2,313 research outputs found
Investigating a simple model of cutaneous wound healing angiogenesis
A simple model of wound healing angiogenesis is presented, and investigated using numerical and asymptotic techniques. The model captures many key qualitative features of the wound healing angiogenic response, such as the propagation of a structural unit into the wound centre. A detailed perturbative study is pursued, and is shown to capture all features of the model. This enables one to show that the level of the angiogenic response predicted by the model is governed to a good approximation by a small number of parameter groupings. Further investigation leads to predictions concerning how one should select between potential optimal means of stimulating cell proliferation in order to increase the level of the angiogenic response
A near infrared spectroscopic study of the interstellar gas in the starburst core of M82
Researchers used the McDonald Observatory Infrared Grating Spectrometer, to complete a program of spatially resolved spectroscopy of M82. The inner 300 pc of the starburst was observed with 4 inch (50 pc) resolution. Complete J, H and K band spectra with resolution 0.0035 micron (lambda/delta lambda=620 at K) were measured at the near-infrared nucleus of the galaxy. Measurements of selected spectral features including lines of FeII, HII and H2 were observed along the starburst ridge-line, so the relative distribution of the diagnostic features could be understood. This information was used to better define the extinction towards the starburst region, the excitation conditions in the gas, and to characterize the stellar populations there
Phylogeny, biogeography and diversification patterns of side-necked turtles (Testudines: Pleurodira)
Pleurodires or side-necked turtles are today restricted to freshwater environments of South America, Africa– Madagascar and Australia, but in the past they were distributed much more broadly, being found also on Eurasia, India and North America, and marine environments. Two hypotheses were proposed to explain this distribution; in the first, vicariance would have shaped the current geographical distribution and, in the second, extinctions constrained a previously widespread distribution. Here, we aim to reconstruct pleurodiran biogeographic history and diversification patterns based on a new phylogenetic hypothesis recovered from the analysis of the largest morphological dataset yet compiled for the lineage, testing which biogeographical process prevailed during its evolutionary history. The resulting topology generally agrees with previous hypotheses of the group and shows that most diversification shifts were related to the exploration of new niches, e.g. littoral or marine radiations. In addition, as other turtles, pleurodires do not seem to have been much affected by either the Cretaceous– Palaeogene or the Eocene–Oligocene mass extinctions. The biogeographic analyses highlight the predominance of both anagenetic and cladogenetic dispersal events and support the importance of transoceanic dispersals as a more common driver of area changes than previously thought, agreeing with previous studies with other non-turtle lineages.Fil: Ferreira, Gabriel S.. Universidade de Sao Paulo; Brasil. Senckenberg Centre For Human Evolution And Palaeoenvironment; Alemania. Universität TĂĽbingen; AlemaniaFil: Bronzati Filho, Mario. Bayerische Staatssammlung fĂĽr Paläontologie und Geologie; AlemaniaFil: Langer, Max C.. Universidade de Sao Paulo; BrasilFil: Sterli, Juliana. Museo PaleontolĂłgico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentin
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Change is good: adapting strategies for archaeological prospection in a rapidly changing technological world
Ye
Blade loss transient dynamics analysis, volume 1. Task 1: Survey and perspective
An analytical technique was developed to predict the behavior of a rotor system subjected to sudden unbalance. The technique is implemented in the Turbine Engine Transient Rotor Analysis (TETRA) computer program using the component element method. The analysis was particularly aimed toward blade-loss phenomena in gas turbine engines. A dual-rotor, casing, and pylon structure can be modeled by the computer program. Blade tip rubs, Coriolis forces, and mechanical clearances are included. The analytical system was verified by modeling and simulating actual test conditions for a rig test as well as a full-engine, blade-release demonstration
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BradPhys to BradViz or from archaeological science to heritage science
YesArchaeology is a broad church and its role as a “two culture” discipline is frequently cited. This position at the interface of the arts and sciences remains central to archaeological activity but there have been significant changes in the structure of archaeology and its relationship to society overall. The growth of heritage science, in particular, is driving change and development within archaeology at a national and international level. This paper discusses these developments in relation to the author's own research trajectory and discusses the significance of such change
Unveiling the prehistoric landscape at Stonehenge through multi-receiver EMI
YesArchaeological research at Stonehenge (UK) is increasingly aimed at understanding the dynamic of the wider archaeological landscape. Through the application of state-of-the-art geophysical techniques, unprecedented insight is being gathered into the buried archaeological features of the area. However, applied survey techniques have rarely targeted natural soil variation, and the detailed knowledge of the palaeotopography is consequently less complete. In addition, metallic topsoil debris, scattered over different parts of the Stonehenge landscape, often impacts the interpretation of geophysical datasets. The research presented here demonstrates how a single multi-receiver electromagnetic induction (EMI) survey, conducted over a 22 ha area within the Stonehenge landscape, offers detailed insight into natural and anthropogenic soil variation at Stonehenge. The soil variations that were detected through recording the electrical and magnetic soil variability, shed light on the genesis of the landscape, and allow for a better definition of potential palaeoenvironmental and archaeological sampling locations. Based on the multi-layered dataset, a procedure was developed to remove the influence of topsoil metal from the survey data, which enabled a more straightforward identification of the detected archaeology. The results provide a robust basis for further geoarchaeological research, while potential to differentiate between modern soil disturbances and the underlying sub-surface variations can help in solving conservation and management issues. Through expanding this approach over the wider area, we aim at a fuller understanding of the human–landscape interactions that have shaped the Stonehenge landscape
Blade loss transient dynamics analysis, volume 2. Task 2: Theoretical and analytical development. Task 3: Experimental verification
The component element method was used to develop a transient dynamic analysis computer program which is essentially based on modal synthesis combined with a central, finite difference, numerical integration scheme. The methodology leads to a modular or building-block technique that is amenable to computer programming. To verify the analytical method, turbine engine transient response analysis (TETRA), was applied to two blade-out test vehicles that had been previously instrumented and tested. Comparison of the time dependent test data with those predicted by TETRA led to recommendations for refinement or extension of the analytical method to improve its accuracy and overcome its shortcomings. The development of working equations, their discretization, numerical solution scheme, the modular concept of engine modelling, the program logical structure and some illustrated results are discussed. The blade-loss test vehicles (rig full engine), the type of measured data, and the engine structural model are described
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Preparing for the future: A reappraisal of archaeo-geophysical surveying on Irish National Road Schemes 2001-2010
yesThis document reviews Legacy Data generated from 10 years’ worth of road scheme activity in
Ireland to determine how archaeological geophysical surveys could be carried out on national
roads in the future. The geophysical surveys were carried out by several different contractors
across a range of challenging field conditions, geologies, weather and seasons. The research is
based upon the results of linear schemes but also has validity for wider approaches. The
findings of this research are based upon the compilation of all terrestrial archaeological
geophysical surveys carried out on behalf of the National Roads Authority (NRA), a review of
the success or otherwise of those surveys in comparison with ground-observed excavations and
in combination with experimental surveys that tested previously held assumptions or
knowledge to determine best practice methods for the future.
The use and success of geophysical surveys in Ireland differ quite significantly from those in the
UK, from where many of the methods of assessment were derived or adapted. Many of these
differences can be attributed to geology. Ireland has a very high percentage of Carboniferous
limestone geology, overlain mostly by tills and frequent occurrences of peat. These soils can
reduce, to some extent, the effectiveness of magnetometer surveys; the most frequently used
geophysical technique in Ireland. However, magnetometer data can be maximised in these
cases by increasing the spatial resolution to produce effective results. An increase in spatial
resolution is also effective generally, for enhancing the chances of identifying archaeological
features by discriminating between archaeological and geological anomalies as well as
increasing anomaly definition and visualisation of small and subtle archaeological features.
Seasonal tests have determined that Irish soils are generally suitable for year round earth
resistance assessments although some counties in the southeast of the country may experience
very dry soils at the surface during some periods of the year.
A variety of sampling strategies were used in the past, however it is now apparent that detailed
assessments across the full length and width of a proposed road corridor are the most
appropriate form of geophysical investigation. Magnetometer surveys are generally suitable for
most Irish soils and geologies, although exceptions apply in areas of near-surface igneous
deposits, deep peat and alluvial soils; however magnetometer surveys are not capable of
identifying all types of archaeological features and other methods will be required for a full
evaluation.
Analysis of the Legacy Data has determined that in general the NRA archaeological geophysical surveys were historically used in a very positive way on road schemes. The range of features
assessed or identified account for most types of archaeological sites in Ireland. These have
provided a significant archive of case studies that will be of benefit to future archaeological
geophysical research and will help to protect the globally dwindling archaeological resource
that is threatened by development-led or commercially driven projects
Cell reprogramming shapes the mitochondrial DNA landscape.
Individual induced pluripotent stem cells (iPSCs) show considerable phenotypic heterogeneity, but the reasons for this are not fully understood. Comprehensively analysing the mitochondrial genome (mtDNA) in 146 iPSC and fibroblast lines from 151 donors, we show that most age-related fibroblast mtDNA mutations are lost during reprogramming. However, iPSC-specific mutations are seen in 76.6% (108/141) of iPSC lines at a mutation rate of 8.62 Ă— 10-5/base pair. The mutations observed in iPSC lines affect a higher proportion of mtDNA molecules, favouring non-synonymous protein-coding and tRNA variants, including known disease-causing mutations. Analysing 11,538 single cells shows stable heteroplasmy in sub-clones derived from the original donor during differentiation, with mtDNA variants influencing the expression of key genes involved in mitochondrial metabolism and epidermal cell differentiation. Thus, the dynamic mtDNA landscape contributes to the heterogeneity of human iPSCs and should be considered when using reprogrammed cells experimentally or as a therapy
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