15,362 research outputs found

    Who is failing abused and neglected children?

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    This is a response to an article by Nigel Speight and Jane Wynne, ‘Is the Children Act failing severely abused and neglected children?’, published in this journal in March 2000.1 Overall, we consider the article to be polemical and inadequately argued. Many of the points made are unsubstantiated and there are errors of fact. Where does evidence based practice go if senior practitioners prefer anecdotes and personal belief to research findings? Restrictions on space preclude an exhaustive reply to all the points Speight and Wynne raise, so we have confined ourselves to addressing those considered most significant

    Structural changes in cartilage and collagen studied by high temperature Raman spectroscopy

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    Understanding the high temperature behavior of collagen and collagenous tissue is important for surgical procedures and biomaterials processing for the food, pharmaceutical, and cosmetics industries. One primary event for proteins is thermal denaturation that involves unfolding the polypeptide chains while maintaining the primary structure intact. Collagen in the extracellular matrix of cartilage and other connective tissue is a hierarchical material containing bundles of triple-helical fibers associated with water and proteoglycan components. Thermal analysis of dehydrated collagen indicates irreversible denaturation at high temperature between 135°C and 200°C, with another reversible event at ∼60-80°C for hydrated samples. We report high temperature Raman spectra for freeze-dried cartilage samples that show an increase in laser-excited fluorescence interpreted as conformational changes associated with denaturation above 140°C. Spectra for separated collagen and proteoglycan fractions extracted from cartilage indicate the changes are associated with collagen. The Raman data also show appearance of new features indicating peptide bond hydrolysis at high temperature implying that molecular H2O is retained within the freeze-dried tissue. This is confirmed by thermogravimetric analysis that show 5-7 wt% H2O remaining within freeze-dried cartilage that is released progressively upon heating up to 200°C. Spectra obtained after exposure to high temperature and re-hydration following recovery indicate that the capacity of the denatured collagen to re-absorb water is reduced. Our results are important for revealing the presence of bound H2O within the collagen component of connective tissue even after freeze-drying and its role in denaturation that is accompanied by or perhaps preceded by breakdown of the primary polypeptide structure

    Holey goats: multiple cases of supratrochlear foramina in the humerus of caprines from the New Kingdom pharaonic town of Amara West, northern Sudan

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    Supratrochlear foramina (STF) were recorded in fifteen per cent of goat and sheep/goat humeri from the New Kingdom pharaonic town of Amara West, in modern northern Sudan. To the authors’ knowledge, this trait has never before been reported in the published literature for goats or sheep, whether from archaeological or modern contexts. The aim of this work is twofold: to contribute to the growing corpus of studies addressing the incidence and aetiology of STF, and to raise awareness for their possible presence in caprines, thus encouraging their identification and recording in archaeological assemblages

    Comparison of VLBI, TV and traveling clock techniques for time transfer

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    A three part experiment was conducted to develop and compare time transfer techniques. The experiment consisted of (1) a very long baseline interferometer (VLBI), (2) a high precision portable clock time transfer system between the two sites, and (3) a television time transfer. A comparison of the VLBI and traveling clock shows each technique can perform satisfactorily at the five nsec level. There was a systematic offset of 59 nsec between the two methods, which we attributed to a difference in epochs between VLBI formatter and station clock. The VLBI method had an internal random error of one nsec at the three sigma level for a two day period. Thus, the Mark II system performed well, and VLBI shows promise of being an accurate method of time transfer. The TV system, which had technical problems during the experiment, transferred time with a random error of about 50 nsec

    Encountering authority and avoiding trouble: young migrant men’s narratives of negotiation in Europe

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    Drawing on data from seven European countries (Czech Republic, Finland, France, Germany, Ireland, Italy and the United Kingdom), this article seeks to identify how young migrant men engage with authority and avoid conflict against a backdrop of increasing hostility towards migrants in many European countries. As this article contends, even those with permanent residency status in the host country often find themselves having to justify their legitimacy to carry out daily tasks, resulting in many young male migrants living with feelings of perpetual insecurity. As such, a number of coping strategies are employed by young migrant men in order to assuage such feelings and mitigate potential risks. Focusing on the lived experiences of this group, as described in narrative interviews, our study found that many young migrant men are required to enter into negotiations with authority figures, where there is a considerable power differential. Acting as risk assessors, they find themselves forced to navigate complex and challenging social relations and support networks. We show how self-limiting behaviour intended to avoid or control interactions with authority and the negotiations conducted to minimize the risk of ‘trouble’ by young migrant men not only are problematic in the context of day-to-day activities but can very often have a detrimental impact on their lives

    A Matrix Hyperbolic Cosine Algorithm and Applications

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    In this paper, we generalize Spencer's hyperbolic cosine algorithm to the matrix-valued setting. We apply the proposed algorithm to several problems by analyzing its computational efficiency under two special cases of matrices; one in which the matrices have a group structure and an other in which they have rank-one. As an application of the former case, we present a deterministic algorithm that, given the multiplication table of a finite group of size nn, it constructs an expanding Cayley graph of logarithmic degree in near-optimal O(n^2 log^3 n) time. For the latter case, we present a fast deterministic algorithm for spectral sparsification of positive semi-definite matrices, which implies an improved deterministic algorithm for spectral graph sparsification of dense graphs. In addition, we give an elementary connection between spectral sparsification of positive semi-definite matrices and element-wise matrix sparsification. As a consequence, we obtain improved element-wise sparsification algorithms for diagonally dominant-like matrices.Comment: 16 pages, simplified proof and corrected acknowledging of prior work in (current) Section

    Zonal wind observations during a geomagnetic storm

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    In situ measurements taken by the Wind and Temperature Spectrometer (WATS) onboard the Dynamics Explorer 2 spacecraft during a geomagnetic storm display zonal wind velocities that are reduced in the corotational direction as the storm intensifies. The data were taken within the altitudes 275 to 475 km in the dusk local time sector equatorward of the auroral region. Characteristic variations in the value of the Dst index of horizontal geomagnetic field strength are used to monitor the storm evolution. The detected global rise in atmospheric gas temperature indicates the development of thermospheric heating. Concurrent with that heating, reductions in corotational wind velocities were measured equatorward of the auroral region. Just after the sudden commencement, while thermospheric heating is intense in both hemispheres, eastward wind velocities in the northern hemisphere show reductions ranging from 500 m/s over high latitudes to 30 m/s over the geomagnetic equator. After 10 hours storm time, while northern thermospheric heating is diminishing, wind velocity reductions, distinct from those initially observed, begin to develop over southern latitudes. In the latter case, velocity reductions range from 300 m/s over the highest southern latitudes to 150 m/s over the geomagnetic equator and extend into the Northern Hemisphere. The observations highlight the interhemispheric asymmetry in the development of storm effects detected as enhanced gas temperatures and reduced eastward wind velocities. Zonal wind reductions over high latitudes can be attributed to the storm induced equatorward spread of westward polar cap plasma convection and the resulting plasma-neutral collisions. However, those collisions are less significant over low latitudes; so zonal wind reductions over low latitudes must be attributed to an equatorward extension of a thermospheric circulation pattern disrupted by high latitude collisions between neutrals transported via eastward winds and ions convecting westward

    Genome scan of Diabrotica virgifera virgifera for genetic variation associated with crop rotation tolerance

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    Crop rotation has been a valuable technique for control of Diabrotica virgifera virgifera for almost a century. However, during the last two decades, crop rotation has ceased to be effective in an expanding area of the US corn belt. This failure appears to be due to a change in the insect's oviposition behaviour, which, in all probability, has an underlying genetic basis. A preliminary genome scan using 253 amplified fragment-length polymorphism (AFLP) markers sought to identify genetic variation associated with the circumvention of crop rotation. Samples of D. v. virgifera from east-central Illinois, where crop rotation is ineffective, were compared with samples from Iowa at locations that the behavioural variant has yet to reach. A single AFLP marker showed signs of having been influenced by selection for the circumvention of crop rotation. However, this marker was not diagnostic. The lack of markers strongly associated with the trait may be due to an insufficient density of marker coverage throughout the genome. A weak but significant general heterogeneity was observed between the Illinois and Iowa samples at microsatellite loci and AFLP markers. This has not been detected in previous population genetic studies of D. v. virgifera and may indicate a reduction in gene flow between variant and wild-type beetles
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