491 research outputs found

    Partitioning the power set of [n][n] into CkC_k-free parts

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    We show that for n3,n5n \geq 3, n\ne 5, in any partition of P(n)\mathcal{P}(n), the set of all subsets of [n]={1,2,,n}[n]=\{1,2,\dots,n\}, into 2n212^{n-2}-1 parts, some part must contain a triangle --- three different subsets A,B,C[n]A,B,C\subseteq [n] such that ABA\cap B, ACA\cap C, and BCB\cap C have distinct representatives. This is sharp, since by placing two complementary pairs of sets into each partition class, we have a partition into 2n22^{n-2} triangle-free parts. We also address a more general Ramsey-type problem: for a given graph GG, find (estimate) f(n,G)f(n,G), the smallest number of colors needed for a coloring of P(n)\mathcal{P}(n), such that no color class contains a Berge-GG subhypergraph. We give an upper bound for f(n,G)f(n,G) for any connected graph GG which is asymptotically sharp (for fixed kk) when G=Ck,Pk,SkG=C_k, P_k, S_k, a cycle, path, or star with kk edges. Additional bounds are given for G=C4G=C_4 and G=S3G=S_3.Comment: 12 page

    Low cost analog signal processing for massive radio telescope arrays

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    Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 38).Measurement and analysis of redshifted 21cm hydrogen emissions is a developing technique for studying the early universe. The primary time of interest corresponds to a signal in the the 100-200MHz frequency band. The Omniscope is a new type of radio telescope array being developed at MIT which images the entire sky in this band at low resolution using spatial Fourier transforms. In order to gain the maximum benefit from this type of telescope, a regular array of more than 10,000 antennas will eventually be necessary. I detail a low cost analog signal path which was developed to test and refine the signal processing and imaging pathways of the Omniscope. This signal path begins at the output of a preexisting antenna design and ends with digitization.by Eben A. Kunz.M.Eng

    The Existence Of The International Anarcho-Syndicalism Movement Based On Indonesian Law Perspective

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    Anarcho-syndicalism is an ideology in which workers want to work freely, not bound by rules. Anarcho-syndicalism is an ideology that wants the dissolution of all political power institutions that are narrated to oppress and exploit workers to be replaced by free communities bound by socio-economic interests. This research aims to find out the existence of the anarcho-syndicalist movement based on international law and the readiness of national law in facing the threat of anarcho-syndicalist ideology in Indonesia. The research method used in this research is normative legal research (library research) which has relevance to the research issues studied. Sources and legal materials used are primary, secondary, and tertiary legal materials. Based on the results of the research that has been carried out, it is known that the existence of the anarcho-syndicalism movement in terms of International Law has an impact on the application of the Right to freedom of association for workers/laborers as regulated in ILO (International Labour Organization) Convention No. 87 of 1948 concerning freedom of association and protection of the right to organize. Furthermore, the State has regulated people who join organizations to commit criminal offenses or prohibited organizations will be subject to imprisonment or fines, namely by what is written in the Criminal Code/KUHP (Kitab Undang-Undang Hukum Pidana) Article 261 concerning Participation in Organisations to commit Criminal Offences

    Evidence that protein thiols are not primary targets of intracellular reactive oxygen species in growing Escherichia coli

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    The oxidizability of cysteine residues is exploited in redox chemistry and as a source of stabilizing disulfide bonds, but it also raises the possibility that these side chains will be oxidized when they should not be. It has often been suggested that intracellular oxidative stress from hydrogen peroxide or superoxide may result in the oxidation of the cysteine residues of cytoplasmic proteins. That view seemed to be supported by the discovery that one cellular response to hydrogen peroxide is the induction of glutaredoxin 1 and thioredoxin 2. In this study we used model compounds as well as alkaline phosphatase to test this idea. Our results indicate that molecular oxygen, superoxide, and hydrogen peroxide are very poor oxidants of N-acetylcysteine and of the protein thiols of alkaline phosphatase in vitro. Copper could accelerate thiol oxidation, but iron did not. When alkaline phosphatase was engineered to remain in the cytoplasm of live cells, unnaturally high concentrations of hydrogen peroxide were required to oxidize it to its active, disulfide-dependent form, and toxic levels of superoxide had no effect. At the same time, far lower concentrations of these oxidants were sufficient to poison key metalloenzymes. The elimination of glutaredoxin 1 and thioredoxin 2 did not change these results, raising the question of why E. coli induces them during peroxide stress. In fact, when catalase/peroxidase mutants were chronically stressed with hydrogen peroxide, the absence of glutaredoxin 1 and thioredoxin 2 did not impair growth at all, even in a minimal medium over many generations. We conclude that physiological levels of reduced oxygen species are not potent oxidants of typical protein thiols. Glutaredoxin and thioredoxin must either have an alternative purpose or else play a role under culture conditions that differ from the ones we tested

    New Age Constraints on the Break-Up of Rodinia and Amalgamation of Southwestern Gondwana from the Choquequirao Formation in Southwestern Peru

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    The Choquequirao Formation is a \u3e3 km-thick amphibolite-grade succession that outcrops in the Central Andes of southern Peru. To constrain its age and tectonostratigraphic setting, detrital zircon and metamorphic zircon, titanite, and rutile U–Pb isotopic analyses were conducted. Mantle-derived c. 640 Ma detrital zircons constrain the maximum age of the lower part of the succession and 550–490 Ma metamorphic zircon domains constrain its minimum age. The absence of early Paleozoic detrital zircons suggests that deposition predated early Paleozoic orogenesis in southwestern Gondwana. The close similarity of detrital zircon age spectra to those from sediments deposited on the Arequipa basement suggests that the Choquequirao Formation was deposited on the Arequipa Terrane. Metamorphic titanite dates are highly overdispersed, yet they overlap with c. 460 Ma peak metamorphism recorded by metamorphic zircon. Pb-loss pathways displayed by metamorphic titanite have a lower intercept that overlaps with c. 325 Ma metamorphic rutile, which corresponds to Hercynian orogenesis. A poorly constrained upper intercept of c. 510 Ma may correspond to Pampean and/or early Famatinian orogenesis. We interpret the Cryogenian–Ediacaran Choquequirao Formation as having been deposited during the opening of the Palaeo-Iapetus (Puncoviscana–Clymene) Ocean between eastern Arequipa and southern Kalahari prior to the subsequent collision with southwestern Amazonia during the Pampean Orogeny

    Adipocytes enhance murine pancreatic cancer growth via a hepatocyte growth factor (HGF)-mediated mechanism

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    INTRODUCTION: Obesity accelerates the development and progression of pancreatic cancer, though the mechanisms underlying this association are unclear. Adipocytes are biologically active, producing factors such as hepatocyte growth factor (HGF) that may influence tumor progression. We therefore sought to test the hypothesis that adipocyte-secreted factors including HGF accelerate pancreatic cancer cell proliferation. MATERIAL AND METHODS: Murine pancreatic cancer cells (Pan02 and TGP-47) were grown in a) conditioned medium (CM) from murine F442A preadipocytes, b) HGF-knockdown preadipocyte CM, c) recombinant murine HGF at increasing doses, and d) CM plus HGF-receptor (c-met) inhibitor. Cell proliferation was measured using the MTT assay. ANOVA and t-test were applied; p < 0.05 considered significant. RESULTS: Wild-type preadipocyte CM accelerated Pan02 and TGP-47 cell proliferation relative to control (59 ± 12% and 34 ± 12%, p < 0.01, respectively). Knockdown of preadipocyte HGF resulted in attenuated proliferation vs. wild type CM in Pan02 cells (35 ± 5% vs. 68 ± 14% greater than control; p < 0.05), but proliferation in TGP-47 cells remained unchanged. Recombinant HGF dose-dependently increased Pan02, but not TGP-47, proliferation (p < 0.05). Inhibition of HGF receptor, c-met, resulted in attenuated proliferation versus control in Pan02 cells, but not TGP-47 cells. CONCLUSIONS: These experiments demonstrate that adipocyte-derived factors accelerate murine pancreatic cancer proliferation. In the case of Pan02 cells, HGF is responsible, in part, for this proliferation

    Bridging the Gap Between the Foreland and Hinterland II: Geochronology and Tectonic Setting of Ordovician Magmatism and Basin Formation on the Laurentian Margin of New England and Newfoundland

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    Ordovician strata of the Mohawk Valley and Taconic allochthon of New York and the Humber margin of Newfoundland record multiple magmatic and basin-forming episodes associated with the Taconic orogeny. Here we present new U-Pb zircon geochronology and whole rock geochemistry and neodymium isotopes from Early Paleozoic volcanic ashes and siliciclastic units on the northern Appalachian margin of Laurentia. Volcanic ashes in the Table Point Formation of Newfoundland and the Indian River Formation of the Taconic allochthon in New York yield dates between 466.16 ± 0.12 and 464.20 ± 0.13 Ma. Red, bioturbated slate of the Indian River Formation record a shift to more juvenile neodymium isotope values suggesting sedimentary contributions from the Taconic arc-system by 466 Ma. Eight ashes within the Trenton Group in the Mohawk Valley were dated between 452.63 ± 0.06 and 450.68 ± 0.12 Ma. These ashes contain zircon with Late Ordovician magmatic rims and 1.4 to 1.0 Ga xenocrystic cores that were inherited from Grenville basement, suggesting that the parent magmas erupted through the Laurentian margin. The new geochronological and geochemical data are integrated with a subsidence model and data from the hinterland to refine the tectonic model of the Taconic orogeny. Closure of the Iapetus Ocean by 475 Ma via collision of the peri-Gondwanan Moretown terrane with hyperextended distal fragments of the Laurentian margin is not clearly manifested on the autochthon or the Taconic allochthon other than an increase in sediment accumulation. Pro-foreland basins formed during the Middle Ordovician when these terranes were obducted onto the Laurentian margin. 466 to 464 Ma ashes on the Laurentian margin coincide with a late pulse of magmatism in both the Notre Dame arc in Newfoundland and the Shelburne Falls arc of New England that is potentially related to break-off of an east-dipping slab. Following slab reversal, by 455 Ma, the Bronson Hill arc was established on the new composite Laurentian margin. Thus, we conclude that Late Ordovician strata in the Mohawk Valley and Taconic allochthon of New York and on the Humber margin of Newfoundland were deposited in retro-foreland basins

    Outcomes of Recurrent Head and Neck Cutaneous Squamous Cell Carcinoma

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    Recurrent, advanced stage cutaneous squamous cell carcinoma (cSCC) is uncommon with limited publications on patient outcomes. A retrospective study including patients who underwent surgical resection for recurrent, advanced stage cSCC of the head and neck was performed (n = 72). Data regarding tumor site, stage, treatment, parotid involvement, perineural invasion, positive margins, metastasis, and disease-free survival was analyzed. The majority of patients were male (85%) and presented with recurrent stage III (89%) cSCC. Two-year disease-free survival was 62% and decreased to 47% at 5 years. Parotid involvement, positive margins, nodal metastasis, or the presence of perineural invasion did not correlate with decreased survival (P > .05). Distant metastasis was a strong indicator of poor overall survival (P < .001). Adjuvant postoperative radiotherapy did not improve overall survival (P = .42). Overall survival was poor for patients with advanced recurrent cSCC despite the combined treatment with surgery and radiotherapy
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