scholarly journals Structural conditions on complex networks for the Michaelis–Menten input–output response

2018 ◽  
Vol 115 (39) ◽  
pp. 9738-9743 ◽  
Author(s):  
Felix Wong ◽  
Annwesha Dutta ◽  
Debashish Chowdhury ◽  
Jeremy Gunawardena
Keyword(s):  
Single Molecule ◽  
Thermodynamic Equilibrium ◽  
Enzyme Catalysis ◽  
Regular Structure ◽  
Coarse Graining ◽  
Necessary And Sufficient Condition ◽  
Input Output ◽  
Linear Framework ◽  
Necessary And Sufficient ◽  
Fundamental Formula

The Michaelis–Menten (MM) fundamental formula describes how the rate of enzyme catalysis depends on substrate concentration. The familiar hyperbolic relationship was derived by timescale separation for a network of three reactions. The same formula has subsequently been found to describe steady-state input–output responses in many biological contexts, including single-molecule enzyme kinetics, gene regulation, transcription, translation, and force generation. Previous attempts to explain its ubiquity have been limited to networks with regular structure or simplifying parametric assumptions. Here, we exploit the graph-based linear framework for timescale separation to derive general structural conditions under which the MM formula arises. The conditions require a partition of the graph into two parts, akin to a “coarse graining” into the original MM graph, and constraints on where and how the input variable occurs. Other features of the graph, including the numerical values of parameters, can remain arbitrary, thereby explaining the formula’s ubiquity. For systems at thermodynamic equilibrium, we derive a necessary and sufficient condition. For systems away from thermodynamic equilibrium, especially those with irreversible reactions, distinct structural conditions arise and a general characterization remains open. Nevertheless, our results accommodate, in much greater generality, all examples known to us in the literature.

On the Relationship between the Supply-Driven and the Demand-Driven Input — Output Model

1989 ◽  
Vol 21 (11) ◽  
pp. 1533-1539 ◽  
Author(s):  
E Dietzenbacher
Keyword(s):  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Input Output ◽  
Demand Pull ◽  
The Stability ◽  
Necessary And Sufficient ◽  
Fixed Input ◽  
The Relationship

In this paper, the relationship between the assumptions in the supply-driven and the demand-driven input-output model is discussed. A necessary and sufficient condition is given for the stability of the input coefficients, the output coefficients, and both coefficients. For both models, the effects of a demand pull on the total outputs and on the primary inputs are analytically expressed. Also, the effects of a supply push on the total outputs and on the final outputs are expressed, again for both models. In general, the assumption of fixed input coefficients in the demand-driven model does not hold, but computations are still based on it. A necessary and sufficient condition is given for the correctness of the computed total outputs, both for a demand pull and a supply push. Similar results are obtained for the supply-driven input — output model.

Steps on (001) Si Surfaces

1987 ◽  
Vol 91 ◽  
Author(s):  
D. E. Aspnes ◽  
J. Ihm
Keyword(s):  
Thermodynamic Equilibrium ◽  
Configurational Entropy ◽  
Antiphase Domain ◽  
Sufficient Condition ◽  
Domain Formation ◽  
Necessary And Sufficient Condition ◽  
Relative Enthalpy ◽  
Polar Materials ◽  
Necessary And Sufficient

ABSTRACTPrimitive (001) surfaces contain only biatomic (ao/2) steps and thereby provide a topological way of suppressing antiphase domain formation in polar materials heteroepitaxially grown on nonpolar (001) substrates. We show that thermodynamic equilibrium is a necessary and sufficient condition to form primitive (001) Si surfaces due to a π-bonded step reconstruction that lowers the relative enthalpy of reconstructed [110] biatomic steps by 0.04 eV per step atom, and to correlation, which freezes out the step configurational entropy thereby suppressing the formation of all other types of steps. Implications for general vicinal (001) Si surfaces are discussed.

A Proposed Framework Emphasizing Auditor Reliability over Auditor Independence

2003 ◽  
Vol 17 (3) ◽  
pp. 257-266 ◽  
Author(s):  
Mark H. Taylor ◽  
F. Todd DeZoort ◽  
Edward Munn ◽  
Martha Wetterhall Thomas
Keyword(s):  
Public Interest ◽  
Auditor Independence ◽  
Public Confidence ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Accounting Profession ◽  
The Public ◽  
Necessary And Sufficient

This paper introduces an auditor reliability framework that repositions the role of auditor independence in the accounting profession. The framework is motivated in part by widespread confusion about independence and the auditing profession's continuing problems with managing independence and inspiring public confidence. We use philosophical, theoretical, and professional arguments to argue that the public interest will be best served by reprioritizing professional and ethical objectives to establish reliability in fact and appearance as the cornerstone of the profession, rather than relationship-based independence in fact and appearance. This revised framework requires three foundation elements to control subjectivity in auditors' judgments and decisions: independence, integrity, and expertise. Each element is a necessary but not sufficient condition for maximizing objectivity. Objectivity, in turn, is a necessary and sufficient condition for achieving and maintaining reliability in fact and appearance.

The Power of Public Positions

2018 ◽  
Author(s):  
Thomas Sinclair
Keyword(s):  
Detailed Analysis ◽  
Political Authority ◽  
The State ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
State Institutions ◽  
State Of Nature ◽  
Necessary And Sufficient

The Kantian account of political authority holds that the state is a necessary and sufficient condition of our freedom. We cannot be free outside the state, Kantians argue, because any attempt to have the “acquired rights” necessary for our freedom implicates us in objectionable relations of dependence on private judgment. Only in the state can this problem be overcome. But it is not clear how mere institutions could make the necessary difference, and contemporary Kantians have not offered compelling explanations. A detailed analysis is presented of the problems Kantians identify with the state of nature and the objections they face in claiming that the state overcomes them. A response is sketched on behalf of Kantians. The key idea is that under state institutions, a person can make claims of acquired right without presupposing that she is by nature exceptional in her capacity to bind others.

Interest rate option hedging portfolios without bank account

2019 ◽  
Vol 37 (1) ◽  
pp. 134-142
Author(s):  
Alberto Bueno-Guerrero
Keyword(s):  
Design Methodology ◽  
Contingent Claim ◽  
Necessary And Sufficient Condition ◽  
Barrier Option ◽  
Bank Account ◽  
Content Type ◽  
Option Hedging ◽  
Hedging Portfolio ◽  
Necessary And Sufficient ◽  
First Time

Purpose This paper aims to study the conditions for the hedging portfolio of any contingent claim on bonds to have no bank account part. Design/methodology/approach Hedging and Malliavin calculus techniques recently developed under a stochastic string framework are applied. Findings A necessary and sufficient condition for the hedging portfolio to have no bank account part is found. This condition is applied to a barrier option, and an example of a contingent claim whose hedging portfolio has a bank account part different from zero is provided. Originality/value To the best of the authors’ knowledge, this is the first time that this issue has been addressed in the literature.

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