Abstract:
:In savannas, predicting how vegetation varies is a longstanding challenge. Spatial patterning in vegetation may structure that variability, mediated by spatial interactions, including competition and facilitation. Here, we use unique high-resolution, spatially extensive data of tree distributions in an African savanna, derived from airborne Light Detection and Ranging (LiDAR), to examine tree-clustering patterns. We show that tree cluster sizes were governed by power laws over two to three orders of magnitude in spatial scale and that the parameters on their distributions were invariant with respect to underlying environment. Concluding that some universal process governs spatial patterns in tree distributions may be premature. However, we can say that, although the tree layer may look unpredictable locally, at scales relevant to prediction in, e.g., global vegetation models, vegetation is instead strongly structured by regular statistical distributions.
journal_name
Proc Natl Acad Sci U S Aauthors
Staver AC,Asner GP,Rodriguez-Iturbe I,Levin SA,Smit IPJdoi
10.1073/pnas.1819391116subject
Has Abstractpub_date
2019-05-28 00:00:00pages
10681-10685issue
22eissn
0027-8424issn
1091-6490pii
1819391116journal_volume
116pub_type
杂志文章abstract::Defining the links between cell division and DNA replication is essential for understanding normal cell cycle progression and tumorigenesis. In this report we explore the effect of phosphorylation of cell division cycle 6 (Cdc6), a DNA replication initiation factor, by polo-like kinase 1 (Plk1) on the regulation of ch...
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.1013557107
更新日期:2010-11-16 00:00:00
abstract::Cholinergic neuromodulation is involved in all aspects of sensory processing and is crucial for processes such as attention, learning and memory, etc. However, despite the known roles of acetylcholine (ACh), we still do not how to disentangle ACh contributions from sensory or task-evoked changes in functional magnetic...
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.1808507115
更新日期:2018-12-18 00:00:00
abstract::N-methyl-D-aspartate (NMDA) glutamate receptor-mediated increases in intracellular calcium are thought to play a critical role in synaptic plasticity. The mechanisms by which changes in cytoplasmic calcium transmit the glutamate signal to the nucleus, which is ultimately important for long-lasting neuronal responses, ...
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.95.10.5773
更新日期:1998-05-12 00:00:00
abstract::"Functional connectivity" techniques are commonplace tools for studying brain organization. A critical element of these analyses is to distinguish variance due to neurobiological signals from variance due to nonneurobiological signals. Multiecho fMRI techniques are a promising means for making such distinctions based ...
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.1720985115
更新日期:2018-02-27 00:00:00
abstract::We identified the phosphatidylinositol transfer protein (PITP) as being responsible for a powerful latent, nucleotide-independent, Golgi-vesiculating activity that is present in the cytosol but is only manifested as an uncontrolled activity in a cytosolic protein subfraction, in which it is separated from regulatory 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.95.19.11181
更新日期:1998-09-15 00:00:00
abstract::The x-ray structure of rubredoxin has been refined by energy minimization. The computed structure is constrained to have standard bond lengths, bond angles, and planar trans peptide groups. Also, since most of the steric overlaps have been relieved, it has a very low energy. As judged by the root mean square (RMS) dev...
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.71.9.3736
更新日期:1974-09-01 00:00:00
abstract::The ability of polynucleotides or polynucleotide duplexes such as poly(I).poly(C) to induce interferon production is proposed to depend on the existence of certain stable glycosidic orientations. It appears that a slight increase in instability of 1--3 kcal/mole (1 cal = 4.184 J) in the conformational regions near 20 ...
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.76.3.1018
更新日期:1979-03-01 00:00:00
abstract::U2 snRNP auxiliary factor 65 kDa (U2AF(65)) is a general splicing factor that contacts polypyrimidine (Py) tract and promotes prespliceosome assembly. In this report, we show that U2AF(65) stimulates alternative exon skipping in spinal muscular atrophy (SMA)-related survival motor neuron (SMN) pre-mRNA. A stronger 5' ...
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.1500639112
更新日期:2015-08-11 00:00:00
abstract::When the visual (striate) cortex (V1) is damaged in human subjects, cortical blindness results in the contralateral visual half field. Nevertheless, under some experimental conditions, subjects demonstrate a capacity to make visual discriminations in the blind hemifield (blindsight), even though they have no phenomena...
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.92.13.6122
更新日期:1995-06-20 00:00:00
abstract::We visualized synchronous dynamic brain networks by using prewhitened (stationary) magnetoencephalography signals. Data were acquired from 248 axial gradiometers while 10 subjects fixated on a spot of light for 45 s. After fitting an autoregressive integrative moving average model and taking the residuals, all pairwis...
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.0509623102
更新日期:2006-01-10 00:00:00
abstract::We describe the use of the matrix eigenvalue decomposition (EVD) and pseudoinverse projection and a tensor higher-order EVD (HOEVD) in reconstructing the pathways that compose a cellular system from genome-scale nondirectional networks of correlations among the genes of the system. The EVD formulates a genes x genes n...
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.0509033102
更新日期:2005-12-06 00:00:00
abstract::Conventional methods of determining the coupling factor alpha(2)(omega)F(omega) for the newly discovered high transition temperature (T(c)) cuprate superconductors by using tunneling and infrared measurements have thus far failed to show the cause of the very high T(c) of these compounds. This is due in part to diffic...
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.85.13.4596
更新日期:1988-07-01 00:00:00
abstract::Network theory provides a powerful tool for the representation and analysis of complex systems of interacting agents. Here, we investigate the U.S. House of Representatives network of committees and subcommittees, with committees connected according to "interlocks," or common membership. Analysis of this network revea...
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.0500191102
更新日期:2005-05-17 00:00:00
abstract::Apolipoprotein E (apoE), a plasma apolipoprotein that plays a central role in lipoprotein metabolism, is localized in the senile plaques, congophilic angiopathy, and neurofibrillary tangles of Alzheimer disease. Late-onset familial and sporadic Alzheimer disease patients have an increased frequency of one of the three...
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.90.17.8098
更新日期:1993-09-01 00:00:00
abstract::The antigenic mosaic of the Archaebacterium Methanobacterium thermoautotrophicum, strain delta H, was analyzed with a panel of six monoclonal antibodies. Five antigenic determinants were identified. One contains N-acetyl-D-glucosamine, another contains N-acetyl-D-galactosamine, and a third contains gamma-glutamylalani...
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.80.20.6346
更新日期:1983-10-01 00:00:00
abstract::Different polyubiquitin chain linkages direct substrates toward distinct cellular pathways. K63-linked ubiquitylation is known to regulate proteasome-independent events such as signal transduction, but its function in the context of heterogeneous ubiquitin chains remains unclear. Here, we report that K63 ubiquitylatio...
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.1716673115
更新日期:2018-02-13 00:00:00
abstract::The nature of chemical bonds of ruthenium(Ru)-quinine(Q) complexes, mononuclear [Ru(trpy)(3,5-t-Bu(2)Q)(OH(2))](ClO(4))(2) (trpy = 2,2':6',2''-terpyridine, 3,5-di-tert-butyl-1,2-benzoquinone) (1), and binuclear [Ru(2)(btpyan)(3,6-di-Bu(2)Q)(2)(OH(2))](2+) (btpyan = 1,8-bis(2,2':6',2''-terpyrid-4'-yl)anthracene, 3,6-t-...
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.1120705109
更新日期:2012-09-25 00:00:00
abstract::Heat shock protein 90-alpha (Hsp90alpha) is an intracellular molecular chaperone. However, it can also be secreted with the underlying regulatory mechanism remaining far from clear. Here we show that the secreted Hsp90alpha is a C-terminal truncated form and its secretion is regulated by the C-terminal EEVD motif via ...
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.0908151106
更新日期:2009-12-15 00:00:00
abstract::Nuclease resistance and RNA affinity are key criteria in the search for optimal antisense nucleic acid modifications, but the origins of the various levels of resistance to nuclease degradation conferred by chemical modification of DNA and RNA are currently not understood. The 2'-O-aminopropyl (AP)-RNA modification di...
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.96.25.14240
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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.1503530112
更新日期:2015-07-07 00:00:00
abstract::The human eosinophil differentiation factor (EDF) gene was cloned from a genomic library in lambda phage EMBL3A by using a murine EDF cDNA clone as a probe. The DNA sequence of a 3.2-kilobase BamHI fragment spanning the gene was determined. The gene contains three introns. The predicted amino acid sequence of 134 amin...
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.84.19.6629
更新日期:1987-10-01 00:00:00
abstract::CD4-expressing T cells in lymphoid organs are infected by the primary strains of HIV and represent one of the main sources of virus replication. Gene therapy strategies are being developed that allow the transfer of exogenous genes into CD4(+) T lymphocytes whose expression might prevent viral infection or replication...
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.94.16.8640
更新日期:1997-08-05 00:00:00
abstract::Murine mucopolysaccharidosis type VII is a heritable disease caused by a spontaneous mutation, gus(mps), closely linked to the beta-glucuronidase structural gene on chromosome 5. Mice homozygous for the mutation have a > 200-fold decrease in beta-glucuronidase mRNA levels and virtually no enzyme activity detectable by...
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.90.14.6567
更新日期:1993-07-15 00:00:00
abstract::Recently, diffraction elements that reverse the color sequence normally observed in planar diffraction gratings have been found in the wing scales of the butterfly Pierella luna. Here, we describe the creation of an artificial photonic material mimicking this reverse color-order diffraction effect. The bioinspired sys...
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.1412240111
更新日期:2014-11-04 00:00:00
abstract::Distributions of sulfur isotopes in geological samples would provide a record of atmospheric composition if the mechanism producing the isotope effects could be described quantitatively. We determined the UV absorption spectra of 32SO2, 33SO2, and 34SO2 and use them to interpret the geological record. The calculated i...
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.0903518106
更新日期:2009-09-01 00:00:00
abstract::Environmental cues are transmitted to the interior of the cell via a complex network of signaling hubs. Receptor tyrosine kinases (RTKs) and trimeric G proteins are two such major signaling hubs in eukaryotes. Conventionally, canonical signal transduction via trimeric G proteins is thought to be triggered exclusively ...
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.1420140112
更新日期:2015-03-03 00:00:00
abstract::BSC-1 cells, epithelial cells of African green monkey kidney origin, show pronounced density-dependent regulation of growth in cell culture. Growth of the cells is rapid to a density of approximately 1.5 x 10(5) cells/per cm(2) in Dulbecco-modified Eagle's medium supplemented with 10% calf serum. Above this "saturatio...
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.75.1.339
更新日期:1978-01-01 00:00:00
abstract::Systemic anthrax, caused by inhalation or ingestion of Bacillus anthracis spores, is characterized by rapid microbial growth stages that require iron. Tightly bound and highly regulated in a mammalian host, iron is scarce during an infection. To scavenge iron from its environment, B. anthracis synthesizes by independe...
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.0607055103
更新日期:2006-12-05 00:00:00
abstract::A mutation that confers resistance to the drug paromomycin is shown to be in the structural gene that codes for the ribosomal RNA in Tetrahymena. This observation was made by exploiting a variant of the ribosomal DNA that distorts amplification of this locus when a new somatic nucleus develops during conjugation. Beca...
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.82.9.2844
更新日期:1985-05-01 00:00:00
abstract::Telomerase activity was identified in extracts from several different mouse cell lines. Addition of telomeric TTAGGG repeats was specific to telomeric oligonucleotide primers and sensitive to pretreatment with RNase A. In contrast to the hundreds of repeats synthesized by the human and Tetrahymena telomerase enzymes i...
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.90.4.1493
更新日期:1993-02-15 00:00:00