18,451 research outputs found
Ethanol production and maximum cell growth are highly correlated with membrane lipid composition during fermentation as determined by lipidomic analysis of 22 saccharomyces cerevisiae strains
No full textOptimizing ethanol yield during fermentation is important for efficient production of fuel alcohol, as well as wine and other alcoholic beverages. However, increasing ethanol concentrations during fermentation can create problems that result in arrested or sluggish sugar-to-ethanol conversion. The fundamental cellular basis for these problem fermentations, however, is not well understood. Small-scale fermentations were performed in a synthetic grape must using 22 industrial Saccharomyces cerevisiae strains (primarily wine strains) with various degrees of ethanol tolerance to assess the correlation between lipid composition and fermentation kinetic parameters. Lipids were extracted at several fermentation time points representing different growth phases of the yeast to quantitatively analyze phospholipids and ergosterol utilizing atmospheric pressure ionization-mass spectrometry methods. Lipid profiling of individual fermentations indicated that yeast lipid class profiles do not shift dramatically in composition over the course of fermentation. Multivariate statistical analysis of the data was performed using partial least-squares linear regression modeling to correlate lipid composition data with fermentation kinetic data. The results indicate a strong correlation (R² = 0.91) between the overall lipid composition and the final ethanol concentration (wt/wt), an indicator of strain ethanol tolerance. One potential component of ethanol tolerance, the maximum yeast cell concentration, was also found to be a strong function of lipid composition (R² = 0.97). Specifically, strains unable to complete fermentation were associated with high phosphatidylinositol levels early in fermentation. Yeast strains that achieved the highest cell densities and ethanol concentrations were positively correlated with phosphatidylcholine species similar to those known to decrease the perturbing effects of ethanol in model membrane systems.Clark M. Henderson, Michelle Lozada-Contreras, Vladimir Jiranek, Marjorie L. Longo, David E. Bloc
Evolution of cooperation among tumor cells
No full textThe evolution of cooperation has a well established theoretical framework based on game theory. This approach has made valuable contributions to a wide variety of disciplines, including political science, economics, and evolutionary biology. Existing cancer theory suggests that individual clones of cancer cells evolve independently from one another, acquiring all of the genetic traits or hallmarks necessary to form a malignant tumor. It is also now recognized that tumors are heterotypic, with cancer cells interacting with normal stromal cells within the issue microenvironment, including endothelial, stromal, and nerve cells. This tumor cell???stromal cell interaction in itself is a form of commensalism, because it has been demonstrated that these nonmalignant cells support and even enable tumor growth. Here, we add to this theory by regarding tumor cells as game players whose interactions help to determine their Darwinian fitness. We marshal evidence that tumor cells overcome certain host defenses by means of diffusible products. Our original contribution is to raise the possibility that two nearby cells can protect each other from a set of host defenses that neither could survive alone. Cooperation can evolve as byproduct mutualism among genetically diverse tumor cells. Our hypothesis supplements, but does not supplant, the traditional view of carcinogenesis in which one clonal population of cells develops all of the necessary genetic traits independently to form a tumor. Cooperation through the sharing of diffusible products raises new questions about tumorigenesis and has implications for understanding observed phenomena, designing new experiments, and developing new therapeutic approaches.Author manuscript. Published in final edited form as: Proc Natl Acad Sci U S A. 2006 September 5; 103(36): 13474-13479.The final published version of this article is located at: www.pnas.org/cgi/doi/10.1073/pnas.0606053103NIH U56 CA113004; to David E. AxelrodR.A. was supported by National Science Foundation (NSF) Grant SES-0240852. D.E.A. was supported by NSF Grant IIS-0312953, National Institutes of Health (NIH) Grant U56 CA113004, and New Jersey Commission on Cancer Research Grant 1076-CCR-SO. K.J.P. is an American Cancer Society Clinical Research Professor and is supported by NIH Grants CA69568, CA102872, and CA093900.NIH CA69568; to Kenneth J. PientaNIH CA102872; to Kenneth J. PientaNIH CA093900; to Kenneth J. PientaNSF SES-0240852; to Robert AxelrodNJ Commission on Cancer Research 1076-CCR-SO; to David E. AxelrodAlso available in PubMed Central. PMCID: PMC155738
Colon_Crypt_Model_041321.nlogo
No full textTitle: Colon_Crypt_Model_041321.nlogo
Research genre: Computer program
Creator: Axelrod, David E.
Date Created: 2021
Extent: 1 digital file (393 KB)
Intended Audience: Science
Description: Computer program that simulates and plots the dynamics of stem cells, transient amplifying cells, differentiated cells, and mutant cells in normal human colon crypts and early colon cancer. It has been calibrated with measurements of human biopsy specimens. Includes graphical user interface, detailed information text, and annotated code. Experiments can be run from the GUI without knowledge of coding, or from the Behavior Space Tool using example code or modified code. It has been used to simulate human colon cancer initiation, therapy, and prevention. Different chemotherapy or prevention intermittent dose schedules can be input. Chemotherapy of heterogeneous and drug resistant early colon cancers can be simulated. Circadian cell proliferation can be selected to investigate chronomodulated chemotherapy dose schedules. Simulated output can be saved in spreadsheet format, or as images of plots of cell numbers as function of time.
The model was developed in the application NetLogo version 5.3.1, and revisions made to also run in NetLogo version 6.2.0. The model will not run on the Web version of NetLogo. NetLogo is a multi-agent programmable modeling environment. It is authored by Uri Wilenski and developed at The Center for Connected Learning (CCL) and Computer-Based Modeling. It is multi-platform (Mac, Windows, or Linux) open source application.
NetLogo version 6.2.0, can be downloaded at http://ccl.northwestern.edu/netlogo/download.shtml. To download the computer program click on the red link “NLOGO" to the left.
Earlier versions of the model and its use have been described in the following publications: Theoret Biol Med Model. 2013;10:66-89. Cancer Chemother Pharmcol 2017;79:889-898. Converg Sci Phys Oncol 2017;3:035004. Cancer Inform 2019;18:1-8. JCO Clin Cancer Inform 2020;4:514-520. A forthcoming publication will describe results of circadian-timed chemotherapy.
Research Domain: Science
Subjects: Chronotherapy: Circadian: Colorectal cancer: Chemotherapy: Agent-based model
Rights statement: The author owns the copyright to this work
Disputatio philosophica de dependentia creaturae a Deo in esse, fieri, et operari
No full textquam auspice Deo , sub praesidio Dn. Ioh. Rod. Ottii ... amico examini subiicit David Holzhalbius author & respondens ...Diss. Hohe Schule Zürich, 169
Finding efficient distinguishers for cryptographic mappings, with an application to the block cipher TEA
No full textCongress on Evolutionary Computation. 8-12 December 2003A simple way of creating new and efficient distinguishers for cryptographic primitives such as block ciphers or hash functions is introduced. This technique is then successfully applied over reduced round versions of the block cipher TEA, which is proven to be weak with less than five rounds
E-book : Industrial Transformation In The Developing World (author: Michael T. Rock & David P. Angel)
No full textArsip Kuliah Online 2010: E-book : Industrial Transformation In The Developing World (author: Michael T. Rock & David P. Angel
Teoria das Situações Didáticas e Engenharia Didática
No full textPonencia presentada en el 1º Simposio Latinoamericano de Didáctica de la Matemática. Bonito (Brasil), 1 al 6 de noviembre de 2016.Fil: Fregona, Dilma. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.Fil: Block, David. Instituto Politécnico Nacional. Centro de Investigación y de Estudios Avanzados; México.Fil: Orús, Pilar. Universitat Jaume I; EspañaEl taller, asociado a la conferencia "A Engenharia Didática entre Pesquisa e Recurso para o Ensino e a Formação de Professores" dictada por Marie-Jeanne Perrin-Glorian (Universidade de Artois/França) e Paula Baltar (UFPE/PE-Brasil), analiza desde la óptica de la teoría de las situaciones didácticas, las decisiones didácticas tomadas en una secuencia de enseñanza de la división y de la multiplicación en N. El documento tomado es una publicación del IREM de Bordeaux (BROUSSEAU, N. et al, 1985), elaborado por docentes de la Escuela Michelet e investigadores en didáctica de la matemática.http://ladima.tuseon.com.br/anais---conferencias-e-oficinas.htmlsubmittedVersionFil: Fregona, Dilma. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.Fil: Block, David. Instituto Politécnico Nacional. Centro de Investigación y de Estudios Avanzados; México.Fil: Orús, Pilar. Universitat Jaume I; EspañaEducación General (incluye capacitación, pedagogía y didáctica
E-book : "industrial Transformations In The Developing World (author: Michael T. Rock & David. P Angel)
No full textArsip Kuliah Online 2010: E-book : "industrial Transformations In The Developing World (author: Michael T. Rock & David. P Angel
Landsat MSS classification of fire fuel types in Wood Buffalo National Park, northern Canada
No full textJ1: Global Ecology & Biogeography Letters; M3: Article; Milne, David Franklin, Steven E. Wilson, Bradley A. Ghitter, Geoff Heathcott, Mark McCaffrey, Thomas M. Ow, Charlotte F. Y.; Source Information: Mar1994, Vol. 4 Issue 2, p33; Subject Term: FOREST fires; Author-Supplied Keyword: Canada (Wood Buffalo National Park); Author-Supplied Keyword: Forest fire; Author-Supplied Keyword: Fuel type classification; Author-Supplied Keyword: Landsat data; Number of Pages: 0p; Document Type: Articl
David Audretsch: A Source of Inspiration, a Co-author, and a Friend
No full textIn this chapter, Enrico Santarelli discusses the profound impact that David had on his career. Beginning with a conference in Budapest, Santarelli and David bocame close friends and colleagues. They went on to collaborate on many papers and projects, several of which Santarelli highlights below
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