8,761 research outputs found
Measurement of the W Mass at LEP2
The mass of the W boson has been measured by the LEP collaborations from the
data recorded during the LEP2 programme at e+ e- centre of mass energies from
161 to 209 GeV, giving the result : mw = 80.450 +/- 0.039 GeV/c^2. This paper
discusses the measurements of the W Mass from direct reconstruction of the
invariant mass of the WW decay products, particular emphasis is placed on the
evaluation of systematic errors. Results on the direct measurement of the W
width are also presented.Comment: Contribution to XXXVIIth Moriond Electroweak Conference, March 2002.
6 pages, 3 figures This version with typos correcte
Solitary-wave solutions of the Degasperis-Procesi equation by means of the homotopy analysis method
The homotopy analysis method is applied to the Degasperis-Procesi equation in order to find analytic approximations to the known exact solitary-wave solutions for the solitary peakon wave and the family of solitary smooth-hump waves. It is demonstrated that the approximate solutions agree well with the exact solutions. This provides further evidence that the homotopy analysis method is a powerful tool for finding excellent approximations to nonlinear solitary waves
Chain: A Dynamic Double Auction Framework for Matching Patient Agents
In this paper we present and evaluate a general framework for the design of
truthful auctions for matching agents in a dynamic, two-sided market. A single
commodity, such as a resource or a task, is bought and sold by multiple buyers
and sellers that arrive and depart over time. Our algorithm, Chain, provides
the first framework that allows a truthful dynamic double auction (DA) to be
constructed from a truthful, single-period (i.e. static) double-auction rule.
The pricing and matching method of the Chain construction is unique amongst
dynamic-auction rules that adopt the same building block. We examine
experimentally the allocative efficiency of Chain when instantiated on various
single-period rules, including the canonical McAfee double-auction rule. For a
baseline we also consider non-truthful double auctions populated with
zero-intelligence plus"-style learning agents. Chain-based auctions perform
well in comparison with other schemes, especially as arrival intensity falls
and agent valuations become more volatile
Generalizing Boolean Satisfiability I: Background and Survey of Existing Work
This is the first of three planned papers describing ZAP, a satisfiability
engine that substantially generalizes existing tools while retaining the
performance characteristics of modern high-performance solvers. The fundamental
idea underlying ZAP is that many problems passed to such engines contain rich
internal structure that is obscured by the Boolean representation used; our
goal is to define a representation in which this structure is apparent and can
easily be exploited to improve computational performance. This paper is a
survey of the work underlying ZAP, and discusses previous attempts to improve
the performance of the Davis-Putnam-Logemann-Loveland algorithm by exploiting
the structure of the problem being solved. We examine existing ideas including
extensions of the Boolean language to allow cardinality constraints,
pseudo-Boolean representations, symmetry, and a limited form of quantification.
While this paper is intended as a survey, our research results are contained in
the two subsequent articles, with the theoretical structure of ZAP described in
the second paper in this series, and ZAP's implementation described in the
third
Gender Violence in Poverty Contexts: The Educational Challenge
This book is concerned with understanding the complex ways in which gender violence and poverty impact on young people?s lives, and with the potential for education to challenge violence. Although there is a growing literature looking at the links between violence, gender or poverty and education in developing countries, few studies look at the interconnections between all these themes. A key premise of this book is that in order to understand the many dimensions of violence in young people?s lives, these interconnections need to be examined. This book is the first major attempt to define the field of gender violence studies in education in poverty contexts. We do this by setting out relevant theoretical perspectives, empirical methodologies and case studies of the impact of gender violence on young people?s lives in families, schools and communities. There are three interrelated aims: 1. To build theoretical and methodological framings for understanding the relationship between gender, violence, poverty and education 2. To explore how young people living in varying contexts of poverty in the Global South learn about, engage in, respond to and resist gender violence 3. To investigate how institutions, including schools, families, communities, governments, international and non-governmental organisations and the media constrain or expand possibilities to challenge gender violence in the Global South The book, edited by Jenny Parkes, combines chapters by well-known and emerging scholars undertaking research on violence
Challenges for Curriculum Leadership in Contemporary Teacher Education
This paper outlines the complex contemporary milieu of Australian teacher education within which curriculum leaders responsible for designing teacher education programs must make their program design decisions. Particular attention is paid to the collision of vertical (‘hierarchical’ or \u27academic rationalist\u27) and horizontal (‘flat’ or \u27student-centred\u27) curriculum discourses as a program design problem that has emerged within the current context; how it is intensified by an unexpected alliance between progressivist and new managerial curriculum discourses; and how this problem may be amplified in graduate entry teacher education programs. This paper concludes with a provocation to see the curriculum tensions and conditions outlined as offering a challenging design problem for the current generation of curriculum leaders responsible for the assembly of teacher education programs
Generalizing Boolean Satisfiability II: Theory
This is the second of three planned papers describing ZAP, a satisfiability
engine that substantially generalizes existing tools while retaining the
performance characteristics of modern high performance solvers. The fundamental
idea underlying ZAP is that many problems passed to such engines contain rich
internal structure that is obscured by the Boolean representation used; our
goal is to define a representation in which this structure is apparent and can
easily be exploited to improve computational performance. This paper presents
the theoretical basis for the ideas underlying ZAP, arguing that existing ideas
in this area exploit a single, recurring structure in that multiple database
axioms can be obtained by operating on a single axiom using a subgroup of the
group of permutations on the literals in the problem. We argue that the group
structure precisely captures the general structure at which earlier approaches
hinted, and give numerous examples of its use. We go on to extend the
Davis-Putnam-Logemann-Loveland inference procedure to this broader setting, and
show that earlier computational improvements are either subsumed or left intact
by the new method. The third paper in this series discusses ZAPs implementation
and presents experimental performance results
Genetic variability, stability and heritability for quality and yield characteristics in provitamin A cassava varieties
Open Access Article; Published online: 25 Jan 2020Cassava is widely consumed in many areas of Africa, including Ghana, and is a major part of most household diets. These areas are characterized by rampant malnutrition, because the tuberous roots are low in nutritional value. Provitamin A biofortified cassava varieties have been developed by the International Institute for Tropical Agriculture, but adoption of these varieties in Ghana will largely depend on their agronomic performance, including fresh root yield, dry matter content, resistance to major pests and diseases, mealiness, starch content and the stability of these traits. Eight provitamin A varieties with two white checks were planted in three environments for two seasons to determine stability and variability among the varieties for important traits. There were significant variations in performance between varieties and between environments for cassava mosaic disease, root number, fresh root yield and starch content. High broad-sense heritability and genetic advance were observed in all traits, except for storage root number, and could be exploited through improvement programs. This study identified the best performing enhanced provitamin A varieties for traits that are key drivers of variety adoption in Ghana. In view of this, some varieties can be recommended for varietal release after on-farm testing. The study also showed the possibility of tapping heterosis after careful selection of parents
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