Competing interactions give rise to two-state behavior and switch-like transitions in charge-rich intrinsically disordered proteins

The most commonly occurring intrinsically disordered proteins (IDPs) are polyampholytes, which are defined by the duality of low net charge per residue and high fractions of charged residues. Recent experiments have uncovered surprises regarding sequence-ensemble relationships of model polyampholytic IDPs. These include differences in conformational preferences for sequences with lysine vs. arginine, and the suggestion that well-mixed sequences either form globules or conformations with ensemble averages that are reminiscent of ideal chains wherein intra-chain and chain-solvent interactions are counterbalanced. Here, we explain these observations by analyzing results from atomistic simulations. We find that polyampholytic IDPs generally sample two distinct stable states, namely globules and self-avoiding walks. Globules are favored by electrostatic attractions between oppositely charged residues, whereas self-avoiding walks are favored by favorable free energies of hydration of charged residues. We find sequence-specific temperatures of bistability at which globules and self-avoiding walks can coexist. At these temperatures, ensemble averages over coexisting states give rise to statistics that resemble ideal chains without there being an actual counterbalancing of intra-chain and chain-solvent interactions. At equivalent temperatures, arginine-rich sequences tilt the preference toward globular conformations whereas lysine-rich sequences tilt the preference toward self-avoiding walks. This stems from intrinsic differences in free energies of hydration between arginine and lysine. We also identify differences between aspartate and glutamate containing sequences, whereby the shorter aspartate sidechain engenders preferences for metastable, necklace-like conformations. Finally, although segregation of oppositely charged residues within the linear sequence maintains the overall two-state behavior, compact states are highly favored by such systems.

The Functional Logic of Odor Information Processing in the Drosophila Antennal Lobe

In the early olfactory pathway of Drosophila, Olfactory Sensory Neurons (OSNs) multiplicatively encode the odorant identity and the concentration profile. Projection Neurons (PNs) responses in the Antennal Lobe (AL), in turn, exhibit strong transients at odorant onset/offset and stable steady-state behavior. What is the functional logic the of diverse set of Local Neurons (LNs) in the AL Addressing this question may shed light on the key characteristics of odor information processing in the AL, and odorant recognition and olfactory associative learning in the downstream neuropils of the early olfactory system. To address the computation performed by each LN type, we exhaustively evaluated all circuit configurations of the Antennal Lobe. We found that, across model parameterizations, presynaptic inhibition of the OSN-to-PN synapse is essential for odorant identity recovery in steady-state, while postsynaptic excitation and inhibition facilitate on-/off-set event detection. The onset and offset events indicate changing odorant identities, and together with the identity recovery in steady-state, suggest that the AL is an event-based odorant identity recovery processor.

India’s Withdrawal from Regional Comprehensive Economic Partnership (RCEP)

The Sino-US competition in the Indo-Pacific has become a central issue in international relations and how the competition of both countries affects state behavior. This article attempts to provide explanations of India's behavior in deciding to leave the Regional Comprehensive Economic Partnership (RCEP) agreement by using the neoclassical realism theory. Neoclassical realism believes that the actors' behavior is influenced by the constellation of international structures and domestic constellations. India's exit from RCEP was influenced by structural changes in the Indo-Pacific region, with the loss of China's balance of power marked by the withdrawal of the United States from the Trans-Pacific Partnership (TPP). Moreover, the condition has been exacerbated by the pressure received by Narendra Modi at the domestic level with the emergence of rejection of India's involvement in RCEP. It has influenced Narendra Modi's perception, who was active in the region with the two factors above, decided to resign from RCEP.

Elites in the Making and Breaking of Foreign Policy

Scholarship on elites and foreign policy has made important advances in identifying who elites are, what elites want, and how elites influence foreign policy. This review assesses these advances, focusing on the tension between elites’ expertise, on the one hand, and resentment of elites as selfish or unrepresentative of the people's interests, on the other. What remains missing in the literature on elites and foreign policy are the dynamics of elite politics. The same elites can behave very differently in different settings, and elites frequently do not get what they want on foreign policy despite strong preferences. To understand this variation, we need more research on three kinds of elite politics: how elites attain their positions; their incentives once they arrive in those positions; and how elites relate to each other and to mass publics. Without attending to elite politics, we miss important sources of state behavior. Expected final online publication date for the Annual Review of Political Science, Volume 25 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

The Detailed Doubly Fed Induction Wind Generator for Electromagnetic Transients Calculations and its Initialization in ATP

The Alternative Transients Program (ATP) is one of the most used electromagnetic transient programs due to its powerful modeling capability and versatility. However, it has limitations as regards the automatic initialization of power electronics devices and control systems. To overcome this drawback, a simple methodology is presented in this paper to initialize a detailed model of a doubly fed induction wind generator implemented in ATP. The methodology is based on the automatic initialization of this device and it is divided into two stages. The first one consists of offline calculations to obtain initial steady-state values of certain model variables and, in the second one, these results are used as ATP model parameters. The simulation is started by means of auxiliary switches also included in the model. To validate the methodology, the transient and steady-state behavior of 4 case studies was evaluated. The analysis of these results shows that the steady-state values calculated by ATP for t = 0 are the desired ones and the oscillograms present a steady-state condition. The proposed methodology makes it possible to accurately initialize a detailed DFIG-type generator model in ATP, without the need to sacrifice simulation time to wait for variables to reach a steady state.

Unpacking Strategic Behavior in Cyberspace: A Schema-Driven Approach

The contemporary literature on cybersecurity and related interstate interactions often cites the need to overcome uncertainty due to an inherent deficit of information about cyber operations. While this notion continues to appear relevant in studies that advance our understanding of state behavior in cyberspace, noticeable gaps remain. These gaps particularly stem from the limited utility of cyber operations to shift the balance of strategic power between states or to signal intent and resolve effectively. In response, this article advances a cognitive-cultural framework wherein behavior reflects preferences derived from schema usage. Using cross-national wargames, the article illustrates the schematic use of strategic culture as a basis for deriving strategic objectives and the means with which these are achieved. Consequently, the article serves as the initial foray in expanding our understanding of interstate behavior in cyberspace.

Tracing Strategic Preferences in Cyberspace: The Role of Regional and Domestic Strategic Culture

Our understanding of strategic preferences in cyberspace rests on the material and strategic factors that shape state behavior. This, however, is derived from the actions of established cyber powers. Given the material resources required to effectively operate in this environment and repeated interactions that form the boundaries of accepted behavior, the literature does not adequately explain the emergence of strategic preferences among novice actors. The article posits that these are not exclusively the function of either the material or strategic factors. Instead, strategic culture features prominently in the selection of strategic preferences that shape state behavior in cyberspace.

Thermodynamics of Moist Air for Vacuum Technology

The paper is focused on the developing a predictive mathematical model for describing thermodynamic processes connected with the moist air depressurization in vacuum chambers. Equations of the mathematical description are based on principles of the energy and mass conservation, which are complemented by the moist air thermodynamics, the state behavior of water and vapor, including principles of the critical flow. The described problem has been solved using the MATLAB software. In the paper, two cases are applied and discussed: the vacuum drying and the specimen chamber of an environmental scanning electron microscope. The specific requirements are especially important for environmental scanning electron microscopes, where it is possible to observe samples, which contain water, in their natural condition. If the air pressure, temperature and humidity do not have suitable values, observed sample may be dried or damaged.

Steady-State Planning in Expected Reward Multichain MDPs

The planning domain has experienced increased interest in the formal synthesis of decision-making policies. This formal synthesis typically entails finding a policy which satisfies formal specifications in the form of some well-defined logic. While many such logics have been proposed with varying degrees of expressiveness and complexity in their capacity to capture desirable agent behavior, their value is limited when deriving decision-making policies which satisfy certain types of asymptotic behavior in general system models. In particular, we are interested in specifying constraints on the steady-state behavior of an agent, which captures the proportion of time an agent spends in each state as it interacts for an indefinite period of time with its environment. This is sometimes called the average or expected behavior of the agent and the associated planning problem is faced with significant challenges unless strong restrictions are imposed on the underlying model in terms of the connectivity of its graph structure. In this paper, we explore this steady-state planning problem that consists of deriving a decision-making policy for an agent such that constraints on its steady-state behavior are satisfied. A linear programming solution for the general case of multichain Markov Decision Processes (MDPs) is proposed and we prove that optimal solutions to the proposed programs yield stationary policies with rigorous guarantees of behavior.