6,880 research outputs found

    Short Note: Report of mummified leopard seal carcass in the southern Dry Valleys, McMurdo Sound, Antarctica.

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    The wide spread occurrence of mummified seal and penguin carcasses tens of kilometres from the open ocean is an interesting phenomenon occurring in the Antarctic Dry Valleys. Mummified seal carcasses were first reported by Scott’s expedition in 1903 (Scott 1969), and live seals and seal carcasses have since been reported many kilometres from the nearest ice-free ocean. Seal carcasses found in the McMurdo Dry Valleys are predominantly crabeater seals (Lobodon carcinophaga (Hombron & Jacquinot)) with a smaller number of Weddell seals, (Leptonychotes weddellii (Lesson)), also reported. Here we present only the second published report of a leopard seal carcass from the McMurdo Dry Valleys

    Journal publishing with Acrobat: the CAJUN project

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    The publication of material in electronic form should ideally preserve, in a unified document representation, all of the richness of the printed document while maintaining enough of its underlying structure to enable searching and other forms of semantic processing. Until recently it has been hard to find a document representation which combined these attributes and which also stood some chance of becoming a de facto multi-platform standard. This paper sets out experience gained within the Electronic Publishing Research Group at the University of Nottingham in using Adobe Acrobat software and its underlying PDF (Portable Document Format) notation. The CAJUN project1 (CD-ROM Acrobat Journals Using Networks) began in 1993 and has used Acrobat software to produce electronic versions of journal papers for network and CD-ROM dissemination. The paper describes the project's progress so far and also gives a brief assessment of PDF's suitability as a universal document interchange standard

    catena-Poly[[[diaqua­(nitrato-κ2 O,O′)(2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)neodymium(III)]-μ-cyanido-κ2 N:C-[dicyanidoplatinum(II)]-μ-cyanido-κ2 C:N] acetonitrile solvate 2,2′:6′,2′′-terpyridine hemisolvate]

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    The title compound, {[NdPt(CN)4(NO3)(C15H11N3)(H2O)2]·CH3CN·0.5C15H11N3}n, was isolated from solution as a one-dimensional coordination polymer. The Nd3+ site in the structure has a ninefold coordination with a distorted tricapped trigonal-prismatic geometry, while the PtII ion is coordinated by four cyanide groups in an almost regular square-planar geometry. Cis-bridging by the tetracyanidoplatinate anions links the Nd3+ cations, forming the one-dimensional chains. Additionally, each Nd3+ contains coordin­ation by two water mol­ecules, one tridentate 2,2′:6′,2′′-terpyridine mol­ecule, and one bidentate nitrate anion. 2,2′:6′,2′′-Terpyridine and acetonitrile solvent mol­ecules are incorporated between the chains, the former form π-stacking inter­actions (average inter­planar distance 3.33 Å) with terpyridine mol­ecules located in the chains. Relatively long Pt⋯Pt inter­actions [3.847 (1) Å] are observed in the structure. O—H⋯N and O—H⋯O hydrogen bonding interactions between the consituents consolidates the crystal packing

    The topographical relationship between visual field loss and peripapillary retinal nerve fibre layer thinning arising from long-term exposure to vigabatrin

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    Background The antiepileptic drug vigabatrin is associated with characteristic visual field loss (VAVFL) and thinning of the peripapillary retinal nerve fibre layer (PPRNFL); however, the relationship is equivocal. Objective The aim of this study was to determine the function–structure relationship associated with long-term exposure to vigabatrin, thereby improving the risk/benefit analysis of the drug. Methods A cross-sectional observational design identified 40 adults who had received long-term vigabatrin for refractory seizures, who had no evidence of co-existing retino-geniculo-cortical visual pathway abnormality, and who had undergone a standardized protocol of perimetry and of optical coherence tomography (OCT) of the PPRNFL. Vigabatrin toxicity was defined as the presence of VAVFL. The function–structure relationship for the superior and inferior retinal quadrants was evaluated by two established models applicable to other optic neuropathies. Results The function–structure relationship for each model was consistent with an optic neuropathy. PPRNFL thinning, expressed in micrometres, asymptoted at an equivalent visual field loss of worse than approximately − 10.0 dB, thereby preventing assessment of more substantial thinning. Transformation of the outcomes to retinal ganglion cell soma and axon estimates, respectively, resulted in a linear relationship. Conclusions Functional and structural abnormality is strongly related in individuals with vigabatrin toxicity and no evidence of visual pathway comorbidity, thereby implicating retinal ganglion cell dysfunction. OCT affords a limited measurement range compared with perimetry: severity cannot be directly assessed when the PPRNFL quadrant thickness is less than approximately 65 µm, depending on the tomographer. This limitation can be overcome by transformation of thickness to remaining axons, an outcome requiring input from perimetry

    A burst chasing x-ray polarimeter

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    Gamma-ray bursts are one of the most powerful explosions in the universe and have been detected out to distances of almost 13 billion light years. The exact origin of these energetic explosions is still unknown but the resulting huge release of energy is thought to create a highly relativistic jet of material and a power-law distribution of electrons. There are several theories describing the origin of the prompt GRB emission that currently cannot be distinguished. Measurements of the linear polarization would provide unique and important constraints on the mechanisms thought to drive these powerful explosions. We present the design of a sensitive, and extremely versatile gamma-ray burst polarimeter. The instrument is a photoelectric polarimeter based on a time-projection chamber. The photoelectric time-projection technique combines high sensitivity with broad band-pass and is potentially the most powerful method between 2 and 100 keV where the photoelectric effect is the dominant interaction process. We present measurements of polarized and unpolarized X-rays obtained with a prototype detector and describe the two mission concepts; the Gamma-Ray Burst Polarimeter (GRBP) for the U.S. Naval Academy satellite MidSTAR-2, and the Low Energy Polarimeter (LEP) onboard POET, a broadband polarimetry concept for a small explorer mission
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