Retrodicting the rise, spread, and fall of large-scale states in the Old World

Understanding the rise, spread, and fall of large-scale states in the ancient world has occupied thinkers for millennia. However, no comprehensive mechanistic model of state dynamics based on their insights has emerged, leaving it difficult to evaluate empirically or quantitatively the different explanations offered. Here I present a spatially- and temporally-resolved agent-based model incorporating several hypotheses about the behavior of large-scale (>200 thousand km2) agrarian states and steppe nomadic confederations in Afro-Eurasia between the late Bronze and the end of the Medieval era (1500 BCE to 1500 CE). The model tracks the spread of agrarian states as they expand, conquer the territory of other states or are themselves conquered, and, occasionally, collapse. To accurately retrodict the historical record, several key contingent regional technological advances in state military and agricultural efficiencies are identified. Modifying the location, scale, and timing of these contingent developments allows quantitative investigation of historically-plausible alternative trajectories of state growth, spread, and fragmentation, while demonstrating the operation and limits of the model. Under nominal assumptions, the rapid yet staggered increase of agrarian state sizes across Eurasia after 600 BCE occurs in response to intense military pressure from ‘mirror‘ steppe nomadic confederations. Nevertheless, in spite of various technological advances throughout the period, the modeled creation and spread of new agrarian states is a fundamental consequence of state collapse and internal civil wars triggered by rising ‘demographic-structural’ pressures that occur when state territorial growth is checked yet (warrior elite) population growth continues. Together the model’s underlying mechanisms substantially account for the number of states, their duration, location, spread rate, overall occupied area, and total population size for three thousand years.

Towards the Stable Evolution of Dendrites in the Case of Intense Convection in the Melt

The solid-phase pattern in the form of a dendrite is one of the frequently met structures produced from undercooled liquids. In the last decades, an analytical approach describing the steady-state crystal growth in the presence of conductive heat and mass transport has been constructed. However, experimental works show that crystal patterns frequently grow in the presence of convection. In this paper, a theoretical description based on convective heat and solute concentration transport near the solid/liquid phase interface is developed. The stable regime of crystallization in the presence of vigorous convection near the steady-state crystal vertex is studied. The stability analysis, determining the stable growth mode, and the undercooling balance law have been applied to deduce the stable values for the growth rate and tip diameter. Our analytical predictions (with convective transport) well describe experimental data for a small melt undercooling. Moreover, we compare both convective and conductive mechanisms in the vicinity of the crystal vertex. Our theory shows that convective fluxes substantially change the steady-state growth of crystals.

Ubiquitous mRNA decay fragments in E. coli redefine the functional transcriptome

Bacterial mRNAs have short life cycles, in which transcription is rapidly followed by translation and degradation within seconds to minutes. The resulting diversity of mRNAs impacts their functionality but has remained unresolved. Here we quantitatively map the 3' status of cellular RNAs in Escherichia coli during steady-state growth and report a large fraction of molecules (median>60%) that are fragments of canonical full-length mRNAs. The majority of RNA fragments are decay intermediates following endonuclease cleavage by RNase E and yet-unknown nucleases, whereas nascent RNAs contribute to a smaller fraction. Despite the prevalence of decay intermediates in total RNA, they are underrepresented in the pool of ribosome-associated transcripts and can thus distort quantifications for the abundance of full-length, functional mRNAs. The large heterogeneity within mRNA molecules in vivo highlights the importance in discerning functional transcripts and provides a lens for studying the dynamic life cycle of mRNAs.

Fiscal Economic Instruments for the Sustainable Management of Natural Resources in Coastal Marine Areas of the Yucatan Peninsula

Fiscal economic instruments (FEI) are indirect regulation mechanisms that generate public revenue for the state through rights to use, charges, and concessions. In Mexico, some of these instruments can be used in the surveillance, administration, and preservation of the environment. In this paper, we analyze the changes in Federal and State growth rates of expenditure budgets in critical areas of the Yucatan Peninsula coast to describe their contribution to sustainable development during the last 12 years. We present an adaptation of the methodological guide of economic instruments for environmental management from CEPAL, with 2013 as the base year for the Gross Domestic Product (GDP) deflator and the use of the Protocol of Nagoya year as an international compromise signed by Mexico. The results obtained show that the expenditure budgets respond to economic, political, and short-term security attention without expectations for sustainability. However, alarming evidence of severe environmental deterioration in the coast is diminishing natural attraction, from tourism, for example, which is the main source of income in the region. The effective use of FEI by local governments may be useful to addressing environmental challenges from a decentralization process with better awareness of the importance of coastal areas for regional sustainability.

Cell Growth Model with Stochastic Gene Expression Helps Understand the Growth Advantage of Metabolic Exchange and Auxotrophy

Cooperative behaviors are highly prevalent in the wild, but their evolution is not understood. Metabolic flux models can demonstrate the viability of metabolic exchange as cooperative interactions, but steady-state growth models cannot explain why cooperators grow faster.

CAPITAL AND GROWTH

This paper develops and discusses a neoclassical growth model with two inputs: physical capital stock and combined stock of human and intellectual capital. The production process is subject to diminishing returns to capital in perfect markets, in sharp contrast to new endogenous growth models that assume increasing returns to capital in imperfect markets. The model finds that a high saving rate raises both transitional and steady state growth rates of output through increases in physical, human, and intellectual investments that augment labor productivity—a key extension of the Solow (1956)-Swan (1956) growth model. Additionally, the paper derives an optimal rule for choosing the saving rate that maximizes consumer welfare. Implications for growth policies are drawn.

A high content microscopy screening identifies genes involved in cell width control in Bacillus subtilis

How cells control their size is a fundamental question of biology. In bacteria, cell shape is imposed by the extracellular cell wall, in particular by the continuous polymer of peptidoglycan (PG) that surrounds the cell. Thus, bacterial cell morphogenesis results from the coordinated action of the proteins assembling and degrading the PG shell. Remarkably, during steady-state growth, most bacteria maintain a defined shape along generations, suggesting that an error-proof mechanism tightly controls the process. In the rod-shaped model for Gram-positive bacteria, Bacillus subtilis, it is well known that the average cell length varies as a function of growth rate but that cell diameter remains constant throughout its cell cycle and across growth conditions. Here, in an attempt to shed light on the cellular circuits controlling bacterial cell width, we developed a screen to identify genetic determinants of cell width in B. subtilis. Using HCS (high-content screening) fluorescence microscopy and semi-automated measurement of single-cell dimensions, we screened a library of ~ 4000 single knockout mutants. We identified 12 mutations significantly altering cell diameter, in genes that belong to several functional groups. In particular, these results highlight a link between cell width control and metabolism.

Solid-State Growth of Cspbi3 Perovskites: Phases Formation and Stability

Totally inorganic perovskites are playing an increasingly important role for their potential applications in optoelectronics devices. However, a big problem to be solved is the role of the different phases, the presence of which is closely linked to the growth method and to the role of impurities. In this article, we propose a solvent-free, solid-state growth method, which allows to obtain samples free of any organic residues. The analysis of structural (XRD and Raman measurements), optical (absorption, steady-time and time-resolved luminescence) and morphological (HRTEM imaging), permitted to understand the phase evolution during the synthesis as a function of the temporal duration. The dynamic equilibrium process at high temperature between the CsPbI3 and the starting precursors, CsI and PbI2, plays a fundamental role in the final phase. If, from one side, the α and δ phases are related to the exact stoichiometry, on the other hand an excess of CsI permits the formation of room temperature stable perovskite γ-phase and, with a further excess, the secondary Cs4PbI6 phase is obtained.

THE ENDOGENEITY OF THE STEADY-STATE GROWTH RATE

This study aims to estimate the steady-state growth rate or the natural growth rate and to determine whether the steady-state growth rate is endogenous to demand conditions or not. In order to achieve these aims, this study makes an econometric analysis using ordinary least squares method based on the data of Turkey covering the period 1969-2006. The present study estimates the natural growth rate and analyzes whether the natural growth rate is endogenous or not. But, different from the previous studies, the present study makes estimations in the conditions that capital-output ratio remains constant. According to the results of the study, the steady-state or natural growth rate is 5.71% in Turkey for the period 1969-2006. Moreover, the natural growth rate becomes 9.51% in the boom periods. This result shows that the steady-state or natural growth rate is endogenous to demand conditions in Turkey. Thus, the present study provides evidence for the Thirlwall’s (1969) theory in a different manner. Keywords: Natural growth rate, endogeneity, steady-state, capital-output ratio, economic history of Turkey