Dynamic synchronization of sympathetic oscillators

Synchronous activity of single postganglionic sympathetic neurones (PGNs) underlies rhythmical or semi-rhythmical burst discharges recorded from peripheral sympathetic nerves. It is still controversial whether this rhythmicity is generated by an autonomous sympathetic oscillator. Previous studies have demonstrated that activity of single PGNs innervating the caudal ventral artery (CVA) of the rat's tail has a dominant rhythm (T-rhythm). The frequency of T- rhythm is different from the cardiac frequency and can be different from those of ventilatory and respiratory rhythms, suggesting that T-rhythm is generated by an oscillator independent of periodic drives originating from the arterial baroreceptors, the ventilation afferents and the respiratory network. Using the rat's tail circulation as a model, the purpose of the present study is: 1) to determine whether activity from different single PGNs is generated by multiple oscillators. 2) to establish whether synchronization of single PGNs is an obligatory feature and if not, how it is regulated. 3) to determine whether periodically driven single PGN oscillators exhibit dynamics as predicted by the theory of nonlinear coupled oscillators. 4) to explain the discharge behaviour of whole nerve activity based on the findings at single PGN level. The experiments were conducted in anaesthetized Sprague-Dawley rats. Population PGN activity was recorded from the ventral collector nerve (VCN) of the tail. Single PGN activity was recorded focally from the surface of the CVA. The interaction between two single PGNs was studied by recording two units simultaneously. The discharge behaviours of PGNs in response to a periodic input were studied using the central respiratory drive (CRD) and lung-inflation cycle (LlC)-related activity as the driving forces. The findings from the present study suggest that: 1) Activity of CVA PGNs is generated by multiple oscillators independent of CRD, LIC-related activity and cardiac activity. 2) The multiple PGN oscillators are capable of dynamic synchronization. 3) When subjected to frequency changes of LICs, single PGNs exhibit dynamics, such as 1:1 entrainment, relative coordination, high order rational frequency-lock, asynchrony, characterising nonlinear coupled oscillators. 4) Population PGN activity should be considered as output activity from a pool of dynamically interactive multiple oscillators rather than that from a single oscillator

Public debt in developing countries : has the market-based model worked?

Over the past 25 years, significant levels of public debt and external finance are more likely to have enhanced macroeconomic vulnerability than economic growth in developing countries. This applies not just to countries with a history of high inflation and past default, but also to those in East Asia, with a long tradition of prudent macroeconomic policies and rapid growth. The authors examine why with the help of a conceptual framework drawn from the growth, capital flows, and crisis literature for developing countries with access to the international capital markets (market access countries or MACs). They find that, while the chances of another generalized debt crisis have receded since the turbulence of the late 1990s, sovereign debt is indeed constraining growth in MACs, especially those with debt sustainability problems. Several prominent MACs have sought to address the debt and external finance problem by generating large primary fiscal surpluses, switching to flexible exchange rates, and reforming fiscal and financial institutions. Such country-led initiatives completely dominate attempts to overhaul the international financial architecture or launch new lending instruments, which have so far met with little success. While the initial results of the countries'initiatives have been encouraging, serious questions remain about the viability of the model of market-based external development finance. Beyond crisis resolution, which has received attention in the form of the sovereign debt restructuring mechanism, the international financial institutions may need to ramp up their role as providers of stable long-run development finance to MACs instead of exiting from them.

Path to Tanzanian and Kenyan development in the postwar international order : the unresolved theoretical development debate.

This dissertation attempts to test the applicability of the neoclassical, orthodox Marxist, and dependency paradigms in light of the development experiences of Tanzania and Kenya. The larger goal of the dissertation is a preliminary formulation of an alternative development approach which is non-essentialist and class focused. In chapter one, the dissertation format as well as statements of the problems are introduced. In chapter two, the international context within which the two countries must operate is discussed. In chapter three, the three theoretical approaches are critically examined. In chapter four, the colonial history of Tanzania and Kenya, designed to acquaint the readers with the two countries is sketched. In chapter five, the two countries\u27 actual development experiences are examined. Specifically, the role of the state, the industrial and agricultural development experiences of both countries are closely examined. In chapter six, the three theoretical paradigms in light of the experiences of Tanzania and Kenya are assessed. The assessment shows that none of the paradigms fully describes or adequately explains their process of development. Finally, in chapter seven, an all-encompassing alternative development approach based on the concept of overdetermination is proposed

Towards Interaction Protocol Operations for Large Multi-agent Systems

It is widely accepted that role-based modelling is quite adequate in the context of multi-agent systems (MAS) modelling techniques. Unfortunately, very little work has been reported on how to describe the relationships between several role models. Furthermore, many authors agree on that protocols need to be encapsulated into high-level abstractions. The synthesis of role models is an operation presented in the OORAM methodology that allows us to build new role models from others in order to represent the interrelations they have. To the best of our knowledge this operation has to be performed manually at protocol level and works with protocols expressed by means of messages. In this paper, we present two algorithms to extract the protocol of a role from the protocol of a role model and vice versa that automate the synthesis or role models at the protocol level. Furthermore, in order to deal with protocol descriptions in a top down approach both operations work with protocols expressed by means of an abstraction call multi-role interaction (mRI)

Subtype Universes

We introduce a new concept called a subtype universe, which is a collection of subtypes of a particular type. Amongst other things, subtype universes can model bounded quantification without undecidability. Subtype universes have applications in programming, formalisation and natural language semantics. Our construction builds on coercive subtyping, a system of subtyping that preserves canonicity. We prove Strong Normalisation, Subject Reduction and Logical Consistency for our system via transfer from its parent system UTT[?]. We discuss the interaction between subtype universes and other sorts of universe and compare our construction to previous work on Power types

A Complete Axiom System for Propositional Interval Temporal Logic with Infinite Time

Interval Temporal Logic (ITL) is an established temporal formalism for reasoning about time periods. For over 25 years, it has been applied in a number of ways and several ITL variants, axiom systems and tools have been investigated. We solve the longstanding open problem of finding a complete axiom system for basic quantifier-free propositional ITL (PITL) with infinite time for analysing nonterminating computational systems. Our completeness proof uses a reduction to completeness for PITL with finite time and conventional propositional linear-time temporal logic. Unlike completeness proofs of equally expressive logics with nonelementary computational complexity, our semantic approach does not use tableaux, subformula closures or explicit deductions involving encodings of omega automata and nontrivial techniques for complementing them. We believe that our result also provides evidence of the naturalness of interval-based reasoning

Strategic Issues, Problems and Challenges in Inductive Theorem Proving

Abstract(Automated) Inductive Theorem Proving (ITP) is a challenging field in automated reasoning and theorem proving. Typically, (Automated) Theorem Proving (TP) refers to methods, techniques and tools for automatically proving general (most often first-order) theorems. Nowadays, the field of TP has reached a certain degree of maturity and powerful TP systems are widely available and used. The situation with ITP is strikingly different, in the sense that proving inductive theorems in an essentially automatic way still is a very challenging task, even for the most advanced existing ITP systems. Both in general TP and in ITP, strategies for guiding the proof search process are of fundamental importance, in automated as well as in interactive or mixed settings. In the paper we will analyze and discuss the most important strategic and proof search issues in ITP, compare ITP with TP, and argue why ITP is in a sense much more challenging. More generally, we will systematically isolate, investigate and classify the main problems and challenges in ITP w.r.t. automation, on different levels and from different points of views. Finally, based on this analysis we will present some theses about the state of the art in the field, possible criteria for what could be considered as substantial progress, and promising lines of research for the future, towards (more) automated ITP

On space efficiency of algorithms working on structural decompositions of graphs

Dynamic programming on path and tree decompositions of graphs is a technique that is ubiquitous in the field of parameterized and exponential-time algorithms. However, one of its drawbacks is that the space usage is exponential in the decomposition's width. Following the work of Allender et al. [Theory of Computing, '14], we investigate whether this space complexity explosion is unavoidable. Using the idea of reparameterization of Cai and Juedes [J. Comput. Syst. Sci., '03], we prove that the question is closely related to a conjecture that the Longest Common Subsequence problem parameterized by the number of input strings does not admit an algorithm that simultaneously uses XP time and FPT space. Moreover, we complete the complexity landscape sketched for pathwidth and treewidth by Allender et al. by considering the parameter tree-depth. We prove that computations on tree-depth decompositions correspond to a model of non-deterministic machines that work in polynomial time and logarithmic space, with access to an auxiliary stack of maximum height equal to the decomposition's depth. Together with the results of Allender et al., this describes a hierarchy of complexity classes for polynomial-time non-deterministic machines with different restrictions on the access to working space, which mirrors the classic relations between treewidth, pathwidth, and tree-depth.Comment: An extended abstract appeared in the proceedings of STACS'16. The new version is augmented with a space-efficient algorithm for Dominating Set using the Chinese remainder theore