Children conceived by in vitro fertilisation after fresh embryo transfer

AIMS: To compare the outcome in in vitro fertilisation (IVF) children (after fresh embryo transfer) from multiple and singleton births with one another, and with normally conceived control children. METHODS: A cohort of 278 children (150 singletons, 100 twins, 24 triplets and four quadruplets), conceived by IVF after three fresh embryos had been transferred, born between October 1984 and December 1991, and 278 normally conceived control children (all singletons), were followed up for four years after birth. They were assessed for neonatal conditions, minor congenital anomalies, major congenital malformations, cerebral palsy and other disabilities. Control children, all born at term, were matched for age, sex and social class. RESULTS: The ratio of male:female births was 1.03. Forty six per cent of IVF children were from multiple births; 34.9% were from preterm deliveries; and 43.2% weighed less than 2500 g at birth. The IVF singletons were on average born one week earlier than the controls, weighed 400 g less, and had a threefold greater chance of being born by caesarean section. The higher percentage of preterm deliveries was largely due to multiple births and they contributed to neonatal conditions in 45.0% of all IVF children. The types of congenital abnormalities varied: 3.6% of IVF children and 2.5% of controls had minor congenital anomalies, and 2.5% of IVF children and none of the controls had major congenital malformations. The numbers of each specific type of congenital abnormality were small and were not significantly related to multiple births. IVF children (2.1%) and 0.4% of the controls had mild/moderate disabilities. They were all from multiple births, including two children with cerebral palsy who were triplets. CONCLUSIONS: The outcome of IVF treatment leading to multiple births is less satisfactory than that in singletons because of neonatal conditions associated with preterm delivery and disabilities in later childhood. A reduction of multiple pregnancies by limiting the transfer of embryos to two instead of three remains a high priority.     

Robust real-time unusual event detection using multiple fixed-location monitors

We present a novel algorithm for detection of certain types of unusual events. The algorithm is based on multiple local monitors which collect low-level statistics. Each local monitor produces an alert if its current measurement is unusual, and these alerts are integrated to a final decision regarding the existence of an unusual event. Our algorithm satisfies a set of requirements that are critical for successful deployment of any large-scale surveillance system. In particular it requires a minimal setup (taking only a few minutes) and is fully automatic afterwards. Since it is not based on objects' tracks, it is robust and works well in crowded scenes where tracking-based algorithms are likely to fail. The algorithm is effective as soon as sufficient low-level observations representing the routine activity have been collected, which usually happens after a few minutes. Our algorithm runs in realtime. It was tested on a variety of real-life crowded scenes. A ground-truth was extracted for these scenes, with respect to which detection and false-alarm rates are reported.     

On Scene Segmentation and Histograms-Based Curve Evolution

We consider curve evolution based on comparing distributions of features, and its applications for scene segmentation. In the first part, we promote using cross-bin metrics such as the Earth Mover's Distance (EMD), instead of standard bin-wise metrics as the Bhattacharyya or Kullback-Leibler metrics. To derive flow equations for minimizing functionals involving the EMD, we employ a tractable expression for calculating EMD between one-dimensional distributions. We then apply the derived flows to various examples of single image segmentation, and to scene analysis using video data. In the latter, we consider the problem of segmenting a scene to spatial regions in which different activities occur. We use a nonparametric local representation of the regions by considering multiple one-dimensional histograms of normalized spatiotemporal derivatives. We then obtain semisupervised segmentation of regions using the flows derived in the first part of the paper. Our results are demonstrated on challenging surveillance scenes, and compare favorably with state-of-the-art results using parametric representations by dynamic systems or mixtures of them.     

Pose and motion recovery from feature correspondences and a digital terrain map

A novel algorithm for pose and motion estimation using corresponding features and a digital terrain map is proposed. Using a digital terrain (or digital elevation) map (DTM/DEM) as a global reference enables the elimination of the ambiguity present in vision-based algorithms for motion recovery. As a consequence, the absolute position and orientation of a camera can be recovered with respect to the external reference frame. In order to do this, the DTM is used to formulate a constraint between corresponding features in two consecutive frames. Explicit reconstruction of the 3D world is not required. When considering a number of feature points, the resulting constraints can be solved using nonlinear optimization in terms of position, orientation, and motion. Such a procedure requires an initial guess of these parameters, which can be obtained from dead-reckoning or any other source. The feasibility of the algorithm is established through extensive experimentation. Performance is compared with a state-of-the-art alternative algorithm, which intermediately reconstructs the 3D structure and then registers it to the DTM. A clear advantage for the novel algorithm is demonstrated in variety of scenarios.     

Tracking by Affine Kernel Transformations Using Color and Boundary Cues

Kernel-based trackers aggregate image features within the support of a kernel (a mask) regardless of their spatial structure. These trackers spatially fit the kernel (usually in location and in scale) such that a function of the aggregate is optimized. We propose a kernel-based visual tracker that exploits the constancy of color and the presence of color edges along the target boundary. The tracker estimates the best affinity of a spatially aligned pair of kernels, one of which is color-related and the other of which is object boundary-related. In a sense, this work extends previous kernel-based trackers by incorporating the object boundary cue into the tracking process and by allowing the kernels to be affinely transformed instead of only translated and isotropically scaled. These two extensions make for more precise target localization. A more accurately localized target also facilitates safer updating of its reference color model, further enhancing the tracker's robustness. The improved tracking is demonstrated for several challenging image sequences.     

Graphbots: cooperative motion planning in discrete spaces

Most previous theoretical work on motion planning for a group of robots has addressed the problem of path planning for the individual robots sequentially, in geometrically simple regions of Euclidean space (e.g. a planar region containing polygonal obstacles). In this paper, we define a version of the motion-planning problem in which the robots move simultaneously. We establish conditions under which a team of robots having a particular configuration can move from any start location to any goal destination in a graph-structured space. We show that, for a group of robots that maintain a fixed formation, we can find the “shortest” path in polynomial time, and we give faster algorithms for special kinds of environments     

A mathematical model for metal flow and heat transfer in centrifuge melt spinning

Centrifuge melt spinning (CMS) is a technique used for the production of rapidly solidified metallic ribbons, in which the liquid metal is ejected centrifugally from a rotating crucible onto a quenching copper rim which rotates in the direction opposite the crucible. A numerical model has been developed to describe the hydraulic features of the alloy melt stream, together with the heat flow in the solidifying melt. The model takes into account, among other things, the dragging mechanism caused by the counter-rotation of the casting crucible and the quenching rim, the additional spreading velocity imparted to the melt by centrifugal forces developing on the rotating rim, the increase of heat transfer in the melt due to convection, and the changes of the viscosity of the melt with temperature. Comparison of the mathematical model with experimental results obtained for an Al-12 at. pct Ge alloy indicates that CMS is characterized by heat-transfer coefficients ranging from 3 to 11 * 10⁶ W m⁻² K⁻¹ depending mainly on the velocities of the casting crucible and the rim. The effect of various process parameters, such as crucible and rim velocities, on the dimensions of the obtained ribbons and the effect of the enhanced heat flow in the melt on the reduction of thermal gradients in the ribbon are presented.     

Blaschke products and optimal recovery inH ∞

We examine the error in the optimal estimation of∫ ₋₁ ¹ f(t)w(t)dt by a quadrature formula using values off at equally spaced points of (−1, 1) or at the zeros of ultraspherical polynomials. Heref is known to be an analytic function in the unit disc which is bounded by l andw is a given weight function with prescribed behavior near ±1. A major role in our investigations is played by bounds on (−1, 1) from above and below for the finite Blaschke product which is based in the nodes of the quadrature formula. Optimal estimation of the functionf, rather than its integral, is also studied.