Abstract:
:An expression in the exterior algebra of a Peano space yielding Pappus' theorem was originally given by Doubilet, Rota, and Stein [Doubilet, P., Rota, G.-C. & Stein, J. (1974) Stud. Appl. Math. 8, 185-216]. Motivated by an identity of Rota, I give an identity in a Grassmann-Cayley algebra of step 3, involving joins and meets alone, which expresses the theorem of Pappus.
journal_name
Proc Natl Acad Sci U S Aauthors
Hawrylycz Mdoi
10.1073/pnas.91.8.2909keywords:
subject
Has Abstractpub_date
1994-04-12 00:00:00pages
2909issue
8eissn
0027-8424issn
1091-6490journal_volume
91pub_type
杂志文章abstract::Ectopic expression of transcription factors can reprogram somatic cells to a pluripotent state. However, most of the studies used skin fibroblasts as the starting population for reprogramming, which usually take weeks for expansion from a single biopsy. We show here that induced pluripotent stem (iPS) cells can be gen...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0908450106
更新日期:2009-09-15 00:00:00
abstract::Human embryonic zeta-globin chains are alpha-globin-like chains that are normally present during the first three months of gestation. In this investigation, zeta-globin chains measured by a specific and sensitive radioimmunoassay and by an electrophoretic technique were found to be present in all 7 patients studied wi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.81.19.6188
更新日期:1984-10-01 00:00:00
abstract::Transcriptional activator proteins in bacteria often operate by interaction with the C-terminal domain of the alpha-subunit of RNA polymerase (RNAP). Here we report the discovery of an "anti-alpha" factor Spx in Bacillus subtilis that blocks transcriptional activation by binding to the alpha-C-terminal domain, thereby...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0637648100
更新日期:2003-04-01 00:00:00
abstract::Arsenate is an abundant oxyanion that, because of its ability to mimic the phosphate group, is toxic to cells. Arsenate reductase (EC; encoded by the arsC gene in bacteria) participates to achieve arsenate resistance in both prokaryotes and yeast by reducing arsenate to arsenite; the arsenite is then exported by a spe...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.241397198
更新日期:2001-11-20 00:00:00
abstract::TGF-β activated kinase 1 (TAK1) is a critical signaling hub responsible for translating antigen binding signals to immune receptors for the activation of the AP-1 and NF-κB master transcriptional programs. Despite its importance, known substrates of TAK1 are limited to kinases of the MAPK and IKK families and include ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1608355113
更新日期:2016-08-16 00:00:00
abstract::We are presented with choices each day about how to invest our effort to achieve our goals. Critically, these decisions must frequently be made under conditions of incomplete information, where either the effort required or possible reward to be gained is uncertain. Such choices therefore require the development of po...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1800444115
更新日期:2018-05-29 00:00:00
abstract::We report the development of a practical ultrafast allelic profiling assay for the analysis of short tandem repeats (STRs) by using a highly optimized microfluidic electrophoresis device. We have achieved baseline-resolved electrophoretic separations of single-locus STR samples in 30 sec. Analyses of PCR samples conta...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.94.19.10273
更新日期:1997-09-16 00:00:00
abstract::Markov chain Monte Carlo (MCMC) or the Metropolis-Hastings algorithm is a simulation algorithm that has made modern Bayesian statistical inference possible. Nevertheless, the efficiency of different Metropolis-Hastings proposal kernels has rarely been studied except for the Gaussian proposal. Here we propose a unique ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1311790110
更新日期:2013-11-26 00:00:00
abstract::Many complex systems are organized in the form of a network embedded in space. Important examples include the physical Internet infrastructure, road networks, flight connections, brain functional networks, and social networks. The effect of space on network topology has recently come under the spotlight because of the...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1018962108
更新日期:2011-05-10 00:00:00
abstract::Regulation of gene expression is usually separated into cis and trans components. The separation may become artificial if much of the variation in expression is under multigenic and epistatic (e.g., cis-by-trans) control. There is hence a need to quantify the relative contribution of cis, trans, and cis-by-trans effec...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0711774105
更新日期:2008-04-29 00:00:00
abstract::Social status motivates much of human behavior. However, status may have been a relatively weak target of selection for much of human evolution if ancestral foragers tended to be more egalitarian. We test the "egalitarianism hypothesis" that status has a significantly smaller effect on reproductive success (RS) in for...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1606800113
更新日期:2016-09-27 00:00:00
abstract::Functional reconstitution of membrane proteins within lipid bilayers is crucial for understanding their biological function in living cells. While this strategy has been extensively used with liposomes, reconstitution of membrane proteins in lipidic cubic mesophases presents significant challenges related to the struc...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1603965113
更新日期:2016-07-05 00:00:00
abstract::The utility of adenovirus (Ad) vectors for gene transduction can be limited by receptor specificity. We developed a gene-delivery vehicle in which the potent Ad5 vector was genetically reengineered to display the mucosal-targeting sigma1 protein of reovirus type 3 Dearing (T3D). A sigma1 construct containing all but a...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0400542101
更新日期:2004-04-20 00:00:00
abstract::Vasopressin's action in renal cells to regulate water transport depends on protein phosphorylation. Here we used mass spectrometry-based quantitative phosphoproteomics to identify signaling pathways involved in the short-term V2-receptor-mediated response in cultured collecting duct cells (mpkCCD) from mouse. Using St...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0910646107
更新日期:2010-02-23 00:00:00
abstract::Endogenous circadian rhythms have been described in a wide range of organisms from prokaryotes to man. Although basic circadian mechanisms at the molecular level are genetically fixed, certain properties of circadian rhythms at the organismic level can be modified by environmental conditions and subsequently retained ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.200354997
更新日期:2000-10-24 00:00:00
abstract::The fluorescent vital dye rhodamine 123 (Rh-123), which preferentially accumulates in mitochondrial membranes, can be used as a probe to indicate mitochondrial and hence cellular activity. In this study, mouse bone marrow hematopoietic stem cells were subdivided into Rh-123lo, Rh-123med, and Rh-123hi populations. The ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.87.19.7433
更新日期:1990-10-01 00:00:00
abstract::One of the factors required for the antiviral activity of the synthetic nucleoside, ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide), is the ability of the molecule to adopt the substrate conformation specified by the enzyme for which it is a competitive inhibitor, inosine 5'-phosphate dehydrogenase (IM...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.73.12.4257
更新日期:1976-12-01 00:00:00
abstract::The fusiform face area (FFA) is a region of human cortex that responds selectively to faces, but whether it supports a more general function relevant for perceptual expertise is debated. Although both faces and objects of expertise engage many brain areas, the FFA remains the focus of the strongest modular claims and ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1116333109
更新日期:2012-10-16 00:00:00
abstract::Aminoacyl-tRNA synthetases (amino acid-tRNA ligases, EC 6.1.1.-) catalyze the aminoacylation of specific amino acids onto their cognate tRNAs with extraordinary accuracy. Recent reports, however, indicate that this class of enzymes may play other roles in cellular metabolism. Several aminoacyl-tRNA synthetases are her...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.84.22.7891
更新日期:1987-11-01 00:00:00
abstract::We have used the polymerase chain reaction to amplify the entire coding region of canine factor IX from a hemophilia B animal. When the sequence was compared to that which codes for normal canine factor IX, a single missense mutation was identified. This mutation (G----A at nucleotide 1477) results in the substitution...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.86.24.10095
更新日期:1989-12-01 00:00:00
abstract::B-1a cells reside in both the peritoneal cavity and the spleen. LPS stimulates splenic B-1a to differentiate to plasma cells producing natural IgM specific for microbial and self antigens. However, there are conflicting views as to whether the B-1a cells divide before this differentiation occurs, and hence how the res...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0700001104
更新日期:2007-03-13 00:00:00
abstract::Human skeletal muscle is composed of various muscle fiber types. We hypothesized that differences in metabolism between fiber types could be detected noninvasively with 31P nuclear magnetic resonance spectroscopy during maximal exercise. This assumes that during maximal exercise all fiber types are recruited and all v...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.13.5714
更新日期:1991-07-01 00:00:00
abstract::The past decade of scientific ocean drilling has revealed seemingly ubiquitous, slow-growing microbial life within a range of deep biosphere habitats. Integrated Ocean Drilling Program Expedition 337 expanded these studies by successfully coring Miocene-aged coal beds 2 km below the seafloor hypothesized to be "hot sp...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1707525114
更新日期:2017-10-31 00:00:00
abstract::Three lines of evidence for abrupt tropical climate change, both past and present, are presented. First, annually and decadally averaged delta(18)O and net mass-balance histories for the last 400 and 2,000 yr, respectively, demonstrate that the current warming at high elevations in the mid- to low latitudes is unprece...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0603900103
更新日期:2006-07-11 00:00:00
abstract::Zeatin is the most active and ubiquitous of the naturally occurring cytokinins. The O-glucoside of zeatin, found in all plants examined, is considered to be important in cytokinin transport, storage, and protection against cytokinin oxidases. The enzyme UDPglucose:zeatin O-glucosyltransferase (EC 2.4.1.203) was previo...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.1.284
更新日期:1999-01-05 00:00:00
abstract::The genetic basis for virulence in influenza virus is largely unknown. To explore the mutational basis for increased virulence in the lung, the H3N2 prototype clinical isolate, A/HK/1/68, was adapted to the mouse. Genomic sequencing provided the first demonstration, to our knowledge, that a group of 11 mutations can c...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.111165798
更新日期:2001-06-05 00:00:00
abstract::Although de novo protein design is an important endeavor with implications for understanding protein folding, until now, structures have been determined for only a few 25- to 30-residue designed miniproteins. Here, the NMR solution structure of a complex 73-residue three-helix bundle protein, alpha3D, is reported. The...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.10.5486
更新日期:1999-05-11 00:00:00
abstract::The Hippo pathway is an evolutionarily conserved regulator of organ growth and tumorigenesis. In Drosophila, oncogenic RasV12 cooperates with loss-of-cell polarity to promote Hippo pathway-dependent tumor growth. To identify additional factors that modulate this signaling, we performed a genetic screen utilizing the D...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.2013449117
更新日期:2020-12-01 00:00:00
abstract::The programmed activation/repression of transcription factors in early hematopoietic differentiation has not yet been explored. The DNA-binding protein GATA-1 is required for normal erythroid development and regulates erythroid-expressed genes in maturing erythroblasts. We analyzed GATA-1 expression in early human adu...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.89.14.6353
更新日期:1992-07-15 00:00:00
abstract::The charge-stabilization effect associated with alpha-helices in proteins has been reexamined by microscopic calculations without any a priori assumptions about the dielectric constant of the protein. The calculations reproduce the observed charge stabilization effect of a helix in two well-defined test cases: a histi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.5.2026
更新日期:1991-03-01 00:00:00