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arXiv
Subject Source arXiv URL https://arxiv.org/abs/1001.0128view Article Title Dielectric properties and spin-phonon coupling in multiferroic double perovskite Bi$_2$CoMnO$_6$Authors Satadeep Bhattacharjee; Olle Eriksson; Biplab SanyalAbstract First-principles electronic structure calculations have been performed for the double perovskite Bi$_2$CoMnO$_6$ in its non-centrosymmetric polar state using generalized gradient approximation plus Hubbard U approach. We find that while Co is in a high spin state, Mn is in an intermediate spin state. The calculated dynamical charge tensors are anisotropic reflecting a low-symmetry structure of the compound. Magnetic structure dependent phonon frequencies indicate the presence of spin-phonon coupling. Using Berry phase method, we obtain a spontaneous electronic polarization of 5.88 ${\mu}C/cm^2$ which is close to the experimental value observed for a similar compound, Bi$_2$NiMnO$_6$.Is Part Of 2009-12-31 Identifier ISSN: Category cond-mat.mtrl-sci cond-mat.str-elLicense -
Springer Nature
Subject Source Springer Nature URL http://dx.doi.org/10.3858/emm.2009.41.12.096view Article Title Fibroblasts in three dimensional matrices: cell migration and matrix remodelingAuthors Rhee, SangmyungAbstract {p=Fibroblast-collagen matrix culture has facilitated the analysis of cell physiology under conditions that more closely resemble an in vivo -like environment compared to conventional 2-dimensional (2D) cell culture. Furthermore, it has led to significant progress in understanding reciprocal and adaptive interactions between fibroblasts and the collagen matrix, which occur in tissue. Recent studies on fibroblasts in 3-dimensional (3D) collagen matrices have revealed the importance of biomechanical conditions in addition to biochemical cues for cell signaling and migration. Depending on the surrounding mechanical conditions, cells utilize specific cytoskeletal proteins to adapt to their environment. More specifically, cells utilize microtubule dependent dendritic extensions to provide mechanical structure for matrix contraction under a low cell-matrix tension state, whereas cells in a high cell-matrix tension state utilize conventional acto-myosin activity for matrix remodeling. Results of collagen matrix contraction and cell migration in a 3D collagen matrix revealed that the use of appropriate growth factors led to promigratory and procontractile activity for cultured fibroblasts. Finally, the relationship between cell migration and tractional force for matrix remodeling was discussed., h1=Abstract}Is Part Of Experimental & Molecular Medicine 2009-12-31 , Vol.41 (12) , 858 Identifier EISSN: null ; PISSN: DOI 10.3858/emm.2009.41.12.096Publisher NatureLicense ©2009 The Author(s) -
Springer Nature
Subject Source Springer Nature URL http://dx.doi.org/10.1007/s00018-009-0229-6view Article Title From protein sequences to 3D-structures and beyond: the example of the UniProt KnowledgebaseAuthors Hinz, Ursula; The UniProt ConsortiumAbstract {p=With the dramatic increase in the volume of experimental results in every domain of life sciences, assembling pertinent data and combining information from different fields has become a challenge. Information is dispersed over numerous specialized databases and is presented in many different formats. Rapid access to experiment-based information about well-characterized proteins helps predict the function of uncharacterized proteins identified by large-scale sequencing. In this context, universal knowledgebases play essential roles in providing access to data from complementary types of experiments and serving as hubs with cross-references to many specialized databases. This review outlines how the value of experimental data is optimized by combining high-quality protein sequences with complementary experimental results, including information derived from protein 3D-structures, using as an example the UniProt knowledgebase (UniProtKB) and the tools and links provided on its website ( http://www.uniprot.org/ ). It also evokes precautions that are necessary for successful predictions and extrapolations., h1=Abstract}Is Part Of Cellular and Molecular Life Sciences 2009-12-31 , Vol.67 (7) , 1049 Identifier EISSN: null ; PISSN: DOI 10.1007/s00018-009-0229-6Publisher SpringerLicense ©2009 The Author(s) -
Springer Nature
Subject Source Springer Nature URL http://dx.doi.org/10.3858/emm.2009.41.12.103view Article Title Hypoxia and angiogenesis: regulation of hypoxia-inducible factors via novel binding factorsAuthors Chen, Li; Endler, Alexander; Shibasaki, FutoshiAbstract {p=The mechanisms that regulate angiogenesis in hypoxia or hypoxic microenvironment are modulated by several pro- and antiangiogenic factors. Hypoxia-inducible factors (HIFs) have been established as the basic and major inducers of angiogenesis, but understanding the role of interacting proteins is becoming increasingly important to elucidate the angiogenic processes of a hypoxic response. In particular, with regard to wound healing and the novel therapies for vascular disorders such as ischemic brain and heart attack, it is essential to gain insights in the formation and regulation of HIF transcriptional machineries related to angiogenesis. Further, identification of alternative ways of inhibiting tumor growth by disrupting the growth-triggering mechanisms of increasing vascular supply via angiogenesis depends on the knowledge of how tumor cells develop their own vasculature. Here, we review our findings on the interactions of basic HIFs, HIF-1α and HIF-2α, with their regulatory binding proteins, histone deacetylase 7 (HDAC7) and translation initiation factor 6 (Int6), respectively. The present results and discussion revealed new regulatory interactions of HIF-related mechanisms., h1=Abstract}Is Part Of Experimental & Molecular Medicine 2009-12-31 , Vol.41 (12) , 849 Identifier EISSN: null ; PISSN: DOI 10.3858/emm.2009.41.12.103Publisher NatureLicense ©2009 The Author(s) -
PLOS
Subject 의과학, 인문사회과학 Source PLOS URL http://dx.doi.org/10.1371/journal.pone.0008543view Article Title Abnormal Placental Development and Early Embryonic Lethality in EpCAM-Null MiceAuthors Keisuke Nagao; Jianjian Zhu; Mallorie B Heneghan; Jeffrey C Hanson; Maria I Morasso; Lino Tessarollo; Susan Mackem; Mark C Udey; Mai Har ShamAbstract Background: EpCAM (CD326) is encoded by the tacstd1 gene and expressed by a variety of normal and malignant epithelial cells and some leukocytes. Results of previous in vitro experiments suggested that EpCAM is an intercellular adhesion molecule. EpCAM has been extensively studied as a potential tumor marker and immunotherapy target, and more recent studies suggest that EpCAM expression may be characteristic of cancer stem cells. Methodology/Principal Findings: To gain insights into EpCAM function in vivo, we generated EpCAM −/− mice utilizing an embryonic stem cell line with a tacstd1 allele that had been disrupted. Gene trapping resulted in a protein comprised of the N-terminus of EpCAM encoded by 2 exons of the tacstd1 gene fused in frame to βgeo. EpCAM +/− mice were viable and fertile and exhibited no obvious abnormalities. Examination of EpCAM +/− embryos revealed that βgeo was expressed in several epithelial structures including developing ears (otocysts), eyes, branchial arches, gut, apical ectodermal ridges, lungs, pancreas, hair follicles and others. All EpCAM −/− mice died in utero by E12.5, and were small, developmentally delayed, and displayed prominent placental abnormalities. In developing placentas, EpCAM was expressed throughout the labyrinthine layer and by spongiotrophoblasts as well. Placentas of EpCAM −/− embryos were compact, with thin labyrinthine layers lacking prominent vascularity. Parietal trophoblast giant cells were also dramatically reduced in EpCAM −/− placentas. Conclusion: EpCAM was required for differentiation or survival of parietal trophoblast giant cells, normal development of the placental labyrinth and establishment of a competent maternal-fetal circulation. The findings in EpCAM-reporter mice suggest involvement of this molecule in development of vital organs including the gut, kidneys, pancreas, lungs, eyes, and limbs.Is Part Of PLoS ONE 2009-12-31 , Vol.4 (12) Identifier EISSN: 1932-6203 ; PISSN: DOI 10.1371/journal.pone.0008543Publisher Public Library of ScienceCategory /Biology and life sciences/Developmental biology/Embryology/Embryos; /Biology and life sciences/Cell biology/Cellular types/Animal cells/Epithelial cells; /Research and analysis methods/Specimen preparation and treatment/Staining/Immunofluorescence staining; /Biology and life sciences/Developmental biology/Embryology/Placenta; /Biology and life sciences/Cell biology/Cellular types/Animal cells/Giant cells; /Biology and life sciences/Developmental biology/Embryology/Blastocysts/Trophoblasts; /Biology and life sciences/Developmental biology/Organism development/Organogenesis/Lung development; /Medicine and health sciences/Anatomy/Biological tissue/Epithelium/Epithelial cells; /Biology and life sciences/Anatomy/Biological tissue/Epithelium/Epithelial cells; /Medicine and health sciences/Anatomy/Reproductive system/Placenta; /Biology and life sciences/Anatomy/Reproductive system/Placenta; /Medicine and health sciences/Anatomy/Integumentary system/Hair/Hair follicles; /Biology and life sciences/Anatomy/Integumentary system/Hair/Hair follicles; /Medicine and health sciences/Anatomy/Integumentary system/Skin/Hair follicles; /Biology and life sciences/Anatomy/Integumentary system/Skin/Hair folliclesLicense This is an open-access article distributed under the terms of the Creative Commons Public Domain declaration which stipulates that, once placed in the public domain, this work may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. -
arXiv
Subject 수학 Source arXiv URL https://arxiv.org/abs/1001.0157view Article Title Every central simple algebra is Hopf SchurAuthors Ehud MeirAbstract We show that every central simple algebra A over a field k is Brauer equivalent to a quotient of a finite dimensional Hopf algebra over the same field (that is- A is Hopf Schur). If the characteristic of the field is zero, or if the algebra has a Galois splitting field of degree prime to the characteristic of k, we can take this Hopf algebra to be semisimple. We also show that if F is any finite extension of k, then F is a quotient of a finite dimensional Hopf algebra over k. We use it in order to show why the algebric closeness assumption is necessary in a weak form of Kaplansky's tenth conjecture, due to StefanIs Part Of 2009-12-31 Identifier ISSN: Category math.RA math.QALicense -
Springer Nature
Subject Source Springer Nature URL http://dx.doi.org/10.1186/1752-0509-3-122view Article Title A computational approach to resolve cell level contributions to early glandular epithelial cancer progressionAuthors Kim, Sean HJ; Debnath, Jayanta; Mostov, Keith; Park, Sunwoo; Hunt, C AnthonyAbstract {p=[Background, Three-dimensional (3D) embedded cell cultures provide an appropriate physiological environment to reconstruct features of early glandular epithelial cancer. Although these are orders of magnitude simpler than tissues, they too are complex systems that have proven challenging to understand. We used agent-based, discrete event simulation modeling methods to build working hypotheses of mechanisms of epithelial 3D culture phenotype and early cancer progression. Starting with an earlier software analogue, we validated an improved in silico epithelial analogue (ISEA) for cardinal features of a normally developed MDCK cyst. A set of axiomatic operating principles defined simulated cell actions. We explored selective disruption of individual simulated cell actions. New framework features enabled recording detailed measures of ISEA cell activities and morphology., Results, Enabled by a small set of cell operating principles, ISEA cells multiplied and self-organized into cyst-like structures that mimicked those of MDCK cells in a 3D embedded cell culture. Selective disruption of "anoikis" or directional cell division caused the ISEA to develop phenotypic features resembling those of in vitro tumor reconstruction models and cancerous tissues in vivo. Disrupting either process, or both, altered cell activity patterns that resulted in morphologically similar outcomes. Increased disruption led to a prolonged presence of intraluminal cells., Conclusions, ISEA mechanisms, behaviors, and morphological properties may have biological counterparts. To the extent that in silico-to-in vitro mappings are valid, the results suggest plausible, additional mechanisms of in vitro cancer reconstruction or reversion, and raise potentially significant implications for early cancer diagnosis based on histology. Further ISEA development and use are expected to provide a viable platform to complement in vitro methods for unraveling the mechanistic basis of epithelial morphogenesis and cancer progression.], h1=Abstract}Is Part Of BMC Systems Biology 2009-12-31 , Vol.3 (1) , 1 Identifier EISSN: null ; PISSN: DOI 10.1186/1752-0509-3-122Publisher BioMed CentralLicense ©2009 Kim et al; licensee BioMed Central Ltd. -
arXiv
Subject 수학 Source arXiv URL https://arxiv.org/abs/1001.0191view Article Title Group gradings on restricted Cartan type Lie algebrasAuthors Yuri Bahturin; Mikhail KochetovAbstract For a given abelian group G, we classify the isomorphism classes of G-gradings on the simple restricted Lie algebras of types W(m;1) and S(m;1) (m>=2), in terms of numerical and group-theoretical invariants. Our main tool is automorphism group schemes, which we determine for the simple restricted Lie algebras of types S(m;1) and H(m;1). The ground field is assumed to be algebraically closed of characteristic p>3.Is Part Of Pacific Journal of Mathematics, 253 (2011), no. 2, p. 289-319 2009-12-31 Identifier ISSN: Category math.RALicense -
arXiv
Subject 수학 Source arXiv URL https://arxiv.org/abs/1001.0177view Article Title On the slope of relatively minimal fibrations on rational complex surfacesAuthors Claudia R. Alcantara; Abel Castorena; Alexis G. ZamoraAbstract Given a relatively minimal fibration $f: S \to \Bbb P^1$ on a rational surface $S$ with general fiber $C$ of genus $g$, we investigate under what conditions the inequality $6(g-1)\le K_f^2$ occurs, where $K_f$ is the canonical relative sheaf of $f$. We give sufficient conditions for having such inequality, depending on the genus and gonality of $C$ and the number of certain exceptional curves on $S$. We illustrate how these results can be used for constructing fibrations with the desired property. For fibrations of genus $11\le g\le 49$ we prove the inequality: $$ 6(g-1) +4 -4\sqrt g \le K_f^2.$$Is Part Of 2009-12-31 Identifier ISSN: Category math.AGLicense -
arXiv
Subject Source arXiv URL https://arxiv.org/abs/1001.0110view Article Title On the dimers of PseudoisocyanineAuthors P. O. J. SchererAbstract The self organization of pseudoisocyanine-dimers in dilute aqueous solutions is studied by classical MD simulations. The electronic structure of the dimer is evaluated with the semiempirical ZINDO method to determine the fluctuations of site energies and excitonic coupling. We study different dimer conformations with blue or red shifted absorption maxima as models for H and J-aggregates. The width of the absorption bands is mainly explained by low frequency vibrations whereas the fluctuations of site energies are less important.Is Part Of 2009-12-31 Identifier ISSN: Category physics.chem-phLicense