Prevalence of parent-reported ASD and ADHD in the UK: Findings from the millennium cohort study

The final publication is available at Springer via http://dx.doi.org/10.1007/s10803-013-1849-0The UK prevalence of parent-reported autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD) were estimated from the Millennium Cohort Study. Case definition was if a doctor or health care professional had ever told parents that their child had ASD and/or ADHD. Data were collected in 2008/2009 for 14,043 children. 1.7 % of children were reported as having ASD (95 % CI 1.4-2.0) at mean age 7.2 years (SD = 0.2; range = 6.3-8.2). 1.4 % reportedly had ADHD (95 % CI 1.2-1.7), and 0.3 % had both ASD and ADHD (95 % CI 0.2-0.5). After adjusting for socio-economic disadvantage, only male sex (p < 0.001 for both conditions) and cognitive ability, p = 0.004 (ASD); p = 0.01 (ADHD) remained strongly associated. The observed prevalence of parent-reported ASD is high compared to earlier UK and US estimates. Parent-reported ADHD is low compared to US estimates using the same measure. © 2013 Springer Science+Business Media New York.National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care (CLAHRC) for the South West Peninsul

Profile-Based Optimal Matchings in the Student-Project Allocation Problem

In the Student/Project Allocation problem (spa) we seek to assign students to individual or group projects offered by lecturers. Students provide a list of projects they find acceptable in order of preference. Each student can be assigned to at most one project and there are constraints on the maximum number of students that can be assigned to each project and lecturer. We seek matchings of students to projects that are optimal with respect to profile, which is a vector whose rth component indicates how many students have their rth-choice project. We present an efficient algorithm for finding agreedy maximum matching in the spa context – this is a maximum matching whose profile is lexicographically maximum. We then show how to adapt this algorithm to find a generous maximum matching – this is a matching whose reverse profile is lexicographically minimum. Our algorithms involve finding optimal flows in networks. We demonstrate how this approach can allow for additional constraints, such as lecturer lower quotas, to be handled flexibly

Improved Average Complexity for Comparison-Based Sorting

This paper studies the average complexity on the number of comparisons for sorting algorithms. Its information-theoretic lower bound is $n \lg n - 1.4427n + O(\log n)$. For many efficient algorithms, the first $n\lg n$ term is easy to achieve and our focus is on the (negative) constant factor of the linear term. The current best value is $-1.3999$ for the MergeInsertion sort. Our new value is $-1.4106$, narrowing the gap by some $25\%$. An important building block of our algorithm is "two-element insertion," which inserts two numbers $A$ and $B$, $A<B$, into a sorted sequence $T$. This insertion algorithm is still sufficiently simple for rigorous mathematical analysis and works well for a certain range of the length of $T$ for which the simple binary insertion does not, thus allowing us to take a complementary approach with the binary insertion.Comment: 21 pages, 2 figure

The Quality of Life scale for Children (QoL-C)

This is the author's version of the article, which has been published in final form at http://dx.doi.org/10.1108/JCS-05-2013-0019Purpose – There is a lack of valid and reliable generic measures of Health-Related Quality of Life (HRQoL) for children under eight. The purpose of this paper is to assess the psychometric properties of the newly formulated Quality of Life Scale for Children (QoL-C), which uses a pictorial response format. Design/methodology/approach – In total, 335 primary school children completed the QoL-C on two occasions, two weeks apart. Children aged four to seven were interviewed one-to-one while children aged eight to nine completed the measure as a class activity. Test-re-test reliability, convergent validity and child-parent concordance were assessed. Findings – Only one child refused to complete the QoL-C, which suggests the measure is user-friendly. Test-re-test reliability was moderate for the measure's total score (intraclass correlation coefficient =0.48, 95 percent CI 0.39, 0.57) but low to fair for individual items (K from 0.13 to 0.37). Internal consistency was moderate (α=0.42 time one, 0.53 time two). A small significant correlation was found between the QoL-C and Child Health Meter in the expected direction (r=−0.32), suggesting convergent validity. There was low concordance between the children's QoL-C responses and parent's responses (r=0.19) to a parallel measure. Research limitations/implications – The results suggest that further development of this measure is needed. However, the findings indicate that one-to-one support increases the reliability of very young children's responses. The use of pictures, emoticons and minimal text used in the QoL-C should be investigated further. Originality/value – Low parent-child concordance underscores the importance of younger children getting the opportunity to share their views about their HRQoL

The Complexity of Routing with Few Collisions

We study the computational complexity of routing multiple objects through a network in such a way that only few collisions occur: Given a graph $G$ with two distinct terminal vertices and two positive integers $p$ and $k$, the question is whether one can connect the terminals by at least $p$ routes (e.g. paths) such that at most $k$ edges are time-wise shared among them. We study three types of routes: traverse each vertex at most once (paths), each edge at most once (trails), or no such restrictions (walks). We prove that for paths and trails the problem is NP-complete on undirected and directed graphs even if $k$ is constant or the maximum vertex degree in the input graph is constant. For walks, however, it is solvable in polynomial time on undirected graphs for arbitrary $k$ and on directed graphs if $k$ is constant. We additionally study for all route types a variant of the problem where the maximum length of a route is restricted by some given upper bound. We prove that this length-restricted variant has the same complexity classification with respect to paths and trails, but for walks it becomes NP-complete on undirected graphs

On fractionality of the path packing problem

In this paper, we study fractional multiflows in undirected graphs. A fractional multiflow in a graph G with a node subset T, called terminals, is a collection of weighted paths with ends in T such that the total weights of paths traversing each edge does not exceed 1. Well-known fractional path packing problem consists of maximizing the total weight of paths with ends in a subset S of TxT over all fractional multiflows. Together, G,T and S form a network. A network is an Eulerian network if all nodes in N\T have even degrees. A term "fractionality" was defined for the fractional path packing problem by A. Karzanov as the smallest natural number D so that there exists a solution to the problem that becomes integer-valued when multiplied by D. A. Karzanov has defined the class of Eulerian networks in terms of T and S, outside which D is infinite and proved that whithin this class D can be 1,2 or 4. He conjectured that D should be 1 or 2 for this class of networks. In this paper we prove this conjecture.Comment: 18 pages, 5 figures in .eps format, 2 latex files, main file is kc13.tex Resubmission due to incorrectly specified CS type of the article; no changes to the context have been mad

Social Cost Guarantees in Smart Route Guidance

We model and study the problem of assigning traffic in an urban road network infrastructure. In our model, each driver submits their intended destination and is assigned a route to follow that minimizes the social cost (i.e., travel distance of all the drivers). We assume drivers are strategic and try to manipulate the system (i.e., misreport their intended destination and/or deviate from the assigned route) if they can reduce their travel distance by doing so. Such strategic behavior is highly undesirable as it can lead to an overall suboptimal traffic assignment and cause congestion. To alleviate this problem, we develop moneyless mechanisms that are resilient to manipulation by the agents and offer provable approximation guarantees on the social cost obtained by the solution. We then empirically test the mechanisms studied in the paper, showing that they can be effectively used in practice in order to compute manipulation resistant traffic allocations

Algorithms for flows over time with scheduling costs

Flows over time have received substantial attention from both an optimization and (more recently) a game-theoretic perspective. In this model, each arc has an associated delay for traversing the arc, and a bound on the rate of flow entering the arc; flows are time-varying. We consider a setting which is very standard within the transportation economic literature, but has received little attention from an algorithmic perspective. The flow consists of users who are able to choose their route but also their departure time, and who desire to arrive at their destination at a particular time, incurring a scheduling cost if they arrive earlier or later. The total cost of a user is then a combination of the time they spend commuting, and the scheduling cost they incur. We present a combinatorial algorithm for the natural optimization problem, that of minimizing the average total cost of all users (i.e., maximizing the social welfare). Based on this, we also show how to set tolls so that this optimal flow is induced as an equilibrium of the underlying game

Developmental white matter microstructure in autism phenotype and corresponding endophenotype during adolescence.

During adolescence, white matter microstructure undergoes an important stage of development. It is hypothesized that the alterations of brain connectivity that have a key role in autism spectrum conditions (ASCs) may interact with the development of white matter microstructure. This interaction may be present beyond the phenotype of autism in siblings of individuals with ASC, who are 10 to 20 times more likely to develop certain forms of ASC. We use diffusion tensor imaging to examine how white matter microstructure measurements correlate with age in typically developing individuals, and how this correlation differs in n=43 adolescents with ASC and their n=38 siblings. Correlations observed in n=40 typically developing individuals match developmental changes noted in previous longitudinal studies. In comparison, individuals with ASC display weaker negative correlation between age and mean diffusivity in a broad area centred in the right superior longitudinal fasciculus. These differences may be caused either by increased heterogeneity in ASC or by temporal alterations in the group's developmental pattern. Siblings of individuals with ASC also show diminished negative correlation between age and one component of mean diffusivity-second diffusion eigenvalue-in the right superior longitudinal fasciculus. As the observed differences match for location and correlation directionality in our comparison of typically developing individuals to those with ASC and their siblings, we propose that these alterations constitute a part of the endophenotype of autism.This research was funded by an MRC Clinician Scientist Fellowship to MDS from the UK Medical Research Council (G0701919). LRC was supported by the Gates Cambridge Scholarship Trust. SB-C was supported by the Wellcome Trust, the MRC and the Autism Research Trust, during the period of this work.This is the final published version. It first appeared at http://www.nature.com/tp/journal/v5/n3/full/tp201523a.html

New and simple algorithms for stable flow problems

Stable flows generalize the well-known concept of stable matchings to markets in which transactions may involve several agents, forwarding flow from one to another. An instance of the problem consists of a capacitated directed network, in which vertices express their preferences over their incident edges. A network flow is stable if there is no group of vertices that all could benefit from rerouting the flow along a walk. Fleiner established that a stable flow always exists by reducing it to the stable allocation problem. We present an augmenting-path algorithm for computing a stable flow, the first algorithm that achieves polynomial running time for this problem without using stable allocation as a black-box subroutine. We further consider the problem of finding a stable flow such that the flow value on every edge is within a given interval. For this problem, we present an elegant graph transformation and based on this, we devise a simple and fast algorithm, which also can be used to find a solution to the stable marriage problem with forced and forbidden edges. Finally, we study the stable multicommodity flow model introduced by Kir\'{a}ly and Pap. The original model is highly involved and allows for commodity-dependent preference lists at the vertices and commodity-specific edge capacities. We present several graph-based reductions that show equivalence to a significantly simpler model. We further show that it is NP-complete to decide whether an integral solution exists