2,834 research outputs found
Constructions for cyclic sieving phenomena
We show how to derive new instances of the cyclic sieving phenomenon from old
ones via elementary representation theory. Examples are given involving objects
such as words, parking functions, finite fields, and graphs.Comment: 18 pages, typos fixed, to appear in SIAM J. Discrete Mat
Getting science to the citizen : 'food addiction' at the British Science Festival as a case study of interactive public engagement with high profile scientific controversy
Non peer reviewedPublisher PD
Interlaced particle systems and tilings of the Aztec diamond
Motivated by the problem of domino tilings of the Aztec diamond, a weighted
particle system is defined on lines, with line containing
particles. The particles are restricted to lattice points from 0 to , and
particles on successive lines are subject to an interlacing constraint. It is
shown that marginal distributions for this particle system can be computed
exactly. This in turn is used to give unified derivations of a number of
fundamental properties of the tiling problem, for example the evaluation of the
number of distinct configurations and the relation to the GUE minor process. An
interlaced particle system associated with the domino tiling of a certain half
Aztec diamond is similarly defined and analyzed.Comment: 17 pages, 4 figure
Statistics of leading digits leads to unification of quantum correlations
We show that the frequency distribution of the first significant digits of
the numbers in the data sets generated from a large class of measures of
quantum correlations, which are either entanglement measures, or belong to the
information-theoretic paradigm, exhibit a universal behaviour. In particular,
for Haar uniformly simulated arbitrary two-qubit states, we find that the
first-digit distribution corresponding to a collection of chosen computable
quantum correlation quantifiers tend to follow the first-digit law, known as
the Benford's law, when the rank of the states increases. Considering a
two-qubit state which is obtained from a system governed by paradigmatic spin
Hamiltonians, namely, the XY model in a transverse field, and the XXZ model, we
show that entanglement as well as information theoretic measures violate the
Benford's law. We quantitatively discuss the violation of the Benford's law by
using a violation parameter, and demonstrate that the violation parameter can
signal quantum phase transitions occurring in these models. We also comment on
the universality of the statistics of first significant digits corresponding to
appropriate measures of quantum correlations in the case of multipartite
systems as well as systems in higher dimensions.Comment: v1: 11 pages, 5 figures, 2 tables; v2: 11 pages, 6 figures, 2 tables,
new results added, extended version of the published pape
Surgical Management of Inguinal Hernias at Bugando Medical Centre in Northwestern Tanzania: Our Experiences in a Resource-Limited Setting.
Inguinal hernia repair remains the commonest operation performed by general surgeons all over the world. There is paucity of published data on surgical management of inguinal hernias in our environment. This study is intended to describe our own experiences in the surgical management of inguinal hernias and compare our results with that reported in literature. A descriptive prospective study was conducted at Bugando Medical Centre in northwestern Tanzania. Ethical approval to conduct the study was obtained from relevant authorities before the commencement of the study. Statistical data analysis was done using SPSS software version 17.0. A total of 452 patients with inguinal hernias were enrolled in the study. The median age of patients was 36 years (range 3 months to 78 years). Males outnumbered females by a ratio of 36.7:1. This gender deference was statistically significant (P=0.003). Most patients (44.7%) presented late (more than five years of onset of hernia). Inguinoscrotal hernia (66.8%) was the commonest presentation. At presentation, 208 (46.0%) patients had reducible hernia, 110 (24.3%) had irreducible hernia, 84 (18.6%) and 50(11.1%) patients had obstructed and strangulated hernias respectively. The majority of patients (53.1%) had right sided inguinal hernia with a right-to-left ratio of 2.1: 1. Ninety-two (20.4%) patients had bilateral inguinal hernias. 296 (65.5%) patients had indirect hernia, 102 (22.6%) had direct hernia and 54 (11.9%) had both indirect and direct types (pantaloon hernia). All patients in this study underwent open herniorrhaphy. The majority of patients (61.5%) underwent elective herniorrhaphy under spinal anaesthesia (69.2%). Local anaesthesia was used in only 1.1% of cases. Bowel resection was required in 15.9% of patients. Modified Bassini's repair (79.9%) was the most common technique of posterior wall repair of the inguinal canal. Lichtenstein mesh repair was used in only one (0.2%) patient. Complication rate was 12.4% and it was significantly higher in emergency herniorrhaphy than in elective herniorrhaphy (P=0.002). The median length of hospital stay was 8 days and it was significantly longer in patients with advanced age, delayed admission, concomitant medical illness, high ASA class, the need for bowel resection and in those with surgical repair performed under general anesthesia (P<0.001). Mortality rate was 9.7%. Longer duration of symptoms, late hospitalization, coexisting disease, high ASA class, delayed operation, the need for bowel resection and presence of complications were found to be predictors of mortality (P<0.001). Inguinal hernias continue to be a source of morbidity and mortality in our centre. Early presentation and elective repair of inguinal hernias is pivotal in order to eliminate the morbidity and mortality associated with this very common problem
A Software Process Improvement Roadmap for IEC 62304: an Expert Review
Manufacturers of medical devices must comply with certain legislation and regulations before they can market their products in the European Union (EU). The EU has introduced this legislation and regulation to provide the frameworks by which manufacturers can produce safe and effective medical devices in a consistent manner. The EU has accomplished this by way of Medical Device Directives and harmonised standards. Manufactures, by demonstrating compliance with a harmonised standard, can be presumed to have complied with the essential requirements of the legislation. IEC 62304 Medical device software â Software lifecycle processes is a harmonised standard. However, the standard provides no clear directions for meeting the requirements of the standard. A Software Process Improvement (SPI) Roadmap for IEC 62304:2006 has been developed as a method for aiding medical device software development organizations in implementing the standard. The Roadmap is divided into two levels, the high level consists of the Activities and Tasks necessary for the im-plementation of the standard, while the low level contains the Design Patterns and How-to artefacts linked to the Tasks. This paper presents the findings from the expert review of the high level roadmap
Accessibility levels of Portuguese Enterprise websites: Equal opportunities for all?
Artigo revisto disponĂvel online 18 Maio, 2011 (iFirst)Web accessibility is growing in importance as time goes by. Alongside this growth we find an increasing need for access to Web resources by those with some sort of disability. The Web is very important for spreading information and for promoting interaction between the various elements in society. Given this, it is essential that the Web presents itself as a totally accessible resource, so that it can help disabled citizens and their integration in society. This obligation should be even greater for enterprises as primarily the Web is used as a marketing and business platform.
With this document we present indicators regarding the [lack of] accessibility levels of Portuguese websites. This article is divided into eight parts containing theoretical and background considerations leading up to two different studies which the research team undertook. In the first study (considering WCAG 1.0) we make a comparison between the 1,000 largest Portuguese enterprises (annual sales volume) and the 1,000 best Portuguese SMEs1 using a specialized software tool. In the second study a group of recommendations towards accessibility are made; these recommendations were achieved through a focus group interaction. We do also, however, present an insight into the WCAG 2.0 influence on existent accessibility levels
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