Evolving management for critical pulmonary stenosis in neonates and young infants

Over the years, management of critical pulmonary stenosis in young infants has evolved from surgical reconstruction of the right ventricular outflow tract and closed pulmonary valvotomy to transcatheter balloon valvoplasty. Our study aimed at evaluating how the changing policy for management had affected the immediate and long term outcomes of babies with this cardiac lesion. Interventions were made in 34 infants at a median age of 8.5 days (2-90 days). Reconstruction of the right ventricular outflow tract reconstruction was performed in 10 patients, closed pulmonary valvotomy in 13, and balloon valvoplasty in 11. Initial procedure-related mortality was 50%, 15% and 0% respectively. Multivariate analysis revealed transannular patching of the right ventricular outflow tract, and male sex, to be significant factors for death. For the 27 survivors, the ratio of right ventricular to systemic systolic pressure decreased from 1.6 ± 0.3 to 0.3 ± 0.2 after reconstruction of the outflow tract, 1.8 ± 0.5 to 0.8 ± 0.4 after closed valvotomy, and 1.8 ± 0.6 to 0.9 ± 0.3 after balloon valvoplasty. The decrease was significantly greater after patch reconstruction (p=0.025) that required no further reinterventions. The overall rate of reintervention for the survivors was 37% (10/27). The freedom from reintervention after closed valvotomy was 82%, 64% and 51% at 1, 5 and 10 years respectively. The figure remained at 78% at both 1 and 5 years (p=0.66) after balloon valvoplasty. The higher reintervention rate for closed valvotomy corresponded to the significantly greater residual gradient across the pulmonary valve noted on follow-up (p=0.01). Reinterventions included balloon dilation (n=6), reconstruction of the outflow tract (n=4), and 1 each of ligation of an arterial duct and systemic-pulmonary arterial shunting. The risk factor for reintervention was a hypoplastic right ventricle. In conclusion, transcatheter balloon valvoplasty appears to be the optimum initial approach in view of its low mortality, efficacy at relieving the obstruction, and low rate of reintervention. © Greenwich Medical Media Ltd.published_or_final_versio

Accreting Neutron Stars in Low-Mass X-Ray Binary Systems

Using the Rossi X-ray Timing Explorer (RossiXTE), astronomers have discovered that disk-accreting neutron stars with weak magnetic fields produce three distinct types of high-frequency X-ray oscillations. These oscillations are powered by release of the binding energy of matter falling into the strong gravitational field of the star or by the sudden nuclear burning of matter that has accumulated in the outermost layers of the star. The frequencies of the oscillations reflect the orbital frequencies of gas deep in the gravitational field of the star and/or the spin frequency of the star. These oscillations can therefore be used to explore fundamental physics, such as strong-field gravity and the properties of matter under extreme conditions, and important astrophysical questions, such as the formation and evolution of millisecond pulsars. Observations using RossiXTE have shown that some two dozen neutron stars in low-mass X-ray binary systems have the spin rates and magnetic fields required to become millisecond radio-emitting pulsars when accretion ceases, but that few have spin rates above about 600 Hz. The properties of these stars show that the paucity of spin rates greater than 600 Hz is due in part to the magnetic braking component of the accretion torque and to the limited amount of angular momentum that can be accreted in such systems. Further study will show whether braking by gravitational radiation is also a factor. Analysis of the kilohertz oscillations has provided the first evidence for the existence of the innermost stable circular orbit around dense relativistic stars that is predicted by strong-field general relativity. It has also greatly narrowed the possible descriptions of ultradense matter.Comment: 22 pages, 7 figures, updated list of sources and references, to appear in "Short-period Binary Stars: Observation, Analyses, and Results", eds. E.F. Milone, D.A. Leahy, and D. Hobill (Dordrecht: Springer, http://www.springerlink.com

The clinical features of the piriformis syndrome: a systematic review

Piriformis syndrome, sciatica caused by compression of the sciatic nerve by the piriformis muscle, has been described for over 70 years; yet, it remains controversial. The literature consists mainly of case series and narrative reviews. The objectives of the study were: first, to make the best use of existing evidence to estimate the frequencies of clinical features in patients reported to have PS; second, to identify future research questions. A systematic review was conducted of any study type that reported extractable data relevant to diagnosis. The search included all studies up to 1 March 2008 in four databases: AMED, CINAHL, Embase and Medline. Screening, data extraction and analysis were all performed independently by two reviewers. A total of 55 studies were included: 51 individual and 3 aggregated data studies, and 1 combined study. The most common features found were: buttock pain, external tenderness over the greater sciatic notch, aggravation of the pain through sitting and augmentation of the pain with manoeuvres that increase piriformis muscle tension. Future research could start with comparing the frequencies of these features in sciatica patients with and without disc herniation or spinal stenosis

Not just a matter of size:a hospital-level risk factor analysis of MRSA bacteraemia in Scotland

Background: Worldwide, there is a wealth of literature examining patient-level risk 6 factors for methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia. At the hospital-level it is generally accepted that MRSA bacteraemia is more common in larger hospitals. In Scotland, size does not fully explain all the observed variation among hospitals. The aim of this study was to identify risk factors for the presence and rate of MRSA bacteraemia cases in Scottish mainland hospitals. Specific hypotheses regarding hospital size, type and connectivity were examined. Methods: Data from 198 mainland Scottish hospitals (defined as having at least one inpatient per year) were analysed for financial year 2007-08 using logistic regression (Model 1: presence/absence of MRSA bacteraemia) and Poisson regression (Model 2: rate of MRSA bacteraemia). The significance of risk factors representing various measures of hospital size, type and connectivity were investigated. Results: In Scotland, size was not the only significant risk factor identified for the presence and rate of MRSA bacteraemia. The probability of a hospital having at least one case of MRSA bacteraemia increased with hospital size only if the hospital exceeded a certain level of connectivity. Higher levels of MRSA bacteraemia were associated with the large, highly connected teaching hospitals with high ratios of patients to domestic staff. Conclusions: A hospital’s level of connectedness within a network may be a better measure of a hospital’s risk of MRSA bacteraemia than size. This result could be used to identify high risk hospitals which would benefit from intensified infection control measures

Physics of Neutron Star Crusts

The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.Comment: 182 pages, published version available at <http://www.livingreviews.org/lrr-2008-10

A rough set-based association rule approach implemented on exploring beverages product spectrum

[[abstract]]When items are classified according to whether they have more or less of a characteristic, the scale used is referred to as an ordinal scale. The main characteristic of the ordinal scale is that the categories have a logical or ordered relationship to each other. Thus, the ordinal scale data processing is very common in marketing, satisfaction and attitudinal research. This study proposes a new data mining method, using a rough set-based association rule, to analyze ordinal scale data, which has the ability to handle uncertainty in the data classification/sorting process. The induction of rough-set rules is presented as method of dealing with data uncertainty, while creating predictive if—then rules that generalize data values, for the beverage market in Taiwan. Empirical evaluation reveals that the proposed Rough Set Associational Rule (RSAR), combined with rough set theory, is superior to existing methods of data classification and can more effectively address the problems associated with ordinal scale data, for exploration of a beverage product spectrum.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子

Relativistic Binaries in Globular Clusters

Galactic globular clusters are old, dense star systems typically containing 10\super{4}--10\super{7} stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or two compact objects. In this review, we discuss theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution that leads to relativistic binaries, and current and possible future observational evidence for this population. Our discussion of globular cluster evolution will focus on the processes that boost the production of hard binary systems and the subsequent interaction of these binaries that can alter the properties of both bodies and can lead to exotic objects. Direct {\it N}-body integrations and Fokker--Planck simulations of the evolution of globular clusters that incorporate tidal interactions and lead to predictions of relativistic binary populations are also discussed. We discuss the current observational evidence for cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries as well as possible future detection of relativistic binaries with gravitational radiation.Comment: 88 pages, 13 figures. Submitted update of Living Reviews articl

The Role of Binary Pulsars in Testing Gravity Theories

Radio pulsars are neutron stars (NSs) which emit collimated beams of radio waves, observed as pulses, once per rotation of the NS. A subgroup of the radio pulsars behave as highly stable clocks and monitoring the times of arrival of their radio pulses can provide an accurate determination of their positional, rotational, and orbital parameters, as well as indications on the properties of their space-time environment. In this chapter, we focus on the so-called relativistic binary pulsars, recycled NSs orbiting around a compact companion star. Some of them can be used as unique tools to test general relativity and other gravitational theories. The methodology for exploiting these sources as laboratories for gravity theories is first explained and then some of the most relevant recent results are reviewed. <P /

An evolutionary approach for discovering effective composite features for text categorization

The study of text categorization has assumed special significance in the Internet era in helping us navigate the ocean of web pages and emails that continue to grow in an unrelenting pace. In many previous works on text classifications, it has been shown that composite features consisting of multiple word tokens like statistical phrases can contribute effectively to the classification task. However finding useful composite features through comprehensive search from the vast number of possibilities is often prohibitive in terms of computing resource requirements. In the past, to make the search feasible, we often limit the search space by imposing some parametric constraints like minimum frequency and/or number of words in the composite feature. In this paper we proposed a new evolutionary approach to find effective composite features for classification, an approach that combines probabilistic feature generation with error-biased sampling We demonstrate the effectiveness of our approach using the Reuters-21578 test collection.Department of ComputingRefereed conference pape

Improving Text Classification Performance by Heuristics-Guided Exploration of Derived Features

One important problem facing text classifiers is the vast amount of features, many of which may not be relevant, that one can use in the classification process. Sleeping-Experts are one of those classifiers which can effectively deal with large number of irrelevant attributes. It is an online multiplicative weight updating algorithm similar to the Winnow algorithm. In its original design, it provided context-sensitive text classification by including 'sparse phrases' in the feature set. Although Sleeping-Experts has the capability to handle a large number of features, the combinatorial explosion of derived features like 'sparse phrases' still leads to substantial ineffectiveness and inefficiency when they are exhaustively examined. In this paper we proposed a heuristics-guided approach to the exploration of derived features in relation to the Sleeping-Experts algorithm. Our experiment results show the use of some simple heuristics can improve both the efficiency and effectiveness of text classification based on such modelDepartment of ComputingRefereed conference pape