The structure of graphs not admitting a fixed immersion

We present an easy structure theorem for graphs which do not admit an immersion of the complete graph. The theorem motivates the definition of a variation of tree decompositions based on edge cuts instead of vertex cuts which we call tree-cut decompositions. We give a definition for the width of tree-cut decompositions, and using this definition along with the structure theorem for excluded clique immersions, we prove that every graph either has bounded tree-cut width or admits an immersion of a large wall

Hypothermia in the early neonatal period

Background: Hypothermia in neonates is a common problem and is associated with increased morbidity and mortality. Prevention of hypothermia is therefore an essential aspect of neonatal care especially in the immediate neonatal period. Aim: To evaluate the efficacy of thermal care of the neonate in the labour ward at St Luke's Hospital, Malta. Method: Retrospective study analysing the temperature on admission to the nursery from the labour ward. A consecutive sample of 754 neonates admitted during 2002 was studied. Results: The proportion of babies admitted with normal body temperature (36.5-37.5°C) was 25.5%. The rest were mildly (36.0-36.5°C) (42.2%) or moderately (<36.0°C) (32.2%) hypothermic. Significantly less normothermia was evident in winter births (19.6%) than in summer births (38.1%) (Chi squared=26.5, p<0.0001). Implications: The results indicate the need for an improvement in thermal support in the labour ward.peer-reviewe

Pseudoainhum : a dermatological oddity

An eight week old baby presented with a deep constriction round the base of the third right toe, of one day’s duration. A strand of filamentous material was found and uncoiled from the depths of the cleft which subsequently healed within a week. Recurrence in the same digit four weeks later raised the question of factitious disease. Pseudoainhum refers to a constricting band around a digit or limb, congenital or acquired. It must be distinguished from true ainhum, where a painful, idiopathic constriction of the fifth toe in dark-skinned adults results in spontaneous amputation of the digit.peer-reviewe

Community-Based Production of Open Source Software: What Do We Know About the Developers Who Participate?

This paper seeks to close an empirical gap regarding the motivations, personal attributes and behavioral patterns among free/libre and open source (FLOSS) developers, especially those involved in community-based production, and its findings on the existing literature and the future directions for research. Respondents to an extensive web-survey’s (FLOSS-US 2003) questions about their reasons for work on FLOSS are classified according to their distinct “motivational profiles” by hierarchical cluster analysis. Over half of them also are matched to projects of known membership sizes, revealing that although some members from each of the clusters are present in the small, medium and large ranges of the distribution of project sizes, the mixing fractions for the large and the very small project ranges are statistically different. Among developers who changed projects, there is a discernable flow from the bottom toward the very small towards to large projects, some of which is motivated by individuals seeking to improve their programming skills. It is found that the profile of early motivation, along with other individual attributes, significantly affects individual developers’ selections of projects from different regions of the size range.Open source software, FLOSS project, community-based peer production, population heterogeneity, micro-motives, motivational profiles, web-cast surveys, hierarchical cluster analysis

Information Inequality and Network Externalities: A Comparative Study of the Diffusion of Television and the Internet

This paper sheds light on whether intergroup inequality in Internet access is likely to persist as the diffusion process continues. To what extent is a given level of inequality in technology diffusion (e.g., use of the Internet) a long-term policy challenge or a temporary inconvenience? What general factors account for group-specific patterns of technology adoption? This paper draws on notions of network externalities to help answer this question. It also presents findings from a comparative analysis of household adoption of television from 1948 to 1957 and the Internet from 1994 to 2002.

Photometric properties of lunar terrains derived from Hapke's equation

Hapke's bidirectional reflectance equations provide the most rigorous available description of photometric behavior in terms of physically meaningful parameters. The primary objective of this study was to derive Hapke parameters for the lunar surface from both disk-integrated and disk-resolved photometric data. Hapke's equation was fit to the disk-integrated phase curves and disk-resolved data for dark, average, and bright terrain classes using an iterative, nonlinear least squares algorithm described by Helfenstein. Parameters were initially determined from the disk-integrated data, and the result was applied as a first guess to the iterative solution of parameters for individual terrain classes. Plots are presented of the disk-resolved data normalized to corresponding brightnesses predicted from the disk-integrated solution under the same illumination and viewing geometries. Systematic trends in disk-resolved parameters can be identified. Values for single scattering albedo (w) of the dominantly anorthositic average and bright terrains are significantly larger than the value for the basaltic dark terrains (mare). Values for surge brightness parameters, particle phase function, and average topographic slope angle are also discussed

Computation of LQ Approximations to Optimal Policy Problems in Different Information Settings under Zero Lower Bound Constraints

This paper describes a series of algorithms that are used to compute optimal policy under full and imperfect information. Firstly we describe how to obtain linear quadratic (LQ) approximations to a nonlinear optimal policy problem. We develop novel algorithms that are required as a result of having agents with forward-looking expectations, that go beyond the scope of those that are used when all equations are backward-looking; these are utilised to generate impulse response functions and second moments for the case of imperfect information. We describe algorithms for reducing a system to minimal form that are based on conventional approaches, and that are necessary to ensure that a solution for fully optimal policy can be computed. Finally we outline a computational algorithm that is used to generate solutions when there is a zero lower bound constraint for the nominal interest rate.