Top down and bottom up engineering of bone

The goal of this retrospective article is to place the body of my lab's multiscale mechanobiology work in context of top-down and bottom-up engineering of bone. We have used biosystems engineering, computational modeling and novel experimental approaches to understand bone physiology, in health and disease, and across time (in utero, postnatal growth, maturity, aging and death, as well as evolution) and length scales (a single bone like a femur, m; a sample of bone tissue, mm-cm; a cell and its local environment, μm; down to the length scale of the cell's own skeleton, the cytoskeleton, nm). First we introduce the concept of flow in bone and the three calibers of porosity through which fluid flows. Then we describe, in the context of organ-tissue, tissue-cell and cell-molecule length scales, both multiscale computational models and experimental methods to predict flow in bone and to understand the flow of fluid as a means to deliver chemical and mechanical cues in bone. Addressing a number of studies in the context of multiple length and time scales, the importance of appropriate boundary conditions, site specific material parameters, permeability measures and even micro-nanoanatomically correct geometries are discussed in context of model predictions and their value for understanding multiscale mechanobiology of bone. Insights from these multiscale computational modeling and experimental methods are providing us with a means to predict, engineer and manufacture bone tissue in the laboratory and in the human body.     

Opening up the politics of knowledge and power in bioscience

Public engagement is not in tension with science, but actually a way to be more rigorous - as well as more democratic - about social choice of biotechnology.     

Islam, politics, anthropology

In this paper, we consider anthropology's long and, at times, problematic engagement with the study of Islam and Muslim societies. Specifically, we reflect critically on ongoing anthropological debates about the relationship between Islam and politics and suggest new terms of analysis. Although we pay attention to the state and formal politics, involving various social actors and organizations, we are also interested in everyday politics and micropolitics, arenas where anthropology proves especially adept. It is at the intersection of these multiple levels and where the field of politics is constituted in practice that we situate the analytical focus of the anthropology of Islam and politics in this Special Issue of the Journal of the Royal Anthropological Institute .  

Résumé

Les auteurs s'intéressent ici à la longue, et parfois problématique histoire, de l'étude de l'islam et des sociétés musulmanes par l'anthropologie. L'accent est mis plus précisément sur une réflexion critique relative aux débats anthropologiques actuels sur les liens entre islam et politique, et sur l'exploration de nouveaux termes d'analyse. Tout en prêtant de l'attention à l'État et aux institutions politiques, impliquant différents acteurs sociaux et organisations, nous nous intéressons également à la politique au quotidien et à la micropolitique, domaines dans lesquels l'anthropologie s'avère particulièrement compétente. C'est à l'intersection de ces multiples niveaux, et là où le champ du politique est constitué dans la pratique, que nous situons le point focal de l'analyse anthropologique de l'islam et du politique dans ce numéro spécial du Journal of the Royal Anthropological Institute .     

Inequality from the top down and bottom up: towards a revised Wacquant

In this response I focus on two major themes in Wacquant's trilogy: (1) punishment and the state; and (2) territorial stigmatization. I discuss evidence that supports elements of Wacquant's argument, while at the same time demonstrating the need for an account that brings mediating institutional processes of the state, violence, the civil sphere and neighbourhood mechanisms more fully into the larger theoretical picture. I conclude that ‘bottom-up’ processes of inequality must be integrated with ‘top-down’ forces of the state to advance our theoretical understanding of penality and spatial marginality in federated and unitary governments alike.     

A computational study of liposome logic: towards cellular computing from the bottom up

In this paper we propose a new bottom-up approach to cellular computing, in which computational chemical processes are encapsulated within liposomes. This “liposome logic” approach (also called vesicle computing) makes use of supra-molecular chemistry constructs, e.g. protocells, chells, etc. as minimal cellular platforms to which logical functionality can be added. Modeling and simulations feature prominently in “top-down” synthetic biology, particularly in the specification, design and implementation of logic circuits through bacterial genome reengineering. The second contribution in this paper is the demonstration of a novel set of tools for the specification, modelling and analysis of “bottom-up” liposome logic. In particular, simulation and modelling techniques are used to analyse some example liposome logic designs, ranging from relatively simple NOT gates and NAND gates to SR-Latches, D Flip-Flops all the way to 3 bit ripple counters. The approach we propose consists of specifying, by means of P systems, gene regulatory network-like systems operating inside proto-membranes. This P systems specification can be automatically translated and executed through a multiscaled pipeline composed of dissipative particle dynamics (DPD) simulator and Gillespie’s stochastic simulation algorithm (SSA). Finally, model selection and analysis can be performed through a model checking phase. This is the first paper we are aware of that brings to bear formal specifications, DPD, SSA and model checking to the problem of modeling target computational functionality in protocells. Potential chemical routes for the laboratory implementation of these simulations are also discussed thus for the first time suggesting a potentially realistic physiochemical implementation for membrane computing from the bottom-up.     

Trait-based approaches to conservation physiology: forecasting environmental change risks from the bottom up

Trait-based approaches have long been a feature of physiology and of ecology. While the latter fields drifted apart in the twentieth century, they are converging owing at least partly to growing similarities in their trait-based approaches, which have much to offer conservation biology. The convergence of spatially explicit approaches to understanding trait variation and its ecological implications, such as encapsulated in community assembly and macrophysiology, provides a significant illustration of the similarity of these areas. Both adopt trait-based informatics approaches which are not only providing fundamental biological insights, but are also delivering new information on how environmental change is affecting diversity and how such change may perhaps be mitigated. Such trait-based conservation physiology is illustrated here for each of the major environmental change drivers, specifically: the consequences of overexploitation for body size and physiological variation; the impacts of vegetation change on thermal safety margins; the consequences of changing net primary productivity and human use thereof for physiological variation and ecosystem functioning; the impacts of rising temperatures on water loss in ectotherms; how hemisphere-related variation in traits may affect responses to changing rainfall regimes and pollution; and how trait-based approaches may enable interactions between climate change and biological invasions to be elucidated.     

Science,opinions and politics

Valerie Marett, IMMIGRANTS SETTLING IN THE CITY, Leicester University Press, 1989, 207 pp., £30.00.

Ruth Glass, CLICHES OF URBAN DOOM, Oxford: Basil Blackwell, 1988, 266 pp., £25.00.

Stanley Lieberson and Mary C. Waters, FROM MANY STRANDS: ETHNIC AND RACIAL GROUPS IN CONTEMPORARY AMERICA, New York: Russell Sage Foundation, 1988, 304 pp., $29.95.

Susan J. Smith, THE POLITICS OF ‘RACE’ AND RESIDENCE: CITIZENSHIP, SEGREGATION AND WHITE SUPREMACY IN BRITAIN, Cambridge: Polity Press, 1989, 228 pp., £29.95 and £9.95 (paper).