Comment: Struggles with Survey Weighting and Regression Modeling

Comment: Struggles with Survey Weighting and Regression Modeling [arXiv:0710.5005]Comment: Published in at http://dx.doi.org/10.1214/088342307000000186 the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

Observations on recruitment of postlarval spiny lobsters, Panulirus argus, to the south Florida coast

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Reduction of electrical noise and crosstalk in guidance system components Progress report, Sep. 1965

Servoamplifier and amplifier-detector inspection for gyroscope and accelerometer servo loop

Block-Conditional Missing at Random Models for Missing Data

Two major ideas in the analysis of missing data are (a) the EM algorithm [Dempster, Laird and Rubin, J. Roy. Statist. Soc. Ser. B 39 (1977) 1--38] for maximum likelihood (ML) estimation, and (b) the formulation of models for the joint distribution of the data ${Z}$ and missing data indicators ${M}$, and associated "missing at random"; (MAR) condition under which a model for ${M}$ is unnecessary [Rubin, Biometrika 63 (1976) 581--592]. Most previous work has treated ${Z}$ and ${M}$ as single blocks, yielding selection or pattern-mixture models depending on how their joint distribution is factorized. This paper explores "block-sequential"; models that interleave subsets of the variables and their missing data indicators, and then make parameter restrictions based on assumptions in each block. These include models that are not MAR. We examine a subclass of block-sequential models we call block-conditional MAR (BCMAR) models, and an associated block-monotone reduced likelihood strategy that typically yields consistent estimates by selectively discarding some data. Alternatively, full ML estimation can often be achieved via the EM algorithm. We examine in some detail BCMAR models for the case of two multinomially distributed categorical variables, and a two block structure where the first block is categorical and the second block arises from a (possibly multivariate) exponential family distribution.Comment: Published in at http://dx.doi.org/10.1214/10-STS344 the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

Real-Time Human Motion Capture with Multiple Depth Cameras

Commonly used human motion capture systems require intrusive attachment of markers that are visually tracked with multiple cameras. In this work we present an efficient and inexpensive solution to markerless motion capture using only a few Kinect sensors. Unlike the previous work on 3d pose estimation using a single depth camera, we relax constraints on the camera location and do not assume a co-operative user. We apply recent image segmentation techniques to depth images and use curriculum learning to train our system on purely synthetic data. Our method accurately localizes body parts without requiring an explicit shape model. The body joint locations are then recovered by combining evidence from multiple views in real-time. We also introduce a dataset of ~6 million synthetic depth frames for pose estimation from multiple cameras and exceed state-of-the-art results on the Berkeley MHAD dataset.Comment: Accepted to computer robot vision 201

The measurement of applied forces during anterior single rod correction of adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is the most common form of spinal deformity in paediatrics, prevalent in approximately 2-4% of the general population. While it is a complex three-dimensional deformity, it is clinically characterised by an abnormal lateral curvature of the spine. The treatment for severe deformity is surgical correction with the use of structural implants. Anterior single rod correction employs a solid rod connected to the anterior spine via vertebral body screws. Correction is achieved by applying compression between adjacent vertebral body screws, before locking each screw onto the rod. Biomechanical complication rates have been reported as high as 20.8%, and include rod breakage, screw pull-out and loss of correction. Currently, the corrective forces applied to the spine are unknown. These forces are important variables to consider in understanding the biomechanics of scoliosis correction. The purpose of this study was to measure these forces intra-operatively during anterior single rod AIS correction

UK and EU policy for approval of pesticides suitable for organic systems: Implications for Wales

This study was commissioned by the Welsh Assembly Government (WAG) to review the pesticide approval system in the UK and Europe as far as it affects the use of substances and techniques for crop protection by organic producers in Wales. WAG considers it important that the UK pesticide approval system does not present unnecessary barriers to the development of organic production in Wales. Key Recommendations and scope for further work · WAG should work with the Pesticides Safety Directorate to ensure that the development of pesticide regulatory policy at both National and European level takes full account of the needs of both conventional and organic agriculture and horticulture in the UK. · There is scope for WAG to support the development of a National Pesticide Policy so that regulatory and commercial barriers impeding the development of organic pesticides are minimised. Not only could greater availability of ‘organic pesticides’ have a significant impact on organic production in Wales but there could be important implications for conventional horticulture systems and the use of alternatives to conventional pesticides. · One important regulatory barrier to the registration of ‘organic pesticides’ is the MRL requirement(s) for their approval and this needs to be resolved. Suitable analytical techniques are required to determine firstly whether these substances result in residues, and secondly to identify the breakdown and residue pathways. So far, this issue has not received the attention of any EU Member State. · According to the proposed framework for the 4th Stage Review of EU Pesticides Directive 91/414, notifiers are required to produce a dossier, at their own expense, covering characterisation, human toxicity, ecotoxicity efficacy and other relevant data. The Review includes specific provision for companies notifying the same substance to submit a shared dossier. This will help those businesses (many of which are relatively small companies) to save on the high cost of producing the dossiers. It will also aid the Commission since it will reduce the number of dossiers that have to be considered, and ensure that all the available data is included. WAG should encourage and support the production of collective dossiers; although as yet there is no indication of how this will be done in practice, and further details from the Commission are awaited. · This study has concluded that access to a wider range of ‘organically acceptable pesticides’ would not have a dramatic impact on organic production in Wales. However, in developing an integrated organic policy, WAG should continue to address the pesticides issue. Some of the methods of pest & disease control in organic systems are either physical or multi-cellular e.g. micro-organisms used as biocontrol agents. WAG agri environment policy may provide a vehicle to promote these techniques much more actively. Further, it is important to recognise that while Wales alone is too small to have a major impact on commercial and regulatory pressures, WAG can have an impact by working pro-actively with others to make progress. · There are no published EU or national Member State criteria that can be used to evaluate the acceptability of pesticide substances for organic production. Identifying such criteria and promoting their acceptance at EU level and nationally would allow more active substances to be made available. WAG should work with PSD and others to identify appropriate criteria. · The specific provisions of Article 7 in Annex 2(b) of the Organic Regulation (2092/91) place potential barriers to the adoption of organically acceptable substances for crop protection. There are a number of potentially useful substances currently not included in the Organic Regulation e.g. potassium bicarbonate. WAG should work with PSD and others to identify such substances and support the production of appropriate dossiers. WAG could also encourage further dialogue between the organic sector and Defra to identify amendments in the Organic Regulations to facilitate the inclusion of new pesticides. · Organic pest and disease management is not just a question of inputs but it also relies crucially on advice and extension through initiatives such as Farming Connect and the work of Organic Centre Wales. Long-term commitment to supporting on going advice and extension activities is vital to promote and disseminate best practice in Welsh agriculture and horticulture. · Organic horticulture, vegetable and fruit production systems are particularly sensitive to pest and disease management. Successful control of pests, diseases (and weeds) in these sectors can be critical to the business, and is not assured even when all husbandry and management methods have been effectively applied. Consequently, the use of organically acceptable crop protection methods resulting from future developments (e.g. biopesticides, biological control agents) could have an important role in pest and disease management in these sectors. Both organic and conventional producers in Wales could benefit from having these options available to them and WAG could encourage the adoption of these approaches through appropriate Technology Transfer activities. · The way in which such substances will be regulated at a European level in future is evolving as the review of the Pesticide Directive 91/414 EEC enters the 4th Stage. This stage of the review includes (amongst others) those substances permitted for use in organic production. The guidance documents for the evaluation of applications on plant protection products made from plants or plant extracts and from chemical substances are currently at the draft stage. The response of the Pesticide Safety Directorate and Defra to these developments is not yet clear but this provides an excellent opportunity for WAG to have an input at an early stage in the review process