scholarly journals An intermediate level of abstraction for computational systems chemistry

2017 ◽  
Vol 375 (2109) ◽  
pp. 20160354 ◽  
Author(s):  
Jakob L. Andersen ◽  
Christoph Flamm ◽  
Daniel Merkle ◽  
Peter F. Stadler
Keyword(s):  
Large Scale ◽  
Optimization Techniques ◽  
Reaction Networks ◽  
Computational Techniques ◽  
Complex Reaction ◽  
Level Of Abstraction ◽  
Systems Chemistry ◽  
Quantum Chemical Methods ◽  
The Right ◽  
Computational Systems

Computational techniques are required for narrowing down the vast space of possibilities to plausible prebiotic scenarios, because precise information on the molecular composition, the dominant reaction chemistry and the conditions for that era are scarce. The exploration of large chemical reaction networks is a central aspect in this endeavour. While quantum chemical methods can accurately predict the structures and reactivities of small molecules, they are not efficient enough to cope with large-scale reaction systems. The formalization of chemical reactions as graph grammars provides a generative system, well grounded in category theory, at the right level of abstraction for the analysis of large and complex reaction networks. An extension of the basic formalism into the realm of integer hyperflows allows for the identification of complex reaction patterns, such as autocatalysis, in large reaction networks using optimization techniques. This article is part of the themed issue ‘Reconceptualizing the origins of life’.

scholarly journals Activated Self-Resolution and Error-Correction in Catalytic Reaction Networks

2021 ◽  
Author(s):  
Fredrik Schaufelberger ◽  
Olof Ramstrom
Keyword(s):  
Dynamic System ◽  
Error Correction ◽  
Small Molecule ◽  
Catalytic Reaction ◽  
Reaction Network ◽  
Reaction Networks ◽  
Complex Reaction ◽  
Catalytic Systems ◽  
Systems Chemistry ◽  
Mbh Reaction

<p>To understand the emergence of function in complex reaction networks is a primary goal of systems chemistry and origin-of-life studies. Especially challenging is the establishment of systems that simultaneously exhibit several functionality parameters that can be independently tuned. In this work, a multifunctional complex reaction network of nucleophilic small molecule catalysts for the Morita-Baylis-Hillman (MBH) reaction is demonstrated. The dynamic system exhibited triggered self-resolution, preferentially amplifying a specific catalyst/product set out of a many potential alternatives. By utilizing selective reversibility of the products of the reaction set, systemic thermodynamically driven error-correction could also be introduced. To achieve this, a dynamic covalent MBH reaction based on adducts with internal H-transfer capabilities was developed, displaying rate accelerations of retro-MBH reactions up to 104 times. This study demonstrates how efficient self-sorting of catalytic systems can be achieved through an interplay of several complex emergent functionalities.</p>

scholarly journals Activated Self-Resolution and Error-Correction in Catalytic Reaction Networks

2021 ◽  
Author(s):  
Fredrik Schaufelberger ◽  
Olof Ramstrom
Keyword(s):  
Dynamic System ◽  
Error Correction ◽  
Small Molecule ◽  
Catalytic Reaction ◽  
Reaction Network ◽  
Reaction Networks ◽  
Complex Reaction ◽  
Catalytic Systems ◽  
Systems Chemistry ◽  
Mbh Reaction

<p>To understand the emergence of function in complex reaction networks is a primary goal of systems chemistry and origin-of-life studies. Especially challenging is the establishment of systems that simultaneously exhibit several functionality parameters that can be independently tuned. In this work, a multifunctional complex reaction network of nucleophilic small molecule catalysts for the Morita-Baylis-Hillman (MBH) reaction is demonstrated. The dynamic system exhibited triggered self-resolution, preferentially amplifying a specific catalyst/product set out of a many potential alternatives. By utilizing selective reversibility of the products of the reaction set, systemic thermodynamically driven error-correction could also be introduced. To achieve this, a dynamic covalent MBH reaction based on adducts with internal H-transfer capabilities was developed, displaying rate accelerations of retro-MBH reactions up to 104 times. This study demonstrates how efficient self-sorting of catalytic systems can be achieved through an interplay of several complex emergent functionalities.</p>

Complexity Results and Effective Algorithms for Worst-Case Linear Optimization Under Uncertainties

2020 ◽  
Author(s):  
Hezhi Luo ◽  
Xiaodong Ding ◽  
Jiming Peng ◽  
Rujun Jiang ◽  
Duan Li
Keyword(s):  
Large Scale ◽  
Risk Estimation ◽  
Convex Relaxation ◽  
Linear Optimization ◽  
Optimal Solution ◽  
Optimization Method ◽  
Optimization Techniques ◽  
Worst Case ◽  
Uncertainty Set ◽  
The Right

In this paper, we consider the so-called worst-case linear optimization (WCLO) with uncertainties on the right-hand side of the constraints. Such a problem often arises in applications such as in systemic risk estimation in finance and stochastic optimization. We first show that the WCLO problem with the uncertainty set corresponding to the [Formula: see text]p-norm ((WCLOp)) is NP-hard for p ɛ (1,∞). Second, we combine several simple optimization techniques, such as the successive convex optimization method, quadratic convex relaxation, initialization, and branch-and-bound (B&B), to develop an algorithm for (WCLO2) that can find a globally optimal solution to (WCLO2) within a prespecified ε-tolerance. We establish the global convergence of the algorithm and estimate its complexity. We also develop a finite B&B algorithm for (WCLO∞) to identify a global optimal solution to the underlying problem, and establish the finite convergence of the algorithm. Numerical experiments are reported to illustrate the effectiveness of our proposed algorithms in finding globally optimal solutions to medium and large-scale WCLO instances.

Why Has There Been No People’s Power Rebellion in North Korea?

2018 ◽  
pp. 1-34
Author(s):  
Andrew Jackson
Keyword(s):  
Rural Areas ◽  
North Korea ◽  
Large Scale ◽  
Political Elite ◽  
Information Control ◽  
Al Jazeera ◽  
The North ◽  
New Information ◽  
Effective System ◽  
The Right

One scenario put forward by researchers, political commentators and journalists for the collapse of North Korea has been a People’s Power (or popular) rebellion. This paper analyses why no popular rebellion has occurred in the DPRK under Kim Jong Un. It challenges the assumption that popular rebellion would happen because of widespread anger caused by a greater awareness of superior economic conditions outside the DPRK. Using Jack Goldstone’s theoretical expla-nations for the outbreak of popular rebellion, and comparisons with the 1989 Romanian and 2010–11 Tunisian transitions, this paper argues that marketi-zation has led to a loosening of state ideological control and to an influx of infor-mation about conditions in the outside world. However, unlike the Tunisian transitions—in which a new information context shaped by social media, the Al-Jazeera network and an experience of protest helped create a sense of pan-Arab solidarity amongst Tunisians resisting their government—there has been no similar ideology unifying North Koreans against their regime. There is evidence of discontent in market unrest in the DPRK, although protests between 2011 and the present have mostly been in defense of the right of people to support themselves through private trade. North Koreans believe this right has been guaranteed, or at least tacitly condoned, by the Kim Jong Un government. There has not been any large-scale explosion of popular anger because the state has not attempted to crush market activities outright under Kim Jong Un. There are other reasons why no popular rebellion has occurred in the North. Unlike Tunisia, the DPRK lacks a dissident political elite capable of leading an opposition movement, and unlike Romania, the DPRK authorities have shown some flexibility in their anti-dissent strategies, taking a more tolerant approach to protests against economic issues. Reduced levels of violence during periods of unrest and an effective system of information control may have helped restrict the expansion of unrest beyond rural areas.

White Backlash

2015 ◽  
Author(s):  
Marisa Abrajano ◽  
Zoltan L. Hajnal
Keyword(s):  
Ethnic Diversity ◽  
Republican Party ◽  
Large Scale ◽  
White Americans ◽  
Political Beliefs ◽  
White Backlash ◽  
Political Spectrum ◽  
Racial Divide ◽  
The Right ◽  
Political Backlash

This book provides an authoritative assessment of how immigration is reshaping American politics. Using an array of data and analysis, it shows that fears about immigration fundamentally influence white Americans' core political identities, policy preferences, and electoral choices, and that these concerns are at the heart of a large-scale defection of whites from the Democratic to the Republican Party. The book demonstrates that this political backlash has disquieting implications for the future of race relations in America. White Americans' concerns about Latinos and immigration have led to support for policies that are less generous and more punitive and that conflict with the preferences of much of the immigrant population. America's growing racial and ethnic diversity is leading to a greater racial divide in politics. As whites move to the right of the political spectrum, racial and ethnic minorities generally support the left. Racial divisions in partisanship and voting, as the book indicates, now outweigh divisions by class, age, gender, and other demographic measures. The book raises critical questions and concerns about how political beliefs and future elections will change the fate of America's immigrants and minorities, and their relationship with the rest of the nation.

Evaluation of Ovaries in Patients with Polycystic Ovary Syndrome using Shear Wave Elastography

2020 ◽  
Vol 16 (5) ◽  
pp. 578-583
Author(s):  
Aysegul Altunkeser ◽  
Zeynep Ozturk Inal ◽  
Nahide Baran
Keyword(s):  
Shear Wave ◽  
Large Scale ◽  
Polycystic Ovary ◽  
Shear Wave Elastography ◽  
Left Ovary ◽  
Control Group ◽  
Tissue Elasticity ◽  
Group I ◽  
Pcos Group ◽  
The Right

Background: Shear wave electrography (SWE) is a novel non-invasive imaging technique which demonstrate tissue elasticity. Recent research evaluating the elasticity properties of normal and pathological tissues emphasize the diagnostic importance of this technique. Aims: Polycystic ovarian syndrome (PCOS), which is characterized by menstrual irregularity, hyperandrogenism, and polycystic overgrowth, may cause infertility. The aim of this study was to evaluate the elasticity of ovaries in patients with PCOS using SWE. Methods: 66 patients diagnosed with PCOS according to the Rotterdam criteria (PCOS = group I) and 72 patients with non-PCOS (Control = group II), were included in the study. Demographic and clinical characteristics of the participants were recorded. Ovarian elasticity was assessed in all patients with SWE, and speed values were obtained from the ovaries. The elasticity of the ovaries was compared between the two groups. Results: While there were statistically significant differences between the groups in body mass index (BMI), right and left ovarian volumes, luteinizing hormone and testosterone levels (p<0.05), no significant differences were found between groups I and II in the velocity (for the right ovary 3.89±1.81 vs. 2.93±0.72, p=0.301; for the left ovary 2.88±0.65 vs. 2.95±0.80, p=0.577) and elastography (for the right ovary 36.62±17.78 vs. 36.79±14.32, p=0.3952; for the left ovary 36.56±14.15 vs. 36.26±15.10, p=0.903) values, respectively. Conclusion: We could not obtain different velocity and elastography values from the ovaries of the patients with PCOS using SWE. Therefore, further large-scale studies are needed to elucidate this issue.

scholarly journals Solving the Real Power Limitations in the Dynamic Economic Dispatch of Large-Scale Thermal Power Units under the Effects of Valve-Point Loading and Ramp-Rate Limitations

2021 ◽  
Vol 13 (3) ◽  
pp. 1274
Author(s):  
Loau Al-Bahrani ◽  
Mehdi Seyedmahmoudian ◽  
Ben Horan ◽  
Alex Stojcevski
Keyword(s):  
Large Scale ◽  
Thermal Power ◽  
Optimization Technique ◽  
Economic Dispatch ◽  
Pso Algorithm ◽  
Search Space ◽  
Economic Benefits ◽  
Optimization Techniques ◽  
Ramp Rate ◽  
Dynamic Economic Dispatch

Few non-traditional optimization techniques are applied to the dynamic economic dispatch (DED) of large-scale thermal power units (TPUs), e.g., 1000 TPUs, that consider the effects of valve-point loading with ramp-rate limitations. This is a complicated multiple mode problem. In this investigation, a novel optimization technique, namely, a multi-gradient particle swarm optimization (MG-PSO) algorithm with two stages for exploring and exploiting the search space area, is employed as an optimization tool. The M particles (explorers) in the first stage are used to explore new neighborhoods, whereas the M particles (exploiters) in the second stage are used to exploit the best neighborhood. The M particles’ negative gradient variation in both stages causes the equilibrium between the global and local search space capabilities. This algorithm’s authentication is demonstrated on five medium-scale to very large-scale power systems. The MG-PSO algorithm effectively reduces the difficulty of handling the large-scale DED problem, and simulation results confirm this algorithm’s suitability for such a complicated multi-objective problem at varying fitness performance measures and consistency. This algorithm is also applied to estimate the required generation in 24 h to meet load demand changes. This investigation provides useful technical references for economic dispatch operators to update their power system programs in order to achieve economic benefits.

scholarly journals Non-normality and non-monotonic dynamics in complex reaction networks

2020 ◽  
Vol 2 (4) ◽  
Author(s):  
Zachary G. Nicolaou ◽  
Takashi Nishikawa ◽  
Schuyler B. Nicholson ◽  
Jason R. Green ◽  
Adilson E. Motter
Keyword(s):  
Reaction Networks ◽  
Complex Reaction

Introduction: Configuring the Green New Deal

2021 ◽  
pp. 103530462110176
Author(s):  
Anna Sturman ◽  
Natasha Heenan
Keyword(s):  
Land Use ◽  
Indigenous Peoples ◽  
New Deal ◽  
Large Scale ◽  
Political Strategy ◽  
Right Wing ◽  
Jel Codes ◽  
Economic Stagnation ◽  
Political Project ◽  
The Right

We introduce a themed collection of articles on approaches to configuring a Green New Deal as a response to the current capitalist crisis marked by ecological breakdown, economic stagnation and growing inequality. The Green New Deal is a contested political project, with pro-market, right-wing nationalist, Keynesian, democratic socialist and ecosocialist variants. Critiques of the Green New Deal include pragmatic queries as the feasibility of implementation, and theoretical challenges from the right regarding reliance on state forms and from the left regarding efforts to ameliorate capitalism. They also include concerns about technocratic bias and complaints about lack of meaningful consultation with Indigenous peoples on proposals for large-scale shifts in land use. Debates over the ideological orientation, political strategy and implementation of the Green New Deal must now account for the economic and employment impacts of COVID. JEL Codes: Q43, Q54, Q56, Q58

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