Travelling waves in a tissue interaction model for skin pattern formation

Tissue interaction plays a major role in many morphogenetic processes, particularly those associated with skin organ primordia. We examine travelling wave solutions in a tissue interaction model for skin pattern formation which is firmly based on the known biology. From a phase space analysis we conjecture the existence of travelling waves with specific wave speeds. Subsequently, analytical approximations to the wave profiles are derived using perturbation methods. We then show numerically that such travelling wave solutions do exist and that they are in good agreement with our analytical results. Finally, the biological implications of our analysis are discussed

Analog communication over selective fading channels Interim technical report

Demodulators for analog communication over slowly time varying, frequency selective fading channel

Sequential pattern formation in a model for skin morphogenesis

During morphogenesis regular patterns often develop behind a frontier of pattern formation which travels across the prospective tissue. Here the authors consider the propagating patterns exhibited in a two-dimensional domain by a tissue interaction mechanochemical model for skin pattern formation. It is shown that the model can exhibit travelling waves of complex spatial pattern formation. Two alternative mechanisms that can produce such sequential patterning are presented. In particular, it is demonstrated that the specification of a simple quasi-one-dimensional pattern is all that is required to determine a complex two-dimensional pattern. Finally, the model solutions are related to actual pattern propagation during chick feather primordia initiation

Multidecadal variability in hydro-climate of Okavango river system, southwest Africa, in the past and under future climate

The focus of this paper is to understand the multi-decadal oscillatory component of variability in the Okavango River system, in southwestern Africa, and its potential evolution through the 21st century under climate change scenarios. Statistical analyses and hydrological modelling are used to show that the observed multi-decadal wet and dry phases in the Okavango River and Delta result from multi-decadal oscillations in rainfall, which are likely to be related to processes of internal variability in the climate system, rather than external natural or anthropogenic forcing. Analyses of changes in this aspect of variability under projected climate change scenarios are based on data from a multi-model ensemble of 19 General Circulation Models, which are used to drive hydrological models of the Okavango River and Delta. Projections for the 21st century indicate a progressive shift towards drier conditions attributed to the influence of increasing temperatures on water balance. It is, however, highly likely that multi-decadal oscillations, possibly of similar magnitude to that of 20th century, will be superimposed on the overall trend. These may periodically offset or amplify the mean drying trend. This effect should be accounted for in water and catchment management and climate change adaptation strategies

Parsimonious Shifted Asymmetric Laplace Mixtures

A family of parsimonious shifted asymmetric Laplace mixture models is introduced. We extend the mixture of factor analyzers model to the shifted asymmetric Laplace distribution. Imposing constraints on the constitute parts of the resulting decomposed component scale matrices leads to a family of parsimonious models. An explicit two-stage parameter estimation procedure is described, and the Bayesian information criterion and the integrated completed likelihood are compared for model selection. This novel family of models is applied to real data, where it is compared to its Gaussian analogue within clustering and classification paradigms

An experimental effort to improve the Nimbus high resolution infrared radiometer Final report, 1 May 1964 - 15 Feb. 1965

Electronics modifications and improved detector cooling for Nimbus high resolution infrared radiomete

Monitoring, cajoling and promoting dialogue: what role for supranational human rights bodies in the implementation of individual decisions?

This article analyses the role of supranational human rights bodies in the implementation of their orders and recommendations in individual cases. It elicits the means, roles and impact of supranational mechanisms in triggering implementation processes by looking at the practice of UN treaty bodies and the three regional systems, through the in-depth study of specific cases and semi-structured interviews with relevant stakeholders. The article argues that supranational bodies are doing more than monitoring implementation of orders and recommendations in individual cases despite the scarcity of resources. They use different tools, both persuasive and coercive. Dialogue is central to their work, a dialogue that at times is opened to other actors such as civil society organizations, national human rights institutions and others. However, supranational bodies could do more to enhance the role they have promoting implementation by states of their orders and recommendations

The Diagnosis of Primary Hypothroidism: A Critical Evaluation of the Clinical Features and Laboratory Aids to Diagnosis

Abstract Not Provided