil 5-Likert scale survey used to measure SQOL in nine facets. Nine facet scores and the overall SQOL score were calculated. The results of this survey indicated that there is a positive statistically significant correlation between spiritual quality of life and the participant’s self-described health status and religious beliefs. The highest facet score was found in facet nine (spiritual religious personal beliefs) with an average score of 3.84; whereas and the lowest scoring facet was facet 6 (inner peace) with an average score of 3.64. The overall SQOL score (domain 6) was 15, with a possible range of scores between 4 and 20. Recommendations for future studies include utilizing a larger sample size, a qualitative study to gain insight into geriatric cancer patients’ experiences regarding SQOL, and investigating SQOL interventions and outcomes

Women activists’ experience of local cycling politics

The aim of this research thesis is to explore the experiences of women activists who advocated for cycleways in Newcastle, UK, and in Bremen, Germany, in the 2010s. Using an autoethnographic approach I bring my own campaigning experience to bear, combining my personal account with interviews and policy analysis to navigate and form a critique of the socio-technical landscape of transport politics. Cycling is generally seen as a good thing for health, liveability and the environment, but cycling numbers have been largely stagnant over recent decades in the UK and in Germany. Cycling also suffers from an image problem, especially in low-cycling contexts such as the UK. For cycling to have a larger share as a mode of transport, cycleways, dedicated spaces for cycling, are needed. This is what the women activists demanded from their local decision makers. The findings from this study suggest that women activists experienced systemic exclusion as the politicians ceded control to the technical experts and the vehicular-cycling campaigners’ liberal demands supported institutional practices of designing for the car. In Newcastle, post-political circumstances were present in transport planning. It is this institutional automobility that is holding back the development of cycle- and people-friendly urban environments. Its technocracy can harm local democracy. I argue that social automobility (people’s car use and dependency) is largely a consequence of institutional automobility. A cultural transformation is needed, expressly at the technical-political level to overcome institutionalisation in Bremen, and, in addition in Newcastle, post-political detachment. Cycle campaigning should continue to express radical demands in support of spatial redistribution and dedicated cycleways. To understand how institutional automobility works and manifests itself is important if we want to democratise and humanise urban spaces. It is proposed that politicians who are more aware of the phenomenon would more readily work with cycleway campaigners to reform technical processes for the common good. Future research could involve the sociology of transport engineers and political party orientations in relation to institutional automobility