Psychological characteristics of children with visual impairments: learning, memory and imagery

The performance of children (and sometimes adults) with visual impairments (VI) on a range of tasks that reflect learning, memory and mental imagery is considered in this article. Sometimes the evidence suggests that there are impairments in performance in comparison with typically developing children with vision and sometimes some advantages emerge. The author’s aim is to describe some of her own and others’ findings and explore what they tell us about the cognitive characteristics of such children, so that progress with practical interventions can be advanced through understanding. The article starts by focusing on social-cognitive development and in particular considers the potential benefits of language in that development. This is followed by a review of some studies of learning and memory performance which provide a coherent picture of development without vision and finally ends with a consideration of spatial mental imagery

The International Pulsar Timing Array: First data release

International audienceThe highly stable spin of neutron stars can be exploited for a variety of (astro)physical investigations. In particular, arrays of pulsars with rotational periods of the order of milliseconds can be used to detect correlated signals such as those caused by gravitational waves. Three such 'pulsar timing arrays' (PTAs) have been set up around the world over the past decades and collectively form the 'International' PTA (IPTA). In this paper, we describe the first joint analysis of the data from the three regional PTAs, i.e. of the first IPTA data set. We describe the available PTA data, the approach presently followed for its combination and suggest improvements for future PTA research. Particular attention is paid to subtle details (such as underestimation of measurement uncertainty and long-period noise) that have often been ignored but which become important in this unprecedentedly large and inhomogeneous data set. We identify and describe in detail several factors that complicate IPTA research and provide recommendations for future pulsar timing efforts. The first IPTA data release presented here (and available on-line) is used to demonstrate the IPTA's potential of improving upon gravitational-wave limit

Chronic progressive external ophthalmoplegia. More than meets the eye

Contains fulltext : 93604.pdf (publisher's version ) (Open Access)Radboud Universiteit Nijmegen, 5 juni 2012Promotores : Engelen, B.G.M. van, Heuvel, L.P.W.J. van den132 p

[Mitochondrial diseases; thinking beyond organ specialism necessary]

Item does not contain fulltextMitochondrial disorders are caused by a defect in intracellular energy production. In general, these are multi-system disorders, predominantly affecting organs with high energy requirements. Due to the fact that mitochondrial disorders are not as rare as is generally assumed, and due to the diversity of symptoms, many different medical specialists will at some time be confronted with these patients. Early recognition ofa mitochondrial disorder reduces patient anxiety and avoids unnecessary ancillary investigations and potentially hazardous treatments. A mitochondrial disease should be considered in the event of dysfunction of more than 2 organ systems or processes with high energy requirements, certainly if there is a positive maternal family history. If fatigue includes exercise-induced muscle pain or muscle weakness, and if muscle pain predominantly occurs during exertion, a mitochondrial disease should be considered. The combination ofdiabetes mellitus and deafness is also a strong indicator of mitochondrial disease. An extensive family history should always be taken. In adults, the most frequently occurring mitochondrial syndromes are chronic progressive external ophthalmoplegia (CPEO), maternally inherited diabetes and deafness syndrome (MIDDS) and Leber's hereditary optic neuropathy. Since much research effort is currently being invested in the development of causal medical treatments, the importance of an early diagnosis is likely to become of increasing importance in the future

A toxic shot from the hip

Contains fulltext : 96601.pdf (publisher's version ) (Closed access)A 26-year-old man developed a movement disorder characterised by bradyphrenia, bradykinesia, rigidity, tremor and dystonia, several years after having been shot by a gun in the hip. Laboratory investigations revealed anaemia and porphyria. The authors demonstrate that his neurological condition was a delayed manifestation of lead toxicity, caused by slow absorption of lead from persisting bullet fragments in the hip joint. Treatment with excision of the femoral head and debridement of the hip followed by a total hip, in combination with chelating therapy, led to a remarkable remission