17,278 research outputs found

    Development of the dry tape battery concept Quarterly report no. 3, 9 Dec. 1965 - 8 Mar. 1966

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    Material electrical and chemical properties tested for use in dry tape batterie

    Colorectal Cancer Through Simulation and Experiment

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    Colorectal cancer has continued to generate a huge amount of research interest over several decades, forming a canonical example of tumourigenesis since its use in Fearon and Vogelstein’s linear model of genetic mutation. Over time, the field has witnessed a transition from solely experimental work to the inclusion of mathematical biology and computer-based modelling. The fusion of these disciplines has the potential to provide valuable insights into oncologic processes, but also presents the challenge of uniting many diverse perspectives. Furthermore, the cancer cell phenotype defined by the ‘Hallmarks of Cancer’ has been extended in recent times and provides an excellent basis for future research. We present a timely summary of the literature relating to colorectal cancer, addressing the traditional experimental findings, summarising the key mathematical and computational approaches, and emphasising the role of the Hallmarks in current and future developments. We conclude with a discussion of interdisciplinary work, outlining areas of experimental interest which would benefit from the insight that mathematical and computational modelling can provide

    Object-Oriented Paradigms for Modelling Vascular\ud Tumour Growth: a Case Study

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    Motivated by a family of related hybrid multiscale models, we have built an object-oriented framework for developing and implementing multiscale models of vascular tumour growth. The models are implemented in our framework as a case study to highlight how object-oriented programming techniques and good object-oriented design may be used effectively to develop hybrid multiscale models of vascular tumour growth. The intention is that this paper will serve as a useful reference for researchers modelling complex biological systems and that these researchers will employ some of the techniques presented herein in their own projects

    A note on heat and mass transfer from a sphere in Stokes\ud flow at low PĂ©clet number

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    We consider the low PĂ©clet number, Pe â‰Ș 1, asymptotic solution for steady-state heat and mass transfer from a sphere immersed in Stokes flow with a Robin boundary condition on its surface, representing Newton cooling or a first-order chemical reaction. The application of van Dyke’s rule up to terms of O(Pe3) shows that the O(Pe3 log Pe) terms in the expression for the average Nusselt/Sherwood number are double those previously derived in the literature. Inclusion of the O(Pe3) terms is shown to increase significantly the range of validity of the expansion

    Distribution and reproduction of intertidal species of Aquilonastra and Cryptasterina (Asterinidae) from one tree reef, southern great barrier reef

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    The Asterinidae in tropical regions includes morphospecies complexes in the genera Aquilonastra and Cryptasterina. Cryptic species in these genera have been discovered based on differences in life histories and by attention to previously poorly investigated habitats. Two species with benthic development occur in the intertidal rubble habitat at One Tree Island, southern Great Barrier Reef Aquilonastra byrneae (O'Loughlin and Rowe, 2006) has oral gonopores and is likely to lay benthic eggs masses. The presence of mature gonads in May and June indicates that egg masses should be present in winter. This species may be a protandric hermaphrodite. Cryptasterina sp. is an intragonadal brooder and may be conspecific with the coastal Cryptasterina hystera Dartnall and Byrne, 2003. This species broods its young to the juvenile stage in spring and summer. The juveniles emerge through aboral gonopores. Cryptasterina sp. is a simultaneous hermaphrodite. Aquilonastra byrneae and Cryptasterina sp. are distributed in the high shore rubble habitat at One Tree Reef in distinct bands at 1.5 m and 1.1 m above Lowest Astronomical Tide, respectively

    Wound healing angiogenesis the clinical implications of a simple mathematical model

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    Nonhealing wounds are a major burden for health care systems worldwide. In addition, a patient who suffers from this type of wound usually has a reduced quality of life. While the wound healing process is undoubtedly complex, in this paper we develop a deterministic mathematical model, formulated as a system of partial differential equations, that focusses on an important aspect of successful healing: oxygen supply to the wound bed by a combination of diffusion from the surrounding unwounded tissue and delivery from newly-formed blood vessels. While the model equations can be solved numerically, the emphasis here is on the use of asymptotic methods to establish conditions under which new blood vessel growth can be initiated and wound-bed angiogenesis can progress. These conditions are given in terms of key model parameters including the rate of oxygen supply and its rate of consumption in the wound. We use our model to discuss the clinical use of treatments such as hyperbaric oxygen therapy, wound bed debridement, and revascularisation therapy that have the potential to initiate healing in chronic, stalled wounds

    The interplay between tissue growth and scaffold degradation in engineered tissue constructs

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    In vitro tissue engineering is emerging as a potential tool to meet the high demand for replacement tissue, caused by the increased incidence of tissue degeneration and damage. A key challenge in this field is ensuring that the mechanical properties of the engineered tissue are appropriate for the in vivo environment. Achieving this goal will require detailed understanding of the interplay between cell proliferation, extracellular matrix (ECM) deposition and scaffold degradation.\ud \ud In this paper, we use a mathematical model (based upon a multiphase continuum framework) to investigate the interplay between tissue growth and scaffold degradation during tissue construct evolution in vitro. Our model accommodates a cell population and culture medium, modelled as viscous fluids, together with a porous scaffold and ECM deposited by the cells, represented as rigid porous materials. We focus on tissue growth within a perfusion bioreactor system, and investigate how the predicted tissue composition is altered under the influence of (i) differential interactions between cells and the supporting scaffold and their associated ECM, (ii) scaffold degradation, and (iii) mechanotransduction-regulated cell proliferation and ECM deposition.\ud \ud Numerical simulation of the model equations reveals that scaffold heterogeneity typical of that obtained from ÎŒCT scans of tissue engineering scaffolds can lead to significant variation in the flow-induced mechanical stimuli experienced by cells seeded in the scaffold. This leads to strong heterogeneity in the deposition of ECM. Furthermore, preferential adherence of cells to the ECM in favour of the artificial scaffold appears to have no significant influence on the eventual construct composition; adherence of cells to these supporting structures does, however, lead to cell and ECM distributions which mimic and exaggerate the heterogeneity of the underlying scaffold. Such phenomena have important ramifications for the mechanical integrity of engineered tissue constructs and their suitability for implantation in vivo

    The Dynamics of Presidential Legacies

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    It has been said that one of the few things you can’t do in life a second time is to make a first impression; however, in politics, and especially presidential politics, while it may not be possible to change that first impression, it is possible to change the public’s opinion, and how one might be perceived long after their political career is over. The 43 men who have been the U.S president have been analyzed and scrutinized throughout their lives and political careers. Prior to running for president, they establish a resume that puts them in the public eye. Later, during their campaign, the American public decides whether they have the confidence in the candidate to entrust them with the duties as president. While in office, they are evaluated daily by the press and news media along with the onslaught of polls measuring the publics’ satisfaction, or dissatisfaction, with their performance. The evaluations while in office offer them the opportunity to see how “well” they are doing, and also provide insights as to whether they may or may not be residing in the White House at the end of their first term

    Effect of feeding fermentable fibrerich feedstuffs on meat quality with emphasis on chemical and sensory boar taint in entire male and female pigs

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    Skatole, androstenone and other compounds such as indole cause boar taint in entire male pork. However, female pigs also produce skatole and indole. The purpose of this experiment was to minimise boar taint and increase overall impression of sensory quality by feeding entire male and female pigs with fibrerich feedstuffs. The pigs have been fed three organic diets for either 1 or 2 weeks prior to slaughter of which two diets contained different fermentable fibre-rich feedstuffs – 10–13.3% dried chicory roots or 25% blue lupines. These two treatments were compared with pigs fed with an organic control diet for either 1 or 2 weeks prior to slaughter. Lupines significantly reduced skatole in blood and backfat for both genders after 1 week. Moreover, lupines showed negative impact on growth rate and feed conversion whilst chicory showed no significant differences in this respect. However, the indole concentration was significantly lower in chicory than lupine fed pigs. From a sensory perspective, chicory and lupine feeding reduced boar taint since odour and flavour of manure related to skatole and urine associated to androstenone were minimised. The level of boar taint in the entire male pigs was most effectively reduced after 14 days by both fibre-rich feeds while lupine had the largest influence on ‘‘boar” taint reduction in female pigs
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