1,617 research outputs found
Leadership Through Friendship: The Dangers and Advantages of State Leaders Establishing Close Personal Relations
Logics for Unranked Trees: An Overview
Labeled unranked trees are used as a model of XML documents, and logical
languages for them have been studied actively over the past several years. Such
logics have different purposes: some are better suited for extracting data,
some for expressing navigational properties, and some make it easy to relate
complex properties of trees to the existence of tree automata for those
properties. Furthermore, logics differ significantly in their model-checking
properties, their automata models, and their behavior on ordered and unordered
trees. In this paper we present a survey of logics for unranked trees
Domiciliary chemotherapy with gemcitabine is safe and acceptable to advanced non-small-cell lung cancer patients: results of a feasibility study
Exotic spacetimes, superconducting strings with linear momentum, and (not quite) all that
We derive the general exact vacuum metrics associated with a stationary (non
static), non rotating, cylindrically symmetric source. An analysis of the
geometry described by these vacuum metrics shows that they contain a subfamily
of metrics that, although admitting a consistent time orientation, display
"exotic" properties, such as "trapping" of geodesics and closed causal curves
through every point. The possibility that such spacetimes could be generated by
a superconducting string, endowed with a neutral current and momentum, has
recently been considered by Thatcher and Morgan. Our results, however, differ
from those found by Thatcher and Morgan, and the discrepancy is explained. We
also analyze the general possibility of constructing physical sources for the
exotic metrics, and find that, under certain restrictions, they must always
violate the dominant energy condition (DEC). We illustrate our results by
explicitly analyzing the case of concentric shells, where we find that in all
cases the external vacuum metric is non exotic if the matter in the shells
satisfies the DEC.Comment: 13 pages with no figures. Accepted in PR
Adaptive walks on time-dependent fitness landscapes
The idea of adaptive walks on fitness landscapes as a means of studying
evolutionary processes on large time scales is extended to fitness landscapes
that are slowly changing over time. The influence of ruggedness and of the
amount of static fitness contributions are investigated for model landscapes
derived from Kauffman's landscapes. Depending on the amount of static
fitness contributions in the landscape, the evolutionary dynamics can be
divided into a percolating and a non-percolating phase. In the percolating
phase, the walker performs a random walk over the regions of the landscape with
high fitness.Comment: 7 pages, 6 eps-figures, RevTeX, submitted to Phys. Rev.
The transformative potential of reflective diaries for elite English cricketers
The sport of cricket has a history of its players suffering from mental health issues. The psychological study of cricket and, in particular, the attendant demands of participating at an elite level has not previously received rigorous academic attention. This study explored ten elite male cricketers’ experiences of keeping a daily reflective diary for one month during the competitive season. The aim was to assess how valuable qualitative diaries are in this field. Participants were interviewed regarding their appraisal of the methodology as a self‐help tool that could assist coping with performance pressures and wider life challenges. Three outcomes were revealed: first, that diary keeping was an effective opportunity to reflect upon the past and enhance one’s self (both as an individual and a performer); second, that diary keeping acted as a form of release that allowed participants to progress; and third, that diary keeping allowed participants to discover personal patterns of success that increased the likeliness of optimum performance
- …