1,370 research outputs found
An Algebra of Pieces of Space -- Hermann Grassmann to Gian Carlo Rota
We sketch the outlines of Gian Carlo Rota's interaction with the ideas that
Hermann Grassmann developed in his Ausdehnungslehre of 1844 and 1862, as
adapted and explained by Giuseppe Peano in 1888. This leads us past what Rota
variously called 'Grassmann-Cayley algebra', or 'Peano spaces', to the Whitney
algebra of a matroid, and finally to a resolution of the question "What,
really, was Grassmann's regressive product?". This final question is the
subject of ongoing joint work with Andrea Brini, Francesco Regonati, and
William Schmitt.
The present paper was presented at the conference "The Digital Footprint of
Gian-Carlo Rota: Marbles, Boxes and Philosophy" in Milano on 17 Feb 2009. It
will appear in proceedings of that conference, to be published by Springer
Verlag.Comment: 28 page
The linear mirror for solar energy exploitation
We describe a simple two-dimensional array of plane mirrors operated by only two motors, which collects efficiently Sun light in order to produce electrical power at about the cost of oil. The system preserves the merits of previous
state-of-the-art solar power plants but is simpler and by far less expensive. A first prototype has been operated at the Physics Department of the University of Udine providing a power of 0.56 kW per m2 of mirror surface in mid November
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Kinematic top analyses at CDF
We present an update of the top quark analysis using kinematic techniques in p{bar p} collisions at {radical}s = 1.8 TeV with the Collider Detector at Fermilab (CDF). We reported before on a study which used 19.3 pb{sup {minus}1} of data from the 1992--1993 collider run, but now we use a larger data sample of 67 pb{sup {minus}1}. First, we analyze the total transverse energy of the hard collision in W+{ge}3 jet events, showing the likely presence of a t{bar t} component in the event sample. Next, we compare in more detail the kinematic structure of W+ {ge}3 jet events with expectations for top pair production and with background processes, predominantly direct W+ jet production. We again find W+ {ge} 3 jet events which cannot be explained in terms of background, but show kinematic features as expected from top. These events also show evidence for beauty quarks, in agreement with expectations from top, but not compatible with expectations from backgrounds. The findings confirm the observation of top events made earlier in the data of the 1992--1993 collider run
Seed sequence polymorphism rs2168518 and allele-specific target gene regulation of hsa-miR-4513
Acknowledgements We thank Lisa Michaelis and Dr Karolina PlöĂl (Institute of Human Genetics, University of Regensburg) for excellent technical help and thorough proofreading of the manuscript, respectively. We thank Marina Sauer and Franz-Stephan Attenkofer (Institute of Human Genetics, University of Regensburg) for their support in generating the luciferase reporter vectors. Conflict of Interest statement. The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. Funding German Research Foundation (GR5065/1-1 to F.G.); and the Helmut Ecker Foundation (Ingolstadt, Germany) (no. 05/17 to B.H.F.W).Peer reviewedPublisher PD
A Circulating MicroRNA Profile in a Laser-Induced Mouse Model of Choroidal Neovascularization
Funding: This research was funded by the Deutsche Forschungsgemeinschaft (GR5065/1-1). Author Contributions: Conceptualization, F.G. and B.H.F.W.; Data curation, T.S.; Formal analysis, P.B., M.K., A.A., and T.S.; Funding acquisition, C.K. and F.G.; Investigation, M.K. and B.H.F.W.; Methodology, C.K. and A.A.;Project administration, B.H.F.W.; Resources, M.K., A.A., T.L., and F.G.; Software, C.K. and T.S.; Supervision, T.L., F.G., and B.H.F.W.; Validation, P.B.; Visualization, C.K.; Writingâoriginal draft, C.K. and P.B.; Writingâreview & editing, B.H.F.W. All authors have read and agreed to the published version of the manuscript.Peer reviewedPublisher PD
Precise Critical Exponents for the Basic Contact Process
We calculated some of the critical exponents of the directed percolation
universality class through exact numerical diagonalisations of the master
operator of the one-dimensional basic contact process. Perusal of the power
method together with finite-size scaling allowed us to achieve a high degree of
accuracy in our estimates with relatively little computational effort. A simple
reasoning leading to the appropriate choice of the microscopic time scale for
time-dependent simulations of Markov chains within the so called quantum chain
formulation is discussed. Our approach is applicable to any stochastic process
with a finite number of absorbing states.Comment: LaTeX 2.09, 9 pages, 1 figur
Pleiotropic Locus 15q24.1 Reveals a Gender-Specific Association with Neovascular but Not Atrophic Age-Related Macular Degeneration (AMD)
Genome-wide association studies (GWAS) have identified an abundance of genetic loci associated with complex traits and diseases. In contrast, in-depth characterization of an individual genetic signal is rarely available. Here, we focus on the genetic variant rs2168518 in 15q24.1 previously associated with age-related macular degeneration (AMD), but only with suggestive evidence. In a two-step procedure, we initially conducted a series of association analyses to further delineate the association of rs2168518 with AMD but also with other complex phenotypes by using large independent datasets from the International AMD Genomics Consortium (IAMDGC) and the UK Biobank. We then performed a functional annotation with reference to gene expression regulation based on data from the Genotype-Tissue Expression (GTEx) project and RegulomeDB. Association analysis revealed a gender-specific association with male AMD patients and an association predominantly with choroidal neovascularization. Further, the AMD association colocalizes with an association signal of several blood pressure-related phenotypes and with the gene expression regulation of CYP1A1, a member of the cytochrome P450 superfamily of monooxygenases. Functional annotation revealed altered transcription factor (TF) binding sites for gender-specific TFs, including SOX9 and SRY. In conclusion, the pleiotropic 15q24.1 association signal suggests a shared mechanism between blood pressure regulation and choroidal neovascularization with a potential involvement of CYP1A1
The association between mitochondrial DNA abundance and stroke : A combination of multivariable-adjusted survival and Mendelian randomization analyses
Acknowledgements The authors are grateful to the UK Biobank for allowing us the use of their data. The analyses done in UK Biobank were done under project number 56340. Furthermore, the authors acknowledge the participants and investigators of the MEGASTROKE consortium and the FinnGen Biobank who contributed to the summary statistics data which are made available for further studies. Financial support This work was supported by the VELUX Stiftung [grant number 1156] to DvH and RN, and JL was supported by the China Scholarship Counsel [No.201808500155]. RN was supported by an innovation grant from the Dutch Heart Foundation [grant number 2019T103 to R.N.]. Parts of this work were funded by the Ă
ke Wibergs Foundation (grant number M19-0294 to F.G).Peer reviewedPublisher PD
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