A Theory of Continuum Economies with Idiosyncratic Shocks and Random Matchings

Many economic models use a continuum of negligible agents to avoid considering one person's effect on aggregate characteristics of the economy. Along with a continuum of agents, these models often incorporate a sequence of independent shocks and random matchings. Despite frequent use of such models, there are still unsolved questions about their mathematical justification. In this paper we construct a discrete time framework, in which major desirable properties of idiosyncratic shocks and random matchings hold. In this framework the agent space constitutes a probability space, and the probability distribution for each agent is replaced by the population distribution. Unlike previous authors, we question the assumption of known identity - the location on the agent space. We assume that the agents only know their previous history - what had happened to them before, - but not their identity. The construction justifies the use of numerous dynamic models of idiosyncratic shocks and random matchings.random matching; idiosyncratic shocks; the Law of Large Numbers; aggregate uncertainty; mixing

A Theory of Continuum Economies with Independent Shocks and Matchings

Numerous economic models employ a continuum of negligible agents with a sequence of idiosyncratic shocks and random matchings. Several attempts have been made to build a rigorous mathematical justification for such models, but these attempts have left many questions unanswered. In this paper, we develop a discrete time framework in which the major, desirable properties of idiosyncratic shocks and random matchings hold. The agents live on a probability space, and the probability distribution for each agent is naturally replaced by the population distribution. The novelty of this approach is in the assumption of unknown identity. Each agent believes that initially he was randomly and uniformly placed on the agent space, i.e., the agent's identity (the exact location on the agent space) is unknown to the agent.random matching, idiosyncratic shocks, the Law of Large Numbers, aggregate uncertainty, mixing

Information Trading in Social Networks

This paper considers information trading in fixed networks of economic agents who can only observe and trade with other agents with whom they are directly connected. We study the nature of price competition for information in this environment. The linear network, when the agents are located at the integer points of the real line, is a specific example I completely characterize. For the linear network there always exists a stationary equilibrium, where the strategies do not depend on time. I show that there is an equilibrium where any agent has a nonzero probability of staying uninformed forever. Under certain initial conditions this equilibrium is a limit of equilibria of finite-horizon games. The role of a transversality condition is emphasized, namely that the price in the transaction should not exceed the expected utility of all the agents who get the information due to the transaction. I show that the price offered does not converge to zero with time.Networks; information trading; information diffusion

WAVES IN PLASMAS GENERATED BY A ROTATING MAGNETIC FIELD AND IMPLICATIONS TO RADIATION BELTS

The interaction of rotating magnetic fields (RMF) with magnetized plasmas is a fundamental plasma physics problem with implications to a wide range of areas, including laboratory and space plasma physics. Despite the importance of the topic the basic physics of the phenomenon remains unexplored. An important application of a RMF is its potential use as an efficient radiation source of low frequency waves in space plasmas, including whistler and shear Alfven waves (SAW) for controlled remediation of energetic particles in the Earth's radiation belts. In this dissertation the RMF waves generated in magnetized plasma are studied using numerical simulations with a semi-analytical three-dimensional magnetohydrodynamic (MHD) model and experiments on the generation of whistler and magnetohydrodynamic waves conducted in UCLA's Large Plasma Device. Comparisons of the simulation results with the experimental measurements, namely, measured spatiotemporal wave structures, dispersion relation with finite transverse wave number, wave amplitude dependence on plasma and RMF source parameters, show good agreement in both the whistler and MHD wave regimes. In both the experiments and the 3D MHD simulations a RMF source was found to be very efficient in the generation of MHD and whistler waves with arbitrary polarizations. The RMF source drives significant field aligned plasma currents confined by the ambient magnetic field for both the whistler and MHD wave regimes, resulting in efficient transport of wave energy along the ambient magnetic field. The efficient transfer of the wave energy results in slow decay rates of the wave amplitude along the ambient magnetic field. The circular polarization of the waves generated by the RMF source, slow amplitude decay rate along the ambient magnetic field and nonzero transverse wave number determined by the RMF source size lead to nonlocal gradients of the wave magnetic field in the direction perpendicular to the ambient magnetic field. A RMF can be generated by a system of polyphase alternating currents or by a rotating permanent or superconducting magnet. For the magnetospheric plasma rotating permanent or superconducting magnets are suitable for injection of very low frequency (VLF) shear Alfven and magnetosonic waves. The generation of whistler waves in the magnetosphere plasma requires frequencies of the order of kHz, so in order to inject whistler waves generated by a RMF it is necessary to use an antenna with polyphase alternating currents. The interactions of the waves generated by a RMF source with highly energetic electron population were investigated in LAPD experiment and by test-particle simulations of non-resonant pitch angle scattering of trapped energetic electrons using the electromagnetic fields calculated using the 3D model. It was found in both the experiment and test-particle simulations that waves generated by a RMF source are, indeed, very efficient in pitch angle scattering of trapped hot electrons due to the creation of magnetic field gradients in the direction perpendicular to the ambient magnetic field. Different scenarios for the applications to the precipitation of highly energetic electrons in the magnetosphere are presented

Information Trading in Social Networks

This paper considers information trading in fixed networks of economic agents who can only observe and trade with other agents with whom they are directly connected. We study the nature of price competition for information in this environment. The linear network, when the agents are located at the integer points of the real line, is a specific example I completely characterize. For the linear network there always exists a stationary equilibrium, where the strategies do not depend on time. I show that there is an equilibrium where any agent has a nonzero probability of staying uninformed forever. Under certain initial conditions this equilibrium is a limit of equilibria of finite-horizon games. The role of a transversality condition is emphasized, namely that the price in the transaction should not exceed the expected utility of all the agents who get the information due to the transaction. I show that the price offered does not converge to zero with time

Ялтинская встреча в призме официальной кинохроники: фильм «Крымская конференция» Сергея Герасимова

The article studies one of the most important milestones in documentary and chronicle film during World War II — a documentary about the Crimean (Yalta) Conference of the leaders of the three powers, allies in the Anti-Hitler coalition, held in February 1945. Sergei Gerasimov, a well-known director and winner of the Stalin Prize, was appointed director of the shooting of this film. Together with Gerasimov, a large team of documentary filmmakers, including director Ilya Kopalin and cameramen I. Belyakov, V. Dobronitsky, A. Krichevsky, N. Petrosov, A. Khavchin and R. Khalushakov, went to Crimea to film the conference. Gerasimov perceived his work on this film as an important stage in his professional career and, at the same time, he sought to keep out of harm’s way the Soviet documentary makers, who, according to the party leaders, did not capture events on the fronts convincingly and promptly enough. The author compares the film with various official documents of the conference, using wide-ranging historical research. He seeks to reveal how the inclusion of certain episodes in the final cut reflected the historical and political trends shortly before the Cold War. A lavish reception for the delegations in combination with the gorgeous Crimean palace, originally intended to be a tsar’s residence— this was supposed to produce (and did produce) the effect of a “royal reception” and made it clear that in its foreign policy actions, the Stalinist state was the full-fledged successor to the buried Russian Empire. Understandably, Gerasimov’s official, ideologically regulated film did not reflect all this explicitly. However, the film showed the super objective and the outcome of the Yalta Conference quite adequately: in Yalta, the triumvirate of the allied powers, in which the USSR played the leading role, signed a death sentence to Hitler’s Germany and outlined the post-war world order

Design of front-end for EEG recording

V rámci práce je navržen funkční prototyp snímače biosignálů, který je konstruován pro záznam EEG signálů. Jako jádro je použita kombinace nízko nákladového a~výkonného mikrokontrolleru ESP8266 a~čipu ADS1299. Zařízení je přímo určeno na měření biopotenciálů a~obsahuje 24 bitový AD převodník, filtry, PGA (Programmable gain amplifier) a~další specifické funkce. Pro uživatelsky lepší nastavení čipu, export a~zobrazovaní dat je připraveno GUI v programovacím jazyku Python. Tento prototyp EEG snímače nabízí levnou variantu při zachování parametrů jaké jsou běžné u klinických EEG přístrojů a zároveň nabízí široké spektrum možností konfigurace programového rozhraní.This work proposes a functional biosignal sensor prototype that is designed to record EEG signals. The core is a combination of the low cost and powerful ESP8266 and ADS1299 microcontrollers. The device is directly designed for biopotential measurement and includes a 24 bit AD converter, filters, PGA (Programmable gain amplifier) and other specific functions. This EEG prototype offers a low-cost option while maintaining the parameters common to clinical EEG instruments. it also offers a wide range of program interface configuration options

A Theory of Continuum Economies with Idiosyncratic Shocks and Random Matchings

Many economic models use a continuum of negligible agents to avoid considering one person's effect on aggregate characteristics of the economy. Along with a continuum of agents, these models often incorporate a sequence of independent shocks and random matchings. Despite frequent use of such models, there are still unsolved questions about their mathematical justification. In this paper we construct a discrete time framework, in which major desirable properties of idiosyncratic shocks and random matchings hold. In this framework the agent space constitutes a probability space, and the probability distribution for each agent is replaced by the population distribution. Unlike previous authors, we question the assumption of known identity - the location on the agent space. We assume that the agents only know their previous history - what had happened to them before, - but not their identity. The construction justifies the use of numerous dynamic models of idiosyncratic shocks and random matchings

A Theory of Continuum Economies with Independent Shocks and Matchings

Numerous economic models employ a continuum of negligible agents with a sequence of idiosyncratic shocks and random matchings. Several attempts have been made to build a rigorous mathematical justification for such models, but these attempts have left many questions unanswered. In this paper, we develop a discrete time framework in which the major, desirable properties of idiosyncratic shocks and random matchings hold. The agents live on a probability space, and the probability distribution for each agent is naturally replaced by the population distribution. The novelty of this approach is in the assumption of unknown identity. Each agent believes that initially he was randomly and uniformly placed on the agent space, i.e., the agent's identity (the exact location on the agent space) is unknown to the agent

A Theory of Continuum Economies with Idiosyncratic Shocks and Random Matchings

Many economic models use a continuum of negligible agents to avoid considering one person's effect on aggregate characteristics of the economy. Along with a continuum of agents, these models often incorporate a sequence of independent shocks and random matchings. Despite frequent use of such models, there are still unsolved questions about their mathematical justification. In this paper we construct a discrete time framework, in which major desirable properties of idiosyncratic shocks and random matchings hold. In this framework the agent space constitutes a probability space, and the probability distribution for each agent is replaced by the population distribution. Unlike previous authors, we question the assumption of known identity - the location on the agent space. We assume that the agents only know their previous history - what had happened to them before, - but not their identity. The construction justifies the use of numerous dynamic models of idiosyncratic shocks and random matchings