Thermodynamic cost of external control

Artificial molecular machines are often driven by the periodic variation of an external parameter. This external control exerts work on the system of which a part can be extracted as output if the system runs against an applied load. Usually, the thermodynamic cost of the process that generates the external control is ignored. Here, we derive a refined second law for such small machines that include this cost, which is, for example, generated by free energy consumption of a chemical reaction that modifies the energy landscape for such a machine. In the limit of irreversible control, this refined second law becomes the standard one. Beyond this ideal limiting case, our analysis shows that due to a new entropic term unexpected regimes can occur: The control work can be smaller than the extracted work and the work required to generate the control can be smaller than this control work. Our general inequalities are illustrated by a paradigmatic three-state system.Comment: 11 pages, 3 figure

Coherence of Biochemical Oscillations is Bounded by Driving Force and Network Topology

Biochemical oscillations are prevalent in living organisms. Systems with a small number of constituents cannot sustain coherent oscillations for an indefinite time because of fluctuations in the period of oscillation. We show that the number of coherent oscillations that quantifies the precision of the oscillator is universally bounded by the thermodynamic force that drives the system out of equilibrium and by the topology of the underlying biochemical network of states. Our results are valid for arbitrary Markov processes, which are commonly used to model biochemical reactions. We apply our results to a model for a single KaiC protein and to an activator-inhibitor model that consists of several molecules. From a mathematical perspective, based on strong numerical evidence, we conjecture a universal constraint relating the imaginary and real parts of the first non-trivial eigenvalue of a stochastic matrix.Comment: 12 pages, 13 figure

Skewness and Kurtosis in Statistical Kinetics

We obtain lower and upper bounds on the skewness and kurtosis associated with the cycle completion time of unicyclic enzymatic reaction schemes. Analogous to a well known lower bound on the randomness parameter, the lower bounds on skewness and kurtosis are related to the number of intermediate states in the underlying chemical reaction network. Our results demonstrate that evaluating these higher order moments with single molecule data can lead to information about the enzymatic scheme that is not contained in the randomness parameter.Comment: 5+3 pages, 4 figure

The Social Wellbeing of New York City's Neighborhoods: The Contribution of Culture and the Arts

This report presents the conceptual framework, data and methodology, and findings of a two-year study of culture and social wellbeing in New York City by SIAP with Reinvestment Fund. Building on their work in Philadelphia, the team gathered data from City agencies, borough arts councils, and cultural practitioners to develop a 10-dimension social wellbeing framework—which included construction of a cultural asset index—for every neighborhood in the five boroughs. The research was undertaken between 2014 and 2016.The social wellbeing tool enables a variety of analyses: the distribution of opportunity across the city;identification of areas with concentrated advantage, concentrated disadvantage, aswell as "diverse and struggling" neighborhoods with both strengths and challenges; and analysis of the relationship of"neighborhood cultural ecology" to other features of a healthy community

Culture and Urban Revitalization: A Harvest Document

Advocates have long argued that the economic benefits of the arts and culture provide a firm rationale for public support. Recent scholarship on the "creative class" and "creative economy" is simply the latest effort to link cultural expression to community prosperity. In contrast, the social benefits of cultural engagement have received relatively little attention, even though -- as we shall see -- they provide a stronger case.We need to avoid a simplistic either-or choice between the economic and social impacts of the arts. People who live in our cities, suburbs, and countryside are simultaneously consumers, workers, residents, citizens, and participants. Culture's role in promoting community capacity and civic engagement is central to its potential for generating vital cultural districts. To separate the economic and the social impacts of the arts makes each more difficult to understand.This document provides an overview of the state-of-the-art literature on culture and urban revitalization. In Part 2, we place the creative sector in contemporary context with a discussion of three social dynamics. The "new urban reality" has restructured our cities by increasing social diversity -- fueled by new residential patterns, the emergence of young adult districts, and immigration; expanding economic inequality; and changing urban form. Shifts in the economic and political environment have changed the structure of the creative sector. Finally, the changing balance of government, nonprofit, and for-profit institutions in social policy development -- the shift to transactional policymaking -- has profound implications for cultural policy and the creative sector broadly defined. These three forces -- the new urban reality, the changing structure of the creative sector, and the emergence of transactional policy-making -- define the context within which culture-based revitalization takes place