145 research outputs found
Dynkin TBA's
We prove a useful identity valid for all minimal S-matrices, that
clarifies the transformation of the relative thermodynamic Bethe Ansatz (TBA)
from its standard form into the universal one proposed by Al.B.Zamolodchikov.
By considering the graph encoding of the system of functional equations for the
exponentials of the pseudoenergies, we show that any such system having the
same form as those for the TBA's, can be encoded on only.
This includes, besides the known diagonal scattering, the set of all
related {\em magnonic} TBA's. We explore this class sistematically and
find some interesting new massive and massless RG flows. The generalization to
classes related to higher rank algebras is briefly presented and an intriguing
relation with level-rank duality is signalled.Comment: 29 pages, Latex (no macros) DFUB-92-11, DFTT-31/9
Effects of regulation on a self-organized market
Adapting a simple biological model, we study the effects of control on the
market. Companies are depicted as sites on a lattice and labelled by a fitness
parameter (some `company-size' indicator). The chance of survival of a company
on the market at any given time is related to its fitness, its position on the
lattice and on some particular external influence, which may be considered to
represent regulation from governments or central banks. The latter is rendered
as a penalty for companies which show a very fast betterment in fitness space.
As a result, we find that the introduction of regulation on the market
contributes to lower the average fitness of companies.Comment: 7 pages, 2 figure
Circular analysis in complex stochastic systems
Ruling out observations can lead to wrong models. This danger occurs unwillingly when one selects observations, experiments, simulations or time-series based on their outcome. In stochastic processes, conditioning on the future outcome biases all local transition probabilities and makes them consistent with the selected outcome. This circular self-consistency leads to models that are inconsistent with physical reality. It is also the reason why models built solely on macroscopic observations are prone to this fallacy
Digital Perspectives in History
This article outlines the state of digital perspectives in historical research, some of the methods and tools in use by digital historians, and the possible or even necessary steps in the future development of the digital approach. We begin by describing three main computational approaches: digital databases and repositories, network analysis, and Machine Learning. We also address data models and ontologies in the larger context of the demand for sustainability and linked research data. The section is followed by a discussion of the (much needed) standards and policies concerning data quality and transparency. We conclude with a consideration of future scenarios and challenges for computational research
Printers, Publishers, and Sellers: Actors in the Process of Consolidation of Epistemic Communities in the Early Modern Academic World
This chapter proposes a global view of the set of dynamics of interplay that were generated in the early modern publishing sector around a single astro-nomical work, the Tractatus de sphaera by Johannes de Sacrobosco. The Sphaera, a thirteenth-century tract of geocentric cosmology, rather than remaining a static text, became over the centuries a multiauthored dynamic textual tradition. This essay argues that publishers, printers, and booksellers had a fair share of agency not only in perpetuating but also in shaping the evolution of this long-lasting textual tradition. The present essay traces the ways this agency was configured
Translation by Ribosomes with mRNA Degradation: Exclusion Processes on Aging Tracks
We investigate the role of degradation of mRNA on protein synthesis using the totally asymmetric simple exclusion process (TASEP) as the underlying model for ribosome dynamics. mRNA degradation has a strong effect on the lifetime distribution of the mRNA, which in turn affects polysome statistics such as the number of ribosomes present on an mRNA strand of a given size. An average over mRNA of all ages is equivalent to an average over possible configurations of the corresponding TASEP-both before steady state and in steady state. To evaluate the relevant quantities for the translation problem, we first study the approach towards steady state of the TASEP, starting with an empty lattice representing an unloaded mRNA. When approaching the high density phase, the system shows two distinct phases with the entry and exit boundaries taking control of the density at their respective ends in the second phase. The approach towards the maximal current phase exhibits the surprising property that the ribosome entry flux can exceed the maximum possible steady state value. In all phases, the averaging over the mRNA age distribution shows a decrease in the average ribosome density profile as a function of distance from the entry boundary. For entry/exit parameters corresponding to the high density phase of TASEP, the average ribosome density profile also has a maximum near the exit end
Degradation Parameters from Pulse-Chase Experiments
Pulse-chase experiments are often used to study the degradation of macromolecules such as proteins or mRNA. Considerations for the choice of pulse length include the toxicity of the pulse to the cell and maximization of labeling. In the general case of non-exponential decay, varying the length of the pulse results in decay patterns that look different. Analysis of these patterns without consideration to pulse length would yield incorrect degradation parameters. Here we propose a method that constructively includes pulse length in the analysis of decay patterns and extracts the parameters of the underlying degradation process. We also show how to extract decay parameters reliably from measurements taken during the pulse phase
Critical Steps of Plasmodium falciparum Ookinete Maturation
The egress and fertilization of Plasmodium gametes and development of a motile ookinete are the first crucial steps that mediate the successful transmission of the malaria parasites from humans to the Anopheles vector. However, limited information exists about the cell biology and regulation of this process. Technical impediments in the establishment of in vitro conditions for ookinete maturation in Plasmodium falciparum and other human malaria parasites further constrain a detailed characterization of ookinete maturation. Here, using fluorescence microscopy and immunolabeling, we compared P. falciparum ookinete maturation in Anopheles coluzzii mosquitoes in vivo and in cell culture in vitro. Our results identified two critical steps in ookinete maturation that are regulated by distinct mosquito factors, thereby highlighting the role of the mosquito environment in the transmission efficiency of malaria parasites
Form Factors and Correlation Functions of the Stress--Energy Tensor in Massive Deformation of the Minimal Models
The magnetic deformation of the Ising Model, the thermal deformations of both
the Tricritical Ising Model and the Tricritical Potts Model are governed by an
algebraic structure based on the Dynkin diagram associated to the exceptional
algebras (respectively for ). We make use of these underlying
structures as well as of the discrete symmetries of the models to compute the
matrix elements of the stress--energy tensor and its two--point correlation
function by means of the spectral representation method.Comment: 52 page
- …