104 research outputs found
Spatio-temporal Models of Lymphangiogenesis in Wound Healing
Several studies suggest that one possible cause of impaired wound healing is
failed or insufficient lymphangiogenesis, that is the formation of new
lymphatic capillaries. Although many mathematical models have been developed to
describe the formation of blood capillaries (angiogenesis), very few have been
proposed for the regeneration of the lymphatic network. Lymphangiogenesis is a
markedly different process from angiogenesis, occurring at different times and
in response to different chemical stimuli. Two main hypotheses have been
proposed: 1) lymphatic capillaries sprout from existing interrupted ones at the
edge of the wound in analogy to the blood angiogenesis case; 2) lymphatic
endothelial cells first pool in the wound region following the lymph flow and
then, once sufficiently populated, start to form a network. Here we present two
PDE models describing lymphangiogenesis according to these two different
hypotheses. Further, we include the effect of advection due to interstitial
flow and lymph flow coming from open capillaries. The variables represent
different cell densities and growth factor concentrations, and where possible
the parameters are estimated from biological data. The models are then solved
numerically and the results are compared with the available biological
literature.Comment: 29 pages, 9 Figures, 6 Tables (39 figure files in total
Inferring Binding Energies from Selected Binding Sites
We employ a biophysical model that accounts for the non-linear relationship between binding energy and the statistics of selected binding sites. The model includes the chemical potential of the transcription factor, non-specific binding affinity of the protein for DNA, as well as sequence-specific parameters that may include non-independent contributions of bases to the interaction. We obtain maximum likelihood estimates for all of the parameters and compare the results to standard probabilistic methods of parameter estimation. On simulated data, where the true energy model is known and samples are generated with a variety of parameter values, we show that our method returns much more accurate estimates of the true parameters and much better predictions of the selected binding site distributions. We also introduce a new high-throughput SELEX (HT-SELEX) procedure to determine the binding specificity of a transcription factor in which the initial randomized library and the selected sites are sequenced with next generation methods that return hundreds of thousands of sites. We show that after a single round of selection our method can estimate binding parameters that give very good fits to the selected site distributions, much better than standard motif identification algorithms
Vitalism and the Resistance to Experimentation on Life in the Eighteenth Century
There is a familiar opposition between a âScientific Revolutionâ ethos and practice of experimentation, including experimentation on life, and a âvitalistâ reaction to this outlook. The former is often allied with different forms of mechanism â if all of Nature obeys mechanical laws, including living bodies, âiatromechanismâ should encounter no obstructions in investigating the particularities of animal-machines â or with more chimiatric theories of life and matter, as in the âOxford Physiologistsâ. The latter reaction also comes in different, perhaps irreducibly heterogeneous forms, ranging from metaphysical and ethical objections to the destruction of life, as in Margaret Cavendish, to more epistemological objections against the usage of instruments, the âanatomicalâ outlook and experimentation, e.g. in Locke and Sydenham. But I will mainly focus on a third anti-interventionist argument, which I call âvitalistâ since it is often articulated in the writings of the so-called Montpellier Vitalists, including their medical articles for the EncyclopĂ©die. The vitalist argument against experimentation on life is subtly different from the metaphysical, ethical and epistemological arguments, although at times it may borrow from any of them. It expresses a Hippocratic sensibility â understood as an artifact of early modernity, not as some atemporal trait of medical thought â in which Life resists the experimenter, or conversely, for the experimenter to grasp something about Life, it will have to be without torturing or radically intervening in it. I suggest that this view does not have to imply that Nature is something mysterious or sacred; nor does the vitalist have to attack experimentation on life in the name of some âvital forceâ â which makes it less surprising to find a vivisectionist like Claude Bernard sounding so close to the vitalists
African Linguistics in Central and Eastern Europe, and in the Nordic Countries
Non peer reviewe
Um mundo novo no Atlùntico: marinheiros e ritos de passagem na linha do equador, séculos XV-XX
The domestic effectiveness of international human rights monitoring in established democracies. The case of the UN human rights treaty bodies
A taxonomic backbone for the global synthesis of species diversity in the angiosperm order Caryophyllales
The Caryophyllales constitute a major lineage of flowering plants with approximately 12500 species in 39 families. A taxonomic backbone at the genus level is provided that reflects the current state of knowledge and accepts 749 genera for the order. A detailed review of the literature of the past two decades shows that enormous progress has been made in understanding overall phylogenetic relationships in Caryophyllales. The process of re-circumscribing families in order to be monophyletic appears to be largely complete and has led to the recognition of eight new families (Anacampserotaceae, Kewaceae, Limeaceae, Lophiocarpaceae, Macarthuriaceae, Microteaceae, Montiaceae and Talinaceae), while the phylogenetic evaluation of generic concepts is still well underway. As a result of this, the number of genera has increased by more than ten percent in comparison to the last complete treatments in the Families and genera of vascular plantsâ series. A checklist with all currently accepted genus names in Caryophyllales, as well as nomenclatural references, type names and synonymy is presented. Notes indicate how extensively the respective genera have been studied in a phylogenetic context. The most diverse families at the generic level are Cactaceae and Aizoaceae, but 28 families comprise only one to six genera. This synopsis represents a first step towards the aim of creating a global synthesis of the species diversity in the angiosperm order Caryophyllales integrating the work of numerous specialists around the world
A arqueologia dos fermentados: a etĂlica histĂłria dos Tupi-Guarani
O consumo de bebidas fermentadas Ă© geralmente negligenciado pela literatura arqueolĂłgica, que trata a questĂŁo como tema de interesse secundĂĄrio (recreativo) na histĂłria das populaçÔes humanas. Entretanto, a literatura etnogrĂĄfica das sociedades indĂgenas das terras baixas sul-americanas indica exatamente o oposto: Ă© o alimento vegetal sĂłlido e nĂŁo alcoĂłlico que tende a possuir um papel secundĂĄrio na vida cotidiana e ritualĂstica de diversos coletivos. Os dados arqueolĂłgicos aprofundam temporalmente essa relação entre o ser humano e os fermentados. AlĂ©m disso, os vasos cerĂąmicos arqueolĂłgicos utilizados para o preparo e consumo desses fermentados sĂŁo fundamentais para a compreensĂŁo de processos e eventos histĂłricos que modelaram a dispersĂŁo de uma sĂ©rie de grupos pelo continente
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