A 'large and valuable' Siwalik fossil collection in the archives of the Oxford University Museum of Natural History

This article describes results from a review of South Asian fossils in the Oxford University Museum of Natural History. These materials include two early 19th century collections of fossils from the Siwalik Hills in India. While this assemblage was summarised in 1837 by William Buckland as ‘large and valuable collections of fossil bones’, it has remained largely unstudied and unpublished in any detail since collection. Here, as a precursor to a comprehensive re-evaluation, we establish a chronological and geographical context of one collection event, provide details of its donor, and outline its history after arrival in Oxford. We then describe select taxa in the collection, including a well-preserved maxilla and toothrow of the large extinct giraffid, Sivatherium giganteum, as a basis to justify our current understanding of the biostratigraphic affinity of the assemblage. Conservatively, the collection is a ‘classic’ Upper Siwalik Plio-Pleistocene fauna, possibly the first to be transported to the UK. While further analyses will realise the scientific potential of the fossils, the narrative of their journey from India to Oxford remains incomplete. Further investigation of the hidden history of the collection is warranted

Contact resistance in Polytriarylamine based organic transistors

The paper aims to describe the simulations and measurements performed in order to determine the resistance of source and drain contacts of organic transistors with Polytriarylamine (PTAA) semiconductor. PSpice and MATLAB comparative simulations based on the analytic model are performed. The DC Sweep and parametric simulations are employed to find the electrical characteristics of the transistors, in order obtain the total resistance. The results are processed in accordance to the Transfer Line Method (TLM). This technique uses transistor-like structures of various channel lengths, as these have a layout suitable for extracting and assessing the contact resistance. The TLM structures considered are bottom contact bottom gate transistors with interdigitated electrodes of various channel lengths, their geometry assumed to ensure similar values for the drain and source resistances due to the symmetry. This paper approaches the aspects related to the electrical simulation of basic transistor models in comparison to the measurements

Analytical modeling of contact resistance in organic transistors

Organic thin film transistors (OTFTs) are of significant interest for the development of organic electronics. The devices described in this paper, through measurements, analytic extraction of parameters and simulations, are organic transistor having Polytriarylamine (PTAA) as semiconductor. This paper refers to the determination of the source and drain contact resistance of these PTAA organic transistors. The MATLAB Simulink model is based on an analytic model, for which DC Sweep and parametric simulations were employed in order to obtain the total resistance. The results are processed in accordance to the Transfer Line Method (TLM). This mathematical method uses results on the total channel resistance of the thin film transistors with various channel lengths in order to extrapolate the contact resistance. The TLM structures considered here are bottom contact top gate OTFTs with interdigitated electrodes of various channel lengths. The values of the contact resistance a re considered equal due to the symmetry of the measured structure

A ‘large and valuable’ Siwalik fossil collection in the archives of the Oxford University Museum of Natural History

This article describes results from a review of South Asian fossils in the Oxford University Museum of Natural History. These materials include two early 19th century collections of fossils from the Siwalik Hills in India. While this assemblage was summarised in 1837 by William Buckland as ‘large and valuable collections of fossil bones’, it has remained largely unstudied and unpublished in any detail since collection. Here, as a precursor to a comprehensive re-evaluation, we establish a chronological and geographical context of one collection event, provide details of its donor, and outline its history after arrival in Oxford. We then describe select taxa in the collection, including a well-preserved maxilla and toothrow of the large extinct giraffid, Sivatherium giganteum, as a basis to justify our current understanding of the biostratigraphic affinity of the assemblage. Conservatively, the collection is a ‘classic’ Upper Siwalik Plio-Pleistocene fauna, possibly the first to be transported to the UK. While further analyses will realise the scientific potential of the fossils, the narrative of their journey from India to Oxford remains incomplete. Further investigation of the hidden history of the collection is warranted

Energy transfer from Fe3+ to rare-earth ions in YAG and the problem of sensitization of laser emission

The static and dynamic measurements of Tm3+ spectra in YAG:Fe:Tm show that the 3H4 level is efficiently populated by transfer from Fe3+ in tetrahedral sites. The features of the transfer processes, by investigation of Tm3+ acceptor luminescence characteristics, are presented