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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Algorithmica 19 (1997), S. 354-368 
    ISSN: 1432-0541
    Keywords: Key words. Parallel algorithms, Maximal acyclic sets, Planar graphs.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. Given a graph G=(V,E), the well-known spanning forest problem of G can be viewed as the problem of finding a maximal subset F of edges in G such that the subgraph induced by F is acyclic. Although this problem has well-known efficient NC algorithms, its vertex counterpart, the problem of finding a maximal subset U of vertices in G such that the subgraph induced by U is acyclic, has not been shown to be in NC (or even in RNC) and is not believed to be parallelizable in general. In this paper we present NC algorithms for solving the latter problem for two special cases. First, we show that, for a planar graph with n vertices, the problem can be solved in $O(\log^3 n)$ time with O(n) processors on an EREW PRAM. Second, we show that the problem is solvable in NC if the input graph G has only vertex-induced paths of length polylogarithmic in the number of vertices of G. As a consequence of this result, we show that certain natural extensions of the well-studied maximal independent set problem remain solvable in NC. Moreover, we show that, for a constant-degree graph with n vertices, the problem can be solved in $O(\sqrt{n}\log^3n)$ time with O(n 2 ) processors on an EREW PRAM.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2018-06-29
    Description: The ultrafast laser excitation of matters leads to nonequilibrium states with complex solid-liquid phase-transition dynamics. We used electron diffraction at mega–electron volt energies to visualize the ultrafast melting of gold on the atomic scale length. For energy densities approaching the irreversible melting regime, we first observed heterogeneous melting on time scales of 100 to 1000 picoseconds, transitioning to homogeneous melting that occurs catastrophically within 10 to 20 picoseconds at higher energy densities. We showed evidence for the heterogeneous coexistence of solid and liquid. We determined the ion and electron temperature evolution and found superheated conditions. Our results constrain the electron-ion coupling rate, determine the Debye temperature, and reveal the melting sensitivity to nucleation seeds.
    Keywords: Physics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2018-09-20
    Description: Coxsackievirus A10 (CVA10) recently emerged as a major pathogen of hand, foot, and mouth disease and herpangina in children worldwide, and lack of a vaccine or a cure against CVA10 infections has made therapeutic antibody identification a public health priority. By targeting a local isolate, CVA10-FJ-01, we obtained a potent antibody, 2G8, against all three capsid forms of CVA10. We show that 2G8 exhibited both 100% preventive and 100% therapeutic efficacy against CVA10 infection in mice. Comparisons of the near-atomic cryo–electron microscopy structures of the three forms of CVA10 capsid and their complexes with 2G8 Fab reveal that a single Fab binds a border region across the three capsid proteins (VP1 to VP3) and explain 2G8’s remarkable cross-reactivities against all three capsid forms. The atomic structures of this first neutralizing antibody of CVA10 should inform strategies for designing vaccines and therapeutics against CVA10 infections.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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  • 4
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 2018-06-07
    Description: Ediacaran trace fossils provide key paleontological evidence for the evolution of early animals and their behaviors. Thus far, however, this fossil record has been limited to simple surface trails and relatively shallow burrows. We report possible trackways, preserved in association with burrows, from the terminal Ediacaran Shibantan Member (ca. 551 to ca. 541 million years ago) in the Yangtze Gorges area of South China. These trace fossils represent the earliest known trackways. They consist of two rows of imprints arranged in poorly organized series or repeated groups. These trackways may have been produced by bilaterian animals with paired appendages, although the phylum-level phylogenetic affinity of the trace makers remains unknown. It is possible that the trackways and associated burrows were produced by the same trace maker, indicating a complex behavior involving both walking and burrowing. Together, these trackways and burrows mark the arrival of a new era characterized by an increasing geobiological footprint of bilaterian animals.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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  • 5
    Publication Date: 2018-03-24
    Description: Ultrasonic imaging has been implemented as a powerful tool for noninvasive subsurface inspections of both structural and biological media. Current ultrasound probes are rigid and bulky and cannot readily image through nonplanar three-dimensional (3D) surfaces. However, imaging through these complicated surfaces is vital because stress concentrations at geometrical discontinuities render these surfaces highly prone to defects. This study reports a stretchable ultrasound probe that can conform to and detect nonplanar complex surfaces. The probe consists of a 10 x 10 array of piezoelectric transducers that exploit an "island-bridge" layout with multilayer electrodes, encapsulated by thin and compliant silicone elastomers. The stretchable probe shows excellent electromechanical coupling, minimal cross-talk, and more than 50% stretchability. Its performance is demonstrated by reconstructing defects in 3D space with high spatial resolution through flat, concave, and convex surfaces. The results hold great implications for applications of ultrasound that require imaging through complex surfaces.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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  • 6
    Publication Date: 2011-02-19
    Description: The deep-water Avalon biota (about 579 to 565 million years old) is often regarded as the earliest-known fossil assemblage with macroscopic and morphologically complex life forms. It has been proposed that the rise of the Avalon biota was triggered by the oxygenation of mid-Ediacaran deep oceans. Here we report a diverse assemblage of morphologically differentiated benthic macrofossils that were preserved largely in situ as carbonaceous compressions in black shales of the Ediacaran Lantian Formation (southern Anhui Province, South China). The Lantian biota, probably older than and taxonomically distinct from the Avalon biota, suggests that morphological diversification of macroscopic eukaryotes may have occurred in the early Ediacaran Period, perhaps shortly after the Marinoan glaciation, and that the redox history of Ediacaran oceans was more complex than previously thought.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yuan, Xunlai -- Chen, Zhe -- Xiao, Shuhai -- Zhou, Chuanming -- Hua, Hong -- England -- Nature. 2011 Feb 17;470(7334):390-3. doi: 10.1038/nature09810.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China. xlyuan@nigpas.ac.cn〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21331041" target="_blank"〉PubMed〈/a〉
    Keywords: *Biological Evolution ; *Biota ; *Body Size ; China ; Eukaryota/*classification/cytology/isolation & purification ; *Fossils ; Geologic Sediments ; History, Ancient ; Oceans and Seas ; Oxidation-Reduction ; Phylogeny ; Uncertainty
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2011-04-02
    Description: The current molecular systematics of angiosperms recognizes the basal angiosperms and five major angiosperm lineages: the Chloranthaceae, the magnoliids, the monocots, Ceratophyllum and the eudicots, which consist of the basal eudicots and the core eudicots. The eudicots form the majority of the angiosperms in the world today. The flowering plants are of exceptional evolutionary interest because of their diversity of over 250,000 species and their abundance as the dominant vegetation in most terrestrial ecosystems, but little is known of their very early history. In this report we document an early presence of eudicots during the Early Cretaceous Period. Diagnostic characters of the eudicot fossil Leefructus gen. nov. include simple and deeply trilobate leaves clustered at the nodes in threes or fours, basal palinactinodromous primary venation, pinnate secondary venation, and a long axillary reproductive axis terminating in a flattened receptacle bearing five long, narrow pseudo-syncarpous carpels. These morphological characters suggest that its affinities are with the Ranunculaceae, a basal eudicot family. The fossil co-occurs with Archaefructus sinensis and Hyrcantha decussata whereas Archaefructus liaoningensis comes from more ancient sediments. Multiple radiometric dates of the Lower Cretaceous Yixian Formation place the bed yielding this fossil at 122.6-125.8 million years old. The earliest fossil records of eudicots are 127 to 125 million years old, on the basis of pollen. Thus, Leefructus gen. nov. suggests that the basal eudicots were already present and diverse by the latest Barremian and earliest Aptian.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sun, Ge -- Dilcher, David L -- Wang, Hongshan -- Chen, Zhiduan -- England -- Nature. 2011 Mar 31;471(7340):625-8. doi: 10.1038/nature09811.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Paleontological Institute of Shenyang Normal University, Shenyang 110034, China. sunge@synu.edu.cn〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21455178" target="_blank"〉PubMed〈/a〉
    Keywords: Angiosperms/anatomy & histology/*classification ; Animals ; China ; *Fossils ; *Phylogeny ; Plant Leaves/anatomy & histology/classification ; Time Factors ; Vertebrates
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 8
    Publication Date: 2012-03-20
    Description: Targeted therapies have demonstrated efficacy against specific subsets of molecularly defined cancers. Although most patients with lung cancer are stratified according to a single oncogenic driver, cancers harbouring identical activating genetic mutations show large variations in their responses to the same targeted therapy. The biology underlying this heterogeneity is not well understood, and the impact of co-existing genetic mutations, especially the loss of tumour suppressors, has not been fully explored. Here we use genetically engineered mouse models to conduct a 'co-clinical' trial that mirrors an ongoing human clinical trial in patients with KRAS-mutant lung cancers. This trial aims to determine if the MEK inhibitor selumetinib (AZD6244) increases the efficacy of docetaxel, a standard of care chemotherapy. Our studies demonstrate that concomitant loss of either p53 (also known as Tp53) or Lkb1 (also known as Stk11), two clinically relevant tumour suppressors, markedly impaired the response of Kras-mutant cancers to docetaxel monotherapy. We observed that the addition of selumetinib provided substantial benefit for mice with lung cancer caused by Kras and Kras and p53 mutations, but mice with Kras and Lkb1 mutations had primary resistance to this combination therapy. Pharmacodynamic studies, including positron-emission tomography (PET) and computed tomography (CT), identified biological markers in mice and patients that provide a rationale for the differential efficacy of these therapies in the different genotypes. These co-clinical results identify predictive genetic biomarkers that should be validated by interrogating samples from patients enrolled on the concurrent clinical trial. These studies also highlight the rationale for synchronous co-clinical trials, not only to anticipate the results of ongoing human clinical trials, but also to generate clinically relevant hypotheses that can inform the analysis and design of human studies.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3385933/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3385933/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chen, Zhao -- Cheng, Katherine -- Walton, Zandra -- Wang, Yuchuan -- Ebi, Hiromichi -- Shimamura, Takeshi -- Liu, Yan -- Tupper, Tanya -- Ouyang, Jing -- Li, Jie -- Gao, Peng -- Woo, Michele S -- Xu, Chunxiao -- Yanagita, Masahiko -- Altabef, Abigail -- Wang, Shumei -- Lee, Charles -- Nakada, Yuji -- Pena, Christopher G -- Sun, Yanping -- Franchetti, Yoko -- Yao, Catherine -- Saur, Amy -- Cameron, Michael D -- Nishino, Mizuki -- Hayes, D Neil -- Wilkerson, Matthew D -- Roberts, Patrick J -- Lee, Carrie B -- Bardeesy, Nabeel -- Butaney, Mohit -- Chirieac, Lucian R -- Costa, Daniel B -- Jackman, David -- Sharpless, Norman E -- Castrillon, Diego H -- Demetri, George D -- Janne, Pasi A -- Pandolfi, Pier Paolo -- Cantley, Lewis C -- Kung, Andrew L -- Engelman, Jeffrey A -- Wong, Kwok-Kin -- 1U01CA141576/CA/NCI NIH HHS/ -- CA122794/CA/NCI NIH HHS/ -- CA137008/CA/NCI NIH HHS/ -- CA137008-01/CA/NCI NIH HHS/ -- CA137181/CA/NCI NIH HHS/ -- CA140594/CA/NCI NIH HHS/ -- CA147940/CA/NCI NIH HHS/ -- K23 CA157631/CA/NCI NIH HHS/ -- P01 CA120964/CA/NCI NIH HHS/ -- P30 CA016086/CA/NCI NIH HHS/ -- P50 CA090578/CA/NCI NIH HHS/ -- P50 CA090578-06/CA/NCI NIH HHS/ -- P50CA090578/CA/NCI NIH HHS/ -- R01 CA122794/CA/NCI NIH HHS/ -- R01 CA122794-01/CA/NCI NIH HHS/ -- R01 CA137008/CA/NCI NIH HHS/ -- R01 CA137008-01/CA/NCI NIH HHS/ -- R01 CA137181/CA/NCI NIH HHS/ -- R01 CA137181-01A2/CA/NCI NIH HHS/ -- R01 CA140594/CA/NCI NIH HHS/ -- R01 CA140594-01/CA/NCI NIH HHS/ -- R01 CA163896/CA/NCI NIH HHS/ -- RC2 CA147940/CA/NCI NIH HHS/ -- RC2 CA147940-01/CA/NCI NIH HHS/ -- U01 CA141576/CA/NCI NIH HHS/ -- U01 CA141576-01/CA/NCI NIH HHS/ -- England -- Nature. 2012 Mar 18;483(7391):613-7. doi: 10.1038/nature10937.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22425996" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antineoplastic Combined Chemotherapy Protocols ; Benzimidazoles/*pharmacology/therapeutic use ; Biomarkers, Tumor/genetics/metabolism ; *Clinical Trials, Phase II as Topic ; *Disease Models, Animal ; Drug Evaluation, Preclinical ; Fluorodeoxyglucose F18 ; Genes, p53/genetics ; Humans ; Lung Neoplasms/*drug therapy/enzymology/*genetics/metabolism ; MAP Kinase Signaling System/drug effects ; Mice ; Mitogen-Activated Protein Kinase Kinases/antagonists & inhibitors ; Mutation/genetics ; Pharmacogenetics/*methods ; Positron-Emission Tomography ; Protein-Serine-Threonine Kinases/deficiency/genetics ; Proto-Oncogene Proteins/genetics/metabolism ; Proto-Oncogene Proteins p21(ras)/genetics/metabolism ; Randomized Controlled Trials as Topic ; Reproducibility of Results ; Taxoids/*therapeutic use ; Tomography, X-Ray Computed ; Treatment Outcome ; ras Proteins/genetics/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 9
    Publication Date: 2013-06-21
    Description: In the Drosophila optic lobes, the medulla processes visual information coming from inner photoreceptors R7 and R8 and from lamina neurons. It contains approximately 40,000 neurons belonging to more than 70 different types. Here we describe how precise temporal patterning of neural progenitors generates these different neural types. Five transcription factors-Homothorax, Eyeless, Sloppy paired, Dichaete and Tailless-are sequentially expressed in a temporal cascade in each of the medulla neuroblasts as they age. Loss of Eyeless, Sloppy paired or Dichaete blocks further progression of the temporal sequence. We provide evidence that this temporal sequence in neuroblasts, together with Notch-dependent binary fate choice, controls the diversification of the neuronal progeny. Although a temporal sequence of transcription factors had been identified in Drosophila embryonic neuroblasts, our work illustrates the generality of this strategy, with different sequences of transcription factors being used in different contexts.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3701960/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3701960/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Li, Xin -- Erclik, Ted -- Bertet, Claire -- Chen, Zhenqing -- Voutev, Roumen -- Venkatesh, Srinidhi -- Morante, Javier -- Celik, Arzu -- Desplan, Claude -- GM058575/GM/NIGMS NIH HHS/ -- R01 EY017916/EY/NEI NIH HHS/ -- Canadian Institutes of Health Research/Canada -- England -- Nature. 2013 Jun 27;498(7455):456-62. doi: 10.1038/nature12319. Epub 2013 Jun 19.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, New York University, 100 Washington Square East, New York, New York 10003, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23783517" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Brain/*cytology/growth & development ; *Cell Differentiation ; *Cell Lineage ; Drosophila Proteins/metabolism ; Drosophila melanogaster/anatomy & histology/*cytology/metabolism ; Female ; Gene Expression Regulation ; Male ; Neural Stem Cells/*cytology/metabolism ; Neurons/*cytology/*metabolism ; Time Factors ; Transcription Factors/metabolism ; Visual Pathways/cytology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 10
    Publication Date: 2014-11-14
    Description: Topology, with its abstract mathematical constructs, often manifests itself in physics and has a pivotal role in our understanding of natural phenomena. Notably, the discovery of topological phases in condensed-matter systems has changed the modern conception of phases of matter. The global nature of topological ordering, however, makes direct experimental probing an outstanding challenge. Present experimental tools are mainly indirect and, as a result, are inadequate for studying the topology of physical systems at a fundamental level. Here we employ the exquisite control afforded by state-of-the-art superconducting quantum circuits to investigate topological properties of various quantum systems. The essence of our approach is to infer geometric curvature by measuring the deflection of quantum trajectories in the curved space of the Hamiltonian. Topological properties are then revealed by integrating the curvature over closed surfaces, a quantum analogue of the Gauss-Bonnet theorem. We benchmark our technique by investigating basic topological concepts of the historically important Haldane model after mapping the momentum space of this condensed-matter model to the parameter space of a single-qubit Hamiltonian. In addition to constructing the topological phase diagram, we are able to visualize the microscopic spin texture of the associated states and their evolution across a topological phase transition. Going beyond non-interacting systems, we demonstrate the power of our method by studying topology in an interacting quantum system. This required a new qubit architecture that allows for simultaneous control over every term in a two-qubit Hamiltonian. By exploring the parameter space of this Hamiltonian, we discover the emergence of an interaction-induced topological phase. Our work establishes a powerful, generalizable experimental platform to study topological phenomena in quantum systems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Roushan, P -- Neill, C -- Chen, Yu -- Kolodrubetz, M -- Quintana, C -- Leung, N -- Fang, M -- Barends, R -- Campbell, B -- Chen, Z -- Chiaro, B -- Dunsworth, A -- Jeffrey, E -- Kelly, J -- Megrant, A -- Mutus, J -- O'Malley, P J J -- Sank, D -- Vainsencher, A -- Wenner, J -- White, T -- Polkovnikov, A -- Cleland, A N -- Martinis, J M -- England -- Nature. 2014 Nov 13;515(7526):241-4. doi: 10.1038/nature13891.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics, University of California, Santa Barbara, California 93106-9530, USA. ; Department of Physics, Boston University, Boston, Massachusetts 02215, USA. ; 1] Department of Physics, University of California, Santa Barbara, California 93106-9530, USA [2] Google Inc., Santa Barbara, California 93117, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25391961" target="_blank"〉PubMed〈/a〉
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    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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